The identification and genomic editing of defense-related genes to confer resistance to pathogens is an effective and promising strategy for use in crop breeding. However, resistance is often associated with growth inhibition, a phenomenon referred to as the "trade-off" effect, making enhancing resistance without sacrificing yield challenging. In this study, a novel strategy is presented to enhance broad-spectrum resistance in crops without yield loss by editing susceptibility lncRNAs. RESIS, a pathogen-induced lncRNA that acquired its function in the pathogen response during domestication, is identified. Upon pathogen invasion, RESIS is activated by effector-binding elements on its promoter and subsequently binds to NAA15 and NAA10, two core components of the NatA complex. RESIS enables NAA10 to interact with NAA15 through a sequence that evolves in cultivated rice, enhancing the activity of the NatA complex in the N-terminal acetylation of proteins. RESIS knockout suppresses this process and increases translation during pathogen invasion, conferring resistance to both fungal and bacterial diseases without the growth inhibition typically associated with the direct knockout of the NatA complex. These findings highlight the potential of susceptibility lncRNAs as promising target loci for improving crop broad-spectrum disease resistance without detrimental effects on growth, offering significant prospects for practical applications.

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Understanding the mechanisms that govern microbial community assembly across soil-plant continuum is crucial for predicting the response of ecosystems to environmental changes. However, the impact of the health status of plant on microbial assembly across this continuum still remain poorly understood. Here, we investigated how wheat yellow mosaic (WYM), caused by the wheat mosaic virus transmitted by Polymyxa graminis, affected microbial assembly across soil (bulk soil, rhizosphere soil), and plant (roots and leaves) continuum in a winter wheat (Triticum aestivum L.) system in northern China, using null model analysis. The results showed that deterministic processes dominated the bacterial community assembly, whereas stochastic processes were primarily responsible for the assembly of the fungal communities. With increasing levels of WYM, deterministic processes were greatly enhanced for bacterial community assembly, accompanied by a decrease in community niche breadth. Intensified competition between bacteria and fungi and increased soil total nitrogen (TN) and soil organic carbon (SOC) contents were mainly responsible for the enhanced deterministic processes for bacterial community assembly. Random forest modeling indicated a strong potential of rhizosphere bacterial community assembly for predicting the pathological conditions of wheat. Structural equation modeling showed that disease level was positively correlated with SOC and TN contents, competitions between bacteria and fungi, and the contribution of variable selection processes to the bacterial community assembly in the wheat rhizosphere. Our study revealed the ecological mechanisms underlying the associations between microbial communities and soil-borne disease, and highlighted the significance of microbial community assembly for maintaining soil and plant health.

The co-chaperone DnaJ plays an important role in protein folding and regulation of various physiological activities, and participates in several pathological processes. DnaJ has been extensively studied in many species including humans, drosophila, mushrooms, tomatoes, and Arabidopsis. However, few studies have examined the role of DnaJ in wheat (Triticum aestivum), and the interaction mechanism between TaDnaJs and plant viruses. Here, we identified 236 TaDnaJs and performed a comprehensive genome-wide analysis of conserved domains, gene structure and protein motifs, chromosomal positions and duplication relationships, and cis-acting elements. We grouped these TaDnaJs according to their domains, and randomly selected six genes from the groups for tissue-specific analysis, and expression profiles analysis under hormone stress, and 17 genes for plant virus infection stress. In qRT-PCR, we found that among the 17 TaDnaJ genes tested, 16 genes were up-regulated after wheat yellow mosaic virus (WYMV) infection, indicating that the TaDnaJ family is involved in plant defense response. Subsequent yeast two-hybrid assays verified the WYMV NIa, NIb and 7KD proteins interacted with TaDJC (TraesCS7A02G506000), which had the most significant changes in gene expression levels after WYMV infection. Insights into the molecular mechanisms of TaDnaJ-mediated stress tolerance and sensitivity could inform different strategies designed to improve crop resistance to abiotic and biotic stress. This study provides a basis for future investigation of the TaDnaJ family and plant defense mechanisms.

