Variability of the self-incompatibility reaction in Brassica oleracea L. with S 15 haplotype.
Self-incompatibility (SI) is thought to have played a key role in the evolution of species as it promotes their outcrossing through the recognition and rejection of self-pollen grains. In most species, SI is under the control of a complex, multiallelic S-locus. The recognition system is associated with quantitative variations of the strength of the SI reaction; the origin of these variations is still not elucidated. To define the genetic regulations involved, we studied the variability of the SI response in homozygous S 15 S 15 plants in cauliflower. These plants were obtained from a self-progeny of a self-compatible (SC) plant heterozygous for S 15, which was generated after five selfing generations from one strongly self-incompatible initial plant. We found a continuous phenotypic variation for SI response in the offspring plants homozygous for the S 15 haplotype, from the strict SI reaction to self-compatibility, with a great proportion of the plants being partially self-compatible (PSC). Decrease in SI levels was also observed during the life of the flower. The number of pollen tubes passing through the stigma barrier was higher when counted 3 or 5 days after pollination than one day after pollination. Analysis of the expression of the two key genes regulating self-pollen recognition in cauliflower, the S-locus receptor kinase (SRK) and S-locus cysteine-rich (SCR/SP11) genes, revealed that self-compatibility or PSC was associated with decreased SRK or SCR/SP11 expression. Our work shows the particularly high level of phenotypic plasticity of the SI response associated with certain S-haplotypes in cauliflower.
Hadj-Arab
Houria
H
USTHB FSB Laboratoire de Biologie et Physiologie des Organismes, BP 32 El-Alia, 16111, Alger, Algerie. hhadj_arab@yahoo.fr
Chèvre
Anne-Marie
AM
Gaude
Thierry
T
Chable
Véronique
V
D001937:Brassica / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D014644:Genetic Variation; D006239:Haplotypes; D010641:Phenotype; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D011058:Pollen / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism
D010940:Plant Proteins; C431526:SP11 protein, Brassica; D011494:Protein Kinases; C079832:S-receptor kinase