蓖麻根腐病抗性鉴定及其SSR标记的初步建立

蓖麻根腐病是茄腐镰孢菌(Fusarium solani)引起的根部病害,严重影响蓖麻产量。抗源缺乏制约了抗病品种的选育。为寻找抗病种质、建立抗性分子标记,该研究对252份蓖麻材料的抗性进行了表型和分子标记鉴定。结果表明:(1)浓度为1×10⁶个·mL^-1的孢子悬浮液灌根是一种有效的接种方法; 以接种后枯萎天数为基础的5级评价法,可作为鉴定标准。(2)鉴定出130份抗病材料,其中高抗为105份。(3)野生材料中抗病材料比率(66%)远高于栽培材料(35%),建议将野生材料,尤其是中国华南野生材料的研究利用作为今后抗病育种的重要方向。(4)初步建立了8个与抗性关联的SSR标记。该研究结果提供了有效的根腐病抗性鉴定方法和评价标准,筛选出了一批育种迫切需要的抗病基因资源,初步建立了可用于辅助选择的SSR标记,为蓖麻抗根腐病育种奠定了重要基础。

Identification of resistance to root rot and preliminary establishment of its SSR markers in castor bean

Castor bean root rot is a root disease caused by Fusarium solani, which seriously threatens the production of castor bean. Due to the lack of resistance genes, the breeding for root rot resistance in castor bean is seriously restricted. In order to mine resistant resources and establish resistant molecular markers, the phenotypic and molecular marker identification was performed on the disease resistance of 252 castor bean accessions in this study. The results were as follows:(1)Irrigating roots with the conidia suspension of 1×10⁶ spores·mL^-1 was an effective inoculation method. The 5-grade evaluation method based on the days of wilt after inoculation could be used as the criteria to evaluate the resistant level of accessions objectively.(2)According to the criteria, the resistance of 252 accessions were divided into five grades from high to low, among which Grade 1 was high resistance and Grade 2 was moderate resistance. The number of accessions with different grades from 1 to 5 were 105, 25, 33, 31 and 58, respectively, accounting for 42%, 10%, 13%, 12% and 23%, respectively. A total of 130 resistant accessions were identified, of which 105 were high resistance and 25 were moderate resistance.(3)The proportion of resistant accessions in wild accessions(66%)was much higher than that in cultivated accessions(35%). Among wild accessions from South China, 69% were resistant accessions, and 60% were high resistance accessions. It is strongly suggested that the research and utilization of wild accessions, especially the wild accessions in South China, should be an important direction of resistance breeding in the future.(4)Eight SSR markers associated with the resistance were preliminarily established. Although different resistant accessions carried different markers or marker combinations, most of them carried three to four of the above markers, therefore, they can be used as resistant molecular markers for assisted selection. The results of this study provide an effective method and evaluation criteria for root rot resistance identification, screen out a number of resistance genetic resources urgently needed in breeding, and preliminarily establish the SSR markers available for assisted selection, which lay an important foundation for resistance breeding of castor bean root rot.