果树学报2012，Vol.29Issue(1)：17-23,7.
翠冠梨PG基因家族两成员的克隆及其表达与货架期果实软化的关系
Cloning two members of PG gene family from precocious sandy pear Cuiguan and the relationship between their expression and fruit softening during shelf life
摘要
Abstract
PpPG1 and PpPG2, two numbers of the polygalacturonase gene family were cloned from preco- cious sandy pear Cuiguan （Pyrus pyrifolia Nakai.） fruit by RT-PCR and RACE methods. The results showed that PpPG1 cDNA sequence length is 1 793 bp, which has an open reading frame from 287 to 1 666 nucleotides and encodes a polypeptide including 459 residues. At the same time, PpPG1 DNA se- quence consists of eight exons and seven introns. Predicted isoelectric point （pI） and relative molecular mass of PpPG1 protein were 8.47 and 49.45 ku, respectively. PpPG2 cDNA sequence length is 1 671 bp, which has an open reading frame from 120 to 1 316 nucleotides and encodes a polypeptide including 398 residues. At the same time, PpPG2 DNA sequence consists of three exons and two introns. Predicted iso- electric point （pI） and relative molecular mass of PpPG2 protein were 7.34 and 41.14 ku, respectively. Both PpEG1 and PpEG2 had glucoside hydrolase glyco-hydro-28 superfamily and polygalacturonase conserved domains. The phylogenetic tree analysis showed that PpPG1 and PpPG2 located at two different clades. The semi-quantitative RT-PCR results showed that both PpPG1 and PpPG2 gene expression abun- dance increased and then decreased during summer shelf life （28 to 32 ~C ）. Their expression peaks ap- peared at 16 and 8 days after harvest, respectively. After 1-MCP treatment, PpPG1 expression at postharvest 8 days was inhibited but its expression pattern was not affected. However, PpPG2 expression peak was delayed to postharvest 16 days but its expression abundant was not changed. The fruit characteristics changed after 1-MCP treatment, such as polygalacturonase activity increase speed alleviated, ethylene re- lease rate decreased and fruit firmness decline speed slowed down. It was concluded that PpPG1 and PpPG2 were different numbers of polygalacturonase gene family and their expressions were regulated by ethylene. Both of them played roles in Cuiguan fruit softening during summer shelf life （28 to 32℃ ）.关键词
砂梨/多聚半乳糖醛酸酶/基因克隆/序列分析/表达特点Key words
Pyrus pyrifolia Nakai./Polygalacturonase/Gene cloning/Sequence analysis/Expression characteristic分类
农业科技引用本文复制引用
李慧,丛郁,常有宏,蔺经,盛宝龙..翠冠梨PG基因家族两成员的克隆及其表达与货架期果实软化的关系[J].果树学报,2012,29(1):17-23,7.基金项目
948项目 （）
