IDENTIFICATION OF MOLECULAR MARKERS FOR SEED PURITY TESTING IN HYBRID RICE [Oryza sativa L.]
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Date
2010-07-10
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University of Agricultural Sciences, Bangalore
Abstract
The ability to distinguish and identify hybrids is fundamental for the operational aspects in the seed trade. An experiment was conducted to distinguish rice hybrids form their parental lines, using morphological and SSR molecular markers during 2009-10.
Among all the qualitative and quantitative morphological traits (as per the National DUS Test Guidelines, 2009) studied, flag leaf attitude, flag leaf length and width, days to 50 per cent flowering and maturity, degree of panicle exertion, presence of awns, panicle secondary branching, days to maturity, leaf senescence and seed traits such as 1000 seed weight, grain length and width and shape of grain were found to be more useful for grouping of parents and hybrids. Based on seed colour parental lines DR 714-1-2R was identified by pale yellow, KMR-3R by yellow colour and IR-68897B by yellowish brown however, rest of them were grouped under very pale brown. Based on seed length hybrids and parental lines KMR-3R was grouped as short, where as IR-58025A, IR-58025B, KRH-2, DRRH-2, IR-68897A, IR-68897B, DR 714-1-2 as medium. Based on the seed shape parental line KMR-3R was grouped under semi spherical and rests of the genotypes were grouped under semi long category. The characters such as leaf length (varied from 22.55 cm (KRH-2) to 35.70 cm (IR-68897A), days to 50 per cent flowering (from 73 days (IR-68897B) to 102 days (KMR-3R), secondary branching in the panicle (from weak to clustered), days to maturity from 112 days (IR-68897B) to 134 days (IR-58025B)), 1000 seed weight from 18.63 (IR-58025A) to 24.94g (IR-68897B)), and dehusked grain shape (from semi spherical to elongated) exhibited more variation among the genotypes. The DNA profile of all hybrids and parental lines obtained was able to distinguish each hybrid form their parental lines. The SSR profile of hybrids showed specific bands of both female and male parents and the banding pattern was unique to each hybrids. Out of the 35 Simple Sequence Repeat (SSR) markers distributed across the 12 chromosomes analyzed, 10 were found to be polymorphic. KRH-2 could be clearly identified by using ‘RM 206, RM 234, and RM 276’ based on the banding pattern. Similarly DRRH-2 could be clearly identified by using ‘RM 234, RM 228, and RM 204’ .The results of the grow-out test (GOT) and SSR marker tests were comparable. For comparison of GOT test results with molecular tests for genetic purity, leaf sample collected by random sampling were evaluated by using primer ‘RM 206’ for KRH-2 hybrids and RM 228 for DRRH-2 hybrids revealed 100, 93.34 and 91.43 per cent of purity which were validated with the theoretical purity (GOT) per cent of 100, 95 and 90 per cent, respectively. The random sampling of seed lots are required for conducting the lab GOT using RM 206 marker either to distinguish or to test for hybridity of KRH-2. The validation of the identified markers was done with conventional grow out test. The study has generated some important morphological traits, and molecular markers that can be effectively employed in distinguishing the rice hybrids KRH-2 and DRRH-2 with their parents.
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