Breeding for Anthracnose Disease Resistance in Chili Pepper (Capsicum annum L.) using Gamma Irradiation

Chili peppers were treated with gamma irradiation to develop anthracnose disease resistance. Seeds of chili peppers were irradiated with gamma rays at 0, 100, 200, 300, 400 and 500 Gy to determine the optimal dose for mutation breeding. The LD50 value was calculated to be 264.83 Gy. The 300 Gy gamma-irradiated chili pepper seeds (Capsicum annuum L.) were planted in the experiment field at Nan Agricultural Research and Development Center, Thailand for mutation selection. The results showed that the irradiated chili plants not only survived the anthracnose infection but also produced fruits. These fruits were less affected or unaffected by the anthracnose disease compared to the control group (unirradiated) which showed damages on every part of chili plant. The 28 healthy chili pepper plants in M3 generation that showed anthracnose resistant traits were selected as seeds for M4 generation. Two chili pepper lines in M4 generation exhibited the highest resistance to anthracnose. From the pathogenicity test, those 2 chili pepper lines were found to have resistance to anthracnose disease caused by both Colletotrichum gloeosporioides and Colletotrichum capsici. HIGHLIGHTS Gamma irradiation has been applied to induce mutation in chili peppers to increase anthracnose resistance The gamma-ray dose of 300 Gy was found to be optimum for inducing anthracnose resistance characteristics in chili peppers Two chili pepper anthracnose resistance mutant lines were discovered, with additional desired characteristics: Shrub-shaped plant and erect or upright fruits which are convenient for harvesting GRAPHICAL ABSTRACT