Abstract:

In order to explore the temporal and spatial expression patterns of rice two component system (TCS) genes under drought stress and the relationship between expression of TCS genes and drought resistance ability, a whole rice genome microarray was used to analyze the expression profile of rice TCS genes under drought in different organs at different developmental stages and among rice lines with different drought resistance abilities. Results showed that the TCS genes were expressed in a temporal-spatial specific manner under drought stress in rice, behaved with great difference among the expression patterns of different rice organs and quite similar patterns within same tissues; type-A response regulator (RR) genes which may act as negative regulator of cytokinin signaling were mostly repressed by drought, while type-B RR genes which may play a role in positive regulation of cytokinin signaling were mostly induced by drought, these changes were supposed to be related with the enhancement of CK signaling under drought stress, this suppose was confirmed by the down regulation of ethylene receptor genes under drought from cross-talk of different plant hormones signaling; the HisKinase genes (HK5 and HK3) which is homolog with CK receptor genes (AHK2, AHK3, and CRE1) in Arabidopsis were induced by drought, while HK6 which is homolog with AHK5 (cytokinin-independent 2, CKI2)was drought repressed, these results provided a further confirmation of above suppose. The analysis of TCS genes expression profiling in drought resistant introgression lines and IR64 under drought stress did not find significant difference among the expression patterns of different rice lines, this maybe indicates that the TCS genes were related to drought responsiveness, but their effect to the enhancement of drought resistance still need further research.

Key words: Two component signaling components, Drought, Expression profile, Rice