Effects of high nitrogen supply on the susceptibility to coolness at the young microspore stage in rice (Oryza sativa L.): Gene expression analysis in mature anthers

Abstract

Changes in gene expression patterns by high nitrogen (High-N) and High-N plus cooling at the young microspore stage (High-N-cooling) in rice mature anthers were analyzed by semiquantitative RT-PCR with gene specific primers. Gene expression of alpha-expansin 18 (EXPA18) was repressed under High-N-cooling. Betaexpansin 1 (EXPB1), putative aldehyde dehydrogenase (ALDH) and Fructokinase II (FKII) were upregulated under High-N. EXPB1 and FKII were highly expressed under High-N-cooling. Comprehensive examination of gene expression patterns of 26 alpha-expansins, (EXPAs) and 16 beta-expansins (EXPBs) showed that all expansins, (EXPs) except EXPA12 were expressed in the anthers. Gene expression of EXPs did not change under High-N except EXPA1, EXPB1 and EXPB5 which were upregulated. In total, 18 EXPAs and 6 EXPBs, were repressed under High-N-cooling, and among these, EXPA18, EXPA19 and EXPA20 had high similarities in the amino acid sequences, suggesting that these three genes may constitute a distinct functional gene subfamily related to the decrease in the pollen germination ability.