STUDY OF THE ROLE OF TCP TRANSCRIPTION FACTORS IN COTYLEDON OPENING AND EXPANSION IN RESPONSE TO ILLUMINATION

VIOLA, IVANA L; GONZALEZ, DANIEL H; ALEM, ANTONELA L

Congreso; SAIB-SAMIGE Joint Meeting 2020; 2020

SAIB-SAMIGE

TEOSINTE-BRANCHED1/CYCLOIDEA/PCF (TCP) proteins constitute a family of plant-specific transcription factors that control various processes of plant development such as embryogenesis, germination, and the morphogenesis of leaves and flowers. They also participate in the modulation of hormone signaling pathways and the circadian rhythm, thus adjusting cellular processes to internal growth demands and signals received from the environment. Their name is due to the presence of a highly conserved protein domain, called TCP, which is involved in the recognition of specific DNA sequences and the formation of homodimers and heterodimers. Based on distinctive features present both within and outside the TCP domain, TCP proteins are divided into two classes, I and II. In Arabidopsis, the TCP family consists of 24 members, 13 belonging to class I and 11 to class II. In this study, we found that mutant plants in certain class I and class II TCP genes show a delay in the opening and expansion of cotyledons when exposed to light, which indicates that they are required for correct cotyledon opening during photomorphogenesis. We also identified a transcription factor capable of interacting with class I TCP proteins, and we studied the functional significance of these interactions during photomorphogenesis. We observed that the expression of all these transcription factors is regulated at the transcriptional level during photomorphogenesis and that the expression of SAUR genes SAUR6, SAUR14, and SAUR50 is decreased in mutant plants in the genes under study. We also analyzed the relationship of TCP proteins with hormonal pathways involved in photomorphogenesis. Altogether, our results provide evidence on the molecular mechanisms through which TCP proteins modulate the response of cotyledons to light.