Breeding for soft-rot disease (SRD)-resistant Phalaenopsis cultivars is crucial for ensuring sustainable orchid production in tropical regions. Indonesia is one of the centers of origin and diversity of Phalaenopsis. However, information on potential Phalaenopsis donor parents and the mechanisms underlying SRD resistance remains limited, posing challenges for conventional and biotechnological breeding approaches. The concerned study aimed to identify SRD-resistant species among 20 Phalaenopsis species native to Indonesia and determine the viable role of pre-existing mechanical structures in post-infection resistance. The SRD screening successfully identified three additional resistant species, namely, P. corningiana, P. modesta, and P. tetraspis, along with the previously known resistant species, P. amboinensis. Leaf anatomy and epidermal traits were remarkably showing significant differences among the species; however, the correlation of leaf anatomy and epidermal traits with SRD resistance was nonsignificant. The staining of cell wall components (cellulose, pectin, and lignin) revealed no considerable differences between the Phalaenopsis resistant and very susceptible species. The newly identified SRD-resistant species has yet to reach frequent usage in the Phalaenopsis breeding program, recognizing its potential for integration into the Phalaenopsis SRD-resistance breeding program. Study results suggested that physical leaf traits exerted less influence on the resistance response.
Phalaenopsis species, cultivars, Dickeya dadantii, pre-existing defense, soft-rot disease, SRD-resistance
The newly identified SRD-resistant Phalaenopsis species, namely, P. corningiana, P. modesta, and P. tetraspis, are yet to be utilized in a breeding program to authenticate their potential for integration into breeding programs to produce SRD-resistant cultivars.