A chloroplast-localized protein LESION AND LAMINA BENDING affects defence and growth responses in rice.

Understanding how plants allocate their resources to growth or defence is of long-term importance to the development of new and improved varieties of different crops., Using molecular genetics, plant physiology, hormone analysis and Next-Generation Sequencing ( NGS)-based transcript profiling, we have isolated and characterized the rice ( Oryza sativa) LESION AND LAMINA BENDING ( LLB) gene that encodes a chloroplast-targeted putative leucine carboxyl methyltransferase., Loss of LLB function results in reduced growth and yield, hypersensitive response ( HR)-like lesions, accumulation of the antimicrobial compounds momilactones and phytocassanes, and constitutive expression of pathogenesis-related genes. Consistent with these defence-associated responses, llb shows enhanced resistance to rice blast ( Magnaporthe oryzae) and bacterial blight ( Xanthomonas oryzae pv. oryzae). The lesion and resistance phenotypes are likely to be caused by the over-accumulation of jasmonates ( JAs) in the llb mutant including the JA precursor 12-oxo-phytodienoic acid. Additionally, llb shows an increased lamina inclination and enhanced early seedling growth due to elevated brassinosteroid ( BR) synthesis and/or signalling., These findings show that LLB functions in the chloroplast to either directly or indirectly repress both JA- and BR-mediated responses, revealing a possible mechanism for controlling how plants allocate resources for defence and growth. [ABSTRACT FROM AUTHOR]