Journal of Integrative Agriculture

Climate change and agriculture: Impacts and adaptive responses in Iran

Vahid Karimi, Ezatollah Karami, Marzieh Keshavarz

2018, 17(01): 1-15. DOI: 10.1016/S2095-3119(17)61794-5

Abstract ( ) PDF in ScienceDirect

The impacts of climate change on agriculture are still shadowed with uncertainty. However, climate change is expected to adversely affect Iran’s agricultural practices through changes in precipitation, temperature and carbon dioxide fertilization. Therefore, adaptation of this sector to the increasing weather events is imperative. This study is aimed to document the likely impacts of climate change on Iran’s agriculture and the current adaptation efforts made by government and farmers. The review of literature shows that changes in rainfall and water endowments will have significant impacts on crop yield, crops’ water requirements and income and welfare of farm families. The extent of the changes in yield depends on the crop type, assumptions related to the CO₂ fertilization effect, climate scenarios and adaptation abilities. On adaptation, the government’s efforts have been distinguished in the improving agricultural productivity and irrigation development based on current technology, developing new technologies and policy reforms. Farmers’ adaptive responses have also been identified. Some conclusions and recommendations are offered to increase the adaptive capacity of farmers and reduce negative impacts of climate change.

Development of elite restoring lines by integrating blast resistance and low amylose content using MAS

XIAO Wu-ming, PENG Xin, LUO Li-xin, LIANG Ke-qin, WANG Jia-feng, HUANG Ming, LIU Yong-zhu, GUO Tao, LUO Wen-long, YANG Qi-yun, ZHU Xiao-yuan, WANG Hui, CHEN Zhi-qiang

2018, 17(01): 16-27. DOI: 10.1016/S2095-3119(17)61684-8

Abstract ( ) PDF in ScienceDirect

Blast resistance and grain quality are major problems in hybrid rice production in China. In this study, two resistance (R) genes, Pi46 and Pita, along with the gene Wx^b, which mainly affects rice endosperm amylose content (AC), were introgressed into an elite indica restoring line, R8166, which has little blast resistance and poor grain quality through marker-assisted selection (MAS). Eight improved lines were found to have recurrent genome recovery ratios ranging from 88.68 to 96.23%. Two improved lines, R163 and R167, were selected for subsequent studies. R167, which has the highest recovery ratio (96.23%), showed no significant differences in multiple agronomic traits. In contrast, R163 with the lowest recovery ratio (88.68%) exhibited significant differences in heading date and yield per plant compared with the recurrent parent. At two developmental stages, R163 and R167 had greatly enhanced resistance to blast over the recurrent parent. Similar trends were also observed for agronomic traits and blast resistance in R163- and R167-derived hybrids when compared with the counterparts from R8166. In addition, R163, R167, and their derived hybrids significantly improved the grain quality traits, including amylose content (AC), gel consistency (GC), chalky grain rate (CGR), and degree of endosperm chalkiness (DEC). It confirmed the success of efficiently developing elite restoring lines using MAS in this study.

Evaluation of stability and yield potential of upland rice genotypes in North and Northeast Thailand

Wasan Jaruchai, Tidarat Monkham, Sompong Chankaew, Bhalang Suriharn, Jirawat Sanitchon

2018, 17(01): 28-36. DOI: 10.1016/S2095-3119(16)61609-X

Abstract ( ) PDF in ScienceDirect

The planting of upland rice is one cropping option in area with limited water availability and low soil fertility in North and Northeast Thailand. The varietal selection was determined by grain yield potential, wide adaptation, and good stability. This study was aimed at evaluation of indigenous upland rice germplasm for yield and yield stability in multi-locations. Thirty-six upland rice genotypes collected from six provinces of the North and Northeast Thailand and one check variety (Sewmaejan) were assessed under five locations in the rainy seasons of 2009 and 2010. The experiment was laid out in a randomized complete block design with three replications. The genotype grain yield was highly affected by location (59.90%), followed by genotypes (G)×location (L) interaction (12.80%) and genotype (6.79%). The most suitable location for the genotype evaluation was L3 (Khon Kaen-KKU10) which associated with stability of grain yield for all genotypes. Furthermore, biplot and regression analysis indicated that genotype numbers 6 (Jaowmong 1), 10 (Neawmong 1), 18 (Neawdum 1), 19 (Leamna), 20 (Prayaleamkang), 32 (Kunwang 2), and 33 (Kunwang 3) showed great yield stability over five locations. The genotypes will be applicant for upland rice production area and parental base in breeding program.

Identification of the resistance gene to powdery mildew in Chinese wheat landrace Baiyouyantiao

XU Xiao-dan, FENG Jing, FAN Jie-ru, LIU Zhi-yong, LI Qiang, ZHOU Yi-lin, MA Zhan-hong

