Screening a Natural Product-Inspired Library for Anti-Phytophthora Activities

Abstract

Phytophthora is a genus of microorganisms that cause devastating dieback and root-rot diseases in thousands of plant hosts worldwide. The economic impact of Phytophthora diseases on crops and native ecosystems is estimated to be billions of dollars per annum. These invasive pathogens are extremely difficult to control using existing chemical means, and the effectiveness of the few treatments available is being jeopardized by increasing rates of resistance. There is an urgent need to identify new chemical treatments that are effective against Phytophthora diseases. Natural products have long been regarded as “Nature’s medicine chest”, providing invaluable leads for developing front-line drugs and agrochemical agents. Here, we have screened a natural product-inspired library of 328 chemicals against two key Phytophthora species: Phytophthora cinnamomi and Phytophthora agathidicida. The library was initially screened for inhibition of zoospore germination. From these screens, we identified twenty-one hits that inhibited germination of one or both species. These hits were further tested in mycelial growth inhibition studies to determine their half-maximal inhibitory concentrations (IC50s). Four compounds had IC50 values of approximately 10 µM or less, and our best hit had IC50s of approximately 3 µM against both Phytophthora species tested. Overall, these hits may serve as promising leads for the development of new anti-Phytophthora agrochemicals

Phylogeny and Pathogenicity of Phytophthora Species Associated with Artichoke Crown and Root Rot and Description of Phytophthora marrasii sp. nov.

“…This could be achieved through a combination of agronomic and phytosanitary practices, such as the selection of resistant varieties, adoption of proper irrigation practices, avoiding rotation with susceptible crops, and through the use of chemical treatments, although the oomycota fungicides currently available are very limited. The constant discovery of new Phytophthora diseases on crops [71][72][73] has exacerbated the problem of the correct management of these pathogens, emphasizing the need for new bioactive molecules [74].…”

Different Approaches to establish soil health and to combat Phytophthora cinnamomi

“…Unfortunately, these products Open J Plant Sci 9(1): 006-015. DOI: https://dx.doi.org/10.17352/ojps.000059 require repeated applications, as their effectiveness diminishes over time [16], and prolonged use of certain fungicides, such as metalaxyl, can lead to the development of resistance and Pc mutations associated with these compounds [17,18].…”

Sensitivity of the soil-borne pathogen Phytophthora agathidicida, the causal agent of kauri dieback, to the anti-oomycete fungicides ethaboxam, fluopicolide, mandipropamid, and oxathiapiprolin

“…Once infected, kauri can be treated with injections of phosphite (phosphonate) salts, a fungicide that significantly reduces lesion activity and spread, but does not cure the disease , Bradshaw et al 2019. There have been numerous additional screenings of synthetic chemicals and natural products for fungicidal activity against P. agathidicida in vitro (Lawrence et al 2017(Lawrence et al , 2019(Lawrence et al , 2021, although these studies have not yet progressed to in vivo assessments.…”