籽用和肉用印度南瓜果实发育过程中淀粉合成途径相关基因的表达分析

Analysis of Starch Accumulation Related Gene Expression during Seed-used and Meat-used Pumpkin(Cucurbita maxima) Fruit Development

以籽用印度南瓜自交系98-2及肉用印度南瓜自交系312-1为试材,对印度南瓜果实淀粉含量及淀粉代谢相关基因的表达模式进行研究。结果表明:312-1和98-2果实中的总淀粉和支链淀粉积累模式存在明显差异,312-1中总淀粉和支链淀粉积累模式相似,都是随着果实发育逐渐积累,在授粉后40d时达到高峰,随后略有下降,而98-2中总淀粉和支链淀粉含量一直维持在果实发育初期(授粉后5d)水平,没有显著积累的过程;在果实发育的各个时期312-1中总淀粉和支链淀粉含量均极显著高于98-2。2份材料中直链淀粉的积累模式大致相同,都维持在果实发育初期的积累水平,但在果实发育的各个时期312-1中直链淀粉含量均显著或极显著高于98-2。在淀粉组成上,2份材料均是以支链淀粉为主。淀粉合成途径关键酶基因除ISAⅢ、SSSⅡ和SBEⅡ基因外,GPT、AATP、PGM、AGPaseL、GBSSⅠ、SSSⅢ和SBEⅠ基因在2份材料果实发育过程中的表达趋势相似,其表达量在2份材料中存在较大差异,结合2份材料果实中直链淀粉和支链淀粉含量,推测GPT、AATP、AGPaseL、GBSSⅠ、SSSⅡ、SSSⅢ、SBEⅠ和SBEⅡ基因是调控印度南瓜果实中淀粉积累的关键酶基因。

Taking seed-used pumpkin inbred line ‘98-2’ and meat-used pumpkin inbred line ‘312-1’ as test materials,this paper studied on the starch content of pumpkin fruit and expression pattern of starch metabolism related genes.The results indicated that there existed significant differences in accumulation patterns of total starch and amylopectin of‘ 312-1’ and‘ 98-2’ fruits.The accumulation patterns of total starch and amylopectin in ‘312-1’ were similar.They were all accumulated gradually with fruit development,and the peak value appeared in 40 days after pollination,then decreased slightly.While,the contents of total starch and amylopectin in‘ 98-2’ maintained the same level at the early stage of fruit development(5 days after pollination)without significant accumulation process.The contents of total starch and amylopectin in‘ 312-1’ were significantly higher than that in‘ 98-2’ during each fruit development stage.The amylose accumulation pattern in the 2 materials was similar,all maintaining at accumulated level at the early fruit development stage.However,the amylose contents in ‘312-1’ at different fruit development stages were significantly or extremely significantly higher than that of‘ 98-2’.In starch composition,amylopectin was dominant in the 2 materials.In addition to ISA Ⅲ,SSSⅡ and SBEⅡ genes,the GPT,AATP,PGM,AGPaseL,GBSSⅠ, SSS Ⅲ and SBEⅠ genes had similar expression trends during fruit development process of these 2 materials, and their expression quantities had large differences.Combining the amylopectin and amylopectin contents in fruits of these 2 materials,the paper speculated that GPT,AATP,AGPaseL,GBSSⅠ,SSSⅡ,SSS Ⅲ, SBEⅠ and SBEⅡ genes were key genes regulating starch accumulation in pumpkin fruit.