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2024 Vol. 23 No. 9 Previous Issue    Next Issue

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Crop Science
Horticulture
Plant Protection
Animal Science · Veterinary Medicine
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Fire blight disease of pears, caused by Erwinia amylovora, is a devastating bacterial disease, which leads to severe economic losses to the tree fruit industry around the world. In this cover article, the authors studied the interactions between fire blight pathogen and pear valsa canker fungi (Cytospora pyri), another important pathogen on fragrant pear in Xinjiang, China. This is the first report demonstrating that both pathogens co-existed on pear trees and physically interacted with each other, leading to more severe diseases. The findings provide new knowledge in understanding bacterial–fungal–plant interactions for disease management of tree fruits. The cover photos were provided by Prof. Baishi Hu, Nanjing Agricultural University, China. For more details, please see the full article on pages 3045–3054.


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Review

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Advances in the study of waterlogging tolerance in plants Zhengyuan Xu, Lingzhen Ye, Qiufang Shen, Guoping Zhang 2024, 23(9): 2877-2897.  DOI: 10.1016/j.jia.2023.12.028 Abstract ( )   PDF in ScienceDirect   Waterlogging is one of the major abiotic stresses threatening crop yields globally.  Under waterlogging stress, plants suffer from oxidative stress, heavy metal toxicity and energy deficiency, leading to metabolic disorders and growth inhibition.  On the other hand, plants have evolved waterlogging-tolerance or adaptive mechanisms, including morphological changes, alternation of respiratory pathways, antioxidant protection and endogenous hormonal regulation.  In this review, recent advances in studies on the effects of waterlogging stress and the mechanisms of waterlogging tolerance in plants are presented, and the genetic differences in waterlogging tolerance among plant species or genotypes within a species are illustrated.  We also summarize the identified QTLs and key genes associated with waterlogging tolerance.

Crop Science

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Natural variation in the cytochrome c oxidase subunit 5B OsCOX5B regulates seed vigor by altering energy production in rice Chengwei Huang, Zhijuan Ji, Qianqian Huang, Liling Peng, Wenwen Li, Dandan Wang, Zepeng Wu, Jia Zhao, Yongqi He, Zhoufei Wang 2024, 23(9): 2898-2910.  DOI: 10.1016/j.jia.2023.06.018 Abstract ( )   PDF in ScienceDirect   Seed vigor is a crucial trait for the direct seeding of rice.  Here we examined the genetic regulation of seed vigor traits in rice, including germination index (GI) and germination potential (GP), using a genome-wide association study approach.  One major quantitative trait locus, qGI6/qGP6, was identified simultaneously for both GI and GP.  The candidate gene encoding the cytochrome c oxidase subunit 5B (OsCOX5B) was validated for qGI6/qGP6.  The disruption of OsCOX5B caused the vigor traits to be significantly lower in Oscox5b mutants than in the japonica Nipponbare wild type (WT).  Gene co-expression analysis revealed that OsCOX5B influences seed vigor mainly by modulating the tricarboxylic acid cycle process.  The glucose levels were significantly higher while the pyruvic acid and adenosine triphosphate levels were significantly lower in Oscox5b mutants than in WT during seed germination.  The elite haplotype of OsCOX5B facilitates seed vigor by increasing its expression during seed germination.  Thus, we propose that OsCOX5B is a potential target for the breeding of rice varieties with enhanced seed vigor for direct seeding.

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Fine mapping and characterization of a major QTL for grain length, QGl.cau-2D.1, that has pleiotropic effects in synthetic allohexaploid wheat Mingming Wang, Jia Geng, Zhe Zhang, Zihan Zhang, Lingfeng Miao, Tian Ma, Jiewen Xing, Baoyun Li, Qixin Sun, Yufeng Zhang, Zhongfu Ni 2024, 23(9): 2911-2922.  DOI: 10.1016/j.jia.2023.09.009 Abstract ( )   PDF in ScienceDirect   Grain size is one of the determinants of grain yield, and identifying the genetic loci that control grain size will be helpful for increasing grain yield. In our previous study, a quantitative trait locus (QTL) for grain length (GL), QGl.cau-2D.1, was identified from an F2 population developed from the cross between the natural (TAA10) and synthetic (XX329) allohexaploid wheat. In the present study, we mainly fine mapped and validated its genetic effects. To this end, multiple near-isogenic lines (NILs) were obtained through marker-assisted selection with TAA10 as the recurrent parent. The secondary populations derived from 25 heterozygous recombinants were used for fine mapping of QGl.cau-2D.1, and the allele from XX329 significantly increased GL, thousand-grain weight (TGW), total spikelet number per spike (TSN) and spike compactness (SC). Using NILs for XX329 (2D+) and TAA10 (2D−), we determined the genetic and pleiotropic effects of QGl.cau-2D.1. The target sequences were aligned with the wheat reference genome RefSeq v2.1 and spanned an ~0.9 Mb genomic region. TraesCS2D03G0114900 (ortholog of Os03g0594700) was predicted as the candidate gene based on whole-genome re-sequencing and expression analyses. In summary, the map-based cloning of QGl.cau-2D.1 will be useful for improving grain weight with enhanced GL and TSN.

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Quantifying source–sink relationships in leaf-color modified rice genotypes during grain filling Zhenxiang Zhou, Paul C. Struik, Junfei Gu, Peter E. L. van der Putten, Zhiqin Wang, Jianchang Yang, Xinyou Yin 2024, 23(9): 2923-2940.  DOI: 10.1016/j.jia.2024.03.034 Abstract ( )   PDF in ScienceDirect   Leaf-color modification can affect canopy photosynthesis, with potential effects on rice yield and yield components.  Modulating source–sink relationships through crop management is often used to improve crop productivity.  This study investigated whether and how modifying leaf color alters source–sink relationships and whether current crop cultivation practices remain applicable for leaf-color modified genotypes.  Periodically collected data of total biomass and nitrogen (N) accumulation in rice genotypes of four genetic backgrounds and their leaf-color modified variants (greener or yellower) were analyzed, using a recently established modelling method to quantify the source–sink (im)balance during grain filling.  Among all leaf-color variants, only one yellower-leaf variant showed a higher source capacity than its normal genotype.  This was associated with greater post-flowering N-uptake that prolonged the functional leaf-N duration, and this greater post-flowering N-uptake was possible because of reduced pre-flowering N-uptake.  A density experiment showed that current management practices (insufficient planting density accompanied by abundant N application) are unsuitable for the yellower-leaf genotype, ultimately limiting its yield potential.  Leaf-color modification affects source–sink relationships by regulating the N trade-off between pre-and post-flowering uptake, as well as N translocation between source and sink organs.  To best exploit leaf-color modification for improving crop productivity, adjustments of crop management practices are required.

