Expression of Fusarium wilt resistant gene, FocBo1, in association with disease resistant phenotypes of cabbage breeding lines = 양배추 육성계통을 이용한 시들음병 저항성과 FocBo1 유전자 발현과의 관계 분석

Abstract

Fusarium wilt, caused by a fungal pathogen Fusarium oxysporum f. sp. conglutinans (Foc), is a destructive disease of Brassica oleracea var. capitata. Currently, there are reports concerning molecular markers linked to Fusarium wilt disease resistance gene (FocBo1) in cabbage. In this study, we have studied a relationship between the FocBo1 gene and six cabbage breeding lines obtained from Asia Seed Company. The six cabbage breeding lines were evaluated resistance levels to Foc by combing of disease phenotypes and fungal biomass in planta. Of 6 breeding lines, KR-518 and OK-517 presented strong resistance and RK-P6-1, moderately resistance, whereas MT-624, JK-2, and HY-164, were susceptible to Foc. To define the correlation between the wilt disease resistance phenotype and the presence of resistance FocBo1 gene, we employed RT-PCR with MTK-C marker, which is known to be linked to FocBo1 resistant gene. The results exhibited inaccuracy in differentiating resistant and susceptible plants with genomic DNA samples, but it shows 100% correlation with cDNAs, indicating there is exceptional breeding line that contains FocBo1 gene in its genome with no expression. After cloning and sequencing the MTK-C product, a specific molecular marker, FocBo1-C, was developed which amplify a single, easily resolved band from cDNA of cabbage breeding lines with FocBo1 gene. Altogether, these results indicate that the three cabbage breeding lines in resistant category contain the resistance FocBo1 gene and moreover, the expression level of FocBo1 affect the degree of resistance of cabbage breeding lines, suggest the semidominant nature of FocBo1 gene in cabbage.