2018, 17(01): 37-45. DOI: 10.1016/S2095-3119(16)61610-6

Abstract ( ) PDF in ScienceDirect

Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is one of the most damaging diseases to wheat in the world. The cultivation of resistant varieties of wheat is essential for controlling the powdery mildew epidemic. Wheat landraces are important resources of resistance to many diseases. Mapping powdery mildew resistance genes from wheat landraces will promote the development of new varieties with disease resistance. The Chinese wheat landrace Baiyouyantiao possesses characteristic of disease resistance to powdery mildew. To identify the resistance gene in this landrace, Baiyouyantiao was crossed with the susceptible cultivar Jingshuang 16 and seedlings of parents and F₁, BC₁, F₂, and F_2:3were tested with Bgt isolate E09. The genetic results showed that the resistance of Baiyouyantiao to E09 was controlled by a single recessive gene, tentatively designated PmBYYT. An Illumina wheat 90K single-nucleotide polymorphism (SNP) array was applied to screen polymorphisms between F₂-resistant and F₂-susceptible DNA bulks for identifying the chromosomal location of PmBYYT. A high percentage of polymorphic SNPs between the resistant and susceptible DNA bulks was found on chromosome 7B, indicating that PmBYYT may be located on this chromosome. A genetic linkage map of PmBYYT consisting of two simple sequence repeat markers and eight SNP markers was developed. The two flanking markers were SNP markers W7BL-8 and W7BL-15, with genetic distances of 3 and 2.9 cM, respectively. The results of this study demonstrated the rapid characterization of a wheat disease resistance gene and SNP marker development using the 90K SNP assay. The flanking markers of gene PmBYYT will benefit marker-assisted selection (MAS) and map-based cloning in breeding wheat cultivars with powdery mildew resistance.

New clues concerning pigment biosynthesis in green colored fiber provided by proteomics-based analysis

LI Yan-jun, SUN Shi-chao, ZHANG Xin-yu, WANG Xiang-fei, LIU Yong-chang, XUE Fei, SUN Jie

2018, 17(01): 46-53. DOI: 10.1016/S2095-3119(17)61692-7

Abstract ( ) PDF in ScienceDirect

To separate the proteins related to pigment synthesis in green colored fiber (GCF), we performed a comparative proteomic analysis to identify the differentially expressed proteins between green cotton fiber and a white near-isogenic line (NIL). One differential spot identified as phenylocumaran benzylic ether redutase-like protein (PCBER) was expressed only in GCF, but was not found in white colored fiber (WCF) at any time points. Since PCBER was a key enzyme in lignans biosynthesis, total lignans were extracted from GCF and WCF and their content was determined by using a chromotropic acid spectrophotometric method. The results showed that total lignans content in GCF was significantly higher than that in WCF. The qPCR analysis for two PLR genes associated with lignans biosynthesis showed that the expression level of two genes was much higher in GCF than that in WCF at 24 and 27 days post anthesis (DPA), which may be responsible for the higher lignans content in GCF. Our study suggested that PCBER and lignans may be responsible for the color difference between GCF and WCF. Additionally, p-dimethylaminocinnamaldehyde (DMACA) staining demonstrated that the pigment in GCF was not proanthocyanidins, and was different from that in brown colored fiber (BCF). This study provided new clues for uncovering the molecular mechanisms related to pigment biosynthesis in GCF.

Constitutive expression of feedback-insensitive cystathionine γ-synthase increases methionine levels in soybean leaves and seeds

YU Yang, HOU Wen-sheng, Yael Hacham, SUN Shi, WU Cun-xiang, Ifat Matityahu, SONG Shi-kui, Rachel Amir, HAN Tian-fu

2018, 17(01): 54-62. DOI: 10.1016/S2095-3119(16)61599-X

Abstract ( ) PDF in ScienceDirect

Soybean (Glycine max (L.) Merr.) is a major crop that provides plant-origin protein and oil for humans and livestock. Although the soybean vegetative tissues and seeds provide a major source of high-quality protein, they suffer from low concentration of an essential sulfur-containing amino acid, methionine, which significantly limits their nutritional quality. The level of methionine is mainly controlled by the first unique enzyme of methionine synthesis, cystathione γ-synthase (CGS). Aiming to elevate methionine level in vegetative tissues and seeds, we constitutively over-expressed a feedback-insensitive
Arabidopsis CGS (AtD-CGS) in soybean cultivars, Zigongdongdou (ZD) and Jilinxiaoli 1 (JX). The levels of soluble methionine increased remarkably in leaves of transgenic soybeans compared to wild-type plants (6.6- and 7.3-fold in two transgenic ZD lines, and 3.7-fold in one transgenic JX line). Furthermore, the total methionine contents were significantly increased in seeds of the transgenic ZD lines (1.5- to 4.8-fold increase) and the transgenic JX lines (1.3- to 2.3-fold increase) than in the wild type. The protein contents of the transgenic soybean seeds were significantly elevated compared to the wild type, suggesting that the scarcity of methionine in soybeans may limit protein accumulation in soybean seeds. The increased protein content did not alter the profile of major storage proteins in the seeds. Generally, this study provides a promising strategy to increase the levels of methionine and protein in soybean through the breeding programs.

Characterization of groundnut (Arachis hypogaea L.) collection using quantitative and qualitative traits in the Mediterranean Basin

Engin Yol, Seymus Furat, Hari D Upadhyaya, Bulent Uzun

2018, 17(01): 63-75. DOI: 10.1016/S2095-3119(17)61675-7

Abstract ( ) PDF in ScienceDirect

This study was conducted to determine the genetic diversity and relationship among 256 groundnut genotypes of which 132 belong to subsp. hypogaea (Arachis hypogaea L.) and 124 to subsp. fastigiata (Arachis fastigiata L.). The collection was evaluated for eight quantitative and five qualitative traits during three consecutive years under Mediterranean climate conditions. Coefficient of variation (CV) significantly differed among the genotypes for all the studied quantitative traits ranged from 9.10 to 33.98%, while the highest CV was recorded for seed yield. The subspecies of hypogaea and fastigiata displayed significant differences for quantitative traits except for numbers of pods per plant and seed yield. Principal component analyses showed that the first three principal components accounted for 68.14% variation for quantitative traits. Major traits that accounted for the variation by the three principal components (PCs) include days to the first flowering, days to 50% flowering, number of pods per plant and shelling percentage. The groundnut collection also offers wide seed coat color diversity which affects the crop marketability. The information on variations in quantitative and qualitative traits identified in the present investigation provided useful genotypes which would be serving parents. These parental genotypes can be used in groundnut breeding programs to develop desirable cultivars in Mediterranean Basin and globally.

