Breeding for drought tolerance in crops
AbstractTolerance to drought is under complex genetic control and selection for it often presents difficult challenges to plant breeders. With classical breeding methods, combining or pyramiding many different desirable genes in one background is nearly impossible because the tests required to reveal the presence of those genes in the off-spring are not available. The objective of this paper is to review the various approaches employed by research-ers to develop drought tolerant varieties of crop plants with emphasis on the potential of biotechnological techn-iques in addressing this concern. Screening methods for field evaluation, physiological evaluation and the use of molecular-genetic techniques have been outlined. The use of biotechnological methods provides the most op-timistic means of detecting the presence of genes conditioning drought tolerance. Biotechnological techniques also provide a better understanding of the genetic control of complexly inherited traits and lead to the developm-ent of markers that could enhance breeding for drought tolerance. Molecular markers such as isozymes, storage proteins, restriction fragment length polymorphism (RFLP) and random amplified polymorphic DNA (RAPD), provide powerful means of identifying genetic loci associated with drought tolerance for use in marker-assisted selection (MAS). The development of saturated molecular genetic maps could lead to detection of markers sig-nificantly associated with quantitative trait loci (QTL) that determine drought tolerance, which could make sele-ction for drought tolerance more effective than conventional phenotypic methods.
(Journal of Applied Science and Technology: 2001 6(1-2): 116-122)
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