毛棉苗期抗旱性状的QTL定位

Mapping QTLs for Traits Related to Drought Tolerance at the Seedling Stage in an Inter-Specific Gossypium hirsutum × Gossypium tomentosum F_(2:3) Population

【目的】通过分析毛棉苗期抗旱相关性状的数量性状位点(Quantitative trait locus,QTL),以期检测稳定的主效QTL,促进栽培品种抗旱性状遗传改良及提高抗旱育种效率。【方法】以四倍体野生种毛棉(Gossypium tomentosum)和陆地棉品种中棉所12(CCRI 12)的种间杂种F2及其F2:3家系为研究材料,用于基因型分型的F2有188个系,用于表型分型的F2:3家系有149个株系。分别在干旱胁迫和正常灌水2个环境下调查表型数据。采用复合区间作图法对F2:3家系苗期相关性状抗旱系数进行QTL定位。【结果】对苗期相关性状抗旱系数的QTL定位分析,共得到16个QTL,其中与株高、叶片数、叶绿素含量、脯氨酸含量、丙二醛含量抗旱系数相关的QTL分别有5个、1个、3个、3个、4个,分布在13条染色体上。来自毛棉的5个加性QTL分别为qSHDC-19-1、qSHDC-19-2、qSLNDC-5-1、qMDADC-24-1、qMDADC-24-2,其加性效应值为0.10~0.22,解释变异9.4%~25.8%。【结论】这些与抗旱相关的QTL有助于棉花抗旱分子标记辅助选择。

[Objective] The aim of this study was to reveal the genetic basis of drought tolerance traits and detect major quantitative trait loci （QTLs） by mapping drought tolerance QTLs on the Gossypium tomentosum genome. This information may be useful for developing drought-tolerant cotton cultivars. [Method] The present study examined the genetic basis of drought tolerance in 188 F2 lines and 149 F2：3 lines developed from an interspecific cross between a wild cotton species, Gossypium tomentosum, and an upland cotton variety （CCRI 12）. Five morpho-physiological traits （i.e., height, number of leaves, and chlorophyll, malon- dialdehyde, and proline contents） were assessed under water-limited （Wl） and well-watered （W2） conditions during the seedling stage. Additionally, the composite interval mapping method was used for QTL mapping of drought resistance coefficients for the abovementioned traits. [Results] Sixteen significant QTLs were detected on 13 chromosomes in the F23 population. We detected five QTLs for plant height, one for the number of leaves, three for chlorophyll content, three for leaf malondialdehyde content, and four for proline content. The qSHDC-19-1, qSHDC-19-2, qSLNDC-5-1, qMDADC-24-1, and qMDADC-24-2 alleles were derived from G. tomentosum, and explained 9.4%-25.8% of the phenotypic variation. [Conclusion] These results may help elu- cidate the genetic basis of drought tolerance in cotton, and may be important for breeding programs involved in marker-assisted development of new cultivars with improved tolerance to drought stress.