甘蓝型油菜茎秆菌核病抗性与木质素及其单体比例的相关性分析及QTL定位

菌核病是一类非专一性的植物真菌病原菌，寄主范围广泛，严重危害农作物的生产。对高世代重组自交系群体(RIL)及F₂群体终花期茎秆进行菌核病抗性接种鉴定，根据构建的近红外模型对接种鉴定的茎秆木质素含量、单体组分比例进行测定，并进行相关性分析和QTL定位。结果表明在2013年和2014年RIL群体茎秆菌斑大小与木质素含量呈极显著负相关，相关系数分别为–0.348和–0.286，与单体G/S呈显著正相关，相关系数分别为0.198和0.167。2014年F₂群体菌斑大小与木质素含量呈极显著负相关，相关系数为–0.306，与单体G/S相关性为0.142。F_2:3家系抗(感)植株茎部切片间苯三酚染色观察表明抗性较强的材料木质素含量高于抗性较弱的材料。根据已构建的重组自交系高密度SNP遗传图谱，利用复合区间作图法对上述性状进行QTL分析，共检测到18个QTL，其中9个菌核病抗性相关QTL分布于A05、A06、C04和C06染色体，单个QTL可解释的表型变异为2.38%~12.05%；3个木质素含量QTL分别位于A04、A05和C01染色体，单个QTL可解释表型变异的2.03%~13.75%。6个木质素单体G/S QTL分布于A08、C03和C07染色体，单个QTL可解释表型变异的2.06%~8.66%。本文研究结果为油菜菌核病抗性育种提供了新的思路和理论基础。

Correlation Analysis of Sclerotinia Resistance with Lignin Content and Monomer G/S and its QTL Mapping in Brassica napus L.

Sclerotinia sclerotiorum is a fungal pathogen causing disease in a wide range of plants, resulting in serious damage in crop production. The detached stem inoculation assay of RIL and F₂ populations at final flowering stage was conducted, near infrared (NIR) spectroscopy was used to measure lignin content and monomer G/S in the stem, and correlation analysis and QTL mapping for these traits were performed. The lesion size of the RIL had a significantly negative correlation with lignin content, with a correlation coefficient at –0.348 and –0.286 in 2013 and 2014, respectively. The monomer G/S was significantly correlated with lesion size in the RIL population, and the correlation coefficient at 0.198 and 0.167 in 2013 and 2014, respectively. The lesion size of F₂ in 2014 was significantly and negatively correlated with lignin content in the stem, with a correlation coefficient at –0.306. The cross sections of resistant and susceptible plants from F_2:3 family were stained with phloroglucinol-HCl, showing that the content of lignin was significantly lower in the less resistant materials than in more resistant plants. According to the high density SNP genetic maps and composite interval mapping, a total of 18 QTLs were identified, which were located on A04, A05, A06, A08, C01, C03, C04, C06, and C07 chromosomes, with the explained phenotypic variation by individual QTL ranging from 2.38% to 12.05% for nine QTLs of lesion size, from 2.03% to 13.75% for three QTLs of lignin content, and from 2.06% to 8.66% for six QTLs of monomer G/S. The research results provide some new insights for the Sclerotinia resistance breeding in B. napus.