Genetic Dissection of Grain Size Traits Through Genome-Wide Association Study Based on Genic Markers in Rice

Not AvailableGrain size plays a significant role in rice, starting from affecting yield to consumer preference, which is the driving force for deep investigation and improvement of grain size characters. Quantitative inheritance makes these traits complex to breed on account of several alleles contributing to the complete trait expression. We employed genome-wide association study in an association panel of 88 rice genotypes using 142 new candidate gene based SSR (cgSSR) markers, derived from yield-related candidate genes, with the efficient mixed-model association coupled mixed linear model for dissecting complete genetic control of grain size traits. A total of 10 significant associations were identified for four grain size-related characters (grain weight, grain length, grain width, and length-width ratio). Among the identified associations, seven marker trait associations explain more than 10% of the phenotypic variation, indicating major putative QTLs for respective traits. The allelic variations at genes OsBC1L4, SHO1 and OsD2 showed association between 1000-grain weight and grain width, 1000-grain weight and grain length, and grain width and length-width ratio, respectively. The cgSSR markers, associated with corresponding traits, can be utilized for direct allelic selection, while other significantly associated cgSSRs may be utilized for allelic accumulation in the breeding programs or grain size improvement. The new cgSSR markers associated with grain size related characters have a significant impact on practical plant breeding to increase the number of causative alleles for these traits through marker aided rice breeding programs.Not Availabl

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Not AvailableBACKGROUND To improve production efficiency, positive alleles corresponding to yield-related attributes must be accumulated in a single elite background. We designed and used cgSSR markers, which are superior to random SSR markers in genome-wide association study, to identify genomic regions that contribute to panicle characters and grain yield in this study. RESULTS As evidenced by the high polymorphic information content value and gene diversity coefficient, the new cgSSR markers were determined to be highly informative. These cgSSR markers were employed to generate genotype data for an association panel evaluated for four panicle characters and grain yield over three seasons. For five traits, 17 significant marker–trait associations on six chromosomes were discovered. The percentage of phenotypic variance that could be explained ranged from 4% to 13%. Unrelated gene-derived markers had a strong association with target traits as well. CONCLUSION Trait-associated cgSSR markers derived from corresponding or related genes ensure their utility in direct allele selection, while other linked markers aid in allele selection indirectly by altering the phenotype of interest. Through a marker-assisted breeding approach, these marker–trait associations can be leveraged to accumulate favourable alleles for yield enhancement in rice. © 2022 Society of Chemical Industry.ICA

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Not AvailableEleven pigmented rice genotypes were evaluated to estimate genetic parameters, heritability and association. The results indicated that, genotypic variation was high among the lines. The distinct seasonal effect on plant performance for antioxidant capacity, anthocyanin, flavonoids, head rice recovery and test weights was also observed. Wet season favoured the crop performance in all genotypes as compared to drought conditions. The differential accumulation of different quality traits such as AOA, anthocyanin content, flavonoids content, etc showed high heritability, which would be transfer to high yeilding popular rice cultivars through conventional or geneticaly modification techniques. The line Mamihunger was chosen as donor of the high-quality rice grain and Annapurna for high yield. Further, Mamihunger are foreseen to be good in nutritional quality and industry use.Not Availabl

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Not AvailableSeed germination plays cardinal roles in seedling establishment and their successive growth. However, seed germination is retarded by far-red (FR) enrichment under low light stress, and the inhibitory signalling mechanism remains ambiguous. Our results indicated that low light treatment, both in the open and growth chamber conditions, inhibits rice seed germination by decreasing the gibberellin (GA) contents. To explore the mechanism of GA-deficiency under low light stress, differential expression profiling of GA-anabolic, -catabolic, ABA -anabolic, catabolic, and SLR1 was investigated, revealing that expression of ABA- anabolic, GA-catabolic genes and SLR1 was upregulated with a simultaneous downregulation of ABA-catabolic and GA-anabolic genes under low light treatment. These results suggested that FR-induced GA inadequacy is resulted by upregulation of SLR1 and GAcatabolism genes consequently increase DELLA that further subsided GA-responses in the germinating rice seeds. Moreover, we provided evidence that FR-induced GA inadequacy demotes rice seed germination by decreasing amylase activity, eventually decreasing the carbohydrate solubilization in the germinating seeds. Finally, we suggest that under low light stress, due to a retarded conversion of phytochrome A to their bioactive form, the ABA-catabolic genes were eventually upregulated with a simultaneous downregulation of GA-anabolic genes. Consequently, a lower GA pool fails to leverage the GA-dependent DELLA degradation, further shutting down the expected GA responses that reduce germination efficiency under FRenriched light.Not Availabl

