Inheritance of the vernalization response determined by doubled haploids in spring oilseed rape (Brassica napus L.)

The presence of a vernalization requirement can delay floral initiation until the cold requirement of the plant has been satisfied. Breeders attempting to develop early-maturing cultivars should be aware and have an understanding of the genetic basis of factors such as vernalization response to assess potential impact on their programs. The ability to generate doubled haploid (DH) lines from oilseed rape (Brassica napus) has led to the use of DH populations in genetic studies. The objective of this study was to determine the mode of inheritance of the vernalization response in spring B. napus with DH lines. A set of Fl-derived DH lines from crosses between spring oilseed rape parent lines were evaluated for their response to vernalization. The use of DH lines allowed the exposure of the individuals of identical genotype to two different treatments, vernalization and no vernalization. The vernalization treatment consisted of exposure of germinated seeds for 2 wk at 4°C. Seeds of the non-vernalized treatment were germinated at 22°C. Comparison between treatments of the final leaf number on the main raceme (FLN) was used to assess the vernalization response. The results indicated that there is a gene for nonresponse to vernalization in the spring oilseed rape cultivar Karat. FLN offers a direct measure of vernalization response, since leaf initiation ceases when floral initiation begins.