Occurrence and frequency of putatively Y chromosome linked DNA markers in Cannabis sativa L.

DNA from female and male hemp (Cannabis sativa L.) plants belonging to nine different varieties were screened with180 RAPD primers in a search for sex-associated DNA markers. About 1500bands were produced in total, nine primers were found yielding one or two DNA bands amplified in all nine male DNA bulks and absent in all female DNA bulks. These putatively male-associated markers were then scored in three different F1progenies, deriving from a cross between a common male parent and three different female plants. The sex of the progeny was accurately scored on the basis of the floral phenotype, and the presence of the nine male-associated markers was verified by RAPD analysis. In all three progenies examined, all the male plants showed the DNA markers previously identified by bulk segregant analysis (BSA) on the hemp varieties, while all the female plants lacked them. The fact that the association between these markers and the staminate phenotype is found when examining male plants of distantly related varieties, and that such linkage is never broken when different progenies are examined, strongly supports the hypothesis that the markers found are physically located on the Y chromosome, in a region excluded from recombination during meiosis. Another marker was shown to be present in the male parent, in all the male plants of each progeny, and in 50% of the female progenies, while it was absent in the female parent; the possible occurrence of markers deriving from multiple amplification sites of the genome is discussed. This revised version was published online in August 2006 with corrections to the Cover Date.