Morpho-biochemical and molecular profiling for Charcoal Rot (CR) disease resistance in Mung Bean [Vigna radiata (L.) Wilczek] landraces

Abstract

Background: Charcoal Rot (CR) poses a significant threat to mung bean crops by reducing yield, making the development of resistant varieties crucial for stable production and food security. This study evaluated 19 newly identified mung bean landraces using biochemical traits and SSR markers, revealing genetic variability, CR disease reactions, and traits influencing yield and resistance, which provide valuable insights for breeding CR-resistant, high-yielding varieties.

Methods and results: Mung bean landraces were evaluated for their response to CR using 4 biochemical parameters, and 10 SSR markers to assess genetic variability and disease resistance. The results revealed substantial variability in morpho-quantitative traits, and showed a significant variation in CR disease reaction (21% resistance, and 16% moderately resistance). Biochemical characterization suggested that, phenolic content (PHE), Peroxidase (POX) and polyphenol oxidase (PPO) activities exhibited narrow ranges, suggesting more uniformity in these biochemical traits under CR stress. Yield (YLD) showed a positive correlation with the number of pods per plant (NPDP) (0.459), PPO (0.912), PHE (0.867), and total chlorophyll (TCL) (0.864), but showed a negative correlation with POX (-0.64), indicating their positive influence on productivity. Conversely, CR resistance was strongly negatively correlated with YLD (-0.86). Moreover, as per the principal component analysis (PCA), 80.5% of the total variance was explained by the first three principal components. However, molecular characterization suggested the PIC values ranged from 0.281 to 0.871, with an average 0.58 indicating moderate to high polymorphism. Principal coordinate analysis (PCoA) grouped landraces based on their genetic makeup under CR stress, and the first three axes explained most of the variation (82.03%). Phylogenetic tree analysis confirmed the PCoA groupings with similarity coefficient varied from 0.57 to 0.98, suggesting the landraces within a cluster had lower genetic distances, and resistant and moderately CR resistant landraces fell into separate clusters.

Conclusion: The findings can be effectively utilized to develop CR-resistant mung bean varieties with enhanced productivity, contributing to stable mung bean production and food security.

Keywords: Charcoal rot (CR); Landrace; Mung bean; Resistance.