The overall goal of this special focus of the Journal of Integrative Agriculture is to provide empirical evidence of the impacts of the COVID-19 pandemic on agriculture and the effectiveness of the coping strategies in China. Several key issues are discussed with an in-depth study on: agricultural production, consumer food purchasing behaviors, agricultural and food marketing and international trade, rural poverty, and policy responses. We hope these studies could provide readers with a better understanding of the effects of the COVID-19 pandemic on farmers, consumers and traders in China and derive informative experience and lessons for China and the rest of world. The cover image of coronavirus is from the U.S. Centers for Disease Control and Prevention (CDC)
Haynaldia villosa (2n=14, VV), a wild grass of the subtribe Triticeae, serves as potential gene resources for wheat genetic improvement. The translocation of wheat-H. villosa 6VS/6AL showed more superiority in plant growth and disease resistance, and significant proteome changes during grain development. Our results demonstrated that the 6VS chromosome of H. villosa carries abundant stress-defensive proteins that have potential values for wheat genetic improvement. The photos were provided by Prof. YAN Yue-ming from Capital Normal University, China. See pages 2628–2642 for more details.
As a lysine acetyltransferase, FgGCN5 in Fusarium graminearum has been functionally characterized in hyphal vegetative growth, asexual and sexual reproduction, deoxynivalenol (DON) biosynthesis and plant infection. However, the roles of the conserved motifs/domains in FgGCN5 are unclear. Here, the four conserved sequence motifs (I–IV) were presented in the catalytic domain, a bromodomain in the carboxy-terminus and a conserved E130 in FgGCN5 were identified and characterized. Each conserved motif in the catalytic domain and E130 are essential for correct functions of the gene. The conserved bromodomain plays important roles in DON production and pathogen virulence. This was the first report to identify the functions of conserved motifs/domains in FgGCN5, which will contribute to our understanding of the mechanism(s) by which FgGCN5 regulates F. graminearum. The photo was provided by Associate Prof. ZHOU Shanyue from Qingdao Agricultural University, China. See pages 2477–2487 for more details.
As the leading source of meat around the world, pig is a favorable model to study the molecular mechanisms for skeletal muscle growth and development. The accomplishment of pig reference genome provided us novel insights into livestock production traits and genomics. The development of multi-omics makes it possible to understand myogenesis mechanisms comprehensively in the post-genome era. Numerous studies revealed that enhancers, a kind of non-coding sequence in the genome, play key roles in transcriptional regulation. We overviewed enhancers’ functions in skeletal muscle development and prospected the future orientation of scientific research in farm animals’ genetics and molecular breeding. A profound overview of enhancer functions along with abundant databases and accurate classification was displayed. We prospected the promising future envision of eRNA in regulating skeletal muscle development. It not only provides new ideas in production traits improvement for future farm animal breeding, but also would be helpful for model research of embryonic development, disease treatment, organ transplantation, personality mood and intent emotion detection in the life science. Learning a good knowledge of the untold story between enhancers and skeletal muscles may promote the study for agriculture and biotechnology to a new great level. The photo was provided by Prof. TANG Zhonglin from Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences. See pages 2137–2149 for more details.
Rhododendron fortunei has beautiful flowers with bright colors showing high ornamental value and economic potential in the flower industry. Polyploid plants usually show superiority in growth, disease resistance, and adaption over their diploid relatives. The cover photo shows the seedlings of R. fortunei treated with different concentrations of oryzalin. This illustration was provided by Dr. Lin Erpei from Zhejiang A&F University. See pages 2016–2026 for more details.
Biofumigation is an increasingly viable method for the control of plant-parasitic nematodes (PPNs) and offers an alternative to synthetic nematicides, including methyl bromide. PPNs damage crop yield and quality worldwide, with the financial toll of the pest estimated to be more than US$100 billion annually. The process of biofumigation acts through the growth and incorporation of specific plant material, often sourced from the Brassicaceae family, into the soil, where plants or plant byproducts release nematotoxic isothiocyanates. Cover photo demonstrates one method of biofumigation control of PPNs. In this example, a biofumigant crop is grown to an optimal life stage, macerated to release glucosinolates and myrosinase, and then tilled under to break down and release glucosinolate hydrolysis products. The illustration was provided by Rebecca Brennan from the University of Massachusetts Amherst, USA. See pages 1680–1690 for a review article evaluating research endeavors exploring the utility of biofumigation and seeking to provide a costbenefit assessment of the status of biofumigation for the control of PPNs.
