Exploitation of interspecific diversity for monocot crop improvement

Abstract

In many cultivated crop species there is limited genetic variation available for the development of new higher yielding varieties adapted to climate change and sustainable farming practises. The distant relatives of crop species provide a vast and largely untapped reservoir of genetic variation for a wide range of agronomically important traits that can be exploited by breeders for crop improvement. In this paper, in what we believe to be the largest introgression programme undertaken in the monocots, we describe the transfer of the entire genome of Festuca pratensis into Lolium perenne in overlapping chromosome segments. The L. perenne/F. pratensis introgressions were identified and characterised via 131 simple sequence repeats and 1612 SNPs anchored to the rice genome. Comparative analyses were undertaken to determine the syntenic relationship between L. perenne/ F. pratensis and rice, wheat, barley, sorghum and Brachypodium distachyon. Analyses comparing recombination frequency and gene distribution indicated that a large proportion of the genes within the genome are located in the proximal regions of chromosomes which undergo low/very low frequencies of recombination. Thus, it is proposed that past breeding efforts to produce improved varieties have centred on the subset of genes located in the distal regions of chromosomes where recombination is highest. The use of alien introgression for crop improvement is important for meeting the challenges of global food supply and the monocots such as the forage grasses and cereals, together with recent technological advances in molecular biology, can help meet these challenges.

Fluorescence chromosome banding and FISH mapping in perennial ryegrass, Lolium perenne L.

“…Due to the lack of a standardized karyotype of L. perenne , no correlation between LGs and individual chromosomes has been established so far through FISH mapping. Neither the analysis of alien substitution lines [38] nor alien introgression lines [39] has provided unambiguous identification of all L. perenne chromosomes. Indeed, as noted by Kopecky and Studer [1], only one of the seven chromosomes had so far been discriminated.…”

“…The accumulation of many such regional assignments should lead to the development of an integrative cytogenetic map. Such an integrative cytogenetic map will provide an alternative approach for analyses of recombination (cM) along the chromosome [39] and reveal the extent of unmapped genomic regions. It could also help to resolve contradictory chromosome assignments of markers [21] and LG map discrepancies [22].…”

Pentaploid Wheat Hybrids: Applications, Characterisation, and Challenges

“…The genetic variability that is combined from hexaploid and tetraploid wheat into a pentaploid hybrid has great potential in crop improvement (Eberhard et al, 2010; Martin et al, 2013; Kalous et al, 2015). However, while several reviews have focussed on the successful establishment of interspecific wheat hybrids (Sharma and Gill, 1983; Jiang et al, 1993; Friebe et al, 1996), little emphasis has been placed on developing efficient methods to incorporate these pentaploid hybrids into commercial breeding practices.…”

“…They also focussed on the genes that had been successfully transferred from related wild species into commercial wheat cultivars up to that time. Jiang et al (1993) discussed further advances in successful alien gene transfer from related species into cultivated bread and durum wheat. Friebe et al (1996) comprehensively reviewed a number of important wheat-alien translocations and their potential in plant breeding for developing pest and disease resistance.…”

Molecular Cytogenetic Characterization of two Triticum–Secale–Thinopyrum Trigeneric Hybrids Exhibiting Superior Resistance to Fusarium Head Blight, Leaf Rust, and Stem Rust Race Ug99

“…Many trigeneric hybrids have been produced by crossing intergeneric hybrids or amphiploids with another species, such as Triticum – Secale – Agropyron (Gupta and Fedak, 1986), Triticum – Secale – Aegilops (Orellana et al, 1989), Triticum – Secale – Hordeum (Fernandez-Escobar and Martin, 1989), Triticum – Secale – Thinopyrum (Yu et al, 1993), and Triticum – Secale – Leymus (Li et al, 2006). These trigeneric hybrids have been used as bridges to transfer useful genes or characters from wild species into wheat (Jiang et al, 1993). …”