Diversity and Distribution of Calonectria Species in Soils from Eucalyptus urophylla × E. grandis, Pinus massoniana, and Cunninghamia lanceolata Plantations in Four Provinces in Southern China

Abstract

The species of Calonectria include many notorious plant pathogens and are widely distributed around the world. Leaf blight caused by Calonectria species is considered one of the most prominent diseases in Eucalyptus plantations in China. Some Calonectria species isolated from soils in Eucalyptus plantations are highly pathogenic to inoculated Eucalyptus genotypes. In southern China, the plantation trees Cunninghamia lanceolata, Eucalyptus spp., and Pinus massoniana are always adjacently planted, especially in FuJian, GuangDong, GuangXi, and YunNan Provinces. The aim of this study was to understand the diversity and distribution of Calonectria in soils from plantations of different tree species in different geographic regions. Soil samples were collected from 12 sampling sites in Eucalyptus urophylla × E. grandis, P. massoniana, and C. lanceolata plantations in FuJian, GuangDong, GuangXi, and YunNan Provinces. Approximately 250 soil samples were collected from each sampling site, and a total of 2991 soil samples were obtained. A total of 1270 Calonectria isolates were obtained from 1270 soil samples. The 1270 isolates were identified based on DNA sequence comparisons of the partial gene regions of act, cmdA, his3, rpb2, tef1, and tub2. These isolates were identified as 11 Calonectria species: Calonectria aconidialis (69.50%), C. kyotensis (13.10%), C. hongkongensis (10.80%), C. ilicicola (2.50%), C. asiatica (2.36%), C. curvispora (0.31%), C. chinensis (0.24%), C. pacifica (0.24%), C. yunnanensis (0.16%), and C. canadiana (0.08%) in the C. kyotensis species complex and C. eucalypti (0.71%) in the C. colhounii species complex. The three dominant species, C. aconidialis, C. kyotensis, and C. hongkongensis, were widely distributed. The richness of Calonectria (percentage of soil samples that yielded Calonectria) in soils in the eastern regions (relatively humid regions) was higher than that in the western regions. The Calonectria richness of E. urophylla × E. grandis, P. massoniana, and C. lanceolata plantations decreased gradually. For each of the three dominant species, its richness in the eastern regions was generally higher than that in the western regions; the species richness was highest in E. urophylla × E. grandis plantations for C. aconidialis, while for each of C. kyotensis and C. hongkongensis, its species richness was highest in P. massoniana plantations. The genetic variation in C. aconidialis, C. kyotensis, and C. hongkongensis was more greatly affected by geographic region than by plantation tree species. This study expanded our understanding of the richness, species diversity, and distribution characteristics of Calonectria in soils from the plantations of different tree species in different geographic regions in southern China. Results in this study enhanced our understanding of the influencing characteristics of geographic region and tree species on the species and genetic diversity of soilborne fungi.

Wide Distribution and Intraspecies Diversity in the Pathogenicity of Calonectria in Soil from Eucalyptus Plantations in Southern Guangxi of China

“…The four species in the C. kyotensis species complex accounted for 97.9% of all the isolates obtained in this study. This is consistent with the results of previous studies showing that Calonectria species in the C. kyotensis species complex, especially C. aconidialis, C. hongkongensis, and C. kyotensis, are the dominant species distributed in the soil of Eucalyptus plantations in southern China [9,[23][24][25]. In addition to soil isolation, C. aconidialis, C. kyotensis, C. hongkongensis, and C. chinensis were also occasionally isolated from diseased Eucalyptus tissues [8,28,55].…”

“…hongkongensis , and C . kyotensis , are the dominant species distributed in the soil of Eucalyptus plantations in southern China [ 9 , 23 , 24 , 25 ]. In addition to soil isolation, C. aconidialis , C. kyotensis , C .…”

“…Currently, 137 Calonectria species have been discovered worldwide [ 12 , 15 , 16 , 20 , 21 , 22 , 23 ]. Among these, 84 species have been isolated from the soil near agricultural crops, plantations, natural forests, and unknown forest types in Asia, Africa, North America, and South America [ 9 , 12 , 15 , 16 , 20 , 22 , 23 , 24 , 25 , 26 , 27 ].…”

Effect of antifungal botanical extracts on seed-borne fungi prevalence and germination of Terminalia ivorensis seeds in Ghana

“…and Sclerotinia sclerotiorum. Li [24] isolated Fusarium, Penicillium, and Aspergillus from Pinus massoniana seeds in China. Gomes, [25] discovered a varied spectrum of fungi linked with the seeds of Brazilian savanna tree species, including Colletotrichum sp., Fusarium sp.…”