芜菁种质资源根肿病抗性鉴定及组织显微观察OACSTPCD

Clubroot is one of the main diseases of cruciferous crops.Screening the clubroot resistant(CR)materials of turnip(Brassica rapa ssp.rapifera),clarifying the distribution of CR genes,and analyzing the disease-resistance mechanism in turnip can provide a theoretical and practical basis for the breeding of turnip CR varieties.In this study,the resistance of 25 turnip materials to clubroot was identified by inoculating Plasraodiophora brassicae at the artificial seedling stage,the resistance genes were detected by molecular markers,and the infection process of Plasraodiophora brassicae and pathological changes of root were observed by Phloxine-B staining and paraffin section techniques.As a results,4 materials(immune and highly resistant),among which WJ-9,WJ-21,and WJ-22 exhibited immunity,while WJ-14 exhibited high resistance.In addition,WJ-10,WJ-13,and WJ-18 exhibit disease tolerance;and 18 susceptible(susceptible and highly susceptible)materials were identified.The total number of CR genes in the tested materials was in descending order:Crr3＞CRb＞Crr1a=CrrA5＞CRc＞Crr1＞CRa.WJ-22 was the material with the most resistance genes,containing a total of 6 resistance genes.There were differences in the infection process and pathological changes of Plasmodiophora brassicae in resistant and susceptible turnip roots.Compared with the susceptible material,the root hairs were infected later,the infection amount was less,and the cortex was not infected in the resistant materials.The root cells of the susceptible material would swell after Plasmodiophora brassicae invade,and the structure would be disordered.Swollen cells squeezed and destroyed root canals.The cell structure of the disease-resistant material was completed.In this study,4 turnip resources with resistance to clubroot were identified,the CR genes carried by them were clarified,and the infection process and tissue structure differences between resistant and susceptible materials were explored.It provides a scientific basis for cultivating varieties with durable resistance to clubroot.