クロマメにおけるSCARおよびqRT-PCRベース絶対定量によるYMV抵抗性遺伝子型の迅速検出の開発

Black gram [Vigna mungo (L.) Hepper] is an important food legume whose productivity in the Indian subcontinent has declined due to multiple abiotic and biotic stresses, particularly Yellow Mosaic Virus (YMV), a major yield-limiting pathogen. To support the development of YMV-resistant varieties, the present study aimed to identify reliable molecular markers associated with YMV resistance. A bi-parental mapping population was developed from two contrasting genotypes-NUK 17 - 05 (highly resistant) and VUG 49 (highly susceptible)-and subjected to bulked segregant analysis using RAPD markers. A polymorphic RAPD marker (OPAD17) linked to resistance was identified and subsequently converted into a stable SCAR marker, designated SCAR15 (238 bp). SCAR15 consistently differentiated resistant and susceptible parents based on band intensity and was validated using F₂ individuals representing extreme phenotypes. qRT-PCR analysis confirmed that resistance was associated with copy number variation at the SCAR15 locus. Resistant lines showed a copy number > 0.1 with a mean value of 1.85, whereas susceptible lines had a mean copy number of 0.06. These results demonstrate that YMV resistance in the studied population is linked to genomic copy number variation. The SCAR15 marker developed in this study provides a robust tool for marker-assisted selection and breeding of YMV-resistant black gram genotypes.