Title : Comparative analysis between the reproductive strategies of the cultivated Moringa oleifera and its wild and endangered relative Moringa peregrina
The Moringaceae is a family of 13 species portraying a range of adaptations to mostly dry or wet tropical habitats. This study is focused on comparative analysis of two closely related species; Moringa peregrine; a wild plant, native to Israel, in the dry tropical regions, and Moringa oleifera; a native to the wet tropics of India and is now prevalent throughout warm tropical or Mediterranean regions. Both species are utilized for food, medicine, energy and cosmetics. Despite the increasing interest in these plants, very little is known about their sexual reproduction and its significance for the production of seed-oil yields. In order to characterize the reproductive strategies of both species we conducted a study on mature trees under Mediterranean conditions. We recorded bloom phenology and compared the foraging behavior of the two most frequent flower visitors; the honey bee (Apis mellifera) and the carpenter bee (Xylocopa pubescence). We found that M. peregrina bloom was bimodal while that of M. oleifera peaked only once. Visitation rate and number of visited flowers of the honey bee were significantly higher than those of the carpenter bee. The pollen grains of both species were found to be uniquely immersed in copious amounts of a cream-like substance (pollenkit). Removal of this pollenkit resulted in reduced viability under hot temperatures (40°C) and reduced invitro germinability, which was restored when it was pre-hydrated. Close inspection of the pistil revealed that the style was a hollow tube with the receptive tissue present > 1mm inside the tube. Attempts to force pollen inside the stylar tube resulted in a significantly larger number of grains reaching the receptive region when the pollenkit was present, further stressing the significance of this unique media to the reproductive success. The stylar tube was also found to preserve pollen viability under extreme temperatures.