甜瓜幼苗下胚轴长度多世代联合遗传分析

Joint genetic analysis of hypocotyl length of melon seedlings using multiple generations

为了探明甜瓜幼苗下胚轴长度的遗传规律,以下胚轴长度差异明显的2个自交系329-1(P_(1))和Afgsnake(P_(2))为亲本构建1个F2和2个BC_(1)群体(B_(1)和B_(2)分别为F_(1)与P_(1)和P_(2)的BC_(1)),通过多世代联合分析法研究幼苗下胚轴长度的遗传方式。结果表明,甜瓜幼苗下胚轴长度表现出明显的数量性状特征,其最佳遗传模型为E-0,即2对加性-显性-上位性主基因+加性-显性-上位性多基因模型。2个主基因的加性效应较弱,其显性效应和互作效应较强,且易受环境因素的影响。春季B_(1:2)、B_(2:2)和F_(2:3)世代主基因遗传率分别为30.56%、67.56%和85.93%,秋季其主基因遗传率分别为77.01%、78.35%和83.95%,多基因遗传率(43.93%)主要存在春季B_(1:2)世代。研究结果明确了甜瓜幼苗下胚轴长度遗传方式,可为幼苗株型遗传改良提供理论依据。

Melon seedling raising under high-temperature seasons easily causes rapid hypocotyl prolongation leading to seedling overgrowth,which further affects quality of the seedlings.In order to clarify the genetic low of hypocotyl length of melon seedlings,two melon inbred lines 329-1(P_(1))and Afgsnake(P_(2)),which showed contrasting hypocotyl lengths at seeding stage,were used to develop one F2 and two BC_(1) populations(B_(1) and B_(2) act as the BC_(1) populations with F_(1)×P_(1) and F_(1)×P_(2),respectively).A method involving joint genetic analysis with multiple generations was used to pinpoint out the genetic model controlling hypocotyl length of melon seedlings.The results showed that hypocotyl length of melon seedlings revealed the typical characters of quantitative traits but deviated from the normal distribution.Long hypocotyl trait tended to conduct in recessive inheritance.The optimal genetic pattern for this trait was E-0 model,i.e.,two pairs of additive-dominance-epitasis major genes+additive-dominant-epistasis polygenes.In this model,additive effects of the two major genes was comparatively small but the dominant effects played a main role;interactive effects were observed among these genes.These genetic effects were also most sensitive to environment.Three generations(B_(1:2),B_(2:2)and F_(2:3))had major-gene heritabilities of 30.56%,67.56%and 85.93%in spring and 77.01%,78.35%and 83.95%in autumn,respectively.The heritability of polygene(43.93%)was only detected in B_(1:2) generation in spring.Selection efficiency of the major genes was much high in the early period of the generations(F2 and B_(2))and their self-bred progenies.B_(1) could be more suitable for selection for polygenes in special season.This study revealed the genetic pattern of hypocotyl length of melon seeding,offering a theoretical basis for genetic improvement of plant architecture for melon seedlings.