Wild Beet Beta Vulgaris Research Articles

Assessment of interspecific hybridization between wild beet Beta vulgaris L. subsp. maritima and cultivated sugar beet under Moroccan conditions

Obtaining a viable and fertile beet hybrid resulting from wild and cultivated sugar beet crosses under Moroccan conditions is challenging. To deal with hybridization, barriers in sugar beet, such as concordance of flowering period between biannual and annual subspecies, flowering aptitude according to vernalization requirement, genotype incompatibility and hybrid sterility, should be overcome. In our study, interspecific hybrids were obtained from crosses between 17 cultivated sugar beet Beta vulgaris subsp. vulgaris and 17 Beta vulgaris subsp. maritima, collected in different regions of Morocco. Twenty-two agro-morphological traits were used for the evaluation of 208 hybrid plants, under greenhouse conditions. CH and WH hybrids were collected on cultivated and wild parents separately. Most of the hybrids behaved as annual plants, of which 83.17% were able to flower and produce seeds without any vernalization requirements. All WH hybrids and 57.06% of CH hybrids were morphologically similar to their wild parent. However, 24% of CH hybrids were phenotypically similar to their cultivated parent. The remaining CH hybrid plants were behaving as intermediate genotypes between both wild and cultivated parents. Our results showed the success of interspecific beet crosses and emphasized the high variability among hybrid genotypes. This is of great importance for sugar beet improvement and breeding programs and interspecific crosses patterns understanding.

Emergence of gynodioecy in wild beet (Beta vulgaris ssp. maritima L.): a genealogical approach using chloroplastic nucleotide sequences.

Gynodioecy is a breeding system where both hermaphroditic and female individuals coexist within plant populations. This dimorphism is the result of a genomic interaction between maternally inherited cytoplasmic male sterility (CMS) genes and bi-parentally inherited nuclear male fertility restorers. As opposed to other gynodioecious species, where every cytoplasm seems to be associated with male sterility, wild beet Beta vulgaris ssp. maritima exhibits a minority of sterilizing cytoplasms among numerous non-sterilizing ones. Many studies on population genetics have explored the molecular diversity of different CMS cytoplasms, but questions remain concerning their evolutionary dynamics. In this paper we report one of the first investigations on phylogenetic relationships between CMS and non-CMS lineages. We investigated the phylogenetic relationships between 35 individuals exhibiting different mitochondrial haplotypes. Relying on the high linkage disequilibrium between chloroplastic and mitochondrial genomes, we chose to analyse the nucleotide sequence diversity of three chloroplastic fragments (trnK intron, trnD-trnT and trnL-trnF intergenic spacers). Nucleotide diversity appeared to be low, suggesting a recent bottleneck during the evolutionary history of B. vulgaris ssp. maritima. Statistical parsimony analyses revealed a star-like genealogy and showed that sterilizing haplotypes all belong to different lineages derived from an ancestral non-sterilizing cytoplasm. These results suggest a rapid evolution of male sterility in this taxon. The emergence of gynodioecy in wild beet is confronted with theoretical expectations, describing either gynodioecy dynamics as the maintenance of CMS factors through balancing selection or as a constant turnover of new CMSs.