Isolation and identification of Esteya vermicola and its potential for controlling pinewood nematode

Abstract

Pine wilt disease is a devastating forest disease worldwide caused by the pinewood nematode (PWN; Bursaphelenchus xylophilus). Esteya vermicola is widely recognized as a promising bio‐control agent effective against PWN. During a survey of associated microorganisms of Pinus yunnanensis in Southwest China, a novel isolate of E. vermicola was obtained. This isolate produced two types of conidia. One type of conidia was hyaline, unicellular, bacilloid, and non‐adhesive. The second type of conidia is solitary, hyaline, unicellular asymmetric elliptic or lunate, concave inward, ending slightly apiculate, adhesive on the concave surface, and contained an ovoid endospore‐like structure. Only the lunate conidia showed infection activity against PWN. This novel isolate produced a high proportion of infective lunate conidia and exhibited high adhesion and infection activity against PWN by adhering to the nematode within 48 h and killing 74.5% of the tested PWN individuals within 4 days. Given that the isolate was obtained from P. yunnanensis, it may be well adapted to the endogenous environment of pine trees. The isolate shows potential as a bio‐control agent against a plant‐parasitic nematode in the field.

The essential role of arginine biosynthetic genes in lunate conidia formation, conidiation, mycelial growth, and virulence of nematophagous fungus, Esteya vermicolaCBS115803

“…Strains NK13222 and ATCC74485 yield lunate conidia in nutrient‐poor media, such as Water Agar (WA), and bacilloid conidia in nutrient‐rich media 19 . In comparison, strain CNU120806 and CBS115803 predominantly produces lunate conidia in PDA medium and fewer lunate conidia in nutrient‐deficient Corn Meal Agar (CMA) and WA than in PDA 24,40 . According to our findings, E. vermicola CBS115803 demonstrates more vigorous mycelial growth and higher conidia yield on nutrient‐rich CM and PDA medium.…”

“…19 In comparison, strain CNU120806 and CBS115803 predominantly produces lunate conidia in PDA medium and fewer lunate conidia in nutrient-deficient Corn Meal Agar (CMA) and WA than in PDA. 24,40 According to our findings, E. vermicola CBS115803 demonstrates more vigorous mycelial growth and higher conidia yield on nutrient-rich CM and PDA medium. Additionally, the fungus tends to form lunate conidia more efficiently in nutrient-rich culture media.…”

“…These differences can be attributed to the significant environmental variations in the locations where different strains were discovered. Consequently, after undergoing the process of natural selection, various fungal strains have successfully adapted to diverse natural environments 24,40 . Currently, only the genome of E. vermicola CBS115803 has been sequenced, 42 making it impossible to analyze the genetic differences among several strains at the genome level.…”

“…Despite its ability to grow for a few more days on PDA medium compared to CM, the CBS115803 strain still initiates mortality after a few days. Furthermore, evidence suggests an inverse correlation between the nutritional status of the medium and the infectivity of E. vermicola CBS115803, with poorer nutritional status leading to heightened infectivity 40 . The supplementation of glycine facilitated the synthesis of E. vermicola CBS115803 conidia, demonstrating augmented predation capabilities and heightened tolerance to environmental adversities 27 .…”

The Fight against Plant-Parasitic Nematodes: Current Status of Bacterial and Fungal Biocontrol Agents

“…Currently, nine isolates of Esteya spp. are described and they are frequently associated with insects [ 106 , 134 ]. Two Esteya spp.…”