The fragrance of cooked rice consist of more than 200 volatile compounds such as hydrocarbons, alcohols, aldehydes, ketones, acids esters phenols, pyrazines, and other compounds (Mega, 1984; Paule and Power, 1989; Tsugita et al., 1980 and Yajima et al., 1978).A comparative study of the volatile components of aromatic and non-aromatic rice varieties showed that 2-acetyle-1-pyrroline (2AP), which contributed to specific flavour in aromatic rice and has comparably lower odour threshold among rice volatiles, occurs at higher levels in aromatic rice varieties and at significantly lower levels in non-aromatic varieties (Buttery et al., 1983). Numerous studies have shown that 2AP is the only volatile compound in which the relationship between its concentration in rice and sensory intensity has been established (Mega, 1984; Paule and Power, 1989; Tsugita et al., 1980 and Yajima et al., 1978
Louis M.T Bradbury et al (2005) A perfect marker for fragrance genotyping in rice .Allele specific amplification (ASA) is a low cost robust technique that can be utilized to discriminate between alleles that differ by SNP’s insertion or deletions, within a single PCR tube. Fragrance in rice, a recessive trait, has been shown to be due to an eight bp deletion and three SNP’s in a gene on chromosome 8 which encodes a putative betaine aldehyde dehydrogenase 2(BAD2).Here report a single tube ASA assay which allows discrimination between fragrant and non-fragrant rice varieties and identifies homozygous fragrant, homozygous non fragrant and heterozygous non fragrant in a population segregating for fragrance. External primers generate a fragment of approximately 580bp as a positive control of each sample. Internal and corresponding external primers produces a 355 bp fragrant from a non-fragrant allele and 257 bp fragrant from a fragrant allele, allowing simple analysis on agarose gel.
Sunil Archak et al (2007) Basmati rice is a very special type of aromatic rice known world-wide for distinct aroma .Traditional Basmati rice cultivars, confined to Indo-Gangetic regions of the Indian subcontinent, are often reported to be adulterated with cross bread Basmati varieties and long-grain non-Basmati rice varieties in the Export market. At present, there is no commercial scale technology to reliable detect adulteration. Here report high through put multiplex microsatellite marker assay for detection and quantification of adulteration in Basmati rice.
Gous Miah, et al (2013) study of microsatellite markers and their applications in rice breeding programs to improve blast disease resistance. Over the last few decades, the use of molecular markers has played an increasing role in rice breeding and genetics of the different types of molecular markers, microsatellites have been utilized most extensively, because they can be readily amplified by PCR and the large amount of allelic variation at each locus. Microsatellites are also known simple sequence repeats and typically composed of 1-6 nucleotide repeats. These markers are abundant, distributed throughout the genome and are highly polymorphic compared with other genetic markers, as well as being species-specific and co-dominant. For these reasons, they have become increasingly important genetic markers in rice breeding programs. The evolution of new biotype of pests and diseases as well as the pressure of climate change pose serious challenges to rice breeders, Recent advances in rice genomics have now made it possible to identify and map a number of genes through linkage to existing DNA markers. Among the more noteworthy examples of genes that have been tightly linked to molecular markers in rice are those that confer resistance or tolerance to blast, therefore, in combination with conventional breeding approach, marker assisted selection(MAS) can be used to monitor the presence or lack of these genes in breeding populations. The cost effective finely mapped microsatellite markers and MAS strategies should provide opportunities for breeders to develop high yield blast resistance rice cultivars. The aim of this review is to summarize the current knowledge concerning the linkage of microsatellite markers to rice blast resistance genes, as well as to explore the use of MAS rice breeding programs aimed at improving blast resistance
Meti et al, (2013) designed the study about genetic diversity analysis in aromatic rice genotypes using microsatellite based SSR marker. The SSR markers were used to determine the allelic diversity and relationship among 48 traditional indigenous aromatic rice germplasm grown under eastern part of India. Out of 30 primers 12 primers showed DNA amplification and polymorphism among 48 aromatic rice genotypes. A total of 28 bands appeared by using 12 SSR primers in 48 aromatic rice varieties. The number of alleles per locus ranged from 1 to 5 with an average 2.08.Out of 28 bands, 25 bands were polymorphic and three were monomorphic bands. Most of primers showed highest polymorphic information content (PIC). Phenotypic characteristics are significantly correlated with genotypic characters. The analysis indicates that the 48 traditional indigenous aromatic rice genotypes were grouped into two major clusters. One cluster had 11 varieties and the second cluster had 37 varieties on the basis if the group of land races. Based on this study, the larger range of similarity values using SSR markers provides greater confidence for the assessment of genetic relationship among the varieties. The information obtained from the SSR profile helps to identify the variety diagnostic markers in 48 traditional indigenous aromatic rice genotypes. Significant genetic variation at maximum number of loci between varieties indicates rich genetic resources in rice. The intra inter genetically variation might be useful for breeders to improve the aromatic rice varieties through selective breeding and cross breeding programs and also protect these unique germplasm under intellectual property rights (IPR)
TQ Zheng et al, (2017) Rice milling quality is the final part of grain yield making it for eating and a complex trait that remains poorly understood genetically. Three components of rice milling quality, that is brown rice rate and head rice rate and related rice grain shape traits were genetically dissected by the QTL mapping approach using a set of 231 random rice introgression lines and 160 SSR markers. A total of 10 genomic regions were found to be associated with rice grain shape and milling quality traits. Of these, one major QTL on chromosome 7 had large effect on rice grain shape and milling quality and was detected consistently in several related populations of rice, which offers an opportunity for marker aided improvement of rice milling quality and QTL cloning
