Deep sequencing of small RNAs reveals ribosomal origin of microRNAs in Oryza sativa and their regulatory role in high temperature

MicroRNAs are small noncoding regulatory RNAs which control gene expression by mRNA degradation or translational repression. They are significant molecular players regulating important biological processes such as developmental timing and stress response. We report here the discovery of miRNAs derived from ribosomal DNA using the small RNA datasets of 16 deep sequencing libraries of rice. Twelve putative miRNAs were identified based on highly stringent criteria of novel miRNA prediction. Surprisingly, 10 putative miRNAs (mi_7403, mi_8435, mi_12675, mi_4266, mi_4758, mi_4218, mi_8200, mi_4644, mi_14291, mi_16235) originated from rDNA of rice chromosome 9. Expression analysis of putative miRNAs and their target genes in heat tolerant and susceptible rice cultivars in control and high temperature treated seedlings revealed differential regulation of rDNA derived miRNAs. This is the first report of rDNA derived miRNAs in rice which indicates their role in gene regulation during high temperature stress in plants. Further studies in this area will open new research challenges and opportunities to broaden our knowledge on gene regulation mechanisms

Rice biofortification: breeding and genomic approaches for genetic enhancement of grain zinc and iron contents

Rice is a highly consumed staple cereal cultivated predominantly in Asian countries, which share 90% of global rice production. Rice is a primary calorie provider for more than 3.5 billion people across the world. Preference and consumption of polished rice have increased manifold, which resulted in the loss of inherent nutrition. The prevalence of micronutrient deficiencies (Zn and Fe) are major human health challenges in the 21st century. Biofortification of staples is a sustainable approach to alleviating malnutrition. Globally, significant progress has been made in rice for enhancing grain Zn, Fe, and protein. To date, 37 biofortified Fe, Zn, Protein and Provitamin A rich rice varieties are available for commercial cultivation (16 from India and 21 from the rest of the world; Fe > 10 mg/kg, Zn > 24 mg/kg, protein > 10% in polished rice as India target while Zn > 28 mg/kg in polished rice as international target). However, understanding the micronutrient genetics, mechanisms of uptake, translocation, and bioavailability are the prime areas that need to be strengthened. The successful development of these lines through integrated-genomic technologies can accelerate deployment and scaling in future breeding programs to address the key challenges of malnutrition and hidden hunger

Development and evaluation of introgression lines with yield enhancing genes of the Indian mega-variety of rice, MTU1010

MTU 1010 is an early maturing and high-yielding mega rice variety widely grown in an area of 3 Mha. It is characterised by limited grain number and panicle branching. To improve the grain number in MTU 1010, an IRRI breeding line, IR121055-2-10-5 was utilized as donor to transfer yield-enhancing genes Gn1a and OsSPL14 (associated with increased grain number and better panicle branching, respectively) into MTU1010 by Marker-Assisted Backcross Breeding (MABB). At each backcross generation, foreground selection was carried out with Gn1a and OsSPL14- specific molecular markers, whilst background selection was done with a set of SSR markers polymorphic between the IR121055-2-10-5 and MTU1010. With the use of a gene-specific marker, homozygous BC2 F2 plants carrying the yield-enhancing gene were identified and advanced through pedigree-method of selection till BC2 F6 and best performing ten lines were selected and evaluated in replicated station trials for yield contributing traits, where grain number and brancing per panicle exhibited high significant and positive correlation with single plant yield. Three promising lines namely RP6353-5-8-13-24, RP6353-26-13-39-5 and RP6353-32-12-8-16 with higher grain number and yield than MTU1010 were identified and nominated for evaluation in Initial Varietal Trial-Aerobic (IVT-Aerobic) of All India Crop Improvement Programme on Rice (AICRP), of which RP6353-26-13-39-5 (IET28674), was promoted for further testing

Not Available

Not AvailableThis paper presents the results of studies conducted in India to enhance the yield potential of improved Samba Mahsuri (ISM) using marker-assisted selection for the presence of yield target traits, i.e. high grain number, strong culm and panicle branching, which are governed by the genes Gn1a, SCM2 and OsSPL14, respectively. Phenotypic evaluation of the F4 population derived from the cross ISM Ã x YPK-267 was carried out for growth and yield related traits. Promising lines were identified for further use in rice breeding programmes.Not Availabl