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Prediction of the potential distribution and analysis of the freezing injury risk of winter wheat on the Loess Plateau under climate change Qing Liang, Xujing Yang, Yuheng Huang, Zhenwei Yang, Meichen Feng, Mingxing Qing, Chao Wang, Wude Yang, Zhigang Wang, Meijun Zhang, Lujie Xiao, Xiaoyan Song 2024, 23(9): 2941-2954.  DOI: 10.1016/j.jia.2024.02.006 Abstract ( )   PDF in ScienceDirect   Determining the suitable areas for winter wheat under climate change and assessing the risk of freezing injury are crucial for the cultivation of winter wheat.  We used an optimized Maximum Entropy (MaxEnt) Model to predict the potential distribution of winter wheat in the current period (1970–2020) and the future period (2021–2100) under four shared socioeconomic pathway scenarios (SSPs).  We applied statistical downscaling methods to downscale future climate data, established a scientific and practical freezing injury index (FII) by considering the growth period of winter wheat, and analyzed the characteristics of abrupt changes in winter wheat freezing injury by using the Mann-Kendall (M-K) test.  The results showed that the prediction accuracy AUC value of the MaxEnt Model reached 0.976.  The minimum temperature in the coldest month, precipitation in the wettest season and annual precipitation were the main factors affecting the spatial distribution of winter wheat.  The total suitable area of winter wheat was approximately 4.40×107 ha in the current period.  In the 2070s, the moderately suitable areas had the greatest increase by 9.02×105 ha under SSP245 and the least increase by 6.53×105 ha under SSP370.  The centroid coordinates of the total suitable areas tended to move northward.  The potential risks of freezing injury in the high-latitude and -altitude areas of the Loess Plateau, China increased significantly.  The northern areas of Xinzhou in Shanxi Province, China suffered the most serious freezing injury, and the southern areas of the Loess Plateau suffered the least.  Environmental factors such as temperature, precipitation and geographical location had important impacts on the suitable area distribution and freezing injury risk of winter wheat.  In the future, greater attention should be paid to the northward boundaries of both the winter wheat planting areas and the areas of freezing injury risk to provide the early warning of freezing injury and implement corresponding management strategies.

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Impacts of high temperature, relative air humidity, and vapor pressure deficit on the seed set of contrasting maize genotypes during flowering Xin Dong, Baole Li, Zhenzhen Yan, Ling Guan, Shoubing Huang , Shujun Li, Zhiyun Qi, Ling Tang, Honglin Tian, Zhongjun Fu, Hua Yang 2024, 23(9): 2955-2969.  DOI: 10.1016/j.jia.2023.09.007 Abstract ( )   PDF in ScienceDirect   Heat stress is a major constraint to current and future maize production at the global scale.  Male and female reproductive organs both play major roles in increasing seed set under heat stress at flowering, but their relative contributions to seed set are unclear.  In this study, a 2-year field experiment including three sowing dates in each year and 20 inbred lines was conducted.  Seed set, kernel number per ear, and grain yield were all reduced by more than 80% in the third sowing dates compared to the first sowing dates.  Pollen viability, silk emergence ratio, and anthesis–silking interval were the key determinants of seed set under heat stress; and their correlation coefficients were 0.89***, 0.65***, and –0.72***, respectively.  Vapor pressure deficit (VPD) and relative air humidity (RH) both had significant correlations with pollen viability and the silk emergence ratio.  High RH can alleviate the impacts of heat on maize seed set by maintaining high pollen viability and a high silk emergence ratio.  Under a warming climate from 2020 to 2050, VPD will decrease due to the increased RH.  Based on their pollen viability and silk emergence ratios, the 20 genotypes fell into four different groups.  The group with high pollen viability and a high silk emergence ratio performed better under heat stress, and their performance can be further improved by combining the improved flowering pattern traits.

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Strategies for improving crop comprehensive benefits via a decision-making system based on machine learning in the rice‒rape, rice‒wheat and rice‒garlic rotation systems in Southwest China Xinrui Li, Xiafei Li, Tao Liu, Huilai Yin, Hao Fu, Yongheng Luo, Yanfu Bai, Hongkun Yang, Zhiyuan Yang, Yongjian Sun, Jun Ma, Zongkui Chen 2024, 23(9): 2970-2988.  DOI: 10.1016/j.jia.2023.10.005 Abstract ( )   PDF in ScienceDirect   Rice‒rape, rice‒wheat and rice‒garlic rotations are common cropping systems in Southwest China, and they have played a significant role in ensuring ecological and economic benefits (EB) and addressing the challenges of China’s food security in the region.  However, the crop yields in these rotation systems are 1.25‒14.73% lower in this region than the national averages.  Intelligent decision-making with machine learning can analyze the key factors for obtaining better benefits, but it has rarely been used to enhance the probability of obtaining such benefits from rotations in Southwest China.  Thus, we used a data-intensive approach to construct an intelligent decision‒making system with machine learning to provide strategies for improving the benefits of rice–rape, rice–wheat, and rice–garlic rotations in Southwest China.  The results show that raising the yield and partial fertilizer productivity (PFP) by increasing seed input under high fertilizer application provided the optimal benefits with a 10% probability in the rice–garlic system.  Obtaining high yields and greenhouse gas (GHG) emissions by increasing the N application and reducing the K application provided suboptimal benefits with an 8% probability in the rice–rape system.  Reducing N and P to enhance PFP and yield provided optimal benefits with the lowest probability (8%) in the rice‒wheat system.  Based on the predictive analysis of a random forest model, the optimal benefits were obtained with fertilization regimes by reducing N by 25% and increasing P and K by 8 and 74%, respectively, in the rice–garlic system,  reducing N and K by 54 and by 36%, respectively, and increasing P by 38% in rice–rape system, and reducing N by 4% and increasing P and K by 65 and 23% in rice–wheat system.  These strategies could be further optimized by 17‒34% for different benefits, and all of these measures can improve the effectiveness of the crop rotation systems to varying degrees.  Overall, these findings provide insights into optimal agricultural inputs for higher benefits through an intelligent decision-making system with machine learning analysis in the rice–rape, rice‒wheat, and rice–garlic systems.

