Mycoherbicides for the Noxious Meddlesome: Can Colletotrichum be a Budding Candidate?

Abstract

Invasive plant species are a major threat to biodiversity and agricultural productivity. Hence, efforts to manage these menace involves extensive and effective use of chemical herbicides amongst others. However, not only is the impact of control with chemical herbicides short-lived but also leads to negative impact on human health and environment due to non-target herbicide-drift and runoff from the sprayed areas. This has ushed in much-anticipated nature-based potential regulators of weed species, in an attempt to lower the utilisation of chemical herbicides. Mycoherbicides have been seen as a benign, eco-friendly, host-specific, and replacement for chemical herbicides. There are several noteworthy genera of fungus that have been proved to be effective against weeds. They either produce strong phytotoxins or are often used as spore/conidia-based solutions and applied as a spray in growth media. One of such potential genera is Colletotrichum Corda 1831. Compared to other potent fungal genera, with well-established roles in conferring herbicidal activities by producing competent phytotoxins, only a few species under genus Colletotrichum are known to produce fungal metabolites be used as phytotoxins. This article elucidates the current understanding of using spore suspension/phytotoxin of Colletotrichum as a weedicide. We also discuss the interaction between fungal metabolites release and Colletotrichum-target plant, from a molecular and biochemical point of view. This review article has been written to accentuate on the potency of Colletotrichum, and to serve as an eye-opener to consider this genus for further fruitful investigations. However, inconsistency associated with mycoherbicides in terms of viability and efficacy under field conditions, production of bioactive compound, slow natural dispersal ability, etc., have often reduced their utility. Hence, our study emphasizes on the need to do extensive research in elucidating more phytotoxins from necrotrophic phytopathogenic microorganisms with novel mode of action for field application.

Microbe Related Chemical Signalling and Its Application in Agriculture

“…tagetis has shown promising results which causes up to 100% mortality against a few weed species [ 141 ]. There are a few genera of fungus that are often used as mycoherbicides, including Phytophthora, Sclerotinia, Alternaria and the most famous genera being Colletotrichum [ 142 , 143 ]. A few Colletotrichum spp.…”

“…A few Colletotrichum spp. including C. goleosporioides, C. higginsianum, C. orbiculare and C. truncatum produce mycotoxin such as colletochlorin-A,-E and -F, orcinol, tyrosol and dirhamnolipid which targets weed such as Aeschynomene virginica, Sonchus arvensis and Xanthium spinosum [ 8 , 141 , 143 , 144 , 145 , 146 ].…”

Colletotrichum echinochloae: A Potential Bioherbicide Agent for Control of Barnyardgrass (Echinochloa crus-galli (L.) Beauv.)

“…Several other species within the genus Colletotrichum have been investigated as potential mycoherbicide agents [ 29 , 30 ]. Additional examples include Coltru, as the principal biocontrol agent in C. truncatum , which was investigated to control hemp sesbania ( Sesbania exaltata ) [ 31 ].…”

Secondary metabolites produced byColletotrichumspp. on different olive cultivars

“…Indeed, Ballio et al (Ballio et al, 1969) had demonstrated that the causal agent of OA produced in vitro aspergillomarasmin B, a phytotoxic derivative of lycomarasmin. Numerous other bioactive secondary metabolites produced in vitro by Colletotrichum species have been since isolated and identified from culture fluids, they mostly included polyketides, terpenoids, peptides and aminoacid derivatives, alkaloids, derivatives of shikimic acid and metabolites of mixed biosynthetic origin (Chakraborty and Ray, 2021; Chapla et al, 2014; Chen et al, 2019; García-Pajón and Collado, 2003; Kim and Shim, 2019; Li et al, 2022; Masi et al, 2020; Moraga et al, 2019; Sun et al, 2022; Xu et al, 2019, 2021). The interest of above mentioned studies has focused mainly on the potential applications of these metabolites either in pharmacology as drugs or in agriculture as natural substances with antifungal and herbicidal activity (Kim and Shim, 2019; Masi et al, 2017).…”