Assessment of genetic effects on important breeding traits in reciprocal DH populations of winter oilseed rape (Brassica napus L.)

Laurencja Sza?a, Teresa Cegielska-Taras, El?bieta Adamska, Zygmunt Kaczmarek

2018, 17(01): 76-85. DOI: 10.1016/S2095-3119(17)61776-3

Abstract ( ) PDF in ScienceDirect

Here we present a study on the genetic effects of agronomic and seed quality traits in double haploid (DH) populations, which were developed by microspore culture from reciprocal F₁ hybrids produced between cultivar Californium and DH W-15. Each of the populations consisted of 25 DH lines. The field experiments were conducted in a randomized complete block design with three replications during three growing seasons. Field observations were recorded on seed yield and its structure: the number of branches and pods per plant, the number of seeds per pod, the 1 000-seed weight, the content of fat in the seeds, and three unsaturated fatty acids (oleic, linoleic, linolenic) in the seed oil. In order to investigate the influence of cross direction on the studied traits, parental effects were evaluated on the basis of differences between reciprocal DH populations. The maternal effect was revealed on the number of seeds per pod and the effect of the paternal form on linolenic acid content. The occurrence of transgression effects also depended on the direction of crossing and this was particularly noticeable in terms of the number of seeds per pod. The use of multivariate statistical methods allowed for the simultaneous characterization and grouping of tested lines in terms of several traits. Graphic images of the distribution of DH lines in the space of the two first canonical variates showed a great variation between the two reciprocal populations, both in terms of yield and its components, as well as fat and those unsaturated fatty acids.

SSR fingerprinting of 203 sweetpotato (Ipomoea batatas (L.) Lam.) varieties

MENG Yu-sha, ZHAO Ning, LI Hui, ZHAI Hong, HE Shao-zhen, LIU Qing-chang

2018, 17(01): 86-93. DOI: 10.1016/S2095-3119(17)61687-3

Abstract ( ) PDF in ScienceDirect

Simple sequence repeat (SSR) markers have been shown to be a powerful tool for varieties identification in plants. However, SSR fingerprinting of sweetpotato varieties has been a little reported. In this study, a total of 1 294 SSR primer pairs, including 1 215 genomic-SSR and 79 expressed sequence tag (EST)-SSR primer pairs, were screened with sweetpotato varieties Zhengshu 20 and Luoxushu 8 and their 2 F₁ individuals randomly sampled, and 273 and 38 of them generated polymorphic bands, respectively. Four genomic-SSR and 3 EST-SSR primer pairs, which showed good polymorphism, were selected to amplify 203 sweetpotato varieties and gave a total of 172 bands, 85 (49.42%) of which were polymorphic. All of the 203 sweetpotato varieties showed unique fingerprint patterns, indicating the utility of SSR markers in variety identification of this crop. Polymorphism information content (PIC) ranged from 0.5824 to 0.9322 with an average of 0.8176. SSR-based genetic distances varied from 0.0118 to 0.6353 with an average of 0.3100 among these varieties. Thus, these sweetpotato varieties exhibited high levels of genetic similarity and had distinct fingerprint profiles. The SSR fingerprints of the 203 sweetpotato varieties have been successfully constructed. The highly polymorphic SSR primer pairs developed in this study have the potential to be used as core primer pairs for variety identification, genetic diversity assessment and linkage map construction in sweetpotato and other plants.

Identification of salinity-related genes in ENO2 mutant (eno2^–) of Arabidopsis thaliana

ZHANG Yong-hua, CHEN Chao, SHI Zi-han, CHENG Hui-mei, BING Jie, MA Xiao-feng, ZHENG Chao-xing, LI Hong-jie, ZHANG Gen-fa