Green peach aphid Myzus persicae is a widely distributed agricultural pest causing great economic loss of Rosaceae plants and vegetables by ingesting plant sap for nutrition and transmitting viral diseases. The asexual production with high reproductive capacity can promote the aphid outbreak. Cover photo shows the principle feeding sites of M. persicae on radish seedlings, including the young stems (left) and blade surface (right), which was provided by Prof. LI Hu from China Agricultural University. See pages 1447–1457 for more details.
Bleeding canker of pear trees is a devastating disease in China. The disease is epidemically emerging prevalently from April to September in pear-growing regions in Zhejiang, Anhui and Shandong provinces of China, and threatening pear industry currently in China. The photo shows the disease damages trunks and branches of pears, resulting in bleeding canker symptoms, which was provided by Prof. Hu Baishi from Nanjing Agricultural University, China. See pages 887–920 in detail.
Rice is a staple food of about half of the world’s population. Yield and quality have always been the main targets of rice breeding, with grain size and grain weight being important factors that affect these desiderata. Chromosome segment substitution lines (CSSLs) are a complete library of introgression lines with chromosomal segments usually of a distant genotype in an adapted background. CSSLs are valuable genetic resources for basic and applied research on improvement of complex traits. Cover photo shows the phenotype of a long grain CSSL, Z744 (right) with six substitution segments from the donor Xihui 18 and its recipient parent Nipponbare (left), which was provided by Prof. Zhao Fangming from Southwest University, China. See pages 1163–1169 for more details.
Chlorophyll (Chl) biosynthesis is essential for photosynthesis and plant growth. A spontaneous mutant cbd1 with Chl biosynthesis deficiency was discovered in paddy field. By map-based gene cloning, it was confirmed that the cbd1 mutation was caused by an mPingA miniature inverted-repeat transposable element (MITE) inserted in the promoter region of Os10g0502400, encoding a glutamyl-tRNA reductase (GluTR). GluTR catalyzes glutamyl-tRNA into glutamate-1-semialdehyde (GSA) and initiates the Chl biosynthesis, which was attenuated by downregulation of OsHemA gene in cbd1 mutant. A leading peptide exists in the N-terminus of GluTR and guides it to chloroplast. GluTR is unique in rice and plays an essential role in photosynthesis. See pages 612–623 for details.
The potato crop is one of the world’s most important food crops, along with rice, wheat, and maize. Potatoes are widely grown over many latitudes and elevations, especially in developing countries such as China. In 2015, China has been boosting potato production to become the fourth major crop produced in the country following rice, wheat and corn, developing potato as the staple food was also included by the Ministry of Agriculture and Rural Affairs of China in its important agenda. Developing potato as the staple food will not only promote the adjustment of planting structure, achieve the sustainable development of agriculture and safeguard China’s national food security, but also improve and enrich the diet structure of Chinese people. Unfortunately, insect pests are one of the major constraints to commercial production of potato in the world. In this special focus, biology, ecology and management for several key insect pests of potato are addressed including potato tuberworm, Phthorimaea operculella Zeller, as shown in the cover photo. This picture was provided by Prof. Zhang Runzhi from Institute of Zoology, Chinese Academy of Sciences.
