Mapping quantitative trait loci determining seed longevity in tobacco (Nicotiana tabacum L.)

Seed longevity is a crucial issue for germplasm conservation and seed marketing. This trait is determined not only by environmental conditions, but also by genetic factors. Molecular mapping of responsible loci has been performed with several crops, but not with tobacco (Nicotiana tabacum L.). In the present study, we investigate 122 recombinant inbred lines derived from a cross between the cultivars Florida 301 and Hicks. Four germination-related traits were studied by examining seeds either untreated or after controlled deterioration (CD): total germination (TG, %), normal germination (%), time to reach 50 % of TG (h), and the area under the curve after 200 h of germination. Whereas Hicks exhibited high germination percentage and speed in untreated (fresh) seeds, Florida 301 seems to withstand the CD treatment better, having increased seed longevity. In total, four genomic regions located on four different linkage groups (LGs) were identified to be associated with the selected traits. Positive alleles for the individual traits were contributed by both parents. A major quantitative trait locus (QTL) for high percentage TG located on LG 8/18 appeared in both control and deteriorated seeds and was contributed by Hicks. In contrast, Florida 301 donated a favorable allele for germination speed on LG seven after CD only. The position of this locus compared well with a QTL detected in the same population, in a former study examining resistance against the black shank disease caused by Phytophthora nicotianae). The effects of environmental growing conditions of the mother plants on seed longevity are discussed.