Overexpression of Poplar Pyrabactin Resistance-Like Abscisic Acid Receptors Promotes Abscisic Acid Sensitivity and Drought Resistance in Transgenic Arabidopsis

Abstract

Drought stress is an important environmental factor limiting productivity of plants, especially fast growing species with high water consumption like poplar. Abscisic acid (ABA) is a phytohormone that positively regulates seed dormancy and drought resistance. The PYR1 (Pyrabactin Resistance 1)/ PYRL (PYR-Like)/ RCAR (Regulatory Component of ABA Receptor) (PYR/PYL/RCAR) ABA receptor family has been identified and widely characterized in Arabidopsis thaliana. However, their functions in poplars remain unknown. Here, we report that 2 of 14 PYR/PYL/RCAR orthologues in poplar (Populus trichocarpa) (PtPYRLs) function as a positive regulator of the ABA signal transduction pathway. The Arabidopsis transient expression and yeast two-hybrid assays showed the interaction among PtPYRL1 and PtPYRL5, a clade A protein phosphatase 2C, and a SnRK2, suggesting that a core signalling complex for ABA signaling pathway exists in poplars. Phenotypic analysis of PtPYRL1 and PtPYRL5 transgenic Arabidopsis showed that these two genes positively regulated the ABA responses during the seed germination. More importantly, the overexpression of PtPYRL1 and PtPYRL5 substantially improved ABA sensitivity and drought stress tolerance in transgenic plants. In summary, we comprehensively uncovered the properties of PtPYRL1 and PtPYRL5, which might be good target genes to genetically engineer drought-Resistant plants.

Interaction network of ABA receptors in grey poplar

“…Hybrid ABA receptor complexes were found to be functional with a comparable range of IC 50 values of ABA for homologous and heterologous receptor complexes. Our data are consistent with the recent observation of ABA‐hypersensitivity conferred by expression of two RCAR/PYL‐like proteins from the aspen hybrid P. davidiana x P. bolleana in Arabidopsis (Yu et al ., ). In addition, expression of two different poplar PP2Cs in Arabidopsis revealed a negative regulation of drought and ABA responses (Arshad and Mattsson, ; Chen et al ., ).…”

“…A high sequence identity between Arabidopsis RCAR1 and poplar ABA receptors has been reported (Ma et al ., ), indicating a strong conservation in structure and function. Indeed, two poplar ABA receptors conferred an ABA‐hypersensitive phenotype in Arabidopsis (Yu et al ., ). The remarkable functional conservation of the ABA response pathway components might allow for the use of ABA receptors from Arabidopsis to engineer poplar trees with enhanced WUE.…”

A survey of the pyrabactin resistance-like abscisic acid receptor gene family in poplar

“…All these results indicate that PtPYRL1 and PtPYRL5 confer transgenic Arabidopsis seedlings more sensitive to ABA responses. 7 However, whether PtPYRL1 and PtPYRL5 play the similar functions in poplar remains further study.…”

“…Considering that PYR/ PYL/RCARs play potential roles in the tolerance to cellular dehydration, we recently reported that Polulus trichocarpa genome has 14 PYR/PYL/RCAR orthologs (14 PtPYRLs) through a blast search against Arabidopsis thaliana AtPYR1 protein (At4G17870.1) sequence, indicating poplar might have multiple ABA signaling networks. 7 14 PtPYRLs are classified into 3 subclasses, same as those in Arabidopsis. 2,3,7 We used PtPYL1 and PtPYRL5, the genes encoding the closest and the lowest amino acid sequence to AtPYR1, respectively, to transiently express in Arabidopsis thaliana, and found that overexpression of PtPYRL1 or PtPYRL5 decreased germination rates in transgenic Arabidopsis seeds.…”

“…7 14 PtPYRLs are classified into 3 subclasses, same as those in Arabidopsis. 2,3,7 We used PtPYL1 and PtPYRL5, the genes encoding the closest and the lowest amino acid sequence to AtPYR1, respectively, to transiently express in Arabidopsis thaliana, and found that overexpression of PtPYRL1 or PtPYRL5 decreased germination rates in transgenic Arabidopsis seeds. Furthermore, PtPYRL1 and PtPYRL5 enhanced stomatal closure but reduced transpiration rate in transgenic Arabidopsis seedlings, leading to improving drought resistance in these plants.…”