苦瓜MAP30基因序列多态性与苦瓜瓜形连锁分析

Linkage Analysis Between the Polymorphism of MAP30 Gene Sequences and Fruit Phenotype in Bitter Gourd

瓜长和瓜刺是苦瓜瓜形非常重要的两个指标,研究这两个性状可以提高苦瓜的产量并获得理想的瓜形。本研究对从世界各地收集的177份种质资源通过自交获得表型稳定的纯系,并统计果实长度和瓜刺等重要农艺性状。苦瓜MAP30(Momordica anti-HIV protein of 30 kD)蛋白属于核糖体失活蛋白,具有降血糖和抗肿瘤等多种功效,通过对177份苦瓜种质资源中的MAP30基因进行多态性分析,发现MAP30基因编码区存在两个SNP(Single nucleotide polymorphism)位点,分别为20份材料的第6位碱基(G6A)和24份材料的第206位碱基(G206A),对应氨基酸的变化分别为蛋氨酸-异亮氨酸和组氨酸-精氨酸。进一步分析发现第6位(G6A)的20份材料中没有或极少有瓜刺,且瓜长在22~36 cm之间,这些材料主要分布在中国南方;而第206位(G206A)的24份材料大都带有瓜刺,并且瓜长在8.3~40.8 cm之间,这些材料主要从印度等南亚国家收集,更像野生种。以上研究表明,MAP30基因与瓜刺和瓜长连锁,并且可能是这两个性状的数量性状基因,同时也可作为区分野生种和中国驯化种的重要分子标记。

Fruit length and spine are two important traits that can improve fruit yield and obtain ideal fruit shape in bitter gourd breeding.In this study,we have collected 177 germplasm resources of bitter gourd from all over the world and obtained trait-stable lines via self-breeding,then recorded the phenotypes of each germplasm.MAP30 is a ribosome-inactivating protein(RIP)which has many pharmacological benefits on diabetes,tumor disease etc.By polymerase chain reaction(PCR)amplification and sequencing of the coding sequence of the MAP30 gene,the study only found 2 G to A SNPs(single nucleotide polymorphism)at the 6 th(G6 A)and 206 th(G206 A)nucleotide position,where the corresponding amino acids were changed from methionine to isoleucine and histidine to arginine,respectively.Further analysis indicated that the 20 germplasms with G6 A SNP were smooth and spineless on the skin,and the fruits have comparable length ranging from 22 cm to 36 cm.However,the other 24 germplasms with G206 A SNP showed lots of spine on the skin,and fruit lengths also showed lots of variations,ranging from8.3 cm to 40.8 cm.Meanwhile,the study also found that most of the 20 germplasms with G6 A were collected from the south of China,while the other 24 germplasms with G206 A were collected from South Asia countries.Taken together,the study identified MAP30 as a linkage or QTL with fruit length and spine on the skin,and a key molecular marker to distinguish the wild-type germplasm(South Asia countries)from the domesticated ones in China.