Ph.D. Program in Plant Molecular Biology

Friday Seminar by Mr. Aishwarye Sharma

JPK Lab/ Friday/ November16, 2018/ 3.30pm/ Emerging findings of the role of B-box proteins in photomorphogenesis
Category: Research

Emerging findings of the role of B-box proteins in photomorphogenesis

Aishwarye Sharma


Light is a crucial component for plant development, especially during de-etiolation. While photoreceptors such as Phytochromes, Phototropins, Cryptochromes and UVR8 detect light, transcription factors such as HY5 work downstream of these to coordinate photomorphogenesis by regulating several genes. In the recent years, many members of B-box transcription factors have been reported to regulate photomorphogenesis as well. These are a sub-group of Zinc finger transcription factors with 2 B-box domains, one CCT domain and a VP motif.  In Arabidopsis, there are 32 members of B-BOX proteins in which nearly 11 are known to play role in regulation of photomorphogenesis. B-BOX21 (previously known as Salt tolerant homologue 2, STH2) has been extensively explored. B-BOX21 was seen to interact with HY5 and regulate its expression by binding to its promoter in light, while to be ubiquitinated and degraded by COP1 in dark. Furthermore, it was seen that the second B-box domain in B-BOX21 is responsible for DNA binding and transcription activation properties. Apart from this, B-BOX24 was reported as negative regulator of photomorphogenesis which binds to HY5 and renders it incapable of binding to promoter of downstream genes. Also, along with its homologue B-BOX25, B-BOX24 repress a downstream gene of HY5 called B-BOX22. These studies suggest that B-box transcription factors fine-tune plant responses to changing light conditions.