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

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Not AvailableThe present study was aimed to optimize conditions of anther culture and production of doubled haploids of a popular rice hybrid, KRH-2. Immature panicles collected from field grown donor plants were pre-treated at 8°C for eight days and plated on four different basic media for callus induction with different hormonal concentrations and supplements. N6 media with maltose as the carbon source, supplemented with 2 mg L-1 of 2,4-dichlorophenoxyacetic acid (2,4-D), 0.5 mg L-1 of kinetin and 10 mg L-1 of silver nitrate (designated as N6-4 medium) was found to give the highest callus induction (22.4%). The compact calli, which were transferred to MS regeneration medium supplemented with 2.5 mg L-1 of benzyl amino purine (BAP), 0.5 mg L-1 of kinetin and 1.5 mg L-1 of naphthalene acetic acid (NAA) recorded a good regeneration (25.4%). A total of 125 stable, doubled haploid lines (DHLs) were produced through spontaneous doubling of KRH-2 microspores. The lines showed significant variability with respect to key agro-morphological traitsNot Availabl

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Not AvailableBacterial blight (BB) caused by Xanthomonas oryzae pv. oryzae is a major production constraint for rice in India. We introgressed a major dominant BB resistance gene, Xa38 in the genetic background of APMS 6B, a maintainer line of APMS 6A (female parent of DRRH 3) through marker-assisted backcross breeding (MABB). The BB resistance gene, Xa38 was transferred to APMS 6B from the donor, PR 114 (Xa38) through two backcrosses. A single selected true BC2F1 plant having maximum recovery of recurrent parent genome and also high degree of BB resistance was selfed to generate BC2F2s. At BC2F2, plants homozygous for Xa38 were identified and were further confirmed for the absence of two major fertility restorer genes, Rf3 and Rf4. Eight best BC2F2 plants, homozygous positive for Xa38 and homozygous negative for Rf3 and Rf4 were selected and advanced up to BC2F6. At BC2F6, these introgression lines exhibited high degree of BB resistance against multiple Xoo strains and were similar to APMS 6B in respect to different agro-morphological traits.Not Availabl

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Not AvailableDuring the last two decades, night temperatures have increased at a much faster rate than day temperatures and global climate models predict further increase in both frequency and intensity. Such rapid increase during the crop growth stages, particularly during extremely sensitive reproductive and early grain-filling stages of rice (Oryza sativa L.), leads to reduced biomass, grain yield and quality. Field experiments and lab analyses were carried out using three Basmati and two non-Basmati cultivars to study the effect of a wide range of diurnal temperatures and radiation. Night temperature had a significant negative effect on grain yield (P < 0.001) and quality (P < 0.01) beyond 22 ◦C. Reduced spikelet fertility followed by grain weight plant−1 accounted for the decline in yield. Radiation however had a positive influence on yield and grain quality. A definite relationship between maximum day temperature and grain yield could not be established as the temperatures were generally ≤the critical 35 ◦C during sensitive developmental stages. Environment 4 gave significantly highest yield, indicating a narrow window of optimum growing conditions for better yield and quality. Hence, increasing diurnal temperature tolerance in rice is a sustainable approach than altering well established cropping patterns, which will inevitably lead to yield penalties.Not Availabl

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Not AvailableIn our country, significant progress has been made in the development of hybrid rice parental lines both female and male parents with good floral traits. An array of hybrids with good grain quality (both unique Basmati type and medium slender (MS) grain type) is developed. Efforts are focussed on the development of restorer lines through exploitation of inter sub-specific hybridization, recurrent selection and population improvement that will help in the development of highly heterotic rice hybrids. The female parental lines are being improved for traits like stigma exsertion and high outcrossing that helps in higher seed yields, thereby reducing the hybrid seed cost. Efforts are on to develop appropriate parental lines that can help in the development of suitable hybrids in late duration group and also for unfavourable ecologies. Many newly developed parental lines are being fortified with resistance genes for major diseases such as BB, blast and insect pests such as BPH that will help in the development of hybrids having resistance to major pests and diseases.Not Availabl

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Not AvailableBiotechnological tools like molecular markers can add precision to breeding and accelerate breeding efforts. Towards this objective, our research team at ICAR-IIRR has applied marker-assisted breeding (MAB) for improvement of multiple traits like resistance against bacterial blight, blast, gall midge and BPH, heterosis related traits, improvement of low soil P tolerance, grain quality and yield. Through marker-assisted backcross breeding (MABB), a high-yielding, bacterial blight resistant rice variety possessing fine-grain type and low glycemic index (GI), named Improved Samba Mahsuri (ISM) has been developed and released for cultivation by farmers. MABB has also been applied for improving bacterial blight resistance of a few important traditional and evolved Basmati rice varieties and hybrid rