Structure and Cytochemistry of the Stigma and Pollen--Pistil Interaction in Zephyranthes

The stigma in Zephyranthes candida and Z. citrina is of thedry type with a continuous cuticle—pellicle. In some papillae,however, the terminal portion of the cuticle—pellicleis lifted upwards and occasionally even disrupted by the accumulationof a secretion product below it. Both non-specific esterasesand acid phosphatases are present on the stigma surface. Thestyle is solid with a central core of transmitting tissue whichhas conspicuous intercellular spaces containing a matrix thatincludes proteins, polysaccharides and pectic substances. Zephyranthes citrina is self-compatible while Z. candida isself-incompatible. Followng incompatible pollination in Z. candida,pollen germination is normal but pollen tube growth is inhibitedat the junction of the stigma and style. Self-incompatibilitycan be overcome by bud pollination. Protein synthesis is necessaryfor pollen germination in both species. Concanavalin A bindsto the stigma surface of both species, but does not affect pollentube penetration in Z. candida. In crosses between the two speciestypical unilateral incompatibility is observed when Z. candidais used as the pistillate parent. Zephyranthes, stigma-surface enzymes, dry stigma, pollen-pistil interaction, self-incompatibility, unilateral-incompatibility