2018, 17(01): 94-110. DOI: 10.1016/S2095-3119(17)61720-9

Abstract ( ) PDF in ScienceDirect

Abiotic stress poses a great threat to plant growth and can lead to huge losses in yield. Gene enolase2 (ENO2) is important in resistance to abiotic stress in various organisms. ENO2 T-DNA insertion mutant (eno2^–) plants of Arabidopsis thaliana showed complete susceptibility to sodium chloride treatment when were analyzed either as whole plants or by measuring root growth during NaCl treatment. Quantitative real-time RT-PCR (RT-qPCR) was performed to investigate the expression profile of ENO2 in response to NaCl stress in Arabidopsis. The transcript level of ENO2 was rapidly elevated in 300 mmol L^–1 NaCl treatment. ENO2 also responded to 300 mmol L^–1 NaCl treatment at the protein level. To illuminate the mechanism underlying ENO2 resistance to salt at the transcriptional level, we studied the wild-type and eno2^–Arabidopsis lines that were treated with 300 mmol L^–1 NaCl for 18 h using 454 GS FLX, which resulted in an expressed sequence tag (EST) dataset. A total of 961 up-regulated and 746 down-regulated differentially expressed genes (DEGs) were identified in the pairwise comparison WT-18 h:eno2^–-18 h. The DEGs were identified and functionally annotated using the databases of Gene Ontology (GO) and the Kyoto encyclopedia of genes and genomes (KEGG). The identified unigenes were subjected to GO analysis to determine biological, molecular, and cellular functions. The biological process was enriched in a total of 20 GO terms, the cellular component was enriched in 13 GO terms, and the molecular function was enriched in 11 GO terms. Using KEGG mapping, DEGs with pathway annotations contributed to 115 pathways. The top 3 pathways based on a statistical analysis were biosynthesis of the secondary metabolites (KO01110), plant-pathogen interactions (KO04626), and plant hormone signal transduction (KO04075). Based on these results, ENO2 contributes to increased resistance to abiotic stress. In particular, ENO2 is involved in some of the metabolic stress response pathways in Arabidopsis. Our work also demonstrates that this EST dataset will be a powerful resource for further studies of ENO2, such as functional analyses, investigations of biological roles, and molecular breeding. Additionally, 3-phosphoglycerate kinase (PGK), 3-phosphoglycerate kinase 1 (PGK1), triosephosphate isomerase (TPI), and pyruvate kinase (PK) in glycolysis interactions with ENO2 were verified using the yeast two-hybrid experiment, and ENO2 may regulate the expression of PGK, PGK1, TPI, and PK. Taken together, the results from this study reflects that ENO2 gene has an important role in the response to the high salt stress.

Leaf area index based nitrogen diagnosis in irrigated lowland rice

LIU Xiao-jun, CAO Qiang, YUAN Zhao-feng, LIU Xia, WANG Xiao-ling, TIAN Yong-chao, CAO Wei-xing, ZHU Yan

2018, 17(01): 111-121. DOI: 10.1016/S2095-3119(17)61714-3

Abstract ( ) PDF in ScienceDirect

Leaf area index (LAI) is used for crop growth monitoring in agronomic research, and is promising to diagnose the nitrogen (N) status of crops. This study was conducted to develop appropriate LAI-based N diagnostic models in irrigated lowland rice. Four field experiments were carried out in Jiangsu Province of East China from 2009 to 2014. Different N application rates and plant densities were used to generate contrasting conditions of N availability or population densities in rice. LAI was determined by LI-3000, and estimated indirectly by LAI-2000 during vegetative growth period. Group and individual plant characters (e.g., tiller number (TN) and plant height (H)) were investigated simultaneously. Two N indicators of plant N accumulation (NA) and N nutrition index (NNI) were measured as well. A calibration equation (LAI=1.7787LAI₂₀₀₀–0.8816, R²=0.870**) was developed for LAI-2000. The linear regression analysis showed a significant relationship between NA and actual LAI (R²=0.863**). For the NNI, the relative LAI (R2=0.808**) was a relatively unbiased variable in the regression than the LAI (R²=0.33**). The results were used to formulate two LAI-based N diagnostic models for irrigated lowland rice (NA=29.778LAI–5.9397; NNI=0.7705RLAI+0.2764). Finally, a simple LAI deterministic model was developed to estimate the actual LAI using the characters of TN and H (LAI=–0.3375(TH×H×0.01)²+3.665(TH×H×0.01)–1.8249, R²=0.875**). With these models, the N status of rice can be diagnosed conveniently in the field.

Molecular characterization of chalcone isomerase (CHI) regulating flower color in herbaceous peony (Paeonia lactiflora Pall.)

WU Yan-qing, ZHU Meng-yuan, JIANG Yu, ZHAO Da-qiu, TAO Jun

2018, 17(01): 122-129. DOI: 10.1016/S2095-3119(16)61628-3

Abstract ( ) PDF in ScienceDirect

Chalcone isomerase (CHI) is a key enzyme that converts yellow chalcone to colorless naringenin, playing an important regulatory role in color formation of ornamental flowers. We determined the coding sequence of CHI in herbaceous peony using rapid-amplification of cDNA ends (RACE) technology, and subsequently detected the expression pattern of CHI in the inner and outer petals at different developmental stages using qRT-PCR. We cloned the upstream promoter sequences of CHI using genome walking technology and predicted the location of CpG islands and 5´ truncation. In addition, we constructed five dual-luciferase reporter gene carriers and detected the promoter activities of different fragments. Our results showed that the full-length cDNA sequence of CHI was 898 bp, and the 5´-upstream core promoter was located at –1 651 to –2 050 bp region, where contained one CpG island (–1 897 to –2 010 bp) and several important binding sites of transcription factor, such as Sp1, serum response factor (SRF), activating protein (AP)-2alpha and CCAAT/enhancer binding protein (C/EBP)alpha. Expression results showed that the expression of CHI at different developmental stages was generally higher in inner petals than those in outer petals, and the maximum at the bud stage (S1). Thus, this study will provide theoretical basis for an in-depth study of CHI gene function and expression regulation.

Development of a stable SCAR marker for rapid identification of Ganoderma lucidum Hunong 5 cultivar using DNA pooling method and inter-simple sequence repeat markers

CHAO Wen-zheng, TANG Chuan-hong, ZHANG Jing-song, YU Ling, Honda Yoichi

2018, 17(01): 130-138. DOI: 10.1016/S2095-3119(17)61825-2

Abstract ( ) PDF in ScienceDirect

The cultivar Ganoderma lucidum Hunong 5 was obtained using cross-breeding. Hunong 5 has high commercial value due to its high polysaccharide and triterpene content. This is the first report of using a DNA pooling method to develop a stable sequence characterized amplified region (SCAR) marker for rapid identification of the G. lucidum Hunong 5 cultivar. The SCAR marker was developed by first generating and sequencing a distinctive inter simple sequence repeat (ISSR) fragment (882 bp) from G. lucidum Hunong 5 cultivar. A stable SCAR primer pair GLH5F/GLH5R were obtained to identify the cultivar and the SCAR marker is a DNA fragment of 773 bp.

