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Jia L, Zhang X, Zhang Z, Luo W, Nambeesan SU, Li Q, Qiao X, Yang B, Wang L, Zhang S. PbrbZIP15 promotes sugar accumulation in pear via activating the transcription of the glucose isomerase gene PbrXylA1. Plant J 2024; 117:1392-1412. [PMID: 38044792 DOI: 10.1111/tpj.16569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 11/01/2023] [Accepted: 11/20/2023] [Indexed: 12/05/2023]
Abstract
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 between the sucrose content and the expression levels of several sucrose-biosynthesis-related genes (PbrFRK3/8, PbrSPS1/3/4/8, and PbrSPP1) in PbrbZIP15-/PbrXylA1-transgenic fruit/calli. In conclusion, our results suggest that PbrbZIP15-induced soluble sugar accumulation during pear development is at least partly attributed to the activation of PbrXylA1 transcription.
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Affiliation(s)
- Luting Jia
- National Key Laboratory of Crop Genetics and Germplasm Enhancement and Utilization, Sanya Institute of Nanjing Agricultural University, College of Horticulture, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, China
| | - Xu Zhang
- National Key Laboratory of Crop Genetics and Germplasm Enhancement and Utilization, Sanya Institute of Nanjing Agricultural University, College of Horticulture, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, China
| | - Zan Zhang
- National Key Laboratory of Crop Genetics and Germplasm Enhancement and Utilization, Sanya Institute of Nanjing Agricultural University, College of Horticulture, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, China
| | - Weiqi Luo
- U.S. Horticultural Research Laboratory, ARS-USDA, Ft. Pierce, Florida, 34945, USA
- CIPM, NC State University, Raleigh, North Carolina, 27606, USA
| | | | - Qionghou Li
- National Key Laboratory of Crop Genetics and Germplasm Enhancement and Utilization, Sanya Institute of Nanjing Agricultural University, College of Horticulture, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, China
| | - Xin Qiao
- National Key Laboratory of Crop Genetics and Germplasm Enhancement and Utilization, Sanya Institute of Nanjing Agricultural University, College of Horticulture, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, China
| | - Bing Yang
- National Key Laboratory of Crop Genetics and Germplasm Enhancement and Utilization, Sanya Institute of Nanjing Agricultural University, College of Horticulture, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, China
| | - Libin Wang
- National Key Laboratory of Crop Genetics and Germplasm Enhancement and Utilization, Sanya Institute of Nanjing Agricultural University, College of Horticulture, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, China
| | - Shaoling Zhang
- National Key Laboratory of Crop Genetics and Germplasm Enhancement and Utilization, Sanya Institute of Nanjing Agricultural University, College of Horticulture, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, China
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