通讯机构：
[Liangying Dai] C;[Shaohong Qu] I;College of Plant Protection, Hunan Agricultural University, Changsha, China<&wdkj&>Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
通讯机构：
[Yong Liu] I;[Jun Zi Zhu] H;Institute of Plant Protection, Hunan Academy of Agricultural Sciences, Changsha City, Hunan Province, 410125, P.R. China<&wdkj&>Hunan Provincial Key Laboratory for Biology and Control of Plant Diseases and Insect Pests, Hunan Agricultural University, Furong District, Changsha City, Hunan Province, 410128, P.R. China
摘要：
Peach [Prunus persica (L.) Batsch] is an important deciduous fruit tree in the family Rosaceae and is a widely grown fruit in China (Verde et al., 2013). In July and August 2018, a fruit rot disease was observed in a few peach orchards in Zhuzhou city, the Hunan Province of China. Approximately 30% of the fruit in more than 400 trees was affected. Symptoms displayed were brown necrotic spots that expanded, coalesced, and lead to fruit being rotten. Symptomatic tissues excised from the margins of lesions were surface sterilized in 70% ethanol for 10 s, 0.1% HgCl2 for 2 min, rinsed with sterile distilled water three times, and incubated on potato dextrose agar (PDA) at 26°C in the dark. Fungal colonies with similar morphology developed, and eight fungal colonies were isolated for further identification. Colonies grown on PDA were grayish-white with white aerial mycelium. After an incubation period of approximately 3 weeks, pycnidia developed and produced α-conidia and β-conidia. The α-conidia were one-celled, hyaline, fusiform, and ranged in size from 6.0 to 8.4 × 2.1 to 3.1 μm, whereas the β-conidia were filiform, hamate, and 15.0 to 27.0 × 0.8 to 1.6 μm. For molecular identification, total genomic DNA was extracted from the mycelium of a representative isolate HT-1 and the internal transcribed spacer region (ITS), β-tubulin gene (TUB), translation elongation factor 1-α gene (TEF1), calmodulin (CAL), and histone H3 gene (HIS) were amplified and sequenced (Meng et al. 2018). The ITS, TUB, TEF1, CAL and HIS sequences (GenBank accession nos. MT740484, MT749776, MT749778, MT749777, and MT749779, respectively) were obtained and in analysis by BLAST against sequences in NCBI GenBank, showed 99.37 to 100% identity with D. hongkongensis or D. lithocarpus (the synonym of D. hongkongensis) (Gao et al., 2016) (GenBank accession nos. MG832540.1 for ITS, LT601561.1 for TUB, KJ490551.1 for HIS, KY433566.1 for TEF1, and MK442962.1 for CAL). Pathogenicity tests were performed on peach fruits by inoculation of mycelial plugs and conidial suspensions. In one set, 0.5 mm diameter mycelial discs, which were obtained from an actively growing representative isolate of the fungus on PDA, were placed individually on the surface of each fruit. Sterile agar plugs were used as controls. In another set, each of the fruits was inoculated by application of 1 ml conidial suspension (105 conidia/ml) by a spray bottle. Control assays were carried out with sterile distilled water. All treatments were maintained in humid chambers at 26°C with a 12-h photoperiod. The inoculation tests were conducted twice, with each one having three fruits as replications. Six days post-inoculation, symptoms of fruit rot were observed on inoculated fruits, whereas no symptoms developed on fruits treated with agar plugs and sterile water. The fungus was re-isolated and identified to be D. hongkongensis by morphological and molecular methods, thus fulfilling Koch's Postulates. This fungus has been reported to cause fruit rot on kiwifruit (Li et al. 2016) and is also known to cause peach tree dieback in China (Dissanayake et al. 2017). However, to our knowledge, this is the first report of D. hongkongensis causing peach fruit rot disease in China. The identification of the pathogen will provide important information for growers to manage this disease.
