QTL mapping of popping characteristics in popcorn using the model of trisomic inheritance in the endosperm

Chinese. 探讨爆裂玉米膨爆特性的分子遗传基础，为遗传改良和分子标记辅助选择提供有益信息。以普通玉米自交系丹232和爆裂玉米自交系N04为亲本构建259个F2s3家系群体，利用SSR标记构建分子标记遗传图谱，利用三倍体胚乳遗传模型和区间作图法对F2s3群体在两种环境条件下的膨爆特性进行了QTL定位和效应分析。构建的爆裂玉米SSR遗传连锁图谱包含183个标记，覆盖玉米基因组1762.2 cM，标记间平均距离为9.63 cM。爆裂玉米的膨爆特性是由效应不等的多基因控制的数量性状，同时受环境条件的影响。两种环境条件下共检测到18个爆花率QTL，17个膨化体积QTL和21个膨化倍数QTL。单个QTL可解释的表型变异介于4.4%～28.0%，可解释的表型总变异为65.8%～96.6%，基因的作用方式为加性、部分显性、显性和超显性的QTL数目分别为2、1、4、20和1、5、1、22，超显性在膨爆特性的遗传中起着最重要的作用。与以往膨爆特性以加性效应遗传为主的研究结果不一致的主要原因在于三倍体胚乳模型对显性效应的细分和对显性效应较小QTL的显性效应的高估。

English. The objective of this study was to investigate the molecular genetic basis of popping characteristics in popcorn and provide useful message for their genetic improvement and MAS. Two hundred and fifty-nine F2:3 families, derived from the cross between Dan232, a dent corn inbred and N04, a popcorn inbred, were evaluated for popping characteristics under two environments. One hundred and eighty three pairs of SSR markers were used to construct the genetic map. Quantative trait loci (QTL) were identified and their effects were evaluated for PR (popping rate), PV (popping volume) and PF (popping fold), using triploid endosperm genetic model and interval mapping method. The genetic linkage map spanned 1762.2 cM (centimorgan) and was on an average interval of 9.63 cM. Popping characteristics in popcorn were quantitative in nature, which were controlled by multiple genes with different effects and influenced by environments simultaneously. A total of 56 QTL with significant effects were detected under two environments, the numbers of QTL were 18, 17 and 21 for PR, PV and PF, respectively. Contribution to phenotypic variation of a single QTL varied from 4.4% to 28.0%, and total contributions of all QTL were from 65.8% to 96.6%. The amount of QTL showing additive, partial dominant, dominant and over-dominant effects were 2, 1, 4, 20 and 1, 5, 1, 22, respectively. Over-dominance played the most important role in their genetics. This was not consistent with the result of previous researches, in which additive effect was always considered as the most important part. The main reasons might be the detailed division of dominant effect and its overestimation for QTL with small dominant effect by the triploid endosperm genetic model.