Study On DNA Genetic Diversity Of Tobacco Core Germplasm

The genetic diversity among 110 tobacco varieties iucluding flue-cured tobacco, sun/air cured tobacco, burly tobacco, oriental tobacco, rustica tobacco and wild tobacco were assessed by SRAP markers.An optimized PCR reaction systerm for SRAP analysis was established:PCR was performed in a 25μl reaction mixture with DNA (200ng/μl) 1.5μl Primerl (100mmol/μl) 1μl, Primer2 (100mmol/μl) 1μl, dNTP (2mmol) 2.0μl, 10 x Taq Buffer 2.5μl, TaqE (5U/μl) 0.2μl,ddH₂O 16.8μl.Each sample was added 5μl Loading buffer after the amplification. The PCR reaction produts are analysed on 10% natural acrylamide gels and then satined by silver.The 29 wild tobacco and 81 common cultivated tobacco varieties/lines were amplified by 18 SRAP primers selected from 160 primers.In the 110 tobacco cultivated varieties/lines,The number of polymorphic bands amplified by 18 primers in wild tobacco and common tobacco was 206 and 3085, and the average for per-primer was 182 bands. The ratio of polymorphic bands (PPB) was 100% and 44.7% respectively. Only one primer can distinguish the common tobacco from rustica tobacco, That indicated SRAP markers were suitable for the study of germplasm diversity.The UPGMA cluster based on SRAP indicated that the same type tobacco could approximately cluster together, there was some genetic diversity among 7 diffferent type tobacco, but the difference was litter within the same type.The value of genetic similarity coefficient (Dice) of the 81 cultivated common materials is between 0.57～0.99, and the coefficient value among flue-cured tobacco,sun/air cured tobacco, burly tobacco, oriental tobacco was high,ranging from 0.9173 to 0.9895; the coefficient value of rustica tobacco and wild tobacco was lower compared to the others, ranging from 0.6485 to 0.7929.The average value of genetic diversity (h) of the 81 materials is 0.2586 and the value Shannon index (I) is 0.3795,the result indicates tobacco germplasms have highly genetic similarity and relative relationship. The result also shows wild tobacco was related to their origin, but the cultivated tobacco germplasm relationship was not obvious.