MAPKs and acetyl-CoA are associated with Curvularia lunata pathogenicity and toxin production in maize

NI Xuan, GAO Jin-xin, YU Chuan-jin, WANG Meng, Sun Jia-nan, LI Ya-qian, CHEN Jie

2018, 17(01): 139-148. DOI: 10.1016/S2095-3119(17)61697-6

Abstract ( ) PDF in ScienceDirect

Mitogen-activated protein kinase (MAPK) cascades play an important role in extracellular signal transduction and are involved in the pathogenicity of fungal pathogens to host plants. In Curvularia lunata, the roles of two MAPK genes, Clk1 and Clm1, have already been studied. Clk1 is involved in conidia formation and pathogenicity, and Clm1 is closely related to pathogen cell wall formation and pathogenicity to maize leaves. In this study, a third C. lunata MAPK gene, Clh1, which is homologous to hog1, was successfully cloned. We found that a Clh1 deletion mutant had lower intracellular glycerol accumulation than the wild-type stain and was unable to grow normally under osmotic stress conditions. Furthermore, the deletion mutants of three C. lunata MAPK genes (Clk1, Clm1 and Clh1) had lower levels of acetyl-CoA, which is an important intermediate product in the synthesis of melanin and furan toxin, and down-regulated expression of pathogenicity-associated genes. Furthermore, pathogenicity and the ability to produce toxin were restored after adding acetyl-CoA to the culture medium, suggesting that acetyl-CoA is closely involved in the pathogen MAPK signaling pathway.

The PhoR/PhoP two-component system regulates fengycin production in Bacillus subtilis NCD-2 under low-phosphate conditions

GUO Qing-gang, DONG Li-hong, WANG Pei-pei, LI She-zeng, ZHAO Wei-song, LU Xiu-yun, ZHANG Xiao-yun, MA Ping

2018, 17(01): 149-157. DOI: 10.1016/S2095-3119(17)61669-1

Abstract ( ) PDF in ScienceDirect

Bacillus subtilis strain NCD-2 is an excellent biocontrol agent for plant soil-borne diseases, and the lipopeptide fengycin is one of the active antifungal compounds in strain NCD-2. The regulator phoP and its sensor kinase PhoR compose a two-component system in B. subtilis. In this study, the phoR- and phoP-knockout mutants were constructed by in-frame deletion and the role of PhoR/phoP on the production of fengycin was determined. Inactivation of phoR or phoP in B. subtilis decreased its inhibition ability against Botrytis cinerea growth in vitro compared to the strain NCD-2 wild type. The lipopeptides were extracted from strain NCD-2 wild type and its mutant strains by hydrochloric acid precipitate, and the lipopeptides from phoR-null mutant or phoP-null mutant almost lost the inhibition ability against B. cinerea growth compared to the lipopeptides from strain NCD-2 wild type. Fast protein liquid chromatography (FPLC) analysis of the lipopeptides showed that inactivation of phoR or phoP genes reduced the production of fengycin by strain NCD-2. The fengycin production abilities were compared for bacteria under low-phosphate medium (LPM) and high-phosphate medium (HPM), respectively. Results indicated that the regulation of fengycin production by the PhoR/PhoP two-component system occurred in LPM but not in HPM. Reverse transcriptional-PCR confirmed that the fengycin synthetase gene fenC was positively regulated by phoP when cultured in LPM. All of these characteristics could be partially restored by complementation of intact phoR or phoP gene in the mutant. These data indicated that the PhoR/PhoP two-component system greatly regulated fengycin production and antifungal ability in B. subtilis NCD-2 mainly under low-phosphate conditions.

First report of field resistance to cyantraniliprole, a new anthranilic diamide insecticide, on Bemisia tabaci MED in China

WANG Ran, WANG Jin-da, CHE Wu-nan, LUO Chen

2018, 17(01): 158-163. DOI: 10.1016/S2095-3119(16)61613-1

Abstract ( ) PDF in ScienceDirect

The Bemisia tabaci (Gennadius) cryptic species complex comprises important insect pests that cause devastating damage to agricultural crops worldwide. In China, the B. tabaci Mediterranean (MED) (or biotype Q) species is threatening agricultural production all over the country as resistance to commonly used insecticides has increased. This situation highlights the need for alternative pest control measures. Cyantraniliprole, a novel anthranilic diamide insecticide, has been widely employed to control Hemipteran pests. To monitor the levels of resistance to cyantraniliprole in B. tabaci field populations in China, bioassays were conducted for 18 field samples from nine provinces over two years. Compared with median lethal concentration (LC₅₀) for the MED susceptible strain, all field samples had significantly higher resistance to cyantraniliprole. Furthermore, resistance factors (RFs) increased significantly in samples from Shanxi (from 5.62 in 2015 to 25.81 in 2016), Hunan (3.30 in 2015 to 20.97 in 2016) and Hubei (from 9.81 in 2015 to 23.91 in 2016) provinces. This study indicates a considerable decrease in the efficacy of cyantraniliprole against B. tabaci and establishes a baseline of susceptibility that could serve as a reference for future monitoring and management of B. tabaci resistance to cyantraniliprole.