通讯机构：
[Jianping Chen; Liangying Dai] A;Authors to whom correspondence should be addressed.<&wdkj&>College of Plant Protection, Hunan Agricultural University, Changsha 410128, China<&wdkj&>Authors to whom correspondence should be addressed.<&wdkj&>College of Plant Protection, Hunan Agricultural University, Changsha 410128, China<&wdkj&>State Key Laboratory for Quality and Safety of Agro-Products, Institute of Plant Virology, Ningbo University, Ningbo 315211, China
关键词：
long non-coding RNA;Chinese wheat mosaic virus;microRNA target;RNA-sequencing
摘要：
Simple Summary Recent studies have shown that a large number of long noncoding RNAs (lncRNAs) can regulate various biological processes in animals and plants. However, the roles of long non-coding RNAs (lncRNAs) in the interaction between plants and viruses is unclear, particularly for the Chinese wheat mosaic virus (CWMV) interaction. In this study, we used a deep RNA sequencing strategy to profile lncRNAs involved in the response to CWMV infection in Nicotiana benthamiana and analyzed differentially expressed lncRNAs that responded to CWMV infection, using a bioinformatics method. We identified 1175 new lncRNAs in N. benthamiana infected with CWMV, with 65 lncRNAs showing differential expression. These lncRNAs were mainly enriched in plant hormone signal transduction and other pathways according to GO and KEGG pathway enrichment analyses. In addition, differential expression of XLOC_006393 after CWMV infection may be the precursor of NbmiR168c, which can respond to CWMV infection by modulating the expression of its target gene NbAGO1. We believe that our study makes a significant contribution to the literature because these results provide a valuable resource for studying lncRNAs involved in CWMV infection and improving the understanding of the molecular mechanism of CWMV infection. Recent studies have shown that a large number of long noncoding RNAs (lncRNAs) can regulate various biological processes in animals and plants. Although lncRNAs have been identified in many plants, they have not been reported in the model plant Nicotiana benthamiana. Particularly, the role of lncRNAs in plant virus infection remains unknown. In this study, we identified lncRNAs in N. benthamiana response to Chinese wheat mosaic virus (CWMV) infection by RNA sequencing. A total of 1175 lncRNAs, including 65 differentially expressed lncRNAs, were identified during CWMV infection. We then analyzed the functions of some of these differentially expressed lncRNAs. Interestingly, one differentially expressed lncRNA, XLOC_006393, was found to participate in CWMV infection as a precursor to microRNAs in N. benthamiana. These results suggest that lncRNAs play an important role in the regulatory network of N. benthamiana in response to CWMV infection.
摘要：
Histone acetylation is a dynamic modification process co-regulated by histone acetyltransferases (HATs) and histone deacetylases (HDACs). Although HDACs play vital roles in abiotic or biotic stress responses, their members in Triticumaestivum and their response to plant viruses remain unknown. Here, we identified and characterized 49 T. aestivumHDACs (TaHDACs) at the whole-genome level. Based on phylogenetic analyses, TaHDACs could be divided into 5 clades, and their protein spatial structure was integral and conserved. Chromosomal location and synteny analyses showed that TaHDACs were widely distributed on wheat chromosomes, and gene duplication has accelerated the TaHDAC gene family evolution. The cis-acting element analysis indicated that TaHDACs were involved in hormone response, light response, abiotic stress, growth, and development. Heatmaps analysis of RNA-sequencing data showed that TaHDAC genes were involved in biotic or abiotic stress response. Selected TaHDACs were differentially expressed in diverse tissues or under varying temperature conditions. All selected TaHDACs were significantly upregulated following infection with the barley stripe mosaic virus (BSMV), Chinese wheat mosaic virus (CWMV), and wheat yellow mosaic virus (WYMV), suggesting their involvement in response to viral infections. Furthermore, TaSRT1-silenced contributed to increasing wheat resistance against CWMV infection. In summary, these findings could help deepen the understanding of the structure and characteristics of the HDAC gene family in wheat and lay the foundation for exploring the function of TaHDACs in plants resistant to viral infections.
