Research Projects

Root architecture plays a crucial role in plant growth and survival as roots act as an interface for nutrients and water supply from the soil to the plant. Roots have to constantly adapt to the changing environmental and edaphic conditions and rapidly modify their structure in response to these. Phytohormones play an important role in root structure modification and function in close co-ordination with TFs. We had previously identified a heat shock transcriptional repressor, SlHSFB3a, that was predominantly expressed in root tissues under normal growth conditions (Kumar et al., 2021; Majee et al., 2022). The gene was expressed in the primary root tip and lateral root primordia. Manipulation of the gene by over-expression and CRISPR-mediated knockout strongly affected root growth and architecture. SlHSFB3a over-expression lines showed reduced primary root length but a much higher lateral root number while CRISPR knockout lines showed longer primary roots but reduced lateral root number. The strong root phenotypes suggest that SlHSFB3a-mediated target suppression changes in root hormone responses and sensitivities. To identify the molecular basis of the changes brought about by SlHSFB3a, a detailed analysis of the various pathways undergoing change in SlHSFB3a-altered lines will be carried out to identify the primary hormone pathways affected by its expression. An analysis of root growth changes in SlHSFB3a-altered lines in response to different hormones and their inhibitors will be performed to identify the hormones that are most responsible for the changes brought about by SlHSFB3a. This will be complemented with root target analysis using SlHSFB3a-flag tagged lines for chromatin immune-precipitation experiments and ChIP sequencing to identify downstream targets of repression of SlHSFB3a. Hormonal control of cell and tissue-specific expression of SlHSFB3a will be performed using SlHSFB3a promoter-GUS/GFP constructs to identify how different hormones regulate its expression in a cell and tissue-specific manner. Finally, a detailed analysis of the abiotic stress responses of the SlHSFB3a-altered lines will be performed to study whether the dense root architecture in SlHSFB3a over-expression lines or the longer primary root growth in CRISPR knock-out lines affect drought, salinity and heat tolerance in these lines. A molecular analysis of the changes leading to abiotic stress resistance or susceptibility of these lines will be carried out. The studies will help in elucidating the molecular basis and hormonal regulation of SlHSFB3a-mediated root architectural changes and will provide valuable information on how these root growth changes allow the plant to respond to drought, salt and heat stresses so that studies are extended to other Solanaceae crops plants for agricultural value.