CgNPG1 as a Novel Pathogenic Gene of Colletotrichum gloeosporioides From Hevea brasiliensis in Mycelial Growth, Conidiation, and the Invasive Structures Development

Abstract

The rubber tree (Hevea brasiliensis) is a tropical perennial crop for the primary source of natural rubber. Colletotrichum gloeosporioides from Hevea brasiliensis (C. gloeosporioides Hb) and Colletotrichum acutatum from Hevea brasiliensis (C. acutatum Hb) are the causal agents of rubber tree anthracnose and lead to serious loss of natural rubber production. Inoculation tests showed that C. gloeosporioides Hb possessed higher pathogenicity than C. acutatum Hb to the rubber tree. Genomic analysis revealed that an unknown gene, named CgNPG1 (a Novel Pathogenic Gene 1), was presented in the genome of C. gloeosporioides Hb but not identified in C. acutatum Hb. CgNPG1 was predicted to encode a small secretory protein without any conserved domain. To investigate the functions of CgNPG1 in C. gloeosporioides Hb and in C. acutatum Hb, the gene deletion and overexpression mutants were generated. The phenotype analysis showed that deletion of CgNPG1 led to changed conidia morphology, decreased mycelial growth, conidiation, conidia germination rate, appressorium formation rate, and pathogenicity of C. gloeosporioides Hb to the rubber tree. Meanwhile, heterogeneous expression of CgNPG1 in C. acutatum Hb significantly changed the conidia morphology and improved the mycelial growth rate, conidiation, conidia germination rate, appressorium formation rate, and the pathogenicity of C. acutatum Hb to the rubber tree. Consistently, CgNPG1 increased the expression level of CaCRZ1 and CaCMK1 in C. acutatum Hb. These data suggested that CgNPG1 contributed to mycelial growth, conidiation, the development of invasive structures, and the pathogenicity of Colletotrichum to the rubber tree, which might be related to the modulation of CaCRZ1 and mitogen-activated protein kinase CMK1. Our results provided new insight into CgNPG1 in regulating growth and pathogenicity of the Colletotrichum spp.

The Effector Protein CgNLP1 of Colletotrichum gloeosporioides Affects Invasion and Disrupts Nuclear Localization of Necrosis-Induced Transcription Factor HbMYB8-Like to Suppress Plant Defense Signaling

“…The radial growth, conidiation, and appressorium formation assays were performed as described by Liang et al ( 2021 ). For the vegetate growth assay, 5-mm-diameter mycelium disks were inoculated on potato dextrose agar medium and cultured for 6 days, the diameters of the colonies were recorded, and the growth rates were calculated.…”

“…Colletotrichum causes anthracnose on a wide variety of woody plants in tropical, subtropical, and temperate climates (Liang et al, 2021 ). In Colletotrichum , six NLP homologs were identified in the Colletotrichum higginsianum genome.…”

Advances in understanding the mechanism of resistance to anthracnose and induced defence response in tea plants

“…The generation and development of conidia requires direct expression of several key regulators for proper vegetative growth, the assembly of the conidiophore, and spore maturation. Recently, Liang et al (2021) found that the function of CgNpg1 (novel pathogenic gene 1) in C. gloeosporioides is essential for mycelial growth, conidiation, the development of invasive structures such as conidial germination, appressorium formation, and pathogenicity. CgChip6 encodes a novel fungal virulence factor, sterol glycosyl transferase, that is induced by hard surface contact of the conidia and is involved in conidial germination and appressorium formation (Kim et al, 2002).…”

The effector protein CgNLP1 of Colletotrichum gloeosporioides from Hevea brasiliensis disrupts nuclear localization of necrosis-induced transcription factor HbMYB8-like to suppress plant defense signaling

“…Colletotrichum causes anthracnose on a wide variety of woody plants in tropical, subtropical and temperate climates (Liang et al, 2021). C. gloeosporioides is the dominant causal agent of rubber tree anthracnose and leads to serious loss of natural rubber production (Liu et al, 2018).…”