Horticulture

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Overexpression of PbrGA2ox1 enhances pear drought tolerance through the regulation of GA3-inhibited reactive oxygen species detoxification and abscisic acid signaling Guoling Guo, Haiyan Zhang, Weiyu Dong, Bo Xu, Youyu Wang, Qingchen Zhao, Lun Liu, Xiaomei Tang, Li Liu, Zhenfeng Ye, Wei Heng, Liwu Zhu, Bing Jia 2024, 23(9): 2989-3011.  DOI: 10.1016/j.jia.2024.01.012 Abstract ( )   PDF in ScienceDirect   Drought stress is a devastating natural disaster driven by the continuing intensification of global warming, which seriously threatens the productivity and quality of several horticultural crops, including pear.  Gibberellins (GAs) play crucial roles in plant growth, development, and responses to drought stress.  Previous studies have shown significant reductions of GA levels in plants under drought stress; however, our understanding of the intrinsic regulation mechanisms of GA-mediated drought stress in pear remains very limited.  Here, we show that drought stress can impair the accumulation of bioactive GAs (BGAs), and subsequently identified PbrGA2ox1 as a chloroplast-localized GA deactivation gene.  This gene was significantly induced by drought stress and abscisic acid (ABA) treatment, but was suppressed by GA3 treatment.  PbrGA2ox1-overexpressing transgenic tobacco plants (Nicotiana benthamiana) exhibited enhanced tolerance to dehydration and drought stresses, whereas knock-down of PbrGA2ox1 in pear (Pyrus betulaefolia) by virus-induced gene silencing led to elevated drought sensitivity.  Transgenic plants were hypersensitive to ABA, and had a lower BGAs content, enhanced reactive oxygen species (ROS) scavenging ability, and augmented ABA accumulation and signaling under drought stress compared to wild-type plants.  However, the opposite effects were observed with PbrGA2ox1 silencing in pear.  Moreover, exogenous GA3 treatment aggravated the ROS toxic effect and restrained ABA synthesis and signaling, resulting in the compromised drought tolerance of pear.  In summary, our results shed light on the mechanism by which BGAs are eliminated in pear leaves under drought stress, providing further insights into the mechanism regulating the effects of GA on the drought tolerance of plants.

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Silencing of early auxin responsive genes MdGH3-2/12 reduces the resistance to Fusarium solani in apple Qianwei Liu, Shuo Xu, Lu Jin, Xi Yu, Chao Yang, Xiaomin Liu, Zhijun Zhang, Yusong Liu, Chao Li, Fengwang Ma 2024, 23(9): 3012-3024.  DOI: 10.1016/j.jia.2024.03.003 Abstract ( )   PDF in ScienceDirect   Apple replant disease (ARD) has led to severe yield and quality reduction in the apple industry.  Fusarium solani (F. solani) has been identified as one of the main microbial pathogens responsible for ARD.  Auxin (indole-3-acetic acid, IAA), an endogenous hormone in plants, is involved in almost all plant growth and development processes and plays a role in plant immunity against pathogens.  Gretchen Hagen3 (GH3) is one of the early/primary auxin response genes.  The aim of this study was to evaluate the function of MdGH3-2 and MdGH3-12 in the defense response of F. solani by treating MdGH3-2/12 RNAi plants with F. solani.  The results show that under F. solani infection, RNAi of MdGH3-2/12 inhibited plant biomass accumulation and exacerbated root damage.  After inoculation with F. solani, MdGH3-2/12 RNAi inhibited the biosynthesis of acid-amido synthetase.  This led to the inhibition of free IAA combining with amino acids, resulting in excessive free IAA accumulation.  This excessive free IAA altered plant tissue structure, accelerated fungal hyphal invasion, reduced the activity of antioxidant enzymes (SOD, POD and CAT), increased the reactive oxygen species (ROS) level, and reduced total chlorophyll content and photosynthetic ability, while regulating the expression of PR-related genes including PR1, PR4, PR5 and PR8.  It also changed the contents of plant hormones and amino acids, and ultimately reduced the resistance to F. solani.  In conclusion, these results demonstrate that MdGH3-2 and MdGH3-12 play an important role in apple tolerance to F. solani and ARD.

