Analyses of MYMIV-induced transcriptome in Vigna mungo as revealed by next generation sequencing

Genome-wide identification, characterization and primer designing of simple sequence repeats across Leguminosae family

Legumes are important clade of commercially important family Leguminosae that mainly include medicinal, flowering and edible plants. Although the genomic sequence of legumes is accessible, only the limited number of effective simple sequence repeat markers has been identified by prior research. Additional polymorphic simple sequence repeats marker discovery will aid in the genetics and breeding of legumes. In this study, 13 complete genome sequences were screened for the identification of chromosome-wise simple sequence repeats (SSRs) and 1,866,861 SSRs were identified. Based on the study, it was observed that the number of SSRs in non-coding region was more as compared to coding region and frequency of mononucleotides was highest followed by di-nucleotides while penta- and hexa-nucleotide repeats were least frequent one. The identified genome-wide SSRs and newly developed SSR markers, primers and their mapping will provide a powerful means for genetic researches across Leguminosae plants, including genetic diversity and evolutionary origin analysis, fingerprinting, QTL mapping and marker-assisted selection for breeding as well as comparative genomic analysis studies.

Field and agroinoculation screening of national collection of urd bean (Vigna mungo) germplasm accessions for new sources of mung bean yellow mosaic virus (MYMV) resistance

Yellow mosaic disease (YMD) is a major problem in Urd bean (Vigna mungo L.) in India, which causes huge yield losses. Breeding for wide spectrum and durable Mungbean yellow mosaic virus (MYMV) resistance and cultivating resistant cultivars is the most appropriate and effective approach. However, the task has become challenging with the report of at least two species of the virus, viz., Mungbean yellow mosaic virus (MYMV) and Mungbean yellow mosaic India virus (MYMIV) and their recombinants; the existence of various isolates of these species with varied virulence and rapid mutations noted in the virus as well as in the whitefly vector population. Thus the present study was carried out to identify and characterize novel and diverse sources of YMV resistance and develop linked molecular markers for breeding durable and broadspectrum resistant urdbean cultivars against YMV. Towards this goal, we have screened 998 accessions of urdbean national collection of germplasm against YMD Hyderabad isolate both in a field under the natural level of disease incidence and through agro inoculation in the laboratory using viruliferous clones of the same isolate. Ten highly resistant accessions identified through repeated testing have been characterized in terms of reported linked markers. We attempted to see diversity among the ten resistant accessions reported here using earlier reported resistance-linked SCAR marker YMV1 and SSR CEDG180 marker. SCAR marker YMV1 did not amplify with any of the 10 accessions. But with CEDG180, results suggested that 10 accessions shortlisted through field and laboratory tests do not carry PU31 allele and this shows that it may be likely to carry novel gene(s). Further studies are needed to genetically characterize these new sources.

Comparative RNA-Seq analysis unfolds a complex regulatory network imparting yellow mosaic disease resistance in mungbean [Vigna radiata (L.) R. Wilczek]

Yellow Mosaic Disease (YMD) in mungbean [Vigna radiata (L.) R. Wilczek] is one of the most damaging diseases in Asia. In the northern part of India, the YMD is caused by Mungbean Yellow Mosaic India Virus (MYMIV), while in southern India this is caused by Mungbean Yellow Mosaic Virus (MYMV). The molecular mechanism of YMD resistance in mungbean remains largely unknown. In this study, RNA-seq analysis was conducted between a resistant (PMR-1) and a susceptible (Pusa Vishal) mungbean genotype under infected and control conditions to understand the regulatory network operating between mungbean-YMV. Overall, 76.8 million raw reads could be generated in different treatment combinations, while mapping rate per library to the reference genome varied from 86.78% to 93.35%. The resistance to MYMIV showed a very complicated gene network, which begins with the production of general PAMPs (pathogen-associated molecular patterns), then activation of various signaling cascades like kinases, jasmonic acid (JA) and brassinosteroid (BR), and finally the expression of specific genes (like PR-proteins, virus resistance and R-gene proteins) leading to resistance response. The function of WRKY, NAC and MYB transcription factors in imparting the resistance against MYMIV could be established. The string analysis also revealed the role of proteins involved in kinase, viral movement and phytoene synthase activity in imparting YMD resistance. A set of novel stress-related EST-SSRs are also identified from the RNA-Seq data which may be used to find the linked genes/QTLs with the YMD resistance. Also, 11 defence-related transcripts could be validated through quantitative real-time PCR analysis. The identified gene networks have led to an insight about the defence mechanism operating against MYMIV infection in mungbean which will be of immense use to manage the YMD resistance in mungbean.

