'A life or death decision' for pollen tubes in S-RNase-based self-incompatibility.
Mate choice is an essential process during sexual plant reproduction, in which self-incompatibility (SI) is widely adopted as an intraspecific reproductive barrier to inhibit self-fertilization by many flowering plants. Genetic studies show that a single polymorphic S-locus, encoding at least two components from both the pollen and pistil sides, controls the discrimination of self and non-self pollen. In the Solanaceae, Plantaginaceae, and Rosaceae, an S-RNase-based SI mechanism is involved in such a discrimination process. Recent studies have provided some important clues to how a decision is made to accept cross pollen or specifically to reject self pollen. In this review, the molecular features of the pistil and pollen S-specificity factors are briefly summarized and then our current knowledge of the molecular control of cross-pollen compatibility (CPC) and self-pollen incompatibility (SPI) responses, respectively, is presented. The possible biochemical mechanisms of the specificity determinant between the pistil and pollen S factors are discussed and a hypothetical S-RNase endosome sorting model is proposed to illustrate the distinct destinies of pollen tubes following compatible and incompatible pollination.
Chen
Guang
G
Institute of Genetics and Developmental Biology, Chinese Academy of Sciences and National Center for Plant Gene Research, Beijing 100101, China.
Zhang
Bin
B
Zhao
Zhonghua
Z
Sui
Zhenhua
Z
Zhang
Hui
H
Xue
Yongbiao
Y
D000483:Alleles; D003433:Crosses, Genetic; D056426:Genetic Loci / Q000235:genetics*; D007178:Inbreeding; D053205:Pollen Tube / Q000201:enzymology*; D012260:Ribonucleases / Q000378:metabolism*
D012260:Ribonucleases