The influence of Tetranychus cinnabarinus-induced plant defense responses on Aphis gossypii development

MA Guang-min, SHI Xue-yan, KANG Zhi-jiao, GAO Xi-wu

2018, 17(01): 164-172. DOI: 10.1016/S2095-3119(17)61666-6

Abstract ( ) PDF in ScienceDirect

Carmine spider mites (Tetranychus cinnabarinus) and cotton aphids (Aphis gossypii) are both serious pests of cotton, and cause reductions in yields of this key agricultural crop. In order to gain insights into how plant defense responses induced by one herbivore species affect the behavior and performance of another, we examined how infestation with T. cinnabarinus influences the development of A. gossypii using cotton as a model. In this study, we measured the activities of several important biochemical markers and secondary metabolites in the leaves of cotton seedlings responding to infestation by T. cinnabarinus. Furthermore, the influences of T. cinnabarinus infestation on the development of A. gossypii in cotton were also examined. Our data showed that the activities of several key defense enzymes, including phenylalanine ammonia-lyase (PAL), peroxidase (POD), lipoxygenase (LOX), and polyphenol oxidase (PPO), were substantially increased in cotton seedlings responding to spider mite infestation. Further, the contents of gossypol and condensed tannins, key defensive compounds, were significantly enhanced in leaves of cotton seedlings following T. cinnabarinus infestation. Moreover, the T. cinnabarinus-induced production of defense enzymes and secondary metabolites was correlated with infestation density. The developmental periods of A. gossypii on cotton seedling leaves infested with T. cinnabarinus at densities of 10 and 15 individuals cm^–2 were 1.16 and 1.18 times that of control, respectively. Meanwhile, the mean relative growth rates of A. gossypii on cotton leaves infested with T. cinnabarinus at densities of 8, 10 and 15 individuals cm^–2 were significantly reduced. Therefore, these data suggested that the developmental periods of A. gossypii were significantly lengthened and the mean relative growth rates were markedly reduced when cotton aphids were reared on plants infested with high densities of spider mites. This research sheds light on the role that inducible defense responses played in plant-mediated interspecific interactions between T. cinnabarinus and A. gossypii.

Energy and protein requirements for maintenance of Hu sheep during pregnancy

ZHANG Hao, SUN Ling-wei, WANG Zi-yu, MA Tie-wei, DENG Ming-tian, WANG Feng, ZHANG Yan-li

2018, 17(01): 173-183. DOI: 10.1016/S2095-3119(17)61691-5

Abstract ( ) PDF in ScienceDirect

This study aimed to determine the effect of stage and level of feed intake on energy metabolism, carbon-nitrogen (C-N) balance, and methane emission to determine energy and protein requirements for maintenance of maternal body including pregnancy tissues during pregnancy using the method of C-N balance. Twenty-one ewes carrying twin fetuses were randomly divided into three groups of seven ewes each in the digestion and respirometry trial at d 40, 100, and 130 of gestation, respectively. Three groups were fed a mixed diet either for ad libitum intake, 70 or 50% of the ad libitum intake during pregnancy. The results showed that the apparent digestibility of C and N were increased as feeding levels decreased at each stage of gestation. The daily net energy requirements for maintenance (NE_m) were 295.80, 310.09, and 323.59 kJ kg^–1 BW^0.75 (metabolic body weight) with a partial efficiency of metabolisable energy utilization for maintenance of 0.664, 0.644, and 0.620 at d 40, 100, and 130 of gestation, respectively. The daily net protein requirements for maintenance were 1.99, 2.35, and 2.99 g kg^–1 BW^0.75 at d 40, 100, and 130 of gestation, respectively. These results for the nutritional requirements of the net energy and protein may help to formulate more balanced diets for Hu sheep during pregnancy.

Transcriptome analysis of salt-responsive genes and SSR marker exploration in Carex rigescens using RNA-seq

LI Ming-na, LONG Rui-cai, FENG Zi-rong, LIU Feng-qi, SUN Yan, ZHANG Kun, KANG Jun-mei, WANG Zhen, CAO Shi-hao

2018, 17(01): 184-196. DOI: 10.1016/S2095-3119(17)61749-0

Abstract ( ) PDF in ScienceDirect

Carex rigescens (Franch.) V. Krecz is a wild turfgrass perennial species in the Carex genus that is widely distributed in salinised areas of northern China. To investigate genome-wide salt-response gene networks in C. rigescens, transcriptome analysis using high-throughput RNA sequencing on C. rigescens exposed to a 0.4% salt treatment (Cr_Salt) was compared to a non-salt control (Cr_Ctrl). In total, 57 742 546 and 47 063 488 clean reads were obtained from the Cr_Ctrl and Cr_Salt treatments, respectively. Additionally, 21 954 unigenes were found and annotated using multiple databases. Among these unigenes, 34 were found to respond to salt stress at a statistically significant level with 6 genes up-regulated and 28 down-regulated. Specifically, genes encoding an EF-hand domain, ZFP and AP2 were responsive to salt stress, highlighting their roles in future research regarding salt tolerance in C. rigescens and other plants. According to our quantitative RT-PCR results, the expression pattern of all detected differentially expressed genes were consistent with the RNA-seq results. Furthermore, we identified 11 643 simple sequence repeats (SSRs) from the unigenes. A total of 144 amplified successfully in the C. rigescens cultivar Lüping 1, and 69 of them reflected polymorphisms between the two genotypes tested. This is the first genome-wide transcriptome study of C. rigescens in both salt-responsive gene investigation and SSR marker exploration. Our results provide further insights into genome annotation, novel gene discovery, molecular breeding and comparative genomics in C. rigescens and related grass species.

