Poster: Signaling, long distance

Abs # 456: Rice COI1 gene mediates hormone signal interactions and disease resistance

Presenter:	Mei, Chuansheng , mei@uark.edu
Authors	Mei, Chuansheng  (A)   Zhou, Xizngjun  (A)   Yang, Yinong  (A)
Affiliations:	(A): Department of Plant Pathology, University of Arkansas
Web Site:	http://www.uark.edu

Jasmonates are potent lipid signals that play an important role in biotic and abiotic stress response as well as plant growth, development, and senescence. In Arabidopsis, the COI1 gene encodes an F-box protein subunit of E3 ubiquitin ligase (also known as SCF complex) that is an essential component of jasmonate signaling. However, little is known about the COI1-mediated jasmonate signaling in rice and other economically important cereal crops. Recently, we have generated, via RNA interference, transgenic rice lines with suppressed COI1 expression. In this study, we have analyzed the COI1 RNAi transgenic rice for altered hormone sensitivity, gene expression and developmental changes. As expected, the COI1 suppression lines showed reduced sensitivity to methyl jasmonate. Interestingly, the same lines also exhibited reduced sensitivity to abscisic acid and hypersensitivity to gibberellic acid and ethylene. At the molecular level, the suppression lines showed reduced induction of jasmonate and abscisic acid responsive genes and increased induction of gibberelic acid and ethylene responsive genes when treated with the corresponding hormones. Furthermore, the COI1 suppression lines had much longer neck internode due to cell elongation and were significantly taller (35%) than untransformed control plants. Taken together, our data suggest that rice COI1 ortholog encodes a negative regulator of plant height and mediates the complex cross-talks among different plant hormones.