Not Available

Not AvailableNot AvailableNot Availabl

Not Available

Not AvailableA study was conducted to evaluate the genetic variability parameters, correlation and path coefficient analysis for eight yield related traits in segregating F2 population of an aerobic restorer AR 9-18 × YPK 198 (Donor for yield enhancing genes Gn1a and OsSPL14) at ICAR-IIRR, Hyderabad during the kharif, 2019. The results indicated that, productive tiller number, grain number per panicle and plant yield showed high PCV and GCV. Height of plant, productive tiller number, grain number per panicle and plant yield exhibited a high heritability and also high genetic advance as per cent of mean which indicates simple selection would be effective for enhancement of these traits. Correlation studies indicated that plant yield was associated significantly positive with height of plant, productive tiller number, length of panicle and grain number per panicle. High positive direct effect on plant yield was recorded by productive tiller number, grain number per panicle and height of plant.Not Availabl

Not Available

Not AvailableHybrids commercially grown in the country gives 15-20% yield advantage over the best inbred varieties. There is a need to increase the magnitude of heterosis level to 20-30% besides improving grain quality and other desirable traits like plant type, number of productive tillers, flowering duration, desirable plant height, grain type, yield, maintenance ability, disease and insect pest resistance etc. In present study we developed base composite populations suitable to local conditions using original gene pool obtained from International Rice Research Institute (IRRI) by adding 10 component lines for above mentioned different traits. More than 950 productive segregants selections were made and stabilized through pedigree method for desirable traits. The developed lines are superior for different traits. This indicates population improvement strategy is bringing the superior allele into one line in short period of time from different genotypes. This method is very useful to increase diversity in hybrid rice parental lines within known timeICAR-Indian Institute of Rice Researc

Not Available

Not AvailableNot AvailableNot Availabl

Parental Polymorphic Marker Survey and Genetic Diversity Studies among the Popular Maintainer Lines of Hybrid Rice (Oryza sativa L.) for Stigma Exsertion Trait

Parental polymorphic survey using rice satellite (RM) simple sequence repeats (SSR’S) is a pre-requisite for genotypic screening to identify the loci associated with trait of interest among mapping population. In the present study, eight popularly used rice maintainer lines viz., APMS-6B (Improved for Bacterial leaf blight. [1], IR58025B, IR68897B, IR79156B, DRR-6B, DRR-9B, BF-16B and BF2096B were used to study stigma exsertion trait as a single, double and total stigma exsertion. A total of 630RM markers were used to study parental polymorphism among eight maintainer lines and also to map their association with stigma exsertion trait. Among 630, 253 RM markers showed polymorphism with 635 alleles among the eight maintainers which were distributed across twelve chromosomes of rice. The overall parental survey revealed 40.18 per cent of polymorphism among the maintainer lines with a maximum and minimum frequency of 5 and 2 alleles, respectively. The genetic similarity coefficient for the most number of pairs ranged between of 0.2-0.9 with the average value of 0.60 for all possible combinations, indicating moderate genetic diversity among the chosen genotypes. The genotypes grouped according to their place of origin and represents genetic closeness between them. The identified RM polymorphic markers could be used to construct the linkage map and subsequently, to identify the stigma exsertion related QTLs from mapping population developed from different combinations of the rice maintainer lines

Not Available

Not AvailableParental polymorphic survey using rice satellite (RM) simple sequence repeats (SSR’S) is a pre-requisite for genotypic screening to identify the loci associated with trait of interest among mapping population. In the present study, eight popularly used rice maintainer lines viz., APMS-6B (Improved for Bacterial leaf blight). [1], IR58025B, IR68897B, IR79156B, DRR-6B, DRR-9B, BF-16B and BF2096B were used to study stigma exsertion trait as a single, double and total stigma exsertion. A total of 630RM markers were used to study parental polymorphism among eight maintainer lines and also to map their association with stigma exsertion trait. Among 630, 253 RM markers showed polymorphism with 635 alleles among the eight maintainers which were distributed across twelve chromosomes of rice. The overall parental survey revealed 40.18 per cent of polymorphism among the maintainer lines with a maximum and minimum frequency of 5 and 2 alleles, respectively. The genetic similarity coefficient for the most number of pairs ranged between of 0.2-0.9 with the average value of 0.60 for all possible combinations, indicating moderate genetic diversity among the chosen genotypes. The genotypes grouped according to their place of origin Original Research Article Jayaramulu et al.; IJPSS, 34(1): 94-104, 2022; Article no.IJPSS.82835 95 and represents genetic closeness between them. The identified RM polymorphic markers could be used to construct the linkage map and subsequently, to identify the stigma exsertion related QTLs from mapping population developed from different combinations of the rice maintainer lines.Not Availabl