Identification Of Calonectria Species In Guangzhou

Calonectria is a very important genus in plant pathogenic fungi, and there are many species which cause serious diseases on important forest trees and agricultural and horticultural crops in the genus, Guangdong is located in the southern subtropical monsoon climate zone, where the warm and humid climate is suitable for occurrence and development of the disease caused by the fungi of Calonectria. In order to clarify species which cause plant diseases and to establish foundations for the disease control, fungi of Calonectria on plants in Guangzhou were collected, isolated and identified through morphological method and molecular analysis. The results are presented below:16 isolates of Calonectria were isolated from plants in Guangzhou and identified via observation of morphological characters under the standard culture condition and sequence analysis of 5 genes, i.e. ACT, CAL, HIS3, TEF-1α,and TUB2. The results showed that 16 isolates could be identified as 11 species of 5 species complex: Calonectria spathiphyllicola, Ca. callistemonii, Ca. spathiphylli and Ca. hodgesii are in the Ca. cylindrospora species complex; Ca. orientalis is in the Ca. brassicae species complex; Ca. tibouchinae, Ca. pentaseptata and Ca. microconidialis are in the Ca. reteaudii species complex; Ca. crousiana is in the Ca. colhounii species complex; Ca. hongkongensis and Ca. ilicicola are in the Ca. kyotensis species complex. Among them, Ca. spathiphyllicola, Ca. callistemonii and Ca. tibouchinae are new species, Ca. orientalis and Ca. hodgesii are new records species in China. Clusia rosea and Melastoma sp. are new hosts for Calonectria, and Rosa sp. is a new host for Ca. hodgesii, Callistemon rigidus is a new host for Ca. pentaseptata and Ca. crousiana, Melaleuca bracteata is a new host for Ca. pentaseptata, Strelitzia reginae is a new host for Ca. microconidialis, Annona squamosa and Ananas sp. are new hosts for Ca. ilicicola. The photos and descriptions of colony and microscopic morphology of 16 isolates were provided.The result indicated that rich morphological diversity was exsisted in 16 isolates and there species were not easily distinguished only based on morphology, but they could be effectively identified through morphological method combining sequence analysis of ACT, CAL, HIS3, TEF-1α and TUB2. Among the five genes, ACT was the weakest for identification of Calonectria species, however, TEF-1α could effectively distinguish between sibling species in complex group.