Protein lysine acetylation (Kac) is an important post-translational modification mechanism in eukaryotes that is involved in cellular regulation. To investigate the role of Kac in virus-infected plants, we characterized the lysine acetylome of Nicotiana benthamiana plants with or without a Chinese wheat mosaic virus (CWMV) infection. We identified 4,803 acetylated lysine sites on 1,964 proteins. A comparison of the acetylation levels of the CWMV-infected group with those of the uninfected group revealed that 747 sites were upregulated on 422 proteins, including chloroplast localization proteins and histone H3, and 150 sites were downregulated on 102 proteins. Nineteen conserved motifs were extracted and 51 percent of the acetylated proteins located on chloroplast. Nineteen Kac sites were located on histone proteins, including 10 Kac sites on histone 3. Bioinformatics analysis results indicated that lysine acetylation occurs on a large number of proteins involved in biological processes, especially photosynthesis. Furthermore, we found that the acetylation level of chloroplast proteins, histone 3 and some metabolic pathway-related proteins were significantly higher in CWMV-infected plants than in uninfected plants. In summary, our results reveal the regulatory roles of Kac in response to CWMV infection.

Virus-derived small interference RNAs (vsiRNAs) not only suppress virus infection in plants via induction of RNA silencing but also enhance virus infection by regulating host defensive gene expression. However, the underlying mechanisms that control vsiRNA-mediated host immunity or susceptibility remain largely unknown. In this study, we generated several transgenic wheat lines using four artificial microRNA expression vectors carrying vsiRNAs from Wheat yellow mosaic virus (WYMV) RNA1. Laboratory and field tests showed that two transgenic wheat lines expressing amiRNA1 were highly resistant to WYMV infection. Further analyses showed that vsiRNA1 could modulate the expression of a wheat thioredoxin-like gene (TaAAED1), which encodes a negative regulator of reactive oxygen species (ROS) production in the chloroplast. The function of TaAAED1 in ROS scavenging could be suppressed by vsiRNA1 in a dose-dependent manner. Furthermore, transgenic expression of amiRNA1 in wheat resulted in broad-spectrum disease resistance to Chinese wheat mosaic virus, Barley stripe mosaic virus, and Puccinia striiformis f. sp. tritici infection, suggesting that vsiRNA1 is involved in wheat immunity via ROS signaling. Collectively, these findings reveal a previously unidentified mechanism underlying the arms race between viruses and plants.

Horizontal transfer of genetic materials between virus and host has been frequently identified. Three rice planthoppers, Laodelphax striatellus, Nilaparvata lugens, and Sogatella furcifera, are agriculturally important insects because they are destructive rice pests and also the vector of a number of phytopathogenic viruses. In this study, we discovered that a small region (∼300 nucleotides [nt]) of the genome of invertebrate iridescent virus 6 (IIV-6; genus Iridovirus, family Iridoviridae), a giant DNA virus that infects invertebrates but is not known to infect planthoppers, is highly homologous to the sequences present in high copy numbers in these three planthopper genomes. These sequences are related to the short interspersed nuclear elements (SINEs), a class of non-long terminal repeat (LTR) retrotransposons (retroposons), suggesting a horizontal transfer event of a transposable element from the rice planthopper genome to the IIV-6 genome. In addition, a number of planthopper transcripts mapped to these rice planthopper SINE-like sequences (RPSlSs) were identified and appear to be transcriptionally regulated along the different developmental stages of planthoppers. Small RNAs derived from these RPSlSs are predominantly 26 to 28 nt long, which is a typical characteristic of PIWI-interacting RNAs. Phylogenetic analysis suggests that IIV-6 acquires a SINE-like retrotransposon from S. furcifera after the evolutionary divergence of the three rice planthoppers. This study provides further examples of the horizontal transfer of an insect transposon to virus and suggests the association of rice planthoppers with iridoviruses in the past or present.IMPORTANCE This study provides an example of the horizontal transfer event from a rice planthopper genome to an IIV-6 genome. A small region of the IIV-6 genome (∼300 nt) is highly homologous to the sequences presented in high copy numbers of three rice planthopper genomes that are related to the SINEs, a class of retroposons. The expression of these planthopper SINE-like sequences was confirmed, and corresponding Piwi-interacting RNA-like small RNAs were identified and comprehensively characterized. Phylogenetic analysis suggests that the giant invertebrate iridovirus IIV-6 obtains this SINE-related sequence from Sogatella furcifera through a horizontal transfer event in the past. To the best of our knowledge, this is the first report of a horizontal transfer event between a planthopper and a giant DNA virus and also is the first evidence for the eukaryotic origin of genetic material in iridoviruses.

