IDENTIFICATION OF RICE (Oryza sativa L.) VARIETIES USING DUS DESCRIPTORS AND GENE-SPECIFIC MARKERS
Loading...
Date
2021-12-01
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ACHARYA N G RANGA UNIVERSITY
Abstract
The identification of varieties is a vital step during the breeding and registration process, seed production, trade and inspection in crops. The rapid identification and characterization of cultivars or varieties would therefore, provide valuable information for their introduction and genetic improvement. Plant cultivar or variety identification is a critical field as an ever increasing number of varieties are developed every year and the need to identify them unambiguously also increases. Hence, in the present study, an attempt was made to identify 52 rice varieties using 22 DUS descriptors and 25 gene-specific markers.
Out of 22 morphological DUS descriptors studied, four were monomorphic, nine were dimorphic and the remaining nine were polymorphic. Of these 18 traits (both dimorphic and polymorphic), only 10 were essential traits. The descriptor notes of these 10 traits were used for generating DUS 2-D barcode for identification of rice varieties. The 2-D barcode developed using these 10 DUS descriptors was able to distinguish 26 varieties and the remaining 26 genotypes were unable to be distinguished.
The analysis of variance demonstrated significant differences among 52 genotypes for all the traits studied. High PCV and GCV were recorded for the traits viz., panicle number per plant, weight of 1000 fully developed grains and grain yield plant-1 indicating that large amount of variation was present among the genotypes for these characters. Whereas, low PCV and GCV were recorded for the traits viz., grain length, decorticated grain length and length/ breadth ratio indicating that the variability for these characters among the genotypes was
xv
meagre. The variability studies of the present investigation indicated that the estimates of PCV were slightly higher than the corresponding GCV for all the characters indicating that the characters were less influenced by the environment.
High heritability coupled with high genetic advance as per cent of mean was recorded for time of heading, stem length, panicle number per plant, weight of 1000 fully developed grains, decorticated grain width and grain yield plant-1 indicating that these traits were mostly under the control of additive gene action and direct selection of these traits would be effective for crop improvement. While high heritability coupled with moderate genetic advance as per cent of mean was observed for the traits viz., panicle length of main axis, time of maturity, grain length, grain width, decorticated grain length and length/breadth ratio. Out of 25 gene-specific markers used for screening, 18 were polymorphic. The number of alleles of the polymorphic markers ranged from two to three with an average of 2.05 alleles per locus. The PIC values of these gene-specific markers ranged from 0.037 to 0.369 with an average of 0.212. Varietal specific fingerprints were generated using these 18 markers. The order of the alleles of these gene-specific markers were used for generating the fingerprints for all the 52 rice varieties. These fingerprints were able to distinguish 50 genotypes. BPT2295 and Jaya were the two varieties possessing similar DNA fingerprints (allele codes) and could not be distinguished using these allele codes. Using DUS descriptors and gene-specific markers, it was demonstrated to distinguish 26 and 50 varieties respectively, when analysed separately. However, in combination of both DUS descriptors and gene-specific markers, it was possible to distinguish all the 52 rice varieties. These DUS and allele codes together were used to develop QR (Quick Response) codes using an online tool (available at www.barcode-generator.org) for their rapid identification. The dendrogram developed by UPGMA using the polymorphism of genespecific markers grouped all the 52 rice genotypes into seven clusters at 60 % similarity coefficient. Cluster I, II and III comprised of seven, 37 and four genotypes respectively. The genotypes viz., Varadhan, Kasturi, Udayagiri and Vandana formed into four distinct monogenic clusters (Cluster IV, V, VI and VII) indicating that they are genetically divergent from the remaining genotypes. Hierarchical clustering of the 52 genotypes based on morphological data using nearest neighbour methods based on squared Euclidean distance classified the genotypes into four major clusters. Cluster I comprised of 47 genotypes and Cluster II comprised of three genotypes and the remaining two genotypes, Vandana and Rasi formed into two distinct monogenic clusters, appearing to be the more diverse and may be useful as a source for variable characters for rice improvement. In conclusion, in the present study, it was demonstrated that by the combination of DUS traits and molecular markers, it was possible to develop DNA fingerprints which were further converted into QR codes that can be applied for unambiguous identification of all rice varieties
Description
IDENTIFICATION OF RICE (Oryza sativa L.) VARIETIES USING DUS DESCRIPTORS AND GENE-SPECIFIC MARKERS