Effect of Volatile Compounds From Remoistened Plant Tissues on Growth and Germination of Sclerotia ofSclerotium rolfsii

Abstract

Germination of sclerotia and growth of S. rolfsii, which were stimulated by volatile compounds from remoistened, undecomposed plant tissues, were most pronounced when CO2 was removed and O2 added in 24 cm diameter, 9.9 l desiccators. Germination of sclerotia and growth of S. rolfsii were increased by remoistening dried green tissue from alfalfa [Medicago sativa], corn [Zea mays], Crotalaria [Crotalaria spectabilis], kudzu [Pueraria thunbergiana], lespedeza [Lespedeza stipulacea], peanut [Arachis hypogaea] and ramie [Boehmeria nivea]. In a survey of 71 organic volatile compounds, 2 alcohols (including methanol), 3 aldehydes, 2 esters and 2 halogenated hydrocarbons were as stimulatory as remoistened peanut hay to sclerotial germination of S. rolfsii. Methanol (about 2-4 .mu.l/g hay) was detected by microdiffusion analysis of remoistened peanut hay. Germination of sclerotia of S. rolfsii was equal (P = 0.05) in the presence of methanol (7 .mu.l) or peanut hay (2 g) in the desiccators. Addition of pectinase to 1% pectin also increased germination of sclerotia and growth of S. rolfsii, enzymatically released methanol may be a major stimulant emanating from remoistened, undecomposed plant tissue. The proposed pectin-methanol hypothesis may explain, in part, the wide host range of S. rolfsii. These results also expand the list of known stimulants and inhibitors of sclerotial germination of S. rolfsii.