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Dopamine improves apple replant disease resistance by regulating physiological resilience and rhizosphere microbial community structure Peihua Du, Yang Cao, Huaite Liu, Jiahao Ji, Wei Sun, Xueying Zhang, Jizhong Xu, Bowen Liang 2024, 23(9): 3025-3044.  DOI: 10.1016/j.jia.2024.07.011 Abstract ( )   PDF in ScienceDirect   Apple replant disease (ARD) is a complex agricultural problem caused by multiple stressors that can lead to increased reactive oxygen species (ROS) levels and limited nutrient utilization in plants.  However, existing countermeasures cannot effectively address this challenge.  Here, we used Malus hupehensis as a test organism to investigate whether the pleiotropic molecule dopamine can alleviate ARD using pot experiments.  Exogenous application of 100 μmol L–1 dopamine significantly promoted the growth of apple seedlings in the replanted soil, with a relative growth rate increase of 17.44%.  Our results revealed two major pathways by which dopamine regulates ARD resistance in apple trees.  First, dopamine effectively reduces the level of ROS and activates the expression of genes related to nitrogen (N) transport and metabolism.  Among those genes, MdNLP5, MdNRT1.1, MdNLP2, MdNRT2.5, MdNLP3, MdNRT2.4, MdNADH-GAGOT, and MdFd-GAGOT were strongly regulated by dopamine.  These regulatory effects promoted the uptake and utilization of soil N by the plants.  Second, dopamine improved the physical and chemical properties, enhanced microbial community diversity, and promoted mutual cooperation between microbial communities in the soil.  Furthermore, dopamine altered the microbial structure of rhizosphere soil (upregulating Clostridiales, Gaiellales, Sordariales and Mortierellales; downregulating Micrococcales, Longimicrobiales, Hypocreales and Cystobasidiales).  Notably, dopamine significantly upregulated the abundances of Gaiella and Mortierella, both of which were positively correlated with soil urease activity, soil available N content, plant growth and N uptake.  Dopamine also significantly downregulated the abundance of the plant pathogen Gibberella (by 11.71-fold) in replant soil.  Our results provide insights into the mechanisms by which dopamine promotes ARD resistance, and can promote the sustainable development of the apple industry.

Plant Protection

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Cytospora pyri promotes Erwinia amylovora virulence by providing metabolites and hyphae Tong Shen, Mengdi Ye, Yeping Xu, Bohan Ding, Hongtao Li, Li Zhang, Jun Wang, Yanli Tian, Baishi Hu, Youfu Zhao 2024, 23(9): 3045-3054.  DOI: 10.1016/j.jia.2024.05.020 Abstract ( )   PDF in ScienceDirect   Bacterial–fungal interactions are widespread in nature.  We observed that pear orchards affected by Cytospora pyri (formerly Valsa pyri) were often accompanied with Erwinia amylovora.  However, the relationship of the two pathogens was unclear.  The objective of this study was to determine whether the synergistic effect exists between E. amylovora and C. pyri.  We first analyzed the coexistence frequencies of E. amylovora and C. pyri in pear trees.  Virulence of the two pathogens, growth, physical interactions, amylovoran production, and expression of genes for amylovoran biosynthesis were conducted.  Our results showed that E. amylovora and C. pyri could coexist on the same lesion and caused much more severe disease.  We also found that E. amylovora could physically attach to C. pyri and the expression of amylovoran biosynthesis genes were up-regulated with fungal metabolite treatment.  These results indicate that E. amylovora and C. pyri can cooperatively interact, which provides C. pyri with an opportunity to promote bacterial dispersal and production of virulence factor in E. amylovora.

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Identification and characterization of FpRco1 in regulating vegetative growth and pathogenicity based on T-DNA insertion in Fusarium pseudograminearum Haiyang Li, Yuan Zhang, Cancan Qin, Zhifang Wang, Lingjun Hao, Panpan Zhang, Yongqiang Yuan, Chaopu Ding, Mengxuan Wang, Feifei Zan, Jiaxing Meng, Xunyu Zhuang, Zheran Liu, Limin Wang, Haifeng Zhou, Linlin Chen, Min Wang, Xiaoping Xing, Hongxia Yuan, Honglian Li, Shengli Ding 2024, 23(9): 3055-3065.  DOI: 10.1016/j.jia.2024.01.001 Abstract ( )   PDF in ScienceDirect   Fusarium pseudograminearum is a devastating pathogen that causes Fusarium crown rot (FCR) in wheat and poses a significant threat to wheat production in terms of grain yield and quality.  However, the mechanism by which F. pseudograminearum infects wheat remains unclear.  In this study, we aimed to elucidate these mechanisms by constructing a T-DNA insertion mutant library for the highly virulent strain WZ-8A of F. pseudograminearum.  By screening this mutant library, we identified nine independent mutants that displayed impaired pathogenesis in barley leaves.  Among these mutants, one possessed a disruption in the gene FpRCO1 that is an ortholog of Saccharomyces cerevisiae RCO1, encoding essential component of the Rpd3S histone deacetylase complex in F. pseudograminearum.  To further investigate the role of FpRCO1 in F. pseudograminearum, we employed a split-marker approach to knock out FpRCO1 in F. pseudograminearum WZ-8A.  FpRCO1 deletion mutants exhibit reduced vegetative growth, conidium production, and virulence in wheat coleoptiles and barley leaves, whereas the complementary strain restores these phenotypes.  Moreover, under stress conditions, the FpRCO1 deletion mutants exhibited increased sensitivity to NaCl, sorbitol, and SDS, but possessed reduced sensitivity to H2O2 compared to these characteristics in the wild-type strain.  RNA-seq analysis revealed that deletion of FpRCO1 affected gene expression (particularly the downregulation of TRI gene expression), thus resulting in significantly reduced deoxynivalenol (DON) production.  In summary, our findings highlight the pivotal role of FpRCO1 in regulating vegetative growth and development, asexual reproduction, DON production, and pathogenicity of F. pseudograminearum.  This study provides valuable insights into the molecular mechanisms underlying F. pseudograminearum infection in wheat and may pave the way for the development of novel strategies to combat this devastating disease.

