Interspecific hybridization of Trifolium alexandrinum with T. constantinopolitanum using embryo rescue.
The embryo rescue technique was successfully used to raise hybrids between Trifolium alexandrinum and T. constantinopolitanum. As a result of its narrow genetic base, genetic improvement in Egyptian clover (syn. Berseem; T. alexandrinum), an important fodder crop in tropical and subtropical countries, is hampered, thereby making it imperative to introduce alien genes from related species. In a conventional interspecific hybridization program, hybrids could not be raised due to post-fertilization barriers. Of the several combinations tried, pollination 2 days after emasculation was found to be the best. Globular embryos were observed 5-7 days after pollination (DAP), followed by heart-shaped embryos 10-12 DAP. Embryos excised at the heart-shaped stage responded well to EC3 culture medium. Of 612 crosses, 33 healthy embryos could be excised and cultured on EC3 medium. The plumule emerged 8-12 days following inoculation. The embryo-rescued plants were hardened, inoculated with Rhizobium and transferred to the field. The hybrids showed intermediate morphological features with reduced pollen fertility (55-65%) and a chromosomal complement of 2n = 16. Biochemical characterization using isozymes confirmed hybridity.
Roy
A K
AK
Crop Improvement Division, Indian Grassland and Fodder Research Institute, 284003, Jhansi, India. royak@igfri.up.nic.in
Malaviya
D R
DR
Kaushal
P
P
Kumar
B
B
Tiwari
A
A
D003433:Crosses, Genetic; D003470:Culture Media; D006824:Hybridization, Genetic; D007527:Isoenzymes / Q000502:physiology; D011058:Pollen; D012038:Regeneration; D012639:Seeds / Q000196:embryology* / Q000254:growth & development; D029921:Trifolium / Q000235:genetics*
D003470:Culture Media; D007527:Isoenzymes