李琼 梁晓雪 李文龙 侯娟 胡建斌 黄松

摘    要：為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（P1）和Afgsnake（P2）为亲本构建1个F2和2个BC1群体（B1和B2分别为F1与P1和P2的BC1），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B1：2、B2：2和F2：3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B1：2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。

关键词：甜瓜;下胚轴长度;主基因+多基因;遗传分析

中图分类号：S652 文献标志码：A 文章编号：1673-2871（2021）08-026-06

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

LI Qiong1， LIANG Xiaoxue1， LI Wenlong1， HOU Juan1， HU Jianbin1， HUANG Song2

（1. Henan Key Laboratory of Fruit and Cucurbit Biology（Zhengzhou）/College of Horticulture， Henan Agricultural University， Zhengzhou 450002， Henan， China; 2. Xinyang Agriculture and Forestry University， Xinyang 464001， Henan， China）

Abstract： 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 （P1） and Afgsnake （P2）， which showed contrasting hypocotyl lengths at seeding stage， were used to develop one F2 and two BC1 populations （B1 and B2 act as the BC1 populations with F1×P1 and F1×P2， 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 （B1：2， B2：2and F2：3） 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 B1：2 generation in spring. Selection efficiency of the major genes was much high in the early period of the generations （F2 and B2） and their self-bred progenies. B1 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.

Key words： Melon; Hypocotyl length; Major-gene plus polygene; Genetic analysis

甜瓜（Cucumis melo L.）是一年生蔓生植物，为葫芦科遗传多样性最为丰富的种之一。据联合国粮食及农业组织（FAO）数据统计，2018年世界甜瓜栽培面积为104.7万 hm?，总产量达273.5万t，其生产规模居世界十大果品之列[1]。作为一种世界性园艺作物，甜瓜的起源中心在非洲撒哈拉沙漠[2]，而驯化区域则十分广泛，包括整个亚洲（尤其是南亚和东亚）及地中海沿岸的北非和南欧等地[3]，其驯化区域大多属于热带和亚热带气候区，光热资源十分丰富。

作为典型的喜温植物，甜瓜生长期间对温度的要求较高，其生长适温为28～32 ℃，而幼苗对温度的要求更为严格，在10 ℃以下24 h内就出现冷害。……