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Latebreaking Poster

Session: Climate Change: Plants (Latebreaking)

LB 8-68 - Complex genetic interactions among MYC transcription factors underlie seedling photomorphogenesis in Arabidopsis

Thursday, August 10, 2023
5:00 PM – 6:30 PM PDT
Location: ESA Exhibit Hall
Complex genetic interactions among MYC transcription factors underlie seedling photomorphogenesis in ArabidopsisVikas Garhwal and Sreeramaiah N. Gangappa*Affiliations:Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246 West Bengal, India*Author Correspondence, e-mail ngsreeram@iiserkol.ac.inKeywords: MYC, Photomorphogenesis, COP1, HY5AbstractLight is arguably the most critical ecological cue that controls growth and development in plants. Plants have evolved complex mechanisms to cope with fluctuating light signals. Light sensing and signaling mechanism are well-studied, while their crosstalk with hormone signaling pathways needs to be better understood. In Arabidopsis, bHLH transcription factors such as MYC2, MYC3, and MYC4 have been shown to play a vital role in inducing defense responses against herbivory. While the role of MYC2 in light-mediated seedling development has been studied to some extent, that of MYC3 and MYC4 remains unknown. Here, we report the role of MYC3 and MYC4 in seedling development and found that MYC4 negatively regulates seedling photomorphogenesis while MYC3 function seems redundant. However, the genetic analysis between myc3 and myc4 mutants suggests a surprisingly opposite hypocotyl phenotype, i.e., the myc3 myc4 double mutant had significantly longer hypocotyl than the myc3 and myc4 individual mutants and Col-0. Interestingly, the loss of MYC2 function in myc3 myc4 background leads to further enhancement in the hypocotyl growth, as seen in the myc234 triple mutant, suggesting the function of MYC2/3/4 is essential for optimal seedling photomorphogenesis. Further, MYC3 and MYC4 enhanced COP1’s function in promoting hypocotyl growth and suppressing anthocyanin accumulation in light and dark conditions. Further, MYC3 and MYC4 probably function parallel to HY5 as the myc3, and myc4 mutants significantly suppress the exaggerated hypocotyl phenotype of hy5. Together, this study reveals the role of MYC3 and MYC4 in hypocotyl growth and further highlights the complex genetic interactions with MYC2 during seedling development. As MYC proteins are highly conserved across the plant kingdom, we are generating CRISPR-cas-based knockout lines for MYC2 homolog in brassica to understand its function in growth and defense responses.