De novo assembly and characterization of transcriptome towards understanding molecular mechanism associated with MYMIV-resistance in Vigna mungo - A computational study.. [DOI: 10.1101/844639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

The fast climate change affects yield in Vigna mungo via enhancing both biotic and abiotic stresses. Out of all factors, the yellow mosaic disease has the most damaging effect. However, due to lack of reference genome of Vigna mungo, the complete mechanism associated with MYMIV (Mungbean Yellow Mosaic Indian Virus) resistance in Vigna mungo remain elusive to date. Considering this, the authors made an attempt to release new transcriptome and its annotation by employing computational approaches. Quality assessment of the generated transcriptomes reveals that it successfully aligned with 99.03% of the raw reads and hence can be employed for future research. Functional annotation of the transcriptome reveals that 31% and ∼14% of the total transcripts encode lncRNAs and protein-coding sequences, respectively. Further, analysis reveals that, out of total transcripts, only 4536 and 78808 are significantly down and up-regulated during MYMIV infection in Vigna mungo, respectively. These significant transcripts are mainly associated with ribosome, spliceosome, glycolysis /gluconeogenesis, RNA transport, oxidative phosphorylation, protein processing in the endoplasmic reticulum, MAPK signaling pathway - plant, methionine and cysteine metabolism, purine metabolism and RNA degradation. Unlike the previous study, this is for the first time, the present study identified these pathways may play key role in MYMIV resistance in Vigna mungo. Thus, information and transcriptomes data available in the present study make a significant contribution to understanding the genomic structure of Vigna mungo, enabling future analyses as well as downstream applications of gene expression, sequence evolution, and genome annotation.

De novo assembly and characterization of transcriptome towards understanding molecular mechanism associated with MYMIV-resistance in Vigna mungo - A computational study.. [DOI: 10.1101/844639]

The fast climate change affects yield in Vigna mungo via enhancing both biotic and abiotic stresses. Out of all factors, the yellow mosaic disease has the most damaging effect. However, due to lack of reference genome of Vigna mungo, the complete mechanism associated with MYMIV (Mungbean Yellow Mosaic Indian Virus) resistance in Vigna mungo remain elusive to date. Considering this, the authors made an attempt to release new transcriptome and its annotation by employing computational approaches. Quality assessment of the generated transcriptomes reveals that it successfully aligned with 99.03% of the raw reads and hence can be employed for future research. Functional annotation of the transcriptome reveals that 31% and ∼14% of the total transcripts encode lncRNAs and protein-coding sequences, respectively. Further, analysis reveals that, out of total transcripts, only 4536 and 78808 are significantly down and up-regulated during MYMIV infection in Vigna mungo, respectively. These significant transcripts are mainly associated with ribosome, spliceosome, glycolysis /gluconeogenesis, RNA transport, oxidative phosphorylation, protein processing in the endoplasmic reticulum, MAPK signaling pathway - plant, methionine and cysteine metabolism, purine metabolism and RNA degradation. Unlike the previous study, this is for the first time, the present study identified these pathways may play key role in MYMIV resistance in Vigna mungo. Thus, information and transcriptomes data available in the present study make a significant contribution to understanding the genomic structure of Vigna mungo, enabling future analyses as well as downstream applications of gene expression, sequence evolution, and genome annotation.

