Long non-coding RNA-mediated epigenetic response for abiotic stress tolerance in plants

Plants perceive environmental fluctuations as stress and confront several stresses throughout their life cycle individually or in combination. Plants have evolved their sensing and signaling mechanisms to perceive and respond to a variety of stresses. Epigenetic regulation plays a critical role in the regulation of genes, spatiotemporal expression of genes under stress conditions and imparts a stress memory to encounter future stress responses. It is quintessential to integrate our understanding of genetics and epigenetics to maintain plant fitness, achieve desired genetic gains with no trade-offs, and durable long-term stress tolerance. The long non-coding RNA >200 nts having no coding potential (or very low) play several roles in epigenetic memory, contributing to the regulation of gene expression and the maintenance of cellular identity which include chromatin remodeling, imprinting (dosage compensation), stable silencing, facilitating nuclear organization, regulation of enhancer-promoter interactions, response to environmental signals and epigenetic switching. The lncRNAs are involved in a myriad of stress responses by activation or repression of target genes and hence are potential candidates for deploying in climate-resilient breeding programs. This review puts forward the significant roles of long non-coding RNA as an epigenetic response during abiotic stresses in plants and the prospects of deploying lncRNAs for designing climate-resilient plants

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Not AvailablePeanut is grown extensively in different parts of world, where various biotic and abiotic factors limit its productivity and quality. The major fungal biotic constraints to peanut production include rust (Puccinia arachidis Speg.), stem-rot (Sclerotium rolfsii), collar-rot (Aspergillus niger Van Teighem), afla-root (Aspergillus flavus), and late leaf spot (Phaeoisariopsis personata Ber. and M A Curtis), while viral disease constraints are peanut bud necrosis disease (PBND) caused by peanut bud necrosis virus (PBNV) and peanut stem necrosis disease (PSND) caused by tobacco streak virus (TSV). Since, only a few sources of resistance are available in cultivated peanut for some diseases, which has resulted in the limited success of conventional breeding programmes on disease resistance. Moreover, even marker assisted breeding in peanut is in the nascent stage and identification of some major quantitative trait loci (QTLs) for a few fungal disease resitance genes has only recently been reported. Substantial efforts are underway to develop PCR-based markers for the construction of high-density genetic linkage maps. This will enable the breeders to effectively pyramid various biotic stress resistance genes into different agronomically superior breeding populations, in a much shorter time. It is expected that the availability of various costeffective genomic resources (SNPs, whole genome sequencing, KASPar, GBS etc.) and more effective mapping populations (NAM, MAGIC etc.) in the coming years will accelerate the mapping of complex traits in peanut. This review provides an overview of the current developments and future prospects of molecular marker development and their applications for improving biotic-stress resistance in peanut crop.Not Availabl

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Not AvailableStem rot, a devastating fungal disease of peanut, is caused by Sclerotium rolfsii. RNA-sequencing approaches have been used to unravel the mechanisms of resistance to stem rot in peanut over the course of fungal infection in resistant (NRCG-CS85) and susceptible (TG37A) genotypes under control conditions and during the course of infection. Out of about 290 million reads, nearly 251 million (92.22%) high-quality reads were obtained and aligned to the Arachis duranensis and Arachis ipaensis genomes with the average mapping of 78.91% and 78.61%, respectively. In total, about 48.6% of genes were commonly regulated, while approximately 21.8% and 29.6% of uniquely regulated genes from A. duranensis and A. ipaensis genomes, respectively, were identified. Several annotated transcripts, such as receptor-like kinases, jasmonic acid pathway enzymes, and transcription factors (TFs), including WRKY, Zinc finger protein, and C2-H2 zinc finger, showed higher expression in resistant genotypes upon infection. These transcripts have a known role in channelizing the downstream of pathogen perception. The higher expression of WRKY transcripts might have induced the systemic acquired resistance (SAR) by the activation of the jasmonic acid defense signaling pathway. Furthermore, a set of 30 transcripts involved in the defense mechanisms were validated with quantitative real-time PCR. This study suggested PAMP-triggered immunity as a probable mechanism of resistance, while the jasmonic acid signaling pathway was identified as a possible defense mechanism in peanut. The information generated is of immense importance in developing more effective ways to combat the stem rot disease in peanut.Not Availabl

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Not AvailableCo-occurrence of two devastating foliar-fungal diseases of peanut, viz., late leaf spot (LLS), and rust may cause heavy yield loss besides adversely afecting the quality of kernel and fodder. This study reports the mapping of seven novel stressrelated candidate EST-SSRs in a region having major QTLs for LLS and rust diseases using an F2 mapping population (GJG17×GPBD4) consisting of 328 individuals. The parental polymorphism using 1311 SSRs revealed 84 SSRs (6.4%) as polymorphic and of these 70 SSRs could be mapped on 14 linkage groups (LG). QTL analysis has identifed a common QTL (LLSQTL1/RustQTL) for LLS and rust diseases in the map interval of 1.41 cM on A03 chromosome, explaining 47.45% and 70.52% phenotypic variations, respectively. Another major QTL for LLS (LLSQTL1), explaining a 29.06% phenotypic variation was also found on LG_A03. A major rust QTL has been validated which was found harboring R-gene and resistance-related genes having a role in inducing hypersensitive response (HR). Further, 23 linked SSRs including seven novel EST-SSRs were also validated in 177 diverse Indian groundnut genotypes. Twelve genotypes resistant to both LLS and rust were found carrying the common (rust and LLS) QTL region, LLS QTL region, and surrounding regions. These identifed and validated candidate EST-SSR markers would be of great use for the peanut breeding groups working for the improvement of foliar-fungal disease resistance.Not Availabl