Exudation of terpenoids by cotton roots

The terpenoid aldehydes, desoxyhemigossypol, desoxy-6-methoxyhemigossypol, hemigossypol, 6-methoxyhemigossypol, gossypol, 6-methoxygossypol, and 6,6'-dimethoxygossypol, previously reported to be present in cotton roots (Gossypium hirsutum L.) were found on absorbing surfaces adjacent to roots. Infection of hypocotyls by Rhizoctonia solani increased the quantity of terpenoids exuded by roots. Because these compounds are antimicrobial, their presence in the rhizosphere should be considered in studies of the microflora of cotton roots.