Construction of Salmonella Pullorum ghost by co-expression of lysis gene E and the antimicrobial peptide SMAP29 and evaluation of its immune efficacy in specific-pathogen-free chicks

TIAN Qiu-feng, ZHOU Wei, SI Wei, YI Fei, HUA Xin, YUE Min, CHEN Li-ping, LIU Si-guo, YU Shen-ye

2018, 17(01): 197-209. DOI: 10.1016/S2095-3119(17)61696-4

Abstract ( ) PDF in ScienceDirect

In this study, a safety enhanced Salmonella Pullorum (S. Pullorum) ghost was constructed using an antimicrobial peptide gene, and evaluated for its potential as a Pullorum disease (PD) vaccine candidate. The antimicrobial peptide SMAP29 was co-expressed with lysis gene E to generate S. Pullorum ghosts. No viable bacteria were detectable either in the fermentation culture after induction of gene E- and SMAP29-mediated lysis for 24 h or in the lyophilized ghost products. Specific-pathogen-free (SPF) chicks were intraperitoneally immunized with ghosts at day 7 of age and no mortality, clinical symptoms or signs of PD such as anorexia, depression and diarrhea were observed. On challenge with a virulent S. Pullorum strain at 4 wk post-immunization, a comparatively higher level of protection was observed in the S. Pullorum ghost immunized chickens with a minimum of pathological lesions and bacterial loads compared to the birds in inactivated vaccine groups. In addition, immunization with the S. Pullorum ghosts induced a potent systemic IgG response and was associated with significantly increased levels of cytokine IFN-γ and IL-4 and relative percentages of CD4⁺ and CD8⁺ T lymphocytes. Our results indicate that SMAP29 can be employed as a new secondary lethal protein to enhance the safety of bacterial ghosts, and to prepare a non-living bacterial vaccine candidate that can prevent PD in chickens.

Effects of long-term organic fertilization on soil microbiologic characteristics, yield and sustainable production of winter wheat

LI Chun-xi, MA Shou-chen, SHAO Yun, MA Shou-tian, ZHANG Ling-ling

2018, 17(01): 210-219. DOI: 10.1016/S2095-3119(17)61740-4

Abstract ( ) PDF in ScienceDirect

We investigated the soil microbiologic characteristics, and the yield and sustainable production of winter wheat, by conducting a long-term fertilization experiment. A single application of N, P and K (NPK) fertilizer was taken as the control (CK) and three organic fertilization treatments were used: NPK fertilizer+pig manure (T1), NPK fertilizer+straw return (T2), NPK fertilizer+pig manure+straw return (T3). The results showed that all three organic fertilization treatments (T1, T2 and T3) significantly increased both soil total N (STN) and soil organic carbon (SOC) from 2008 onwards. In 2016, the SOC content and soil C/N ratios for T1, T2 and T3 were significantly higher than those for CK. The three organic fertilization treatments increased soil microbial activity. In 2016, the activity of urease (sucrase) and the soil respiration rate (SRS) for T1, T2 and T3 were significantly higher than those under CK. The organic fertilization treatments also increased the content of soil microbial biomass carbon (SMBC) and microbial biomass nitrogen (SMBN), the SMBC/SMBN ratio and the microbial quotient (qMB). The yield for T1, T2 and T3 was significantly higher than that of CK, respectively. Over the nine years of the investigation, the average yield increased by 9.9, 13.2 and 17.4% for T1, T2 and T3, respectively, compared to the initial yield for each treatment, whereas the average yield of CK over the same period was reduced by 6.5%. T1, T2, and T3 lowered the coefficient of variation (CV) of wheat yield and increased the sustainable yield index (SYI). Wheat grain yield was significantly positively correlated with each of the soil microbial properties (P<0.01). These results showed that the long-term application of combined organic and chemical fertilizers can stabilize crop yield and make it more sustainable by improving the properties of the soil.

Nitrogen uptake and transfer in broad bean and garlic strip intercropping systems

TANG Qiu-xiang, Haile Tewolde, LIU Hong-bin, REN Tian-zhi, JIANG Ping-an, ZHAI Li-mei, LEI Bao-kun, LIN Tao, LIU En-ke

2018, 17(01): 220-230. DOI: 10.1016/S2095-3119(17)61772-6

Abstract ( ) PDF in ScienceDirect

Utilization and transfer of nitrogen (N) in a strip intercropping system of garlic (Allium sativum L.) and broad bean (Vicia faba L.) have been investigated rarely. The objectives of this study were to quantify N uptake and utilization by intercropped broad bean and garlic and determine the magnitude of N transfer from broad bean to garlic. Field and pot trials were carried out in the Erhai Lake Basin in China using ¹⁵N tracer applied to the soil or injected into broad bean plants. Strip intercropping of garlic and broad bean increased N absorption (47.2%) compared with sole crop broad bean (31.9%) or sole crop garlic (40.7%) and reduced soil residual N. Nearly 15% of ¹⁵N injected into petioles of broad bean intercropped with garlic was recovered in garlic at harvest, suggesting that N could be transferred from broad bean to strip intercropped garlic. The findings provide a basis for evaluating legumes’ role in optimizing N fertilization when intercropped with non-legumes.

