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Interspecific compatibility barriers, development of interspecific hybrids through embryo rescue and lineage of Trifolium alexandrinum (Egyptian clover)—important tropical forage legume

Malaviya, Devendra R., Roy, Ajoy K., Kaushal, Pankaj, Chakraborti, Mridul, Yadav, Aradhana, Khare, Ambica, Dhir, Richa, Khairnar, Dushyant, George, Ginu Percis
Plant breeding 2018 v.137 no.4 pp. 655-672
Trifolium alexandrinum, ecotypes, forage legumes, genetic background, genetic improvement, hybrids, interspecific hybridization, ovule culture, ovules, pollen tubes
Genetic improvement of Trifolium alexandrinum L. is hampered because of narrow genetic base and lack of interspecies compatibility information. The study was envisaged to understand the interspecies incompatibility and the affinity between T. alexandrinum and 22 species of the genus representing different sections and to develop interspecific crosses. Development of interspecific hybrids with T. resupinatum, T. lappaceum, T. subterraneum, T. vesiculosum and T. echinatum, through embryo rescue, revealed their affinity with T. alexandrinum. Failure of pollen germination or restricted pollen tube growth showed its distant relatedness with T. clypeatum, T. balansae, T. purpureum, T. leucanthum, T. hirtum, T. pilulare and T. hybridum. Pollen tubes reached up to ovule among the crosses with T. alpestre, T. repens and T. nigrescens, whereas it travelled up to ovary among the crosses with T. angustifolium, T. grandiflorum and T. dasyurum indicating need of manipulation to overcome barrier. Thus, incompatibility of T. alexandrinum with many Trifolium species could be overcome through embryo rescue with intensive crossing. Egyptian clover ecotype ‘Fahli’ was more compatible with other species than ‘Mescavi’.