Abstract
Orobanche minor seedlings were attached onto red clover (Trifolium pretense) roots grown in rhizotrons. Approximately 30% of the O. minor seedlings formed tubercles on red clover roots 2 weeks after attachment. Root primordia were appeared on the surface of the tubercles, and crown roots were developed 19 days after attachment. A shoot bud differentiated from crown roots 5 weeks after attachment with or without the cotyledon of O. minor. O. minor parasitism induced little morphological changes in red clover roots during the development process from tubercle formation to shoot differentiation. These observations suggest that O. minor produces growth regulators in its own metabolism to control its differentiation. In addition, the crown roots and the shoot bud differentiated without the cotyledon of O. minor, suggesting the developmental process seems to be the process of adventitious root and shoot formation.
