四倍体鸭茅产量及其构成因素的QTL定位

产量相关性状是复杂的数量性状,对鸭茅的单株产量及构成因素进行QTL分析,可提高育种中对产量性状优良基因选择的效率,同时为鸭茅遗传改良、基因克隆及分子标记辅助育种提供理论依据。以四倍体鸭茅“楷模”和“01436”为亲本杂交而成的作图群体为试验材料,于2014年对洪雅、宝兴两个不同生境下鸭茅株高、旗叶长、倒二叶长、旗叶宽、倒二叶宽、茎粗、花序长、分蘖数、单株干重等9个产量相关性状进行了表型鉴定及相关性分析。此外,在已构建的高密度鸭茅分子遗传图谱的基础上,采用MapQTL 5.0进一步对这些性状QTL定位分析。结果表明,绝大多数性状在亲本间呈显著差异且都整体表现出连续变异,符合数量性状遗传的特征;相关性分析表明,大多数产量相关性状均与干重极显著正相关,与单株干重相关性最好的依次为分蘖、株高;QTL分析发现,控制该9个农艺性状的QTL共60个,洪雅38个,宝兴22个,这些QTL分别定位于分子连锁图谱的1、2、3、4、5共5个连锁群上,单个QTL的贡献率为5.7%~24.7%,单个性状QTL个数为2~15个。其中,控制株高、花序长的QTL各12个,控制倒二叶长、茎粗的QTL各4个,控制旗叶宽、倒二叶宽的QTL各2个,控制单株干重的QTL有6个,影响分蘖的QTL为3个,与旗叶长相关的QTL最多15个。

QTL analysis of nine biomass-related traits in tetraploid orchardgrass using ultra-high-density genetic mapping

We have identified the QTLs(quantitative trait locus) of biomass-related traits in tetraploid orchardgrass in order to improve selection efficiency for good yield genotypes and to provide a basis for molecular-assisted breeding. The test materials used were a hybrid offspring population consisting of 214 individuals from a cross of two cultivars, ‘Kaimo’ (female parent) and ‘01436’ (male parent). In 2014, phenotypic identification and correlation analyses were carried out on nine biomass-related traits in two different habitats, Hongya and Baoxing. Based on the integrated map, the QTLs of nine biomass-related traits were analyzed using MapQTL 5.0: plant height (PH), flag leaf length (FLL), second leaf length (SLL), flag leaf width (FLW), secondleaf width (SLW), stem diameter (SD), inflorescence length (IL), tiller number (TN) and dry weight per plant (DW). Results indicated that most of the traits showed significant differences between parents and followed the normal distribution of continuous variation among populations, conforming with the hereditary characteristics of quantitative traits. Correlation analysis showed that most of the traits were significantly positively correlated with dry weight. The highest correlation with plant dry weight was tiller and plant height. A total of 60 QTLs were identified and distributed into 5 linkage groups (except for LG6 and LG7), with genetic contribution ranging from 5.7%-24.7%. For all of the 60 QTLs, the numbers for controlling plant height, flag leaf length, second leaf length, flag leaf width, second leaf width, stem diameter, inflorescence length, tiller number and dry weight per plant were 12, 15, 4, 2, 2, 4, 12, 3 and 6 respectively.