Читать книгу Biotechnology of Fruit and Nut Crops - Группа авторов - Страница 53

Genetic relationships among traditional Asian mango cultivars and the Florida mangoes have been addressed using biochemical and molecular markers. Isozymes have been widely used to differentiate among cultivars, to determine parentage of existing cultivars, to characterize seedling populations following controlled pollinations and to construct genetic linkage maps. Gan et al. (1981) demonstrated that genetic variation can occur within putative mango cultivars in South-east Asia. Forty-one mango cultivars derived from self- and open-pollinated trees were characterized by Degani et al. (1990), who identified six loci with 17 allelomorphs: (i) PGI, EC 5.3.1.9; (ii) TPI, EC 5.3.1.1; (iii) LAP, EC 3.4.11.1; (iv) IDH, EC 1.1.1.42; (v) PGM, EC 2.7.5.1; and (vi) ACO, EC 4.2.1.3. Using these markers, it was possible to confirm the outcross origin of some mango cultivars, and to demonstrate that the putative parentage of other cultivars was inconsistent with isozyme banding patterns. Degani et al. (1992) later demonstrated that there were two distinct zones of PGI activity, PGI-1 and PGI-2, and showed that four alleles control PGI-2 banding. Schnell and Knight (1992) were able to differentiate zygotic from nucellar seedlings in populations derived from openly pollinated polyembryonic mango rootstocks using IDH, LAP, PGI, PGM and TPI, and a similar work was performed by Degani et al. (1993). Different works used isozymes to show the effect of increasing distance on outcrossing rates in different mango cultivars (Dag et al., 1997,1998, 2001, 2009; Degani et al., 1997). Additionally, isozymes have also been used to study genetic linkage and segregation (Aron et al., 1997).