Unraveling the tripartite interaction of volatile compounds of Streptomyces rochei with grain mold pathogens infecting sorghum

Sorghum is a major grain crop used in traditional meals and health drinks, and as an efficient fuel. However, its productivity, value, germination, and usability are affected by grain mold, which is a severe problem in sorghum production systems, which reduces the yield of harvested grains for consumer use. The organic approach to the management of the disease is essential and will increase consumer demand. Bioactive molecules like mVOC (volatile organic compound) identification are used to unravel the molecules responsible for antifungal activity. The Streptomyces rochei strain (ASH) has been reported to be a potential antagonist to many pathogens, with high levels of VOCs. The present study aimed to study the inhibitory effect of S. rochei on sorghum grain mold pathogens using a dual culture technique and via the production of microbial volatile organic compounds (mVOCs). mVOCs inhibited the mycelial growth of Fusarium moniliforme by 63.75 and Curvularia lunata by 68.52%. mVOCs suppressed mycelial growth and inhibited the production of spores by altering the structure of mycelia in tripartite plate assay. About 45 mVOCs were profiled when Streptomyces rochei interacted with these two pathogens. In the present study, several compounds were upregulated or downregulated by S. rochei, including 2-methyl-1-butanol, methanoazulene, and cedrene. S. rochei emitted novel terpenoid compounds with peak areas, such as myrcene (1.14%), cymene (6.41%), and c-terpinene (7.32%) upon interaction with F. moniliforme and C. lunata. The peak area of some of the compounds, including furan 2-methyl (0.70%), benzene (1.84%), 1-butanol, 2-methyl-(8.25%), and myrcene (1.12)%, was increased during tripartite interaction with F. moniliforme and C. lunata, which resulted in furan 2-methyl (6.60%), benzene (4.43%), butanol, 2-methyl (18.67%), and myrcene (1.14%). These metabolites were implicated in the sesquiterpenoid and alkane biosynthetic pathways and the oxalic acid degradation pathway. The present study shows how S. rochei exhibits hyperparasitism, competition, and antibiosis via mVOCs. In addition to their antimicrobial functions, these metabolites could also enhance plant growth.Peer reviewe

Morphological, pathogenic and genetic variability in Colletotrichum capsici causing fruit rot of chilli in Tamil Nadu, India

Chilli (Capsicum annuum L.) fruit rot disease caused by Colletotrichum capsici under tropical and subtropical conditions, results in qualitative and quantitative yield losses. Twenty (20) isolates of C. capsici were collected from conventional chilli growing areas of Tamil Nadu. In culture, most of the isolates produced cottony, fluffy or suppressed colonies. However, no significant differences were noticed in shape and size of conidia. The reaction of the 20 isolates on an indigenously developed differential set of Capsicum cultivars indicated the existence of different virulences in Tamil Nadu chilli populations. The genetic relationship between 20 morphological groups recognized within C. capsici was investigated using random amplified polymorphic DNA (RAPD) analysis. Molecular polymorphism generated by RAPD confirmed the variation in virulences of C. capsici and different isolates were grouped into two large clusters. The pathological and RAPD grouping of isolates suggested no correlation among the test isolates.Keywords: Chilli, Colletotrichum capsici, variability, RAPDAfrican Journal of Biotechnology, Vol 13(17), 1786-179

Trichoderma virens against Fusarium wilt caused by Fusarium oxysporum f sp. lycopersici

ABSTRACT Tomato (Lycopersicon exculentum L.) is a popular vegetable widely grown in the tropics, wthich is mainly attacked by Fusarium wilt incited by Fusarium oxysporum f sp. lycopersici. In this present scenario, ecofriendly alternative strategies such as use of fungi from rhizosphere and endophytic bacteria are being explored. Fungal antagonistic Trichoderma spp. are effective for the management of soil borne plant pathogens. Efficacy of various isolates of T.virens were evaluated under green house condition for efficacy in suppressing incidence of Fusarium wilt disease and promoting plant growth in tomato. Among the various isolates tested, native isolates of T.virens (Tv 1 ) increased the plant growth and highly inhibited the mycelial growth of the pathogen under in vitro condition. In green house studies seed treatment plus soil application of talc based formulation of T.virens (Tv 1 ) significantly reduced incidence of the diseases (54.66% more efficient than control), compared to the other isolates of T.virens. Expression of various defence related enzymes was found involved in the induction of systemic resistance against pathogen infection. Tomato plants treated with seed @ 4gkg -1 plus soil application of 4kg ha -1 of talc based formulation of T. virens (Tv 1 ) with challenge inoculation of Fusarium enhance the maximum induction of defense enzyme such as Peroxidase (PO), Polyphenol Oxidase (PPO) and Phenylalanine Ammonia Lyase (PAL) rather than the other isolates of T.virens. The enzyme activity increased from 7 th day of sampling and the maximum was observed on 14 th day of sampling and then it slightly decreased