It is well known that aroma in rice is genetically controlled by cell nuclear genes and independent of cytoplasmic heredity, inheritance probably involving modifier genes without maternal effect. Hang et al.
Aromatic rice varieties emit aroma from their leaves, grains and flowering organs at various stages of maturity and several chemical constituents have been shown to be important for rice aroma, 2- acetyl pyrroline 2AP being a key component of rice scent Wongpornchai et al. The accumulation of 2AP in fragrant genotypes may be explained by the presence of mutations resulting in a loss of function of the fgr gene product Bradbury et al.
Genetically modified rice
Aroma in rice is a sensory character, and in the study by Paule and Powers the judges used terms with which they were familiar to describe the odor of scented rice. It is essential for rice breeders to develop reliable, fast and cost-effective evaluation for rice aroma in breeding programs. As sensory quality has always been an important consideration in rice improvement, we used sensory methods including eluting aroma from leaves with dilute KOH and chewing grains for aroma. However, the detection of aroma by sensory or chemical methods is by no means practical when processing large numbers of samples.
Introduction and Review: Rice as a Model Genome
In order to minimize the influence of environmental condition and other factors, identification of aroma in our study was performed on two F 2 populations produced in different years and at different sites. The F 2 plants with high aroma i. In addition, the fragrance fgr gene identified in Kyeema rice O. As the biochemical pathway leading to fragrance in rice is not fully understood, and BAD2 has significant polymorphisms in the coding region of fragrant genotypes relative to non-fragrant genotypes, it is necessary to analyze the biological function of BAD2.
Now genetic transformation of rice and certification of transformants will be the next major step towards determining the role of this gene in the ChB aroma trait.
Molecular mapping for the aroma trait and its subsequent use in selection processes would greatly accelerate the efficiency and precision of aromatic rice breeding programs. Some progress has been made towards the identification of molecular markers linked to fragrance genes, including the SCURM Cordeiro et al.
However, these assays cannot work on a broad range of any one rice sample and predictions made from the results are not of high accuracy. Moreover, with some genotypes segregation distortion would be generated by the genes that reduce the viability of zygote Schimenti, ; van Boven and Weissing, Previous studies on genetic analysis have shown that the gene or quantitative trait loci QTL for aroma and cooked kernel elongation CKE are linked and present on chromosome 8 Ahn et al.
Jain et al.
Genetic analysis and gene fine mapping of aroma in rice (Oryza sativa L. Cyperales, Poaceae)
It thus seems necessary to identify specific molecular markers for special populations or novel aromatic rice varieties. However, samples from breeding programs could be assessed for aroma in the early stages of the development of varieties by using marker-assisted selection to keep the target gene intact.
Based on our results that the aroma gene in ChB is a single recessive gene and the fact that the introgression of gene in good quality rice is available by successive backcrosses in different populations it will be easy to raise aromatic restorer lines to exploit the aroma trait in hybrid rice with the aid of our newly discovered flanking markers Aro7, RM and RM We thank the anonymous reviewers for their comments and Dr. Theor Appl Genet Plant Biotechnol J Mol Breed Mol Genet Genomics Dhulappanavr CV Inheritance of scent in rice.
SEMINAR: Rice genetics in the Genomics Era
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