Summary Auxin plays a fundamental role in plant growth and development, and also influences plant defence against various pathogens. Previous studies have examined the different roles of the auxin pathway during infection by biotrophic bacteria and necrotrophic fungi. We now show that the auxin signalling pathway was markedly down‐regulated following infection of rice by Rice black streaked dwarf virus (RBSDV), a dsRNA virus. Repression of the auxin receptor TIR1 by a mutant overexpressing miR393 increased rice susceptibility to RBSDV. Mutants overexpressing the auxin signalling repressors OsIAA20 and OsIAA31 were also more susceptible to RBSDV. The induction of jasmonic acid (JA) pathway genes in response to RBSDV was supressed in auxin signalling mutants, suggesting that activation of the JA pathway may be part of the auxin signalling‐mediated rice defence against RBSDV. More importantly, our results also revealed that OsRboh‐mediated reactive oxygen species levels played important roles in this defence. The results offer novel insights into the regulatory mechanisms of auxin signalling in the rice–RBSDV interaction.

The phytohormone brassinosteroid (BR) not only plays key roles in regulating plant growth and development but is also involved in modulating the plant defense system in response to pathogens. We previously found that BR application made rice plants more susceptible to the devastating pathogen rice black-streaked dwarf virus (RBSDV), but the mechanism of BR-mediated susceptibility remains unclear. We now show that both BR-deficient and -insensitive mutants are resistant to RBSDV infection. High-throughput sequencing showed that the defense hormone salicylic acid and jasmonic acid pathways were activated in the RBSDV-infected BR mutant. Meanwhile, a number of class III peroxidases (OsPrx) were significantly changed and basal reactive oxygen species (ROS) accumulated in BR mutants. Treatment with exogenous hormones and other chemicals demonstrated that the BR pathway could suppress the levels of OsPrx and the ROS burst by directly binding the promoters of OsPrx genes. Together, our findings indicate that BR-mediated susceptibility is at least partly caused by inhibition of the action of defense hormones, preventing the accumulation of the peroxidase-mediated oxidative burst.

取带1~2个叶原基大小为0.2~0.4 mm的茎尖,在MS+6-BA 1.00 mg·L-1+NAA 0.10 mg·L-1培养基中培养50 d,成苗率50%.试管苗经指示植物检测出试管苗脱毒率为59%,脱毒苗茎段快繁的最佳配方为MS+6-BA 0.20 mg·L-1+NAA 0.20 mg·L-1.双层基质栽培脱毒试管苗生长快、 长势好,微型薯产量高、成本低.

Plant microRNAs (miRNAs) play pivotal roles in many biological processes. Although many miRNAs have been identified in various plant species, the functions of these miRNAs remain largely unknown due to the shortage of effective genetic tools to block their functional activity. Recently, miRNA target mimic (TM) technologies have been applied to perturb the activity of specific endogenous miRNA or miRNA families. We previously reported that Tobacco rattle virus (TRV)-based TM expression can successfully mediate virus-based miRNA silencing/suppression (VbMS) in plants. In this study, we show the Potato virus X (PVX)-based TM expression causes strong miRNA silencing in Nicotiana benthamiana . The PVX-based expression of short tandem target mimic (STTMs) against miR165/166 and 159 caused the corresponding phenotype in all infected plants. Thus, a PVX-based VbMS is a powerful method to study miRNA function and may be useful for high-throughput investigation of miRNA function in N. benthamiana .