摘要：
<jats:p>P3N-PIPO (P3 N-terminal fused with Pretty Interesting Potyviridae ORF), the movement protein of potyviruses, is expressed as a translational fusion with the N-terminus of P3 in potyviruses. As reported in previous studies, P3N-PIPO is expressed via transcriptional slippage at a conserved G2A6 slippery site in the genus Potyvirus. However, it is still unknown whether a similar expression mechanism of P3N-PIPO is used in the other genera of the family Potyviridae. Moreover, due to the extremely low expression level of P3N-PIPO in natural virus-infected plants, the peptides spanning the slippery site which provide direct evidence of the slippage at the protein level, have not been identified yet. In this study, a potato virus X (PVX)-based expression vector was utilized to investigate the expression mechanism of P3N-PIPO. A high expression level of the P3N-PIPO(WT) of turnip mosaic virus (TuMV, genus Potyvirus) was observed based on the PVX expression vector. For the first time, we successfully identified the peptides of P3N-PIPO spanning the slippery site by mass spectrometry. Likewise, the P3N-PIPO(WT) of wheat yellow mosaic virus (WYMV, genus Bymovirus) was also successfully expressed using the PVX expression vector. Integrated proteome and transcriptome analyses revealed that WYMV P3N-PIPO was expressed at the conserved G2A6 site through transcriptional slippage. Moreover, as revealed by mutagenesis analysis, Hexa-adenosine of the G2A6 site was important for the frameshift expression of P3N-PIPO in WYMV. According to our results, the PVX-based expression vector might be used as an excellent tool to study the expression mechanism of P3N-PIPO in Potyviridae. To the best of our knowledge, this is the first experimental evidence dissecting the expression mechanism of a bymovirus P3N-PIPO in the experimental host Nicotiana benthamiana.</jats:p>
关键词：
Gustavus gene;Myzus persicae (Sulzer);fecundity;RNA Interference;Potato virus Y (PVY)
摘要：
Myzus persicae (Sulzer), commonly known as the green peach aphid, is a notorious pest that causes substantial losses to a range of crops and can transmit several plant viruses, including potato virus Y (PVY). Chemical insecticides provide only partial control of this pest and their use is not environmentally sustainable. In recent years, many genes related to growth, development, and reproduction have been used as targets for pest control. These include Gustavus (Gus), a highly conserved gene that has been reported to play an essential part in the genesis of germline cells and, hence, in fecundity in the model insect Drosophila melanogaster. We hypothesized that the Gustavus (Gus) gene was a potential target that could be used to regulate the M. persicae population. In this study, we report the first investigation of an ortholog of Gus in M. persicae, designated MpGus, and describe its role in the fecundity of this insect. First, we identified the MpGus mRNA sequence in the M. persicae transcriptome database, verified its identity with reverse transcription-polymerase chain reaction (RT-PCR), and then evaluated the transcription levels of MpGus in M. persicae nymphs of different instars and tissues with real-time quantitative PCR (RT-qPCR). To investigate its role in regulating the fecundity of M. persicae, we used RNA interference (RNAi) to silence the expression of MpGus in adult insects; this resulted in a significant reduction in the number of embryos (50.6%, P < 0.01) and newborn nymphs (55.7%, P < 0.01) in the treated aphids compared with controls. Interestingly, MpGus was also significantly downregulated in aphids fed on tobacco plants that had been pre-infected with PVYN, concomitant with a significant reduction (34.1%, P < 0.01) in M. persicae fecundity. Collectively, these data highlight the important role of MpGus in regulating fecundity in M. persicae and indicate that MpGus is a promising RNAi target gene for control of this pest species.
摘要：
<jats:p>GRAS transcription factors are widely present in the plant kingdom and play important roles in regulating multiple plant physiological processes. <jats:italic>Brachypodium distachyon</jats:italic> is a model for grasses for researching plant-pathogen interactions. However, little is known about the <jats:italic>BdGRAS</jats:italic> family genes involved in plant response to biotic stress. In this study, we identified 63 genes of the GRAS family in <jats:italic>B. distachyon</jats:italic>. The phylogenetic analysis showed that <jats:italic>BdGRAS</jats:italic> genes were divided into ten subfamilies and unevenly distributed on five chromosomes. qRT-PCR results showed that the <jats:italic>BdGRAS</jats:italic> family genes were involved in the growth and development of <jats:italic>B. distachyon</jats:italic>. Moreover, the expression of the HAM subfamily genes of <jats:italic>BdGRAS</jats:italic> changed during the interaction between <jats:italic>B. distachyon</jats:italic> and <jats:italic>Magnaporthe oryzae</jats:italic>. Interestingly, <jats:italic>BdGRAS31</jats:italic> in the HAM subfamily was regulated by miR171 after inoculation with <jats:italic>M. oryzae</jats:italic>. These results provide insight into the potential functions of the <jats:italic>BdGRAS</jats:italic> family in disease resistance.</jats:p>