De novo assembly and characterization of transcriptome towards understanding molecular mechanism associated with MYMIV-resistance in Vigna mungo - A computational study.. [DOI: 10.1101/844639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

The fast climate change affects yield in Vigna mungo via enhancing both biotic and abiotic stresses. Out of all factors, the yellow mosaic disease has the most damaging effect. However, due to lack of reference genome of Vigna mungo, the complete mechanism associated with MYMIV (Mungbean Yellow Mosaic Indian Virus) resistance in Vigna mungo remain elusive to date. Considering this, the authors made an attempt to release new transcriptome and its annotation by employing computational approaches. Quality assessment of the generated transcriptomes reveals that it successfully aligned with 99.03% of the raw reads and hence can be employed for future research. Functional annotation of the transcriptome reveals that 31% and ∼14% of the total transcripts encode lncRNAs and protein-coding sequences, respectively. Further, analysis reveals that, out of total transcripts, only 4536 and 78808 are significantly down and up-regulated during MYMIV infection in Vigna mungo, respectively. These significant transcripts are mainly associated with ribosome, spliceosome, glycolysis /gluconeogenesis, RNA transport, oxidative phosphorylation, protein processing in the endoplasmic reticulum, MAPK signaling pathway - plant, methionine and cysteine metabolism, purine metabolism and RNA degradation. Unlike the previous study, this is for the first time, the present study identified these pathways may play key role in MYMIV resistance in Vigna mungo. Thus, information and transcriptomes data available in the present study make a significant contribution to understanding the genomic structure of Vigna mungo, enabling future analyses as well as downstream applications of gene expression, sequence evolution, and genome annotation.

Molecular modeling and simulation of three important components of Plant Pathogen Interaction cascade in Vigna mungo

Plant pathogen interaction plays a great role in plant immunity. The regulation of various components of plant pathogen interactions is quite complicated and is very important in establishing relationship among components of this system. Yellow Mosaic Disease is common among legumes such as Vigna mungo. Mungbean Yellow Mosaic India Virus (MYMIV) and whitefly (Bemisia tabaci) is a vector causing the disease. Therefore, it is of interest to document the molecule models of three different components of Plant Pathogen interaction cascade- MAP kinase1, MAP kinase 2 and WRKY33 from V. mungo resistant to MYMIV. Both the MAP kinases were sequenced for this study while WRKY 33 was extracted and modeled from transcripts generated from two different transcriptome libraries, one set MYMIV- challenged, the other fed with aviruliferous whitefly. Post simulation studies revealed that MAPKs contained less percentage of disordered residues and were structurally more stable and than WRKY33.

Development of transcriptome based web genomic resources of yellow mosaic disease in Vigna mungo

Vigna mungo (Urdbean) is cultivated in the tropical and sub-tropical continental region of Asia. It is not only important source of dietary protein and nutritional elements, but also of immense value to human health due to medicinal properties. Yellow mosaic disease caused by Mungbean Yellow Mosaic India Virus is known to incur huge loss to crop, adversely affecting crop yield. Contrasting genotypes are ideal source for knowledge discovery of plant defence mechanism and associated candidate genes for varietal improvement. Whole genome sequence of this crop is yet to be completed. Moreover, genomic resources are also not freely accessible, thus available transcriptome data can be of immense use. V. mungo Transcriptome database, accessible at http://webtom.cabgrid.res.in/vmtdb/ has been developed using available data of two contrasting varieties viz., cv. VM84 (resistant) and cv. T9 (susceptible). De novo assembly was carried out using Trinity and CAP3. Out of total 240,945 unigenes, 165,894 (68.8%) showed similarity with known genes against NR database, and remaining 31.2% were found to be novel. We found 22,101 differentially expressed genes in all datasets, 44,335 putative genic SSR markers, 4105 SNPs and Indels, 64,964 transcriptional factor, 546 mature miRNA target prediction in 703 differentially expressed unigenes and 137 pathways. MAPK, salicylic acid-binding protein 2-like, pathogenesis-related protein and NBS-LRR domain were found which may play an important role in defence against pathogens. This is the first web genomic resource of V. mungo for future genome annotation as well as ready to use markers for future variety improvement program.