AUTHOR=Liu Hangkong , Qian Ming , Song Chunhui , Li Jinjin , Zhao Caiping , Li Guofang , Wang Anzhu , Han Mingyu 

TITLE=Down-Regulation of PpBGAL10 and PpBGAL16 Delays Fruit Softening in Peach by Reducing Polygalacturonase and Pectin Methylesterase Activity

JOURNAL=Frontiers in Plant Science

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2018.01015

DOI=10.3389/fpls.2018.01015

ISSN=1664-462X

ABSTRACT=<p>β-galactosidases are cell wall hydrolases that play an important role in fruit softening. However, <italic>PpBGAL</italic>s mechanism impacting on ethylene-dependent peach fruit softening was still unclear. In this study, we found that <italic>PpBGAL4, -6, -8, -10, -16</italic>, and -<italic>17</italic> may be required for ethylene-dependent peach softening and <italic>PpBGAL10</italic>, -<italic>16</italic> may make a main contribution to it among 17 <italic>PpBGALs</italic>. Utilization of virus-induced gene silencing (VIGS) showed that fruits were firmer than those of the control at 4 and 6 days after harvest (DAH) when <italic>PpBGAL10</italic> and <italic>PpBGAL16</italic> expression was down-regulated. Suppression of <italic>PpBGAL10</italic> and <italic>PpBGAL16</italic> expression also reduced <italic>PpPG21</italic> and <italic>PpPME3</italic> transcription, and polygalacturonase (PG) and pectinmethylesterases (PME) activity. Overall, total cell wall material and protopectin slowly declined, water-soluble pectin slowly increased, and cellulose and hemicellulose was altered significantly at 4 DAH, relative to control fruit. In addition, <italic>PpACO1</italic> expression and ethylene production were also suppressed at 4 DAH because of inhibiting <italic>PpBGAL10</italic> and <italic>PpBGAL16</italic> expression. These results suggested that down-regulation of <italic>PpBGAL10</italic> and <italic>PpBGAL16</italic> expression delays peach fruit softening by decreasing PG and PME activity, which inhibits cell wall degradation and ethylene production.</p>