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

Abstract

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’.

Genetic Diversity and Lineage Based on SSR Markers of Two Genomic Resources among <i>Trifolium</i> Collections Held within the Australian Pastures Genebank

“…The genus Trifolium has been divided in eight sections [1]. In the present study, clustering of T. subterraneum belonging to section Trichocephalum of the genus, with T. alexandrinum and T. salmoneum of section Trifolium, indicated that the three species possessed relatedness which was congruent with earlier reports [3] [16] [17] [18] [19]. In fact, Lotoidea is the largest section and has served as source taxa for the evolution of many other sections [1].…”

Co‐occurrence patterns at four spatial scales implicate reproductive processes in shaping community assembly in clovers

“…Generalist bee species including honeybees, bumblebees and solitary bees are common pollinators of Trifolium (Rao & Stephen, 2009;Zohary & Heller, 1984). Heterospecific pollen transfer is often costly due to post-pollination and postzygotic barriers (Malaviya et al, 2018;Repkova et al, 2006;Roy et al, 2011). While we could not find data quantifying the strength of reproductive isolation in any of the specific species pairs in our study, surveys across the genus suggest that intrinsic barriers in interspecific crosses are substantial and widespread (Abberton, 2007), and hybrids are extremely rare in nature (Zohary & Heller, 1984).…”

Prospects for Trifolium Improvement Through Germplasm Characterisation and Pre-breeding in New Zealand and Beyond

“…More recently, Marshall et al (2008) showed that introgression of reproductive traits from T. nigrescens to T. repens increased the seed yield. Malaviya et al (2018) investigated the interspecies incompatibility and affinity between T. alexandrinum and 22 Trifolium species. Although there was incompatibility among most of the crosses, embryo rescue and intensive crossing produced successful hybrids.…”