Late-acting self-incompatibility: a barrier to self-fertilization in sunnhemp (Crotalaria juncea L.)

In search of causal factors underlying perceived allogamy in sunnhemp (Crotalaria juncea L.), we investigated the breeding system and pollen–pistil interaction. Floral biology study in the species established Fabaceae type hermaphrodite zygomorphic flower with dimorphic anthers. Study of the breeding system revealed preferential success of allogamy despite delayed autonomous selfing mechanism characteristically prevailing in the species. Pollen–pistil interaction study in selfed and crossed pistils revealed significant differences in pollen tube growth rates inside the pistil. Further, in self-pollinated pistils callose formation observed at and around nucellus cells suggesting the late-acting type of self-incompatibility mechanism in the species. To the best of our knowledge, this is the first scientific communication underscoring the prevalence of self-incompatibility mechanism in sunnhemp.