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A unique role of the pyrimidine de novo synthesis enzyme ODCase in Lysobacter enzymogenes Mingming Yang, Yunxiao Tan, Jiabing Ma, Yingjia Zhao, Xia Yan, Nana Wang, Pingping Wang, Jiaqi Tan, Suilong Ai, Xiaofei Liang, Bangshuai Chang, Obadah E. A. Yousif, Chao Zhao, Bo Wang, Guoliang Qian, Lili Huang 2024, 23(9): 3066-3077.  DOI: 10.1016/j.jia.2023.11.047 Abstract ( )   PDF in ScienceDirect   Bacterial species of the genus Lysobacter are environmentally ubiquitous with strong antifungal biocontrol potential.  Heat-stable antifungal factor (HSAF) secreted by the biocontrol bacterium Lysobacter enzymogenes OH11 has broad-spectrum and highly efficient antifungal activity.  Studying the biosynthetic regulations of HSAF would lay an important foundation for strain engineering toward improved HSAF production.  In this work, we demonstrate that Le0752, an orotidine-5´-phosphate decarboxylase enzyme (ODCase) catalyzing a pivotal step of the UMP de novo biosynthesis pathway, is vital for HSAF-mediated antimicrobial activities and growth of L. enzymogenes OH11, but not for twitching motility.  This gene regulates the production of HSAF by affecting the expression of lafB, a key gene in the HSAF biosynthesis operon, through the transcription factor Clp.  Interestingly, bioinformatics analysis revealed that Le0752 belongs to the Group III ODCases, whereas its homologs in the closely related genera Xanthomonas and Stenotrophomonas belong to Group I, which contains most ODCases from Gram-positive bacteria, Gram-negative bacteria and cyanobacteria.  Moreover, the Group I ODCase PXO_3614 from the Xanthomonas oryzae pv.  oryzae PXO99A strain complemented the Le0752 mutant in regulating HSAF-mediated antagonistic activity.  Together, these results highlight the important requirement of de novo pyrimidine biosynthetic enzymes for antibiotic HSAF production in L. enzymogenes, which lays an important foundation for improving HSAF production via metabolic flow design and for dissecting the regulatory functions of bacterial ODCases.

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Induced CTL-S15 gene expression by Bacillus thuringiensis declines susceptibility in Spodoptera exigua Jianqiang Bao, Yuxuan Chen, Suwan Jiang, Rui Liu, Xi Zhang, Fangzheng Zhang, Zhiwei Chen, Chen Luo, Hailong Kong 2024, 23(9): 3078-3088.  DOI: 10.1016/j.jia.2024.01.024 Abstract ( )   PDF in ScienceDirect   It has been reported that C-type lectins (CTLs), which are pattern recognition receptors of the insect innate immunity response, may compete with Cry toxin for the receptor alkaline phosphatase to decrease its toxicity in insects.  However, to date, which CTLs affect larval susceptibility to Bt in Spodoptera exigua is not clear.  In this study, 33 CTL genes were identified from S. exigua.  Based on the number of carbohydrate-recognition domains (CRDs) and the domain architectures, they were classified into three groups: (1) nineteen CTL-S (single-CRD), (2) eight immulectin (dual-CRD) and (3) six CTL-X (CRD with other domains).  RT-qPCR analysis revealed that expression levels of SeCTL-S15, IML-4 and CTL-X6 were upregulated after challenge with Bt and Cry1Ab.  Tissue and developmental stage expression analysis showed that only SeCTL-S15 was mainly expressed in the midgut and larva, respectively.  Knockdown of SeCTL-S15 significantly increased Bt susceptibility, as indicated by reduced survival and larval weight.  These results suggest that CTL-S15 might play a vital role in the low susceptibility of larvae to Bt in S. exigua.  Our results provide new insights into CTL function in insects.

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Knock-in of exogenous sequences based on CRISPR/Cas9 targeting autosomal genes and sex chromosomes in the diamondback moth, Plutella xylostella Shanyu Li, Guifang Lin, Haoqi Wen, Haiyan Lu, Anyuan Yin, Chanqin Zheng, Feifei Li, Qingxuan Qiao, Lu Jiao, Ling Lin, Yi Yan, Xiujuan Xiang, Huang Liao, Huiting Feng, Yussuf Mohamed Salum, Minsheng You, Wei Chen, Weiyi He 2024, 23(9): 3089-3103.  DOI: 10.1016/j.jia.2024.04.029 Abstract ( )   PDF in ScienceDirect   Genetic pest control strategies based on precise sex separation and only releasing sterile males can be accomplished by site-specific genome editing.  In the current study, we showed that the mutation of single-allele Pxfl(2)d can significantly impair the normal mating behavior and testis development in male adults of the notorious cruciferous insect pest Plutella xylostella, in addition to its known functions in the ovarian development in female adults and egg hatching.  Subsequent CRISPR/Cas9-based knock-in experiments revealed that site-specific integration of an exogenous green fluorescent protein (GFP) gene into autosomal Pxfl(2)d for labelling mutants could be achieved.  However, this gene is not a suitable target for GFP insertion to establish a genetically stable knock-in strain because of the severe decline in reproductive capacity.  We further screened for the W-chromosome-linked and Z-chromosome-linked regions to test the knock-in efficiency mediated by CRISPR/Cas9.  The results verified that both types of chromosomes can be targeted for the site-specific insertion of exogenous sequences.  We ultimately obtained a homozygous knock-in strain with the integration of both Cas9 and cyan fluorescent protein (CFP) expression cassettes on a Z-linked region in P. xylostella, which can also be used for early sex detection.  By injecting the sgRNA targeting Pxfl(2)d alone into the eggs laid by female adults of the Z-Cas9-CFP strain, the gene editing efficiency reached 29.73%, confirming the success of expressing a functional Cas9 gene.  Taken together, we demonstrated the feasibility of the knock-in of an exogenous gene to different genomic regions in P. xylostella, while the establishment of a heritable strain required the positioning of appropriate sites.  This study provides an important working basis and technical support for further developing genetic strategies for insect pest control.

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Adipokinetic hormone signaling regulates adult dehydration resistance in the migratory locust Xianliang Huang, Dai Shi, Kai Deng, Shuzhen Jia, Ding Ding, Li Hou, Bing Chen 2024, 23(9): 3104-3117.  DOI: 10.1016/j.jia.2024.03.019 Abstract ( )   PDF in ScienceDirect   Drought events have become more severe under climate change, and this can pose a major threat to the survival of various organisms.  The molecular mechanisms involved in dehydration resistance are not well known.  Here, adults of the migratory locust, Locusta migratoria, were subjected to food-mediated dehydration, and adipokinetic hormone (AKH) signaling was found to play a key role in regulating dehydration resistance.  Specifically, dehydration shortened the lifespan, increased the body weight loss, and reduced the water loss rate in adult locusts.  Global transcriptome profiles revealed variations in tissue-specific gene expression between dehydration-resistant locusts and normal locusts.  Importantly, dehydration selection and exposure induced prominent expression of AKH genes in the retrocerebral complex of adult locusts.  Furthermore, individual knockdown of AKH1, AKH2, or AKH receptor (AKHR) accelerated water loss and shortened the lifespan of adult locusts under dehydration conditions, and trehalose supplementation ameliorated the negative effects caused by interference with AKH or AKHR.  These findings demonstrated that AKH/AKHR signaling-dependent trehalose metabolism plays a crucial role in regulating locust dehydration resistance and thus provide novel insights into the regulatory mechanism underlying drought resistance.

