Ming Qian1,2, Ze Xu1, Zehua Zhang1, Qin Li1, Xiangyan Yan1, Hangkong Liu1, Mingyu Han1, Furui Li1, Jicheng Zheng1, Dong Zhang1, Caiping Zhao3. 1. College of Horticulture, Northwest A&F University, Yangling, China. 2. State Key Laboratory of Crop Genetics and Germplasm Enhancement, Centre of Pear Engineering Technology Research, Nanjing Agricultural University, Nanjing, China. 3. College of Horticulture, Northwest A&F University, Yangling, China. zhcc@nwsuaf.edu.cn.
Abstract
MAIN CONCLUSION: The downregulation of PpPG21 and PpPG22 expression in melting-flesh peach delays fruit softening and hinders texture changes by influencing pectin solubilization and depolymerization. The polygalacturonase (PG)-catalyzed solubilization and depolymerization of pectin plays a central role in the softening and texture formation processes in peach fruit. In this study, the expression characteristics of 15 PpPG members in peach fruits belonging to the melting flesh (MF) and non-melting flesh (NMF) types were analyzed, and virus-induced gene silencing (VIGS) technology was used to identify the roles of PpPG21 (ppa006839m) and PpPG22 (ppa006857m) in peach fruit softening and texture changes. In both MF and NMF peaches, the expression of PpPG1, 10, 12, 23, and 25 was upregulated, whereas that of PpPG14, 24, 35, 38, and 39 was relatively stable or downregulated during shelf life. PpPG1 was highly expressed in NMF fruit, whereas PpPG21 and 22 were highly expressed in MF peaches. Suppressing the expression of PpPG21 and 22 by VIGS in MF peaches significantly reduced PG enzyme activity, maintained the firmness of the fruit during the late shelf life stage, and suppressed the occurrence of the "melting" stage compared with the control fruits. Moreover, the downregulation of PpPG21 and 22 expression also reduced the water-soluble pectin (WSP) content, increased the contents of ionic-soluble pectin (ISP) and covalent-soluble pectin (CSP) and affected the expression levels of ethylene synthesis- and pectin depolymerization-related genes in the late shelf life stage. These results indicate that PpPG21 and 22 play a major role in the development of the melting texture trait of peaches by depolymerizing cell wall pectin. Our results provide direct evidence showing that PG regulates peach fruit softening and texture changes.
MAIN CONCLUSION: The downregulation of PpPG21 and PpPG22 expression in melting-flesh peach delays fruit softening and hinders texture changes by influencing pectin solubilization and depolymerization. The polygalacturonase (PG)-catalyzed solubilization and depolymerization of pectin plays a central role in the softening and texture formation processes in peach fruit. In this study, the expression characteristics of 15 PpPG members in peach fruits belonging to the melting flesh (MF) and non-melting flesh (NMF) types were analyzed, and virus-induced gene silencing (VIGS) technology was used to identify the roles of PpPG21 (ppa006839m) and PpPG22 (ppa006857m) in peach fruit softening and texture changes. In both MF and NMF peaches, the expression of PpPG1, 10, 12, 23, and 25 was upregulated, whereas that of PpPG14, 24, 35, 38, and 39 was relatively stable or downregulated during shelf life. PpPG1 was highly expressed in NMF fruit, whereas PpPG21 and 22 were highly expressed in MF peaches. Suppressing the expression of PpPG21 and 22 by VIGS in MF peaches significantly reduced PG enzyme activity, maintained the firmness of the fruit during the late shelf life stage, and suppressed the occurrence of the "melting" stage compared with the control fruits. Moreover, the downregulation of PpPG21 and 22 expression also reduced the water-soluble pectin (WSP) content, increased the contents of ionic-soluble pectin (ISP) and covalent-soluble pectin (CSP) and affected the expression levels of ethylene synthesis- and pectin depolymerization-related genes in the late shelf life stage. These results indicate that PpPG21 and 22 play a major role in the development of the melting texture trait of peaches by depolymerizing cell wall pectin. Our results provide direct evidence showing that PG regulates peach fruit softening and texture changes.
Authors: Fabrizio Costa; Cameron P Peace; Sara Stella; Sara Serra; Stefano Musacchi; Micaela Bazzani; Silviero Sansavini; W Eric Van de Weg Journal: J Exp Bot Date: 2010-05-12 Impact factor: 6.992
Authors: Ross G Atkinson; Paul W Sutherland; Sarah L Johnston; Kularajathevan Gunaseelan; Ian C Hallett; Deepali Mitra; David A Brummell; Roswitha Schröder; Jason W Johnston; Robert J Schaffer Journal: BMC Plant Biol Date: 2012-08-02 Impact factor: 4.215