Colonization of geranium foliage by Clonostachys rosea f. catenulata, a biological control agent of botrytis grey mould

Abstract

The ecological requirements for the colonization of geranium leaves by the biocontrol agent Clonostachys rosea f. catenulata strain J1446 were investigated. Although this biocontrol agent is a soil-inhabiting fungus, treatment of geranium foliage with the agent can reduce grey mould caused by Botrytis cinerea in the greenhouse. To characterize the extent of foliar colonization, a GUS-transformed isolate of C. rosea f. catenulata was applied to foliage of two geranium cultivars, Pelargonium × hortorum and Pelargonium × domesticum. Population levels of C. rosea f. catenulata were found to be highest on senescent leaves and stems, followed by fully expanded leaves, and lowest on newly emerged leaves of both cultivars. Optimum temperature for leaf and petiole colonization was 20-25°C for both cultivars. The biocontrol agent required at least 12 h of continuous leaf wetness to achieve maximum population densities on the leaves and stems of both cultivars. On whole plants, colonization was significantly higher on wounded leaves, stems, and senescing leaves compared with that on nonwounded leaves, stems, and mature leaves, respectively. GUS staining indicated that the fungus preferentially colonized the wound sites of leaves and the cut portions of stems. Results indicate that this biocontrol agent can successfully colonize the foliage of geraniums, thus demonstrating the endophytic ability of C. rosea f. catenulata in both root and foliar tissues.Résumé : L'auteur a examiné les besoins écologiques pour la colonisation des feuilles du géranium par l'agent de maitrise biologique, Clonostachys rosea f. catenulata, souche J1446. Bien que cet agent de lutte biologique soit un champignon du sol, le traitement des feuilles de géranium avec cet agent peut réduire la moisissure grise causée par le Botrytis cinerea en serre. Pour caractériser l'étendue de la colonisation foliaire, on a appliqué un isolat du C. rosea gus-tranformé sur le feuillage de deux cultivars de géranium, le Pelargonium × hortorum et le Pelargonium × domesticum. On constate une importance décroissante des populations du C . rosea sur les feuilles sénescentes et sur la tige, suivie par les feuilles pleinement développées, et enfin les feuilles les plus basses nouvellement émergées, chez les deux cultivars. Les températures optimales pour la colonisation des feuilles et des pétioles voisinent les 20-25°C, chez les deux cultivars. L'agent de maitrise biologique nécessite au moins 12 heures d'humectation continue des feuilles pour l'obtention de densités de population maximales sur les feuilles et les tiges, chez les deux cultivars. Sur la plante entière, on observe une colonisation significativement plus importante sur les feuilles blessées, les tiges et les feuilles sénescentes, comparativement aux feuilles non blessées, aux tiges et aux feuilles matures respectivement. La coloration GUS indique que le champignon colonise préférentiellement les sites de blessures des feuilles et les parties coupées des tiges. Les résultats indiquent que cet agent de maitrise ...

Biology and applications of Clonostachys rosea

“…Clonostachys rosea could colonize on all the parts of Thrips tabaci and decrease the damage caused by thrips and feeding punctures (Muvea et al 2014). As well, C. rosea f. catenulata could successfully colonize on foliage of geranium cultivars at 20-25°C, and roots of cucumber cultivar at 18-22°C (Chatterton and Punja 2010; Chatterton and Punja 2012).…”

Synergistic Effects of Clonostachys rosea Isolates and Succinate Dehydrogenase Inhibitors Fungicides against Gray Mold on Tomato

“…This result is in accordance with a study of B. subtilis on a strawberry based on next-generation sequencing [ 55 ]. In terms of C. rosea , it was confirmed that C. rosea could successfully colonize the foliage of geraniums and the roots of cucumbers by using a GUS-transformed isolate, demonstrating the endophytic ability of C. rosea in foliar and root tissues [ 14 , 47 ]. In this study, DNA of C. rosea was directly extracted from tomato plants, and the fungal dynamics were analyzed by real-time qPCR to quantify C. rosea DNA.…”

“…Thus, we applied C. rosea at 10 7 conidia mL −1 concentration for the control of B. cinerea in our pot experiments and halved the concentration of C. rosea to 5 × 10 6 conidia mL −1 when combined with the fungicides. Based on Chatterton and Punja’s research, environmental factors such as temperature and pH were major factors that influenced population levels of C. rosea [ 14 , 47 ]. The optimum temperature for leaf colonization was 20–25 °C, and maximum population densities on the leaves required at least 12 h of continuous leaf wetness [ 14 ].…”

“…Based on Chatterton and Punja’s research, environmental factors such as temperature and pH were major factors that influenced population levels of C. rosea [ 14 , 47 ]. The optimum temperature for leaf colonization was 20–25 °C, and maximum population densities on the leaves required at least 12 h of continuous leaf wetness [ 14 ]. Hence, greenhouse environmental conditions were maintained at 90% relative humidity and 25 °C room temperature for the pot experiment to obtain a stable and efficient control effect.…”

“…The application of biological control agents (BCAs) to manage tomato gray mold is a promising alternative to synthetic fungicides [ 9 , 10 , 11 ]. Among them, C. rosea has been shown to be effective in controlling gray mold in several crops, both in field and greenhouse cultivations [ 12 , 13 , 14 , 15 ]. It protects plants against B. cinerea by inhibiting spore production and suppressing gray mold development [ 16 ].…”