Knockdown of a Novel GeneOsTBP2.2Increases Sensitivity to Drought Stress in Rice

Drought stress is a major environmental stress, which adversely affects the biological and molecular processes of plants, thereby impairing their growth and development. In the present study, we found that the expression level ofOsTBP2.2which encodes for a nucleus-localized protein member belonging to transcription factor IID (TFIID) family, was significantly induced by polyethylene glycol (PEG) treatment. Therefore, knockdown mutants ofOsTBP2.2gene were generated to investigate the role of OsTBP2.2 in rice response to drought stress. Under the condition of drought stress, the photosynthetic rate, transpiration rate, water use efficiency, and stomatal conductance were significantly reduced inostbp2.2lines compared with wild type, Dongjin (WT-DJ). Furthermore, the RNA-seq results showed that several main pathways involved in "MAPK (mitogen-activated protein kinase) signaling pathway", "phenylpropanoid biosynthesis", "defense response" and "ADP (adenosine diphosphate) binding" were altered significantly inostbp2.2. We also found thatOsPIP2;6,OsPAOandOsRCCR1genes were down-regulated inostbp2.2compared with WT-DJ, which may be one of the reasons that inhibit photosynthesis. Our findings suggest thatOsTBP2.2may play a key role in rice growth and the regulation of photosynthesis under drought stress and it may possess high potential usefulness in molecular breeding of drought-tolerant rice.