摘要：
<jats:p>Brachypodium distachyon, as an effective model of cereal grains, is susceptible to most destructive cereal pathogens. Senescence associated gene 101 (SAG101) has been studied extensively in Arabidopsis. SAG101 is one of the important regulators of plant immunity. However, no homologous genes of AtSAG101 were found in B. distachyon. In this study, the AtSAG101 gene was transformed into B. distachyon. Three transgenic plant lines containing the AtSAG101 gene were confirmed by PCR and GUS gene activity. There were fewer Puccinia brachypodii urediospores in the AtSAG101-overexpressing plants compared to wild type plants. P. brachypodii biomass was obviously decreased in AtSAG101 transgenic plants. The length of infection hyphae and infection unit areas of P. brachypodii were significantly limited in transgenic plants. Moreover, there were small lesions in AtSAG101 transgenic plants challenged by Magnaporthe oryzae. Salicylic acid accumulation was significantly increased, which led to elevated pathogenesis-related gene expression in transgenic B. distachyon inoculated by P. brachypodii or M. oryzae compared to wild type plants. These results were consistent with infected phenotypes. Overexpression of AtSAG101 in B. distachyon caused resistance to M. oryzae and P. brachypodii. These results suggest that AtSAG101 could regulate plant resistance in B. distachyon.</jats:p>
摘要：
Begomoviruses can modify their transmission vector, Bemisia tabaci, to benefit their spread, although this may not always be the case. Here, the new begomovirus Ramie mosaic virus (RaMoV) and its vector B. tabaci MED, which is dominant in China and many regions of the world, were used as a model to examine direct and indirect interaction and virus transmission by B. tabaci MED of different sexes. No significant direct or indirect effects of RaMoV were observed in B. tabaci MED females, although RaMoV could shorten the life span of B. tabaci MED females by up to 4 days. A test of RaMoV transmission by different sexes of B. tabaci MED showed that there was higher virus transmission efficiency by females than males. Overall, RaMoV is transmitted by B. tabaci MED in a sex-dependent manner, and further research is needed to uncover the mechanism of the difference in RaMoV transmission by different sexes of B. tabaci.
摘要：
The absorption of nutrients and disease resistance are two indispensable physiological processes in plants; however, it is still largely unknown whether there is cross-talk between their molecular signaling pathways. In this study, we identified the rice OsPT8 protein, which is a member of the phosphate transporters (PTs) Pht1 family and also plays a role in rice disease resistance. The transcriptional level of OsPT8 is suppressed after infection with rice pathogens and treatment with pathogen-associated molecular patterns (PAMPs). Overexpression of OsPT8 suppresses rice disease resistance against the pathogens Magnaporthe oryzae and Xanthomonas oryzae pv. oryzae. Accordingly, the transcription level of resistance related genes, such as PAL and PBZ1, is inhibited in plants overexpressing OsPT8 (OsPT8-OX) after inoculation with these pathogens. In OsPT8-OX plants, PAMPs-triggered immunity (PTI) response genes, such as OsRac1 and SGT1, are suppressed during treatment with PAMPs chitin or flg22. Moreover, the typical response of PTI is suppressed after chitin or flg22 treatment. We also identified OsPT8 as an interactor of a rice mitogen-activated protein kinase BWMK1, which is a regulator of disease resistance. Under low phosphate (Pi) conditions, the OsPT8-OX plants display better agronomic traits than the control plants. However, the differences in development between OsPT8-OX and the control plants are reduced upon the increase of Pi concentration. These results demonstrate that OsPT8 regulates the transduction of Pi signaling for development and negatively regulates rice immunity.
摘要：
Citrus Huanglongbing (HLB) is one of the most devastating citrus diseases worldwide. Sensitive and accurate assays are vital for efficient prevention of the spread of HLB-associated "Candidatus Liberibacter spp". "Candidatus Liberibacter spp" that infect Citrus includes "Candidatus Liberibacter asiaticus" (Las), "Candidatus Liberibacter africanus" (Laf) and "Candidatus Liberibacter americanus" (Lam). Of them, Las is the most widespread species. In this study, a set of nested PCR primer pairs were screened to diagnose Las, and the nested PCR method greatly enhanced the sensitivity to detect Las up to 10 times and 100 times compared to qPCR and conventional PCR, respectively. Totally, 1112 samples from 5 different citrus cultivars in 39 different counties and cities were assayed by nested PCR. The results show that 384 samples were HLB-infected; the highest positive detection rate was 79.7% from the lopsided fruit samples, and the lowest positive detection rate was 16.3% from the apical dieback samples. The results indicate that the designed nested PCR primer pairs can detect Las from different symptomatic tissues, different citrus cultivars and different geographic regions. The set of nested PCR primers designed in the present study will provide a very useful supplementation to the current approaches for Las detection.