Animal Science · Veterinary Medicine

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Transcriptome analysis reveals steroid hormones biosynthesis pathway involved in abdominal fat deposition in broilers Yuting Zhu, Yongli Wang, Yidong Wang, Guiping Zhao, Jie Wen, Huanxian Cui 2024, 23(9): 3118-3128.  DOI: 10.1016/j.jia.2023.04.015 Abstract ( )   PDF in ScienceDirect   Excessive abdominal fat deposition reduces the feed efficiency and increase the cost of production in broilers.  Therefore, it is an important task for poultry breeders to breed broilers with low abdominal fat.  Abdominal fat deposition is a highly complex biological process, and its molecular basis remains elusive.  In this study, we performed transcriptome analysis to compare gene expression profiles at different stages of abdominal fat deposition to identify the key genes and pathways involved in abdominal fat accumulation.  We found that abdominal fat weight (AFW) increased gradually from day 35 (D35) to 91 (D91), and then decreased at day 119 (D119).  Accordingly, after detecting differentially expressed genes (DEGs) by comparing gene expression profiles at D35 vs. D63 and D35 vs. D91, and identifying gene modules associated with fat deposition by weighted gene co-expression network analysis (WGCNA), we performed intersection analysis of the detected DEGs and WGCNA gene modules and identified 394 and 435 intersecting genes, respectively.  The results of the Gene Ontology (GO) functional enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses showed that the steroid hormone biosynthesis and insulin signaling pathways were co-enriched in all intersecting genes, steroid hormones have been shown that regulated insulin signaling pathway, indicating the importance of the steroid hormone biosynthesis pathway in the development of broiler abdominal fat.  We then identified 6 hub genes (ACTB, SOX9, RHOBTB2, PDLIM3, NEDD9, and DOCK4) related to abdominal fat deposition.  Further analysis also revealed that there were direct interactions between 6 hub genes.  SOX9 has been shown to bind to proteins required for steroid hormone receptor binding, and RHOBTB2 indirectly regulates the steroid hormones biosynthesis through cyclin factor, and ultimately affect fat deposition.  Our results suggest that the genes RHOBTB2 and SOX9 play an important role in fat deposition in broilers, by regulating steroid hormone synthesis.  These findings provide new targets and directions for further studies on the mechanisms of fat deposition in chicken.

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Supplementation of Lycium barbarum residue increases the growth rate of Tan sheep by enhancing their feed intake and regulating their rumen microbiome and metabolome Yajun Zhang, Xiao Chang, Bing Wang, Dawei Wei, Rongzhen Zhong, Yansheng Guo, Min Du, Guijie Zhang 2024, 23(9): 3129-3144.  DOI: 10.1016/j.jia.2023.10.008 Abstract ( )   PDF in ScienceDirect   Lycium barbarum residue (LBR), a by-product of L. barbarum processing, is packed with bioactive components and can be potentially utilized as a feed additive in animal husbandry.  However, the fundamental understanding of its effectiveness on livestock animals is still lacking, particularly in ruminants.  To explore the effects of LBR on the growth performance, rumen fermentation parameters, ruminal microbes and metabolites of Tan sheep, sixteen fattening rams (aged 4 mon) were fed a basal diet (CON, n=8) or a basal diet supplemented with 5% LBR (LBR, n=8).  The experiment lasted for 70 d, with 10 d adaptation period and 60 d treatment period.  The results showed that the LBR enhanced the average daily feed intake, average daily gain (P<0.05), and ruminal total volatile fatty acids (P<0.01) while decreasing ammonia-nitrogen concentration and rumen pH value (P<0.05).  Additionally, the LBR improved the relative abundances of Prevotella, Succiniclasticum, Ruminococcus, Coprococcus, Selenomonas, and Butyrivibrio (P<0.05) and reduced the relative abundances of Oscillospira and Succinivibrio (P<0.05).  The LBR altered the ruminal metabolome (P<0.01) by increasing the abundances of ruminal metabolites involved in amino acids (e.g., L-proline, L-phenylalanine, L-lysine, and L-tyrosine), pyrimidine metabolism (e.g., uridine, uracil, and thymidine), and microbial protein synthesis (e.g., xanthine and hypoxanthine).  In conclusion, LBR had positive effects on the growth rate of Tan sheep as well as on rumen fermentation parameters, rumen microbiome and rumen metabolome.

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Role of feline ANP32 proteins in regulating polymerase activity of influenza A virus Gang Lu, Feiyan Zheng, Yuqing Xiao, Ran Shao, Jiajun Ou, Xin Yin, Shoujun Li, Guihong Zhang 2024, 23(9): 3145-3158.  DOI: 10.1016/j.jia.2023.11.008 Abstract ( )   PDF in ScienceDirect   Recently, increasing natural infection cases and experimental animal challenge studies demonstrated domestic cats are susceptible to multiple subtypes influenza A virus (IAV) infections.  Notably, some subtype IAV strains could circulate in domestic cats after cross-species transmission and even infected humans, posing a threat to public health.  Host factors related to viral polymerase activity could determine host range of IAV and acidic nuclear phosphoprotein 32 (ANP32) is the most important one among them.  However, role of cat-derived ANP32 on viral polymerase activity and host range of IAV is still unknown.  In the present study, a total of 10 feline ANP32 (feANP32) splice variants (including 5 feANP32A, 3 feANP32B, and 2 feANP32E) were obtained from domestic cats by RT-PCR.  Sequence alignment results demonstrated amino acid deletions and/or insertions occurred among feANP32 variants, but all feANP32 proteins were primarily localized to cell nucleus.  Minigenome replication systems for several representative IAV strains were established and the support ability of feANP32 on IAV polymerase activity was estimated.  The results indicated that most feANP32A and feANP32B splice variants were able to support all the tested IAV strains, though the support activity of a single feANP32 protein on polymerase activity varied among different IAV strains.  In addition, the role of feANP32 in supporting H3N2 canine influenza virus was determined by investigating viral replication in vitro.  Collectively, our study systematically investigated the support activity of feANP32 on IAV, providing a clue for further exploring the mechanism of susceptibility of cats to IAV.