Tomato was bred from Solanum lycopersicum var. cerasiforme, which was domesticated from Solanum pimpinellifolium (PIM). And dramatic changes in fruit size, flavor, and plant tolerance to abiotic/biotic stresses occurred during domestication and breeding. Gene expression variation bridges this phenotypic variation. To analyze the genetic mechanism of tomato flavor and abiotic/ biotic stresses, we constructed a pan-transcriptome, consisting of 41 265 genes, based on the RNAseq of orange-stage fruit of 399 tomato accessions. Furthermore, 6 122 expression presence/ absence variation (ePAV) genes and 3 629 differentially expressed genes (DEGs) were identified during tomato selection. Finally, 19 genes associated with the reduced total soluble solid (TSS) content in fruit of modern tomato cultivars and two resistance genes were identified differently expressed during domestication. It indicated that natural and artificial selection greatly shaped the tomato transcriptome, thereby altering the fruit TSS content and resistance to abiotic/biotic stresses. The photos are provided by the research team of Prof. Huang Sanwen from Agricultural Genomics Institute, Chinese Academy of Agricultural Sciences. See pages 120–132 for details.
Rice panicle and flower development is of importance to improve yield and quality. The spikelet is a unique flower/panicle structure, however, the molecular mechanisms underlying its development and evolution are still unclear. In the mfs3 mutant, a rice spikelet mutant, the margin region of palea degenerated seriously and an extra floret was produced, suggesting that MFS3 mutation affected both palea identity and spikelet meristem determinacy. By mapping-based clone, it was confirmed that the mfs3 mutation was caused by an 83-bp fragment loss and a base substitution in the LOC_Os06g04540 gene, which encoding an AT-hook DNA-binding protein. It was also found that MFS3 gene might regulate REP1 gene which was involved in the palea development and also influence the expression of meristem determination-related genes, OsMADS1, FON1, SNB and OsIDS1. The photos are provided by the research team of Dr. Li Yunfeng from Southwest University, China. See pages 2673–2681 for details.
Apple stem pitting virus (ASPV) is the type species of the genus Foveavirus, family Betaflexiviridae in the order Tymovirales. The virus can cause different pear diseases. Nowadays, the infection status and molecular characteristics of the virus in old pear trees have never been investigated. ASPV isolate LYC is identified from an over 300-year-old tree of a local Pyrus bretschneideri cultivar ‘Chili’ specifically grown at Laiyang area, Shandong Province, China. ASPV-LYC possesses a chimeric genome harboring a recombination region, is serologically and biologically related to other ASPV isolates. It provides clues for understanding molecular evolution of ASPV. The photo is provided by the research team of Prof. Hong Ni from Huazhong Agricultural University, China. See pages 2549–2560 for details.
Virus-induced gene silencing (VIGS), an appealing reverse-genetic strategy, has been developed as a powerful functional genomics tool to assess gene function for species not amenable to stable genetic transformation. Fusarium head blight (FHB) or scab is a devastating disease of wheat (Triticum aestivum) in humid and warm regions. Previous studies have made some contributions to understand the signal pathways involving in FHB resistance. Jasmonic acid (JA) signaling pathway may mediate FHB resistance in wheat. TaAOC, TaAOS, and TaOPR3 involved in JA signal pathway were selected to assess the potential of Barley stripe mosaic virus (BSMV)-VIGS for gene function analysis on FHB resistance. The plants treated with BSMV:TaAOC, BSMV:TaAOS, or BSMV:TaOPR3 showed more susceptible to FHB compared with BSMV:00 and control, implying their positive regulatory role in FHB resistance. The result indicated that it is feasible to unearth more genes that are positive on FHB resistance by BSMV-VIGS. The photo is provided by the team of Prof. Kong Lingrang from College of Agronomy, Shandong Agricultural University. See pages 2183–2192 for details.
Root-knot nematode (Meloidogyne spp., RKN) resistance to nematicides has become both a local and global threat to producing crops economically in protected agriculture. The combination of a fumigant such as dazomet (DZ) or chloropicrin (CP) and non-fumigating nematicide fosthiazate (FOS) showed a synergistic effect on the control of RKN. This effect mainly due to FOS combined with DZ or CP increased the diffusion rate of FOS across the RKN cuticle. The increase in diffusion rate shortens the time for these pesticides to cause cellular lesions in RKN ultimately leading to increased RKN mortality. Secondly, the fumigant prolongs the half-life of the nematicide FOS in the soil making more of it available for a longer period of time to control RKN. The photo is provided by the team of Prof. Cao Aocheng from Institute of Plant Protection, Chinese Academy of Agricultural Sciences. See pages 2093–2106 for details.