Research Projects

Plant growth is marked by multiple growth cycles and transitions like seed germination, juvenile to adult growth, onset of flowering and whole plant senescence. These transitions are regulated by developmental cues but are also strongly influenced by changes in the external environment. They are regulated by a balance between different hormones with GA being one of the key hormones. We had previously identified SlERF36, encoding one of the seven EAR-motif (ERF-associated Amphiphilic Repressor motif) repressor proteins in tomato which, when expressed in tobacco and Arabidopsis, caused early flowering and early senescence in an EAR-dependent manner (Upadhyay et al., 2013, 2014). Manipulation of SlERF36 in tomato (SERB project, 2018-2022), revealed acceleration of all developmental transitions such as germination, organ growth, flowering time, fruit ripening and whole plant senescence when constitutively expressed while its suppression delayed these transitions through changes in the GA-DELLA pathway and basal GA levels (manuscript submitted). The action was conserved in Arabidopsis through its counterparts. The broad spectrum of SlERF36 phenotypes across development suggests complex regulation involving the GA-DELLA pathway as well as GA-DELLA independent pathways, the mechanism of which remains to be deciphered. As an EAR-motif repressor, SlERF36 is expected to recruit specific histone deacetylases (HDACs) that repress downstream targets which inhibit leaf expansion and flowering time in a GA-DELLA dependent and/or independent manner. This project will focus on identifying how SlERF36 directs different processes through GA-DELLA dependent and GA-DELLA independent components through detailed transcriptomic studies and will attempt to identify the HDACs involved in these processes. The entire HDAC family in tomato will be cloned and studied through detailed Virus Induced Gene Silencing of individual HDACs in SlERF36 over-expression lines. Specific HDACs mediating SlERF36 action will be identified by monitoring reversal of phenotypes of leaf expansion and flowering time in HDAC-silenced lines of tomato. Finally, SlERF36 over-expression imparts agricultural value in terms of faster growth and early completion of life cycle by 20-30 days in the nethouse conditions without affecting yield. To investigate if faster growth is associated with a trade-off in terms of susceptibility to abiotic stress responses a detailed study of drought and salinity stress tolerance will be performed in SlERF36 over-expression and suppression/CRISPR lines and the molecular and biochemical basis of their responses elucidated.