Cis-carotene retrograde signaling affects chloroplast development

Date

Tuesday 20 September 2016

Time

12:30-13:30

Venue

CSIRO Black Mountain B1 Lecture Theatre

Speaker

Xin Hou, RSB, The Australian National University

Summary

Evidence is emerging that cis-carotenes are substrates towards the production of apocarotenoid signals (ACS) that regulate plant development. cis-carotenes accumulate in plants carrying mutated carotenoid isomerase (CRTISO); crtiso mutants display phenotypes the association of which with cis-carotene accumulation remains lack of physiological basis. We show that the Arabidopsis crtiso mutant accumulates cis-carotenes in newly emerged leaves under a shorter photoperiod which limits the photoisomerisation of cis-carotenes. cis-carotenes are linked to the absence of prolamellar body (PLB) and can impair chloroplast development thereby delaying chlorophyll biosynthesis. A forward genetic screen identified that the loss-of-function in ζ-carotene isomerase (ziso) in the crtiso mutant restored PLB and leaf greening, indicating that neurosporene isomers and tetra-cis-lycopene are candidate substrates for generating an ACS that interferes with plastid development. Interestingly, the crtiso ziso double mutant repressed DET1 expression. To verify that our candidate ACS signal represses photomorphogenesis, we confirmed that crtiso det1 double mutant restored PLB formation and leaf re-greening when grown under short photoperiods. Finally, we showed that PLB formation and plastid development could be restored in crtiso mutants by treatment with the D15 carotenoid cleavage inhibitor. We hypothesise an ACS signaling model controlling plastid differentiation through regulating nuclear gene expression.

Brief Bio

Dr. Xin Hou received his PhD in 2007 from the Chinese Academy of Sciences and had continued his research in Cancer Signaling until 2012. He performed Postdoctoral research on the regulatory roles of LKB1/NUAK1 signaling pathway in cancer cell proliferation and invasion, at University of Illinois from 2007 to 2008. He had then been appointed as an associate professor at Inner Mongolia University in China until 2012. He has started his second PhD study journey in Plant Sciences at the Australian National University since March 2012. Xin’s research has focused on apocarotenoid signaling (ACS) that regulates plant development, especially in Chloroplast differentiation.

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