F2 screening of sesamum (sesamum indicum L.) genotypes by using molecular markers
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Date
2019-08-09
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Vasantrao Naik Marathwada Krishi Vidyapeeth, Parbhani
Abstract
Sesamum (Sesamum indicum L.), a member of the order Tubiflorae, family Pedaliaceae genus Sesamum and species indicum, having chromosome number 2n-26. It is perhaps the oldest oilseed known and used by human beings (Weiss, 1971). It is an important annual oilseed crop in the tropics and warm subtropics, where it is usually grown in small plots (Bedigian and Harlan, 1986). Due to the presence of potent antioxidant, sesame seeds are known as “the seed of immortality”. Sesamum is described as the “Queen of oilseeds” as it contains high oil (38-54%), protein (18-25%), calcium, phosphorous, oxalic acid and excellent qualities of seed oil and meal (Prasad, 2002).
Seven phenotypical characters, 15 RAPD and 20 SSR primers were used to screen the F2 population. Bulked segregant analysis procedure was used for identifying markers in specific regions of the genome. According to this method, four pooled DNA samples of individuals from a segregating population originating from a single cross were done. The obtained F1 shows light brown colour indicates crossing was done successfully (Baydar, 2000). Within each pool, or bulk the individuals were identical for two individual traits i.e., the leaf pattern and seed coat colour respectively. The gene pools were A- Alternate leaf pattern, O-Opposite leaf pattern, W-White seed coat colour and B-Brown seed coat colour.
In this F2 screening, markers that are polymorphic between the pools and are genetically linked to loci determining the trait were used to construct the pools. Here out of the total 35 primers (RAPD and SSR) screened, we found a single RAPD RPI-7 (33.33% polymorphism) primer and a single SSR primer Hs1871 (100% polymorphism) which distinctly shows the difference between the bulks. Out of sixty F2
individuals of bulk the polymorphic band was seen in twenty six (RAPD RPI-7) and fourteen (SSR Hs1871) samples shows it linkage with brown seed coat colour.
The F2 population segregated in a ratio of 9:3:4 in the field experiment confirming that seed coat colour is controlled by two independent genes interacting to produce epistatic interaction.
The present study may be useful for detection of QTLs of highly diverse and vigorous genotypes for improvement of some major morphological, agronomical and quantitative traits.
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