ABIOTIC STRESS TOLERANCE IN CROPS: CHARACTERIZATION OF GENES CONTRIBUTING TO CELLULAR TOLERANCE IDENTIFIED FROM INDIAN MULBERRY (Morus alba L.)
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Date
2023-02-15
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University of Agricultural Sciences, Bangalore
Abstract
Plants often encounter various stresses such as drought, salinity, extreme temperatures, heavy metal toxicity, etc., which result in reduced plant growth and yield. Indian mulberry (Morus alba L.), widely cultivated in Asia for fruit and silk production, is a stress-tolerant tree crop. This study has attempted to identify and functionally validate genes associated with drought stress response from this hardy crop. A drought transcriptome generated in a previous study (Sequence Read Archive ID: SRX9004356, SRX9004357, SRX9004358 and SRX9004359) was analyzed to identify the stress-responsive genes. Over 1000 genes were differentially expressed and based on the relative fold change and their role in stress tolerance responses, 109 genes were evaluated by in silico expression. Ten select genes were subjected to in vivo expression analysis to examine their relevance under drought and salinity stresses. These genes were found to be induced under these stresses and contribute to cellular-level tolerance in mulberry. To investigate the importance of two uncharacterized genes, designated as MaDUF1068 and MaRRM1-like, the post-transcriptional gene silencing (PTGS) approach was employed using the model plant Nicotiana benthamiana. The
PTGS indicated that these genes have a role in plant developmental processes. MaRRM1-like and MaUSP1-like genes from mulberry were validated through overexpression in Nicotiana tabacum. Overexpression of mulberry genes improved photosynthetic efficiency and stress tolerance compared to wild-type and vector control. MaUSP1-like expressing plants showed a 27-30% increase in biomass and increased tolerance to drought and salinity. The study showed that mulberry has diverse drought-responsive genes and that MaUSP1-like and MaRRM1-like genes are vital in reducing abiotic stress damage and promoting stress tolerance.