Allelopathic momilactones A and B are implied in rice drought and salinity tolerance, not weed resistance

Abstract

Momilactones A and B are allopathic phytoalexins that are involved in weed resistance of rice. There is little knowledge on the roles of momilactones A and B on drought and salinity tolerance. Here we analyzed the contents of momilactones A and B in 30 rice cultivars of various origins including hybrid, foreign, sticky, local, upland sticky, and upland rice of the two subtypes Indica and Japonica. Momilactone contents were compared with salinity tolerance, drought tolerance, weed resistance, total flavonoids, total phenols, and antioxidant capacity. Results show that, contrary to the current knowledge, momilactones A and B have very low correlation with weed resistance, with r coefficients of 0.001 and 0.09, respectively. Correlation was higher with drought tolerance, of 0.65 for momilactones A and 0.27 for momilactones B. Overall we conclude that the development of bioactive reagents derived from momilactones A and B is more potent to reduce salinity and drought stresses than weed tolerance in rice.