Characterization and Functional Analysis of Pyrabactin Resistance-Like Abscisic Acid Receptor Family in Rice

Background: Abscisic acid (ABA) plays crucial roles in regulating plant growth and development, especially in responding to abiotic stress. The pyrabactin resistance-like (PYL) abscisic acid receptor family has been identified and widely characterized in Arabidopsis. However, PYL families in rice were largely unknown. In the present study, 10 out of 13 PYL orthologs in rice (OsPYL) were isolated and investigated. Results: Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analysis showed that expression of OsPYL genes is tissue-specific and display differential response to ABA treatment, implying their functional diversity. The interaction between 10 OsPYL members and 5 protein phosphatase 2C in rice (OsPP2C) members was investigated in yeast two-hybrid and tobacco transient expression assays, and an overall interaction map was generated, which was suggestive of the diversity and complexity of ABA-sensing signaling in rice. To study the biological function of OsPYLs, two OsPYL genes (OsPYL3 and OsPYL9) were overexpressed in rice. Phenotypic analysis of OsPYL3 and OsPYL9 transgenic rice showed that OsPYLs positively regulated the ABA response during the seed germination. More importantly, the overexpression of OsPYL3 and OsPYL9 substantially improved drought and cold stress tolerance in rice. Conclusion: Taken together, we comprehensively uncovered the properties of OsPYLs, which may be good candidates for the improvement of abiotic stress tolerance in rice.