Application of S-RNase allele molecular analysis as a means for elucidating low yields in the pear orchard.

摘要

The European pear carries the gametophytic self-incompatibility fertilization system. Therefore pear orchards need to contain at least 2 cultivars which are fertilization-compatible. However, compatibility between cultivars in the orchard may be full, when the cultivars differ in both of their S-loci, or partial, when they share one of the 2 S-loci. Semi-compatibility between cultivars can lead to a reduced yield, since half of the pollinator's pollen grains are rejected. Identification of semi-compatibility according to yield levels is not easy, since many factors are involved in determining yield. Yet, the application of molecular analysis for the identification of S-RNase alleles can clearly determine the genetic compatibility between cultivars. In Israel, the yield of the European pear is relatively low. The main cultivar is Spadona and its pollinators are Coscia, Gentile and Spadochina. In order to elucidate whether semi-S-RNase allele compatibility can provide an explanation for the low yields, the S-RNase allele content of the 4 cultivars was determined. It was found that Spadona shares one of its S-RNase alleles with each of its pollinators, and therefore is semi-compatible with them. Four S-RNase alleles were cloned, of which 3 were new. In order to identify fully compatible potential pollinators for Spadona, 5 additional cultivars that are currently being considered for introduction in Israel were analysed. In this latter analysis, Lawson was found to be fully compatible with Spadona and 6 new S-RNase alleles were identified..