A new case of late-acting self-incompatibility in Capparis L. (Brassicaceae): C. jacobinae Moric. ex Eichler, an endemic andromonoecious species of the Caatinga, Pernambuco State, Brazil

We studied the reproductive system of Capparis jacobinae Moric ex Eichler (Brassicaceae), based on controlled hand-pollination and observation of pollen tube growth made in a fluorescence microscope. Of 105 self-pollinated flowers only one produced fruits (success = 0.95%), all the other flowers abscised at the same time, between the eighth and tenth day after anthesis. Nevertheless, self- and cross-pollinated pollen tubes reached the micropyle. The rate of penetrated ovules in self-pollinated flowers was lower during the first 24 h after pollination; thereafter this rate was similar between self- and cross-pollinated flowers for treatments of 48 h, 72 h and 96 h after pollination. In addition, we carried out two indirect estimates of the reproductive system, based on pollen/ovule and seed/ovule ratios, which resulted in typical features of xenogamous species. We concluded that C. jacobinae has a late-acting self-incompatibility system. This is the third record of this mechanism for the genus and the first for a species of Capparis endemic to the Caatinga. We suggest that this self-incompatibility system may occur in other species of the same genus and family