JXB Advance Access originally published online on June 22, 2007
Journal of Experimental Botany 2007 58(10):2617-2625; doi:10.1093/jxb/erm109
RESEARCH PAPER |
Virus-induced gene silencing of P23k in barley leaf reveals morphological changes involved in secondary wall formation
1Cryobiosystem Research Center, Faculty of Agriculture, Iwate University, Morioka 020-8550, Japan
2Department of Agro-Science, Faculty of Agriculture, Iwate University, Morioka 020-8550, Japan
* To whom correspondence should be addressed. E-mail: kidou{at}iwate-u.ac.jp
P23k is a monocot-unique protein that is highly expressed in the scutellum of germinating barley seed. Previous expression analyses suggested that P23k is involved in sugar translocation and/or sugar metabolism. However, the role of P23k in barley physiology remains unclear. Here, to elucidate its physiological function, BSMV-based virus-induced gene silencing (VIGS) of P23k in barley leaves was performed. Expression and localization analyses of P23k mRNA in barley leaves showed up-regulation of P23k transcript with increased photosynthetic activity and the localization of these transcripts to the vascular bundles and sclerenchyma, where secondary wall formation is most active. VIGS of the P23k gene led to abnormal leaf development, asymmetric orientation of main veins, and cracked leaf edges caused by mechanical weakness. In addition, histochemical analyses indicated that the distribution of P23k in leaves coincides with the distribution of cell wall polysaccharides. Considering these results together, it is proposed that P23k is involved in the synthesis of cell wall polysaccharides and contributes to secondary wall formation in barley leaves.
Key words: BSMV-based VIGS, Hordeum vulgare L., P23k, sclerenchyma, secondary wall formation, vascular bundles
Received 24 February 2007; Revised 20 April 2007 Accepted 24 April 2007