Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 1/17/2003
Publication Date: 12/1/2004
Citation: Chevreau, E., Bell, R.L. 2004. Pear. Book Chapter. CABI Publishing, Wallingford, pp. 543-565. Interpretive Summary:
Technical Abstract: Biotechnology can offer pear breeders new tools to increase the efficiency of hybrization and selection through the use of molecular markers, or to perform direct improvement of existing cultivars or elite genotypes through somaclonal variation or gene transfer. This review concentrates on the applications of biotechnology which have been reported on pear and quince since 1992. Haploidization of pear, a highly heterozygous species, and th production on homozygous doubled haploid plants would be useful for genetic studies and breeding. Spontaneous haploids have been selected from seedlings and haploids have been induced using irradiated pollen followed by in vitro culture. Efficient techniques for adventitious regeneration from leaves from in vitro shoot cultures are now available for a number of pear genotypes of several species, as well as quince. Irradiation of in vitro shoots has been successfully used to efficiently produce bud mutants with such useful traits as compact growth habit. In vitro techniques have been developed to select for increased tolerance of high pH induced iron chlorosis in quince and Pyrus elaeagrifolia. Genetic transformation using Agrobacterium tumefaciens-mediated methods have produced transgenic plants with the gene for the antimicrobial peptide attacin E to improve resistance to fire blight, the rolC gene to produce dwarf trees, the rolB gene to improve rooting, and the sam-k gene to modify ethylene metabolism and improve post-harvest storage life. Several DNA marker systems have been utilized for cultivar fingerprinting, taxonomic studies, and marker assisted selection. Twenty-eight genes have been cloned from pear, including genes involved in fruit ripening, disease resistance, and self-incompatibility.