WRKY proteins are important transcription factors in plants.They are involved in various plant developmental processes,as well as in coping with diverse biotic and abiotic stresses.In this study,we cloned the coding sequence (CDS)and upstream promoter of OsWRKY7 from Nipponbare to analyze its expression patterns.We first analyzed the relative expression level of OsWRKY7 in different tissues by quantitative real-time PCR(qRT-PCR),and the result showed that OsWRKY7 is mainly expressed in leaves,with a higher expression level in flag leaves than that in seedling leaves.We then constructed the pOsWRKY7-GUS expression vector by fusing the putative promoter with GUS reporter gene and transformed the vector into Nipponbare.Subsequent GUS staining showed that OsWRKY7 promoter had activity in primary root tip,leaf blade and glume.Consistent to the qRT-PCR result,massive GUS spots were stained on the entire leaf blade.We also characterized the inducibility of the pOsWRKY 7-GUS transgenic plants to pathogen infection and hormone treatment.The results showed that the GUS activities in both leaf and root are up-regulated after inoculation with rice bacterial blight pathogen [Xanthomonas oryzae pv.Oryzae (Xoo )]strain P10, as well as after exogenous application of cytokinin and auxin,while salicylic acid treatment represses GUS activity in both leaf and root.Finally,we fused the CDS of OsWRKY7 with the green fluorescent protein and the GAL4 DNA binding domain,respectively to analyze its subcellular localization in rice and transcriptional activity in yeast.The results showed that OsWRKY7 was localized exclusively to the nucleus of rice stem protoplasts,and has transcriptional self-activation activity in yeast.All these data suggested that OsWRKY7 might act as a transcriptional activator in bacterial blight defense and diverse hormone signal transduction pathways.

Y73 is a progeny of asymmetric somatic hybridization between Oryza sativa cv. Dalixiang and the wild rice species Oryza meyeriana. Inoculation with a range of strains of Xanthomonas oryzae pv. oryzae showed that Y73 had inherited a high level of resistance to rice bacterial blight (BB) from its wild parent. An F2 population of 7125 individuals was constructed from the cross between Y73 and a BB-susceptible cultivar IR24. After testing 615 SSR and STS markers covering the 12 rice chromosomes, 186 markers were selected that showed polymorphism between Y73 and IR24. Molecular markers linked to the BB resistance genes in Y73 were scanned using the F2 population and the polymorphic markers. The SSR marker RM128 on chromosome 1, the STS marker R03D159 on chromosome 3 and the STS marker R05D104 on chromosome 5 were found to be linked to the rice BB resistance genes in Y73.

采用化学诱变育种手段选育紫薯新品种,分别用0,0.5％,1.0％,1.5％叠氮化钠(NaN3)对亲本澳大利亚Au1990sp紫甘薯胚性细胞团进行诱变处理6h.结果表明,0.5％ NaN3处理6h效果最好,将0.5％NaN3处理6h胚性细胞团进行再分化,共分化出植株125株,2003年移栽后获得99株系,当年入选14株系,秋天收获时其中有3株系高产,编号为CA06产量达到43.98 t·hm-2,CA11产量达到40.03 t.hm-2,CA17产量达到43.84 t·hm-2,对照组Au1990sp产量为4.95 t·hm-2.诱变后的株系在植株表型、特征、特性与亲本相比有很大的不同.对亲本Au1990sp用NaN3诱变后的株系进行AFLP分析,发现有明显差异,对该品种进行12年的选育,命名为甬紫薯1号,2012年12月获得浙江省非农作物新品种的审定.

水稻白叶枯病是世界和我国各水稻产区的重要病害。该病由黄单胞水稻变种引起，由于病原菌变异频繁、发生规律复杂、地区间差异大，药剂防治效果不佳，从而水稻品种遗传改良是控制该病害的理想途径。然而，目前我国和亚洲的抗性品种携带的抗源主要是Xa4和Xa3基因，抗谱窄、抗性水平低，长期使用该单一抗源，使抗病品种丧失抗性，病原致病型发生变异，导致新致病菌株出现和扩散，引起病害大流行的危险。因而挖掘和利用新基因抗源就成为该病研究的新热点。

Or yza meyeriana, a wild rice species , is highly resistant to rice bacterial blight (BB ) , but the resistance mechanism is still unknown.Nitric oxide ( NO) is an important signaling molecule that plays a pivotal role in plant disease resistance responses .However, little study has focused on whether NO is involved in BB resistance of O. meyeriana.In this study, the effects of BB pathogen inoculation on leaf lesion , NO content, NO subcellular location and xylem ultrastructure were studied in O.meyeriana and a susceptible rice cultivar Nipponbare .Pathogen infection caused yellow necrotic lesions in Nipponbare and brown apoptotic lesion in O.meyeriana, and the lesion length was much longer in Nipponbare than in the wild rice .No difference was found in NO content in Nipponbare after pathogen inoculation .However , NO content was prominently increased by pathogen inoculation in the wild rice , and it was further discovered that NO was largely accumulated in xylem cell wall .In addition, electron microscopic observations showed that BB pathogen inoculation induced the thickening of xylem cell wall in O.meyeriana but not in Nippon-bare.Based on these results , we suggested that NO played an important role in the BB resistance of O.me yeriana, and the role might involve the thickening of xylem cell wall that could inhibit further invasion of the pathogen .

