A mutation in the promoter of the arabinogalactan protein 7‐like gene PcAGP7‐1 affects cell morphogenesis and brassinolide content in pear (Pyrus communis L.) stems. (9th November 2021)

• Record Type: Journal Article
• Authors: Zheng, Xiaodong; Li, Yuchao; Ma, Changqing; Chen, Baoyin; Sun, Zhijuan; Tian, Yike; Wang, Caihong
• Is Part Of: Plant journal. Volume 109:Number 1(2022)
• Page Start: 47
• Page End: 63
• Publication Date: 2021-11-09
• Subjects: brassinolide -- cell morphogenesis -- dwarfing mechanism -- PcAGP7‐1 -- Pyrus communis; Plant molecular biology -- Periodicals; Plant cells and tissues -- Periodicals; Botany -- Periodicals; 580
• DOI: 10.1111/tpj.15548
• Languages: English
• ISSNs: 0960-7412

Abstract

SUMMARY: Dwarfing rootstocks and dwarf cultivars are urgently needed for modern pear cultivation. However, germplasm resources for dwarfing pear are limited, and the underlying mechanisms remain unclear. We previously showed that dwarfism in pear is controlled by the single dominant gene PcDw ( Dwarf ). We report here that the expression of PcAGP7‐1 ( ARABINOGALACTAN PROTEIN 7‐1 ), a key candidate gene for PcDw, is significantly higher in dwarf‐type pear plants because of a mutation in an E‐box in the promoter. Electrophoretic mobility shift assays and transient infiltration showed that the transcription factors PcBZR1 and PcBZR2 could directly bind to the E‐box of the PcAGP7‐1 promoter and repress transcription. Moreover, transgenic pear lines overexpressing PcAGP7‐1 exhibited obvious dwarf phenotypes, whereas RNA interference pear lines for PcAGP7‐1 were taller than controls. PcAGP7‐1 overexpression also enhanced cell wall thickness, affected cell morphogenesis, and reduced brassinolide (BL) content, which inhibited BR signaling via a negative feedback loop, resulting in further dwarfing. Overall, we identified a dwarfing mechanism in perennial woody plants involving the BL‐BZR/BES‐AGP‐BL regulatory module. Our findings provide insight into the molecular mechanism of plant dwarfism and suggest strategies for the molecular breeding of dwarf pear cultivars. Significance Statement: To explore the dwarfism mechanisms of pear, our group showed that the dwarf trait of pear is controlled by a single dominant gene, PcDw . In the present study, we found that the expression of PcAGP7‐1, a key candidate gene of PcDw, was significantly increased in dwarf‐type pears because of an E‐box deficiency in its promoter, and we also identified a novel dwarfing mechanism involving the BL‐BZR/BES‐AGP‐BL regulatory pathway. Our findings promote the exploration of the plant dwarfism mechanism.