ANDROGENIC HAPLOIDS

Haploids are a valuable commodity for plant breeders but they are seldom used as they occur only rarely in nature. This problem was greatly resolved by the experimental induction of haploidy in cultured anthers of Datura innoxia (Guha and Maheshwari 1966), which like many great advances in science was a chance discovery (Guha-Mukherjee 1999). The technology was further defined and improved by the work of Nitsch and Nitsch (1969). It is now well established that it is possible to shift the developmental pattern of microspores from a gametophytic to a sporophytic phase simply by excising and culturing the anthers at the microspore stage of development. The microspores, instead of forming pollen grains, give rise to somatic embryos either directly or after producing a callus. The resulting plants are either haploids or homozygous diploids (dihaploids) as a result of spontaneous or experimentally induced diploidization. Although the impact of androgenic dihaploids has been limited, they have been used to identify breeding lines with desirable traits and for the production of improved varieties of tobacco, wheat, rice and other crops.
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