Hybridization rate and hybrid fitness for Camelina microcarpa Andrz. ex DC (♀) and Camelina sativa (L.) Crantz(Brassicaceae) (♂)

Abstract

Hybridization between crops and their wild relatives has the potential to introduce novel variation into wild populations. Camelina ( Camelina sativa ) is a promising oilseed and cultivars with modified seed characteristics and herbicide resistance are in development, prompting a need to evaluate the potential for novel trait introgression into weedy relatives. Little‐podded false flax (littlepod ; Camelina microcarpa ) is a naturalized weed in Canada and the USA. Here we evaluated the hybridization rate between the three cytotypes of littlepod (♀) and camelina (♂), assessed characteristics of hybrids, and evaluated the fitness of hexaploid littlepod and camelina hybrids in the glasshouse and field. In total we conducted, 1,005 manual crosses with diploid littlepod, 1, 172 crosses with tetraploid littlepod, and 896 crosses with hexaploid littlepod. Hybrids were not produced by the diploids, but were produced by the tetraploids and hexaploids at rates of one hybrid for 2,000 ovules pollinated and 24 hybrids for 25 ovules pollinated, respectively. Hybrids between tetraploid littlepod and camelina showed low pollen fertility and produced a small number of seeds. In the glasshouse, hybrids between hexaploid littlepod and camelina also showed significantly lower pollen fertility and seed production than parental lines, but their seeds showed high viability. A similar pattern was observed in field trials, with hybrids showing earlier flowering, reduced biomass, seed production and seed weight. However, seed produced by the hybrids showed greater viability than that produced by hexaploid littlepod and is potentially the result of a shortened lifecycle. The introgression of lifecycle traits into littlepod populations may facilitate range expansion and contribute to crop gene persistence. Consequently, future work should evaluate the hybridization rate in the field, the fitness of advanced generation backcrosses, and the role of time to maturity in limiting hexaploid littlepod's distribution.

Origin and Evolution of Diploid and Allopolyploid Camelina Genomes was Accompanied by Chromosome Shattering

“…However, little is known about the process of domestication in this taxon, although future population genetic studies in C. microcarpa may elucidate the demographic history of C. sativa. Hybrid formation between C. microcarpa and C. sativa has been observed (Séguin-Swartz et al, 2013;Martin et al, 2018) and may prove to be a valuable tool in generating novel cultivars of C. sativa with drought tolerance, disease resistance, and earlier flowering.…”

Assessing Diversity in theCamelinaGenus Provides Insights into the Genome Structure ofCamelina sativa

“…The collections of C. microcarpa species in different genebanks suggest that it has a diverse range of origin including the Mediterranean region, Armenia (Brock et al 2018), Germany, Poland, Czechia, Slovakia andGeorgia (Martin et al 2017;Smejkal 1971). Diversity studies, analyses of genome size and chromosome number along with the success of hybridization efforts between C. microcarpa and C. sativa (Séguin-Swartz et al 2013;Martin et al 2019) suggested the close relationship between these two species (Brock et al 2018;Martin et al 2017). However, not all the results were so encouraging with varying levels of hybridization success depending on the genotype (Séguin-Swartz et al 2013).…”

Interactions between genetics and environment shape Camelina seed oil composition

“…ex DC [ 16 , 17 ]. With similar genome sizes and well-documented interfertility [ 18 , 19 ], crosses between C. microcarpa and C. sativa could increase genetic diversity in the crop and introduce traits for agronomic improvement. Camelina microcarpa has been estimated to harbor roughly twice the genetic diversity of C. sativa [ 17 ], which further suggests that this wild species could be valuable for breeding programs.…”