Nitrous oxide emissions following seasonal freeze-thaw events from arable soils in Northeast China

CHEN Zhe, YANG Shi-qi, ZHANG Ai-ping, JING Xin, SONG Wei-min, MI Zhao-rong, ZHANG Qingwen, WANG Wen-ying, YANG Zheng-li

2018, 17(01): 231-246. DOI: 10.1016/S2095-3119(17)61738-6

Abstract ( ) PDF in ScienceDirect

Seasonal soil freeze-thaw events may enhance soil nitrogen transformation and thus stimulate nitrous oxide (N₂O) emissions in cold regions. However, the mechanisms of soil N₂O emission during the freeze-thaw cycling in the field remain unclear. We evaluated N₂O emissions and soil biotic and abiotic factors in maize and paddy fields over 20 months in Northeast China, and the structural equation model (SEM) was used to determine which factors affected N₂O production during non-growing season. Our results verified that the seasonal freeze-thaw cycles mitigated the available soil nitrogen and carbon limitation during spring thawing period, but simultaneously increased the gaseous N₂O-N losses at the annual time scale under field condition. The N₂O-N cumulative losses during the non-growing season amounted to 0.71 and 0.55 kg N ha^–1 for the paddy and maize fields, respectively, and contributed to 66 and 18% of the annual total. The highest emission rates (199.2–257.4 μg m^–2 h^–1) were observed during soil thawing for both fields, but we did not observe an emission peak during soil freezing in early winter. Although the pulses of N₂O emission in spring were short-lived (18 d), it resulted in approximately 80% of the non-growing season N₂O-N loss. The N₂O burst during the spring thawing was triggered by the combined impact of high soil moisture, flush available nitrogen and carbon, and rapid recovery of microbial biomass. SEM analysis indicated that the soil moisture, available substrates including NH₄⁺ and dissolved organic carbon (DOC), and microbial biomass nitrogen (MBN) explained 32, 36, 16 and 51% of the N₂O flux variation, respectively, during the non-growing season. Our results suggested that N₂O emission during the spring thawing make a vital contribution of the annual nitrogen budget, and the vast seasonally frozen and snow-covered croplands will have high potential to exert a positive feedback on climate change considering the sensitive response of nitrogen biogeochemical cycling to the freeze-thaw disturbance.

Effects of different drying methods on quality, bacterial viability and storage stability of probiotic enriched apple snacks

CUI Li, NIU Li-ying, LI Da-jing, LIU Chun-quan, LIU Ying-ping, LIU Chun-ju, SONG Jiang-feng

2018, 17(01): 247-255. DOI: 10.1016/S2095-3119(17)61742-8

Abstract ( ) PDF in ScienceDirect

Effects of four different drying methods on the colour, texture, sensory quality, microstructure, bacterial viability and storage stability of probiotic-enriched apple snacks were assessed. The drying methods were air drying (AD), freeze drying (FD), freeze drying followed by microwave vacuum drying (FD+MVD) and air drying followed by explosion puffing drying (AD+EPD). Overall, FD+MVD can be used as a suitable drying method for the development of probiotic enriched apple snacks in consideration of colour, texture, sensory quality, bacterial viability and storage stability. Probiotic bacteria in FD+MVD-dried samples remained above 1×10⁶ CFU g^–1 for 120 days at 25°C. Interestingly, bacterial viability in FD+MVD-dried samples turned out to be significantly higher than FD-dried samples during storage for 120 days.

Phenolic and flavonoid contents of mandarin (Citrus reticulata Blanco) fruit tissues and their antioxidant capacity as evaluated by DPPH and ABTS methods

ZHANG Hua, YANG Yi-fei, ZHOU Zhi-qin

2018, 17(01): 256-263. DOI: 10.1016/S2095-3119(17)61664-2

Abstract ( ) PDF in ScienceDirect

The total phenolic and flavonoid contents in the fruit tissues (peels, pulp residues, seeds, and juices) of 19 citrus genotypes belonged to Citrus reticulata Blanco were evaluated and their antioxidant capacity was tested by 2,2-diphenyl-1-picrylhydrazyl radicals (DPPH) method and 2,2´-azino-bis(3-ethylbenzthiozoline-6)-sulphonic acid (ABTS) method. The total phenolic and flavonoid contents, and their antioxidant capacity varied in different citrus fruit tissues. Generally, the peel had both the highest average of total phenolics (27.18 mg gallic acid equivalent (GAE) g^–1 DW) and total flavonoids (38.97 mg rutin equivalent (RE) g^–1 DW). The highest antioxidant capacity was also the average of DPPH value (21.92 mg vitamin C equivalent antioxidant capacity (VCEAC) g^–1 DW) and average of ABTS value (78.70 mg VCEAC g^–1 DW) in peel. The correlation coefficient between the total phenolics and their antioxidant capacity of different citrus fruits tissues ranged from 0.079 to 0.792, and from –0.150 to 0.664 for the total flavonoids. The antioxidant capacity of fruit tissues were correlated with the total phenoilc content and flavonoid content except in case of the peel. In addition, the total phenolic content and antioxidant capacity varied in different citrus genotypes. Manju and Karamandarin were better genotypes with higher antioxidation and the phenolic content, however Shagan was the poorest genotype with lower antioxidation and the phenolic content.

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