The Journal of Heredity 1986:77(6):445-450
© 1986 The American Genetic Association 77:445-450
research-article |
Segregation distortion and linkage analysis of hand pollinated avocados
Dr. Torres is professor of botany, and Ms. Mau-Lastovicka is research associate in the Department of Botany, University of Kansas, Lawrence, KS 66045. Dr. Vithanage is research scientist, and Dr. Sedgley is principal research scientist, Division of Horticulture, Commonwealth Scientific and Industrial Research Organization, Merbein, Victoria, and Adelaide, South Australia, 5001, Australia, respectively. The authors are grateful for U.S. Department of Agriculture and National Science Foundation travel grants to Australia that made their collaboration possible. This work also was supported by a U.S.-Israeli Binational Agricultural Research and Development Fund grant.
Abstract
Various cultivars of avocado (Persea americana MIll.) were hand pollinated to produce 138 seedings in 29 families with from one to 19 progeny. Because the probability of premature fruit drop is normally very high (about 1000 to 1), some of the hand pollinated progeny that abscissed were rescued with embryo culture. Leaf samples of parents and seedlings were assayed for nine genes that specify seven polymorphic enzyme systemsglutamate oxaloacetate transaminase (GOT), leucine aminopeptidase (LAP), malate dehydrogenase (MDH), phosphoglucose Isomerase (PGI), phosphoglucose mutase (PGM), cathodal peroxidase (CPX) and those phosphate isomerase (TPI)to document the parentage and for further analyses. Families with fewer than four progeny were eliminated from the data sets and several were combined for single-gene segregation and linkage analyses. Some single-gene segregation ratios among the 106 remaining progeny in 10 families were significantly distorted. A linkage analysis indicated that the genes Got1 and Got2 are very tightly linked but those specifying the LAP2, PGI1 and 2, MDH1, PGM1, CPX0 and TPI1 Isozyme sets assorted independently. Eight of the avocado's 12 chromosomes now have Isozyme gene markers.