Agro-ecosystem & Environment

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Mitigation of N2O emissions in water-saving paddy fields: Evaluating organic fertilizer substitution and microbial mechanisms Delei Kong, Xianduo Zhang, Qidong Yu, Yaguo Jin, Peikun Jiang, Shuang Wu, Shuwei Liu, Jianwen Zou 2024, 23(9): 3159-3173.  DOI: 10.1016/j.jia.2024.03.047 Abstract ( )   PDF in ScienceDirect   Water-saving irrigation strategies can successfully alleviate methane emissions from rice fields, but significantly stimulate nitrous oxide (N2O) emissions because of variations in soil oxygen level and redox potential.  However, the relationship linking soil N2O emissions to nitrogen functional genes during various fertilization treatments in water-saving paddy fields has rarely been investigated.  Furthermore, the mitigation potential of organic fertilizer substitution on N2O emissions and the microbial mechanism in rice fields must be further elucidated.  Our study examined how soil N2O emissions were affected by related functional microorganisms (ammonia-oxidizing archaea (AOA), ammonia-oxidizing bacteria (AOB), nirS, nirK and nosZ) to various fertilization treatments in a rice field in southeast China over two years.  In this study, three fertilization regimes were applied to rice cultivation: a no nitrogen (N) (Control), an inorganic N (Ni), and an inorganic N with partial N substitution with organic manure (Ni+No).  Over two rice-growing seasons, cumulative N2O emissions averaged 0.47, 4.62 and 4.08 kg ha−1 for the Control, Ni and Ni+No treatments, respectively.  In comparison to the Ni treatment, the Ni+No fertilization regime considerably reduced soil N2O emissions by 11.6% while maintaining rice yield, with a lower N2O emission factor (EF) from fertilizer N of 0.95%.  Nitrogen fertilization considerably raised the AOB, nirS, nirK and nosZ gene abundances, in comparison to the Control treatment.  Moreover, the substitution of organic manure for inorganic N fertilizer significantly decreased AOB and nirS gene abundances and increased nosZ gene abundance.  The AOB responded to N fertilization more sensitively than the AOA.  Total N2O emissions significantly correlated positively with AOB and nirS gene abundances while having a negative correlation with nosZ gene abundance and the nosZ/nirS ratio across N-fertilized plots.  In summary, we conclude that organic manure substitution for inorganic N fertilizer decreased soil N2O emissions primarily by changing the soil NO3−-N, pH and DOC levels, thus inhibiting the activities of ammonia oxidation in nitrification and nitrite reduction in denitrification, and strengthening N2O reduction in denitrification from water-saving rice paddies.

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Plastic mulch increases dryland wheat yield and water-use productivity, while straw mulch increases soil water storage Hubing Zhao, Guanfei Liu, Yingxia Dou, Huimin Yang, Tao Wang, Zhaohui Wang, Sukhdev Malhi, Adnan Anwar Khan 2024, 23(9): 3174-3185.  DOI: 10.1016/j.jia.2024.01.008 Abstract ( )   PDF in ScienceDirect   Amplifying drought stress and high precipitation variability impair dryland wheat production.  These problems can potentially be minimized by using plastic mulch (PM) or straw mulch (SM).  Therefore, wheat grain yield, soil water storage, soil temperature and water-use productivity of PM and SM treatments were compared with no mulch (CK) treatment on dryland wheat over a period of eight seasons.  Compared to the CK treatment, PM and SM treatments on average significantly increased grain yield by 12.6 and 10.5%, respectively.  Compared to the CK treatment, SM treatment significantly decreased soil daily temperature by 0.57, 0.60 and 0.48°C for the whole seasons, growing periods and summer fallow periods, respectively.  In contrast, compared to the CK treatment, PM treatment increased soil daily temperature by 0.44, 0.51 and 0.27°C for the whole seasons, growing periods and summer fallow periods, respectively.  Lower soil temperature under SM allowed greater soil water storage than under PM.  Soil water storage pre-seeding was 17% greater under the SM than under the PM treatment.  Soil water storage post-harvest was similar for the PM and SM treatments, but evapotranspiration was 4.5% higher in the SM than in the PM treatment.  Consequently, water-use productivity was 6.6% greater under PM than under the SM treatment.  Therefore, PM treatment increased dryland wheat yield and water-use productivity, while straw mulch increased soil water storage.

