Efficacy of Chaetomium Species as Biological Control Agents against Phytophthora nicotianae Root Rot in Citrus

Abstract

Thailand is one of the largest citrus producers in Southeast Asia. Pathogenic infection by Phytophthora, however, has become one of major impediments to production. This study identified a pathogenic oomycete isolated from rotted roots of pomelo (Citrus maxima) in Thailand as Phytophthora nicotianae by the internal transcribed spacer ribosomal DNA sequence analysis. Then, we examined the in vitro and in vivo effects of Chaetomium globosum, Chaetomium lucknowense, Chaetomium cupreum and their crude extracts as biological control agents in controlling this P. nicotianae strain. Represent as antagonists in biculture test, the tested Chaetomium species inhibited mycelial growth by 50~56% and parasitized the hyphae, resulting in degradation of P. nicotianae mycelia after 30 days. The crude extracts of these Chaetomium species exhibited antifungal activities against mycelial growth of P. nicotianae, with effective doses of 2.6~101.4 µg/mL. Under greenhouse conditions, application of spores and methanol extracts of these Chaetomium species to pomelo seedlings inoculated with P. nicotianae reduced root rot by 66~71% and increased plant weight by 72~85% compared to that in the control. The method of application of antagonistic spores to control the disease was simple and economical, and it may thus be applicable for large-scale, highly effective biological control of this pathogen.

Temporal shifts of fungal communities in the rhizosphere and on tubers in potato fields

“…are known fungal biocontrol agents and were mostly found in rhizosphere samples. Chaetomium globosum is reportedly antagonistic to several soil-borne fungal pathogens, including Pythium ultimum (Pietro et al 1992), Phytophthora nicotianae (Hung et al 2015) and Rhizoctonia solani (Sriraj et al 2014).…”

Microbial diversity in leaves, trunk and rhizosphere of coconut palms (Cocos nucifera L.) associated with the coconut lethal yellowing phytoplasma in Grand-Lahou, Cte dIvoire

“…Chaetomium and Phialemonium have been long used as biocontrols of several fungal diseases (Hung et al, 2015;Shanthiyaa et al, 2013;Hiratsuka and Chakravarty, 1999), while Arthrinium has been recommended as a potential biocontrol of the bayoud disease in palm trees (Calvo et al, 2005). The fact that specific fungal organisms were limited to the rizosphere of symptomless palms in Yaokro raises many expectations for the possibility of assessing these for their biocontrol potential against the CILY phytoplasma.…”

Competitive exclusion and metabolic dependency among microorganisms structure the cellulose economy of agricultural soil

“…Chaetomium are also prototrophic, being capable of growth on cellulose in minimal media without the addition of amino acids or cofactors [43], though our methods were not validated for predicting prototrophy in eukaryotic genomes. The rapid growth and self-su ciency of Cellvibrio and Chaetomium were coupled with a strategy of competitive exclusion via the production of antibiotics such as bacteriocin, likely a cellvibriocin [44], and fungicides [45][46][47]. Notably, the same trend in Cellvibrio and Chaetomium populations was observed in a separate SIP cellulose study of agricultural soil, including a late-stage shift towards Actinobacteria [35].…”