AUTHOR=He Yanan , Li Yaping , Cui Lixin , Xie Lixia , Zheng Chongke , Zhou Guanhua , Zhou Jinjun , Xie Xianzhi 

TITLE=Phytochrome B Negatively Affects Cold Tolerance by Regulating OsDREB1 Gene Expression through Phytochrome Interacting Factor-Like Protein OsPIL16 in Rice

JOURNAL=Frontiers in Plant Science

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2016.01963

DOI=10.3389/fpls.2016.01963

ISSN=1664-462X

ABSTRACT=<p>Cross talk between light signaling and cold signaling has been elucidated in the model plant <italic>Arabidopsis</italic> and tomato, but little is known about their relationship in rice. Here, we report that <italic>phytochrome B</italic> (<italic>phyB</italic>) mutants exhibit improved cold tolerance compared with wild type (WT) rice (<italic>Oryza sativa</italic> L. cv. Nipponbare). The <italic>phyB</italic> mutants had a lower electrolyte leakage index and malondialdehyde concentration than the WT, suggesting that they had greater cell membrane integrity and less lipid peroxidation. Real-time PCR analysis revealed that the expression levels of <italic>dehydration-responsive element binding protein 1</italic> (<italic>OsDREB1)</italic> family genes, which functions in the cold stress response in rice, were increased in the <italic>phyB</italic> mutant under normal and cold stress conditions. PIFs are central players in phytochrome-mediated light signaling networks. To explore the relationship between rice PIFs and <italic>OsDREB1</italic> gene expression, we produced overexpression lines of rice <italic>PIF</italic> genes. <italic>OsDREB1</italic> family genes were up-regulated in <italic>OsPIL16</italic>-overexpression lines, which had improved cold tolerance relative to the WT. Chromatin immunoprecipitation (ChIP)-qPCR assay revealed that OsPIL16 can bind to the N-box region of <italic>OsDREB1B</italic> promoter. Expression pattern analyses revealed that <italic>OsPIL16</italic> transcripts were induced by cold stress and was significantly higher in the <italic>phyB</italic> mutant than in the WT. Moreover, yeast two-hybrid assay showed that OsPIL16 can bind to rice PHYB. Based on these results, we propose that phyB deficiency positively regulates <italic>OsDREB1</italic> expression through OsPIL16 to enhance cell membrane integrity and to reduce the malondialdehyde concentration, resulting in the improved cold tolerance of the <italic>phyB</italic> mutants.</p>