Haploids have been available for genetic studies for many years. Prior to the 1960s, they were
mostly obtained spontaneously following interspecific hybridization or through the use of irradiated
pollen, but usually only infrequently and in very small numbers. Haploid methodology took a giant
step forward 40 years ago when Guha and Maheshwari (1964) found that haploid plants could be
obtained on a regular basis and in relatively large numbers by placing immature anthers of
Datura
innoxia
Mill. into culture. This work was rapidly expanded using tobacco (
Nicotiana tabacum
L.),
which became the model species for anther culture experiments. To date, androgenic haploids have
been produced in over 170 species; several good reviews provide lists of these species (Maheshwari
et al., 1982; Bajaj, 1983; Heberle-Bors, 1985; Dunwell, 1996). While efforts have been more
limited, haploids have also been obtained from
in vitro
culture of the female gametophyte in over
30 species (Keller and Korzun, 1996; Lakshmi Sita, 1997). Gynogenesis has been successfully
applied to several species in which androgenesis is generally ineffective, such as sugar beet (
Beta
vulgaris
L.), onion
(Allium
cepa
L.), and the Gerbera daisy (
Gerbera jamesonii
H. Bolus ex Hook).