Impact of Chromosomal Rearrangements on the Interpretation of Lupin Karyotype Evolution

Abstract

Plant genome evolution can be very complex and challenging to describe, even within a genus. Mechanisms that underlie genome variation are complex and can include whole-genome duplications, gene duplication and/or loss, and, importantly, multiple chromosomal rearrangements. Lupins (Lupinus) diverged from other legumes approximately 60 mya. In contrast to New World lupins, Old World lupins show high variability not only for chromosome numbers (2n = 32–52), but also for the basic chromosome number (x = 5–9, 13) and genome size. The evolutionary basis that underlies the karyotype evolution in lupins remains unknown, as it has so far been impossible to identify individual chromosomes. To shed light on chromosome changes and evolution, we used comparative chromosome mapping among 11 Old World lupins, with Lupinus angustifolius as the reference species. We applied set of L. angustifolius-derived bacterial artificial chromosome clones for fluorescence in situ hybridization. We demonstrate that chromosome variations in the species analyzed might have arisen from multiple changes in chromosome structure and number. We hypothesize about lupin karyotype evolution through polyploidy and subsequent aneuploidy. Additionally, we have established a cytogenomic map of L. angustifolius along with chromosome markers that can be used for related species to further improve comparative studies of crops and wild lupins.

The Puzzling Fate of a Lupin Chromosome Revealed by Reciprocal Oligo-FISH and BAC-FISH Mapping

“…Considering BAC-FISH results obtained in previous studies [ 17 , 35 ] and comparative mapping of L. angustifolius and L. albus genome assemblies and linkage maps [ 18 , 36 , 37 ], the pseudochromosome Lang06 sequence of L. angustifolius cv. Tanjil was selected as a template for oligonucleotide design.…”

“…Single copy BAC clones from the L. angustifolius nuclear genome BAC library [ 33 ] identified as Lang06-specific in the previous study [ 17 ] were used. Due to the dispersed mapping pattern of 067H16 BAC clone in wild lupins, one additional probe (059F07) specific to Lang06 [ 34 ] was used instead.…”

“…Preparation of mitotic metaphase spreads and FISH with BAC-based probes (BAC-FISH) was done according to Susek et al [ 17 ] with minor modifications. Young roots (~1 cm long) were treated in a solution of 40% ( v / v ) pectinase (Sigma–Aldrich, Darmstadt, Germany), 3% ( w / v ) cellulase (Sigma–Aldrich), and 1.5% ( w / v ) cellulase ‘Onozuka R-10′ (Serva, Heidelberg, Germany), in 37 °C for 60 min (lateral roots) or 100 min (primary roots).…”

“…Lupin breeding is most advanced in Australia and many European countries, especially in those located in the eastern part of the continent. Parallel to the growing use of lupins in the food industry, their genomic studies and the knowledge on molecular and evolutionary mechanisms underlying the high variability observed in the genus have been advancing [ 13 , 14 , 15 , 16 , 17 , 18 ].…”

A Tale of Two Families: Whole Genome and Segmental Duplications Underlie Glutamine Synthetase and Phosphoenolpyruvate Carboxylase Diversity in Narrow-Leafed Lupin (Lupinus angustifolius L.)

“…According to the proposed evolutionary history of narrow-leafed lupin, it was stated that this species has undergone duplication and/or triplication with several chromosome rearrangements [11,21,36]. Based on a cytogenetic analysis of several species from the Lupinus genus, it was also hypothesized that the lupin karyotype has evolved through polyploidy and subsequent aneuploidy [61]. Global analysis of the narrow-leafed lupin transcriptome and legume genome sequence comparative mapping enabled whole genome duplication (WGD) events to be dated.…”