S14 - Session P6 - Screening of sweet pepper genotypes for resistance to Colletotrichum fructicola, the predominant pathogen associated with fruit anthracnose under protective cultivation in Taiwan

Authors: Zong-ming Sheu *, Ming-Hsueh Chiu

Sweet pepper ( Capsicum annuum L.) is a high-value vegetable crop in Taiwan. Fruit anthracnose is one of the major constraints for sweet pepper production particularly in warm and wet conditions. The disease was incited by several different Colletotrichum species, but the pathogen population under protective cultivation is very less studied. A disease survey on sweet peppers in greenhouse or plastic nethouse was conducted in Taiwan during 2019 to 2020. A total of 51 fungal isolates were preliminarily determined at complex species level by morphology, specific PCR reaction or DNA sequence of the internal transcribed spacer of ribosomal DNA (rDNA-ITS). To confirm the fungal identity, 20 representative isolates were further analyzed by multi-locus phylogeny using the concatenate sequences of ITS, act, chs-1, gapdh, his-3, tub2 gene. The study revealed 5 distinct Colletotrichum species comprising C. scovellei , C. fructicola , C. siamense, C. plurivorum and C. truncatum associated with this farming system. Among them, C. fructicola belonging to C. gloeosporioides senu lato was predominant (~51%). So far, there is no study emphasizing the resistance to C. fructicola on sweet pepper. Therefore, through a pathogenicity test, a virulent strain Coll-1553 of C. fructicola was used to establish an inoculation protocol of resistance screening. A total of 30 sweet pepper genotypes comprising 12 germplasms, 16 breeding lines and 2 check varieties ( cv. Andalus and Hsin-AVRDC No.5 as susceptible and resistant check, respectively) were evaluated by the protocol. This study identified 13 resistant genotypes which produced average lesion size < 7mm in diameter on the inoculated fruits at 7 days after inoculation. However, segregations of resistance or other horticultural traits in most tested accessions were observed. This study first potential resistance source to C. fructicola, shall provide important basis in disease management of the crop particularly under protective cultivation.