Molecular Approaches on Anthracnose and Powdery Mildew Resistance Breeding in Chilli

UNIVERSITY OF AGRICULTURAL SCIENCES, RAICHUR

College of Agriculture, Raichur

Department of Genetics and Plant Breeding

Master’s Seminar – II

Molecular Approaches on Anthracnose and Powdery Mildew Resistance Breeding in Chilli

    Chilli (Capsicum spp.) is an important commercial spice and vegetable crop for small and marginal farmers in Asia, Africa, and South America. In chilli production, anthracnose and powdery mildew are the major constraints, causing more than 50% yield reduction. Anthracnose is one of the most destructive fungal diseases affecting both pre-harvest and post-harvest stages in chilli-growing regions. It is mainly caused by Colletotrichum truncatum, Colletotrichum gloeosporioides, and Colletotrichum acutatum. These species can be identified by morphological or molecular characteristics, with molecular approaches proving more reliable (Ridzuan et al., 2018).

    QTL mapping has been conducted in Capsicum baccatum genotypes (PBC80 and PBC81) and Capsicum chinense genotype (PBC932) to identify specific markers for anthracnose resistance. Identification of proper molecular markers allows differentiation of resistant lines from susceptible ones, which can then be used as valuable sources in further breeding programs (Mahasuk et al., 2016). Suwor et al. (2015) evaluated 35 chilli lines derived from resistant sources (C. baccatum PBC80 and C. chinense PBC932). Using SSR and SCAR markers, they validated resistance, where the primer HpmsE032 amplified a 231 bp DNA fragment associated with resistance to C. capsici at the green fruit stage. This marker proved useful for selecting resistant genotypes derived from PBC80.

    Powdery mildew, caused by Leveillula taurica, is another major fungal disease in Capsicum annuum. Being an obligate pathogen, it significantly affects yield and quality. Molecular markers have been developed for identifying powdery mildew resistance in chilli (Jo et al., 2017). Rajesh et al. (2018) identified SCAR markers from F₂ mapping populations developed between resistant line ‘Odisha Local’ and susceptible line ‘9907-9611’. Sequencing revealed partial similarity with the RPP13-like resistance gene. These markers are valuable in marker-assisted breeding programs for indirect selection of resistant plants.

    Plant diseases remain a major challenge in crop production as they reduce yield, compromise produce quality, and shorten post-harvest storage life. Developing resistant varieties is the most sustainable solution. Conventional breeding through phenotypic selection is time-consuming, whereas molecular breeding, particularly marker-assisted selection (MAS), enables efficient introgression of resistance genes and pyramiding of multiple resistance loci into a single genotype. Additionally, advanced tools such as CRISPR/Cas technology provide opportunities to knock out susceptibility genes, thereby enhancing chilli productivity and quality.

References

• Ridzuan, R., Rafii, M.Y., Ismail, S.I., Mohammad Yusoff, M., Miah, G. and Usman, M., 2018. Breeding for anthracnose disease resistance in chili: Progress and prospects. Int. J. Mol. Sci., 19(10):3122.

• Mahasuk, P., Struss, D. and Mongkolporn, O., 2016. QTLs for resistance to anthracnose identified in two Capsicum sources. Mol. Plant Breed., 36(1):10.

• Suwor, P., Thummabenjapone, P., Sanitchon, J., Kumar, S. and Techawongstien, S., 2015. Phenotypic and genotypic responses of chilli (Capsicum annuum L.) progressive lines with different resistance genes against anthracnose pathogen (Colletotrichum spp.). Eur. J. Plant Pathol., 143(4):725–736.

• Jo, J., Venkatesh, J., Han, K., Lee, H.Y., Choi, G.J., Lee, H.J., Choi, D. and Kang, B.C., 2017. Molecular mapping of PMR1, a novel locus conferring resistance to powdery mildew in pepper (Capsicum annuum). Front. Plant Sci., 8:2090.

• Wankhade, R.R. and Wadikar, M.S., 2018. Identification of sequence-characterized amplified regions (SCARs) markers linking resistance to powdery mildew in chilli pepper (Capsicum annuum L.). Afr. J. Agric. Res., 13(49):2771–2779.