Mapping QTL for vernalization requirement identified adaptive divergence of the candidate geneFlowering Locus Cin polyploidCamelina sativa

Abstract

Vernalization requirement is an integral component of flowering in winter-type plants. The availability of winter ecotypes amongCamelinaspecies facilitated the mapping of QTL for vernalization requirement inC. sativa. An inter- and intraspecific crossing scheme between relatedCamelinaspecies, where two different sources of the winter-type habit were used, resulted in the development of two segregating populations. Linkage maps generated with sequence-based markers identified three QTL associated with vernalization requirement inC. sativa; two from the inter-specific (chromosomes 13 and 20) and one from the intra-specific cross (chromosome 8). Notably, the three loci were mapped to different homologous regions of the hexaploidC. sativagenome. All three QTL were found in proximity toFLOWERING LOCUS C(FLC), variants of which have been reported to affect the vernalization requirement in plants. Temporal transcriptome analysis for winter-typeCamelina alyssumdemonstrated reduction in expression ofFLCon chromosomes 13 and 20 during cold treatment, which would trigger flowering, sinceFLCwould be expected to suppress floral initiation.FLCon chromosome 8 also showed reduced expression in theC. sativassp.pilosawinter parent upon cold treatment, but was expressed at very high levels across all time points in the spring-typeC. sativa. The chromosome 8 copy carried a deletion in the spring-type line, which could impact its functionality. Contrary to previous reports, all threeFLCloci can contribute to controlling the vernalization response inC. sativaand provide opportunities for manipulating this requirement in the crop.