A New Linkage in Tobacco

Abstract

In about seven genetic linkages so far found in Nicotiana species, only one concerns tabacum and another rustica. The rest of the five linkages were discovered in interspecific crosses involving N. tabacum, N. langsdorffii and N. sanderæ¹. Kelaney² found a linkage between a gene Br for broad-constricted leaf with the gene Pk for carmine-pink flowers with a 7.5 per cent crossing-over. Boortzev³ mentions linkage of 4.35 per cent between seed colour and compact habit in N. rustica. Clausen and Cameron⁴ have isolated twenty-four monosomics of tobacco and were able to locate cytologically eighteen genes for sixteen characters in nine chromosomes by crossing the monosomics with a standard tobacco type. In six of the chromosomes identified, more than one gene has been found, but the authors do not mention the position of genes and distances between them.