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Integrated assessment of yield, nitrogen use efficiency and ecosystem economic benefits of use of controlled-release and common urea in ratoon rice production Zijuan Ding, Ren Hu, Yuxian Cao, Jintao Li, Dakang Xiao, Jun Hou, Xuexia Wang 2024, 23(9): 3186-3199.  DOI: 10.1016/j.jia.2024.03.038 Abstract ( )   PDF in ScienceDirect   Controlled-release urea (CRU) is commonly used to improve the crop yield and nitrogen use efficiency (NUE).  However, few studies have investigated the effects of CRU in the ratoon rice system.  Ratoon rice is the practice of obtaining a second harvest from tillers originating from the stubble of the previously harvested main crop.  In this study, a 2-year field experiment using a randomized complete block design was conducted to determine the effects of CRU on the yield, NUE, and economic benefits of ratoon rice, including the main crop, to provide a theoretical basis for fertilization of ratoon rice.  The experiment included four treatments: (i) no N fertilizer (CK); (ii) traditional practice with 5 applications of urea applied at different crop growth stages by surface broadcasting (FFP); (iii) one-time basal application of CRU (BF1); and (iv) one-time basal application of CRU combined with common urea (BF2).  The BF1 and BF2 treatments significantly increased the main crop yield by 17.47 and 15.99% in 2019, and by 17.91 and 16.44% in 2020, respectively, compared with FFP treatment.  The BF2 treatment achieved similar yield of the ratoon crop to the FFP treatment, whereas the BF1 treatment significantly increased the yield of the ratoon crop by 14.81% in 2019 and 12.21% in 2020 compared with the FFP treatment.  The BF1 and BF2 treatments significantly improved the 2-year apparent N recovery efficiency, agronomic NUE, and partial factor productivity of applied N by 11.47–16.66, 27.31–44.49, and 9.23–15.60%, respectively, compared with FFP treatment.  The BF1 and BF2 treatments reduced the chalky rice rate and chalkiness of main and ratoon crops relative to the FFP treatment.  Furthermore, emergy analysis showed that the production efficiency of the BF treatments was higher than that of the FFP treatment.  The BF treatments reduced labor input due to reduced fertilization times and improved the economic benefits of ratoon rice.  Compared with the FFP treatment, the BF1 and BF2 treatments increased the net income by 14.21–16.87 and 23.76–25.96%, respectively.  Overall, the one-time blending use of CRU and common urea should be encouraged to achieve high yield, high nitrogen use efficiency, and good quality of ratoon rice, which has low labor input and low apparent N loss.

Agricultural Economics and Management

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Rural labor migration and farmers’ arrangements of rice production systems in Central China: Insight from the intergenerational division of labor Xue Shen, Quanyu Yang, Rongjun Ao, Shengsheng Gong 2024, 23(9): 3200-3214.  DOI: 10.1016/j.jia.2024.07.042 Abstract ( )   PDF in ScienceDirect   Rice production is crucial for food security in China, and its relationship with rural labor migration has been studied extensively.  Labor migration in rural China has taken new forms in recent years.  There has been a discernible trend wherein adult children have started migrating to cities while their elderly parents return to villages to re-engage in on-farm work.  The phenomenon has notably shaped the intergenerational division of labor (IDL) within households.  However, it remains to be seen how farmers adjust their rice production systems in response to the IDL.  The age of 60 years for employment injury insurance is the eligibility threshold for off-farm employment and is used to obtain a source of exogenous variation in the IDL.  Based on a representative household survey of 1,752 rice farmers in the Hubei Province of Central China, our fuzzy regression discontinuity analysis reveals that farmers in IDL households are more likely to adopt ratoon rice (RR) than single cropping rice (SR) or double cropping rice (DR).  The effect of the IDL varies under different levels of operational scales and specialized agricultural service availability.  Further analysis suggests that farmers’ arrangements are associated with two potential mechanisms of downward intergenerational transfer.  Monetary transfer for urban housing purchases increases RR in IDL households, and time transfer for intergenerational childcare significantly promotes SR in IDL households.  This study enhances the understanding of the relationship between rural labor migration and rice production in China, providing a reference for adjusting rice production systems to ensure food security.

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Dual carbon goal and agriculture in China: Exploring key factors influencing farmers’ behavior in adopting low carbon technologies Jinpeng Zou, Lulin Shen, Fang Wang, Hong Tang, Ziyang Zhou 2024, 23(9): 3215-3233.  DOI: 10.1016/j.jia.2024.07.016 Abstract ( )   PDF in ScienceDirect   Identifying the factors influencing farmers’ adoption of low-carbon technologies (FA) and understanding their impacts are essential for shaping effective agricultural policies amied at emission reduction and carbon sequestration in China.  This study employs a meta-analysis of 122 empirical studies, delves into 23 driving factors affecting FA and addresses the inconsistencies present in the existing literature.  We systematically examine the effect size, source of heterogeneity, and time-accumulation effect of the driving factors on FA.  We find that significant heterogeneity in the factors influencing FA, except for farming experience, sources of heterogeneity from the survey zone, methodology model, technological attributes, report source, financial support, and the sampling year.  Additionally, age, farming experience, and adoption cost negatively correlate with FA.  In contrast, educational level, health status, technical training, economic and welfare cognition, land contract, soil quality, terrain, information accessibility, demonstration, government promotion, government regulation, government support, agricultural cooperatives member, peer effect, and agricultural income ratio demonstrate a positive correlation.  Especially, demonstration and age show a particularly strong correlation.  Finally, the effect of demonstration, age, economic and welfare cognition, farming experience, land contract, soil quality, information accessibility, government promotion, and support, as well as agricultural cooperative membership and peer effects on FA, are generally stable but exhibit varying degrees of attenuation over time.  The effect of village cadre, family income, farm scale, gender, health status, technical training, and off-farm work on FA show notable temporal shifts and maintain a weak correlation with FA.  This study contributes to shaping China’s current low-carbon agriculture policies across various regions.  It encourages policymakers to comprehensively consider the stability of key factors, other potential factors, technological attributes, rural socio-economic context, and their interrelations.

Letter

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Negative feedback regulation of PROG1 in rice Jinlin Bao, Jing Huang, Xiaoqing Yang, Xizhi Li, Shengjie Cheng, Wei Huang, Jun Wang, Jian Jin 2024, 23(9): 3234-3237.  DOI: 10.1016/j.jia.2024.05.006 Abstract ( )   PDF in ScienceDirect

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Identification of a novel multi-drug resistant plasmid co-harbouring extended-spectrum β-Lactamase resistance genes blaPER-4 and blaOXA-10 in Moellerella wisconsensis of sheep Xueliang Zhao, Yongqiang Miao, Hongmei Chen, Honghu Shan, Juan Wang, Yang Wang, Jianzhong Shen, Zengqi Yang 2024, 23(9): 3238-3242.  DOI: 10.1016/j.jia.2024.03.040 Abstract ( )   PDF in ScienceDirect