ISHS Acta Horticulturae 769: XXVII International Horticultural Congress - IHC2006: International Symposium on Asian Plants with Unique Horticultural Potential
ISOLATION AND IDENTIFICATION OF SEVEN NEW S-RNASE GENES FROM PYRUS PYRIFOLIA IN CHINA |
| Authors: | Xiao-Feng Tan, Tana Wuyun, Dang-Quan Zhang, Yan-Ling Zeng, Lin Zhang |
| Keywords: | Pyrus pyrifolia, PCR-RFLP, self-incompatibility, S-gene, S-RNase |
| Abstract:
S-RNase encoded by gametophytically self-incompatible S-gene in plant pistil is an enzyme which causes pollen mRNA or rRNA of plants with identical genotypes to be degraded, resulting in self-incompatibility in plants. The fruiting percentage is less than 10% when cultivars with the same S-gene pollinate each other, but it reaches 60-100% in cultivars with different S-gene. China is rich in species or cultivars in pears (Pyrus spp.), and there are more than 500 cultivars only in Pyrus pyrifolia. However, the genetic resources and S genotypes are not yet clear in those cultivars. In this paper, 48 cultivars of P. pyrifolia in China were studied by PCR-RFLP with specific primers of S-gene, i.e., ‘FTQQYQ’ and ‘anti-IIWPNV’. However, by this method, seven fragments in five cultivars, i.e., ‘Huanghua’, ‘Guiguan’, ‘Changxixue’, ‘Maogong’ and ‘Taihuang’ pears, could not be identified. These fragments were reclaimed, sequenced and compared with the data of GenBank. Seven new alleles of S-RNase were obtained from those cultivars, and parts of their sequences were registered in GenBank. They are S11-RNase, S12-RNase, S13-RNase, S14-RNase, S15-RNase, S16-RNase and S25-RNase, respectively. The partial sequences of the seven genes are highly homological with that of S1-10-RNase gene, and the homology of hyper variable region (HV) of the seven alleles is less than 80%, demonstrating that HV region is the specific segment in which S-RNase recognizes pollen. The results from experiments of controlled cross in different cultivars also corroborate the validity of aforementioned facts. | |
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