Characterization of a novel male sterile mutant of Tagetes patula induced by heat shock

Tagetes patula L. is an annual plant belonging to the Asteraceae family. Currently, commercial F1 cultivars are produced through the use of artificial emasculation which is a very laborious procedure, particularly in view of the composite capitulum structure. To date, no male sterile line is available in this species, but the isolation of such material would provide a valuable tool for the establishment of an efficient cross-pollination system for the production of F1 hybrids. In this study, we report the characterization of a novel pollen abortion mutant of Tagetes patula which was isolated from 1,796 heat shock induced cutting seedlings. Histological and cytological observation demonstrated that the abnormal development of the microspores during the binucleate pollen stage led to pollen abortion, and this was correlated to premature tapetum degeneration. Cross hybridization experiments indicated that a recessive nuclear gene was responsible for the trait. This novel male sterile mutant of Tagetes patula appears to be an applicable material for improving the breeding efficiency of the species and may be used to significantly improve ornamental traits in F1 generations.