Objective: In order to gain further insight into the expression/regulation of marker gene OsPR1b in rice immune response, expression analysis of OsPR1b in rice was carried out. Methods: OsPR1b gene promoter fragment was amplified using the technology of PCR from rice Nipponbare genome and named OsPR1bp. The plas-mid of OsPR1bp::GUS was introduced into japonica rice via Agrobacterium-mediated transformation for further histo-chemical GUS analysis. In addition, the expression level of OsPR1b gene in rice leaves and roots was analyzed af-ter treated with plant hormones, abiotic factors and Xanthomonas oryzae pv. oryzae(Xoo) P10(PXO124) strain re-spectively. Results: The expression level of OsPR1b gene was much higher in leaf than that in stem, root, callus and flower. The expression of OsPR1b in leaves was differentially increased under the treatments of salicylic acid (SA), methyl jasmonate(MeJA), kinetin(KT), abscisic acid(ABA) as well as NaCl and PEG. The expression of OsPR1b in roots was increased under the treatments of MeJA, KT and NaCl. However, the increased fold of ex-pression were different between leaves and roots. Inoculation with P10 alone for 24 h had no effect on OsPR1b ex-pression, while co-treated with MeJA can significantly enhanced the expression level of OsPR1b in leaves. Conclu-sion: OsPR1b is described as a defense gene and the promoter we isolated directed a very low GUS gene expres-sion under normal conditions but responded to salt/drought stress and Xoo, and plants hormones such as JA, KT and ABA probably act as signals to trigger and mediate the systematic response.

A lesion-mimic mutant in rice(Oryza sativa L.),chloroplastic-H2O2-induced lesion 1(chl1),has enhanced resistance to rice blast and bacterial blight.To understand the molecular mechanisms underlying this phenotype and its resistance responses,aproteomics-based approach was used to identify differentially-expressed proteins between chl1 and its wild type.Using two-dimensional fluorescence difference gel electrophoresis technology and mass spectrometry,70 protein spots were successfully identified,of which 46 were up-regulated and 24 were down-regulated in the mutant.These differentially-expressed proteins are involved in diverse biological processes including disease resistance,photosynthesis,oxidation-reduction reaction,amino acid/protein metabolism,chaperoning and carbohydrate metabolism.The complex regulatory network in which these proteins are involved may play an important role in regulating the programmed cell death and the resistance reaction in chl1.

Oryza meyeriana is highly resistant to rice bacterial blight (BB) and this resistance trait has been transferred to cultivated rice (O. sativa) using asymmetric somatic hybridization. However, no resistance genes have yet been cloned. In the present study, a progeny of the somatic hybridization with high BB resistance was crossed with a rice cultivar with high BB susceptibility to develop an F2 population. Using bulked segregant analysis (BSA), 17 polymorphic markers that were linked to rice BB resistance were obtained through scanning a total of 186 simple sequence repeats (SSR) and sequence-tagged site (STS) markers, evenly distributed on 12 chromosomes. A genetic linkage map was then constructed based on the 17 linkage markers and the F2 segregating population, which was followed by mapping for quantitative trait loci (QTLs) for BB resistance. Three QTLs were identified on chromosomes 1, 3 and 5, respectively, and the alleles of the resistant parent at any of the QTLs increased BB resistance. All of the three QTLs had a strong effect on resistance, explaining about 21.5%, 12.3% and 39.2% of the resistance variance, respectively. These QTLs were different from the loci of the BB resistance genes that have been identified in previous studies. The QTLs mapped in this work will facilitate the isolation of novel BB resistance genes and their utilization in rice resistance breeding.