PbrbZIP15 promotes sugar accumulation in pear via activating the transcription of the glucose isomerase gene PbrXylA1

作者：Luting Jia, Xu Zhang, Zan Zhang, Weiqi Luo, Savithri U. Nambeesan, Qionghou Li, Xin Qiao, Bing Yang, Libin Wang, Shaoling Zhang · 发表于：The Plant Journal · 年份：2023 · DOI：10.1111/tpj.16569 · 被引用次数：31 · 研究领域：Plant nutrient uptake and metabolism、Polysaccharides and Plant Cell Walls、Postharvest Quality and Shelf Life Management

The composition and abundance of soluble sugars in mature pear (Pyrus) fruit are important for its acceptance by consumers. However, our understanding of the genes responsible for soluble sugar accumulation remains limited. In this study, a S1-group member of bZIP gene family, PbrbZIP15, was characterized from pear genome through the combined analyses of metabolite and transcriptome data followed by experimental validation. PbrbZIP15, located in nucleus, was found to function in fructose, sucrose, and total soluble sugar accumulation in pear fruit and calli. After analyzing the expression profiles of sugar-metabolism-related genes and the distribution of cis-acting elements in their promoters, the glucose isomerase 1 gene (PbrXylA1), whose corresponding protein catalyzed the isomerization of glucose and fructose in vitro, was identified as a downstream target gene of PbrbZIP15. PbrbZIP15 could directly bind to the G-box element in PbrXylA1 promoter and activate its transcription, as evidenced by chromatin immunoprecipitation-quantitative PCR, yeast one-hybrid, electrophoretic mobility shift assay, and dual-luciferase assay. PbrXylA1, featuring a leucine-rich signal peptide in its N-terminal, was localized to the endoplasmic reticulum. It was validated to play a significant role in fructose, sucrose, and total soluble sugar accumulation in pear fruit and calli, which was associated with the upregulated fructose/glucose ratio. Further studies revealed a positive correlation bet...