Utilization of chitinolytic bacterial isolates to control anthracnose of cocoa leaf caused by Colletotrichum gloeosporioides

Abstract

Colletotrichum spp. are causal agents of anthracnose in many plant species. Biological control of Colletotrichum spp. utilizing bacterial isolates and fungi has been reported. However, chitinolytic bacterial isolate utilization to control anthracnose of cocoa leaf has not seemingly been studied yet. In this study, we used chitinolytic bacterial isolates to reduce anthracnose severity and incidence caused by Colletotrichum gloeosporioides. Identification of the chitinolytic isolates was conducted for their morphological and biochemical traits, and the sequencing of 16S rRNA was to know their related species. Assay of antagonistic bacterial chitinolytic to C. gloeosporioides was conducted in minimum salt medium agar with 2% colloidal chitin as sole carbon source. To examine ability of the chitinolytic isolates in reducing anthracnose severity and incidence, cocoa leaves were treated with the isolates prior infestation of the conidia. Identification of 16S rRNA showed that KR05, LK08, BK13, BK15 and BK17 isolates were Enterobacter sp., Enterobacter cloacae, Bacillus sp., Enterobacter sp., and Bacillus sp., respectively. All chitinolytic isolates inhibited growth of C. gloeosporioides in vitro to some extent. Microscopic studies showed morphological abnormalities of C. gloeosporioides hyphae that is, broken, lytic, rolled, twisted, curled and abnormal branching of hyphae as a result of antagonistic mechanism caused by the chitinolytic isolates. All chitinolytic isolates were able to reduce anthracnose severity and incidence on cocoa leaves from 0.8 to 3.2% and 4 to 12%, respectively.

Morphology, phylogeny and pathogenicity of fungal species associated with leaf blight and stem canker of Theobroma cacao in Malaysia

“…In addition to D. tulliensis , F. proliferatum , F. solani and N. clavispora , several studies have reported the occurrence of other species as plant pathogens associated with T. cacao . For example, Colletotrichum gloeosporioides , Colletotrichum tropicale , Colletotrichum siamense , D. pseudomangiferae , Lasiodiplodia pseudotheobromae , Lasiodiplodia theobromae , Neofusicoccum parvum , Nigrospora sphaerica , Phytophthora palmivora and Phytophthora megakarya (Akrofi et al., 2015; Asare et al., 2021; Huda‐Shakirah et al., 2022; Huda‐Shakirah & Mohd, 2023; Puig et al., 2021; Serrato‐Diaz et al., 2020, 2022; Suryanto et al., 2014; Villanueva et al., 2023).…”

“…In (Akrofi et al, 2015;Asare et al, 2021;Huda-Shakirah et al, 2022;Huda-Shakirah & Mohd, 2023;Puig et al, 2021;Serrato-Diaz et al, 2020Suryanto et al, 2014;Villanueva et al, 2023).…”

Phyllosphere microbial diversity and specific taxa mediate within-cultivar resistance to Phytophthora palmivora in cacao

“…( 28 – 32 ), and Colletotrichum spp. ( 33 ). Despite some success, application of exogenous biocontrol agents may only provide short-term disease suppression [e.g., 50% protection at 5 weeks, with no measurable effect after 7 weeks ( 17 )].…”