Combinatorial effect of heat processing and phytic acid on mineral bioavailability in rice grain

Brown rice is superior to milled rice in terms of bioactive compounds and minerals but also has phytic acid (PA) that may reduce the bioavailability of minerals. Further, various household cooking methods of rice also change the starch matrix, affecting mineral availability. The effect of PA and heat processing methods on Fe and Zn bioavailability from milled rice grain was investigated. Rice with contrasting PA was analyzed for Fe and Zn bioavailability in milled and cooked rice. The genotype Khira, with the lowest PA (2.0 g kg−1), exhibited high Fe and Zn bioavailability, while Phalguni, with the highest PA (11.2 g kg−1), showed low Fe and Zn bioavailability. The PA had a significant negative correlation with Fe and Zn bioavailability. Among three common household cooking methods used (pressure cooking, microwave-assisted cooking and boiling), pressure cooking exerted more remarkable effects on mineral bioavailability than other two methods. Screening rice genotypes for low PA and high Fe, Zn bioavailability can solve the problem of micronutrient malnutrition in countries where people depend on rice as the main staple food. The selection of appropriate cooking methods is also helps to enhance mineral bioavailability

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Additional file 1 of Understanding natural genetic variation for grain phytic acid content and functional marker development for phytic acid-related genes in rice

Additional file 1: Supplementary Fig. S1. The grain PA content of 94 rice genotypes and two landraces for the year 2020 and 2021. Supplementary Fig. S2. Representative image of allelic diversity at the (AAG)n genetic loci of 3’ UTR of the SPDT gene among 96 rice genotypes (uncropped full length gel image). Supplementary Fig. S3. The dendrogram constructed based on the allelic diversity for PA-related candidate genes in 96 rice genotypes. Supplementary Table S1. Candidate genes reported to be associated with grain PA content in rice. Supplementary Table S2. Nucleotide diversity parameters for the SPDT and OsPT8 genes in rice

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Not AvailableAssessing genetic diversity and development of a core set of elite breeding lines is a prerequisite for selective hybridization programes intended to improve the yield potential in rice. In the present study, the genetic diversity of newly developed elite lines derived from indicax tropical japonica and indicax indica crosses were estimated by 38 reported molecular markers. The markers used in the study consist of 24 gene-based and 14 random markers related to grain yield-related QTLs distributed across the rice genome. Genotypic characterization was carried out to determine the genetic similarities between the elite lines. In total, 75 alleles were found using 38 polymorphic markers, with polymorphism information content ranging from 0.10 to 0.51 with an average of 0.35. The genotypes were divided into three groups based on cluster analysis, structure analysis and also dispersed throughout the quadrangle of PCA, but nitrogen responsive lines clustered in one quadrangle. Seven markers (GS3_RGS1, GS3_RGS2, GS5_Indel1, Ghd 7_05SNP, RM 12289, RM 23065 and RM 25457) exhibited PIC values C 0.50 indicating that they were effective in detecting genetic relationships among elite rice. Additionally, a core set of 11 elite lines was made from 96 lines in order to downsize the diversity of the original population into a small set for parental selection. In general, the genetic information collected in this work will aid in the study of grain yield traits at molecular level for other sets of rice genotypes and for selecting diverse elite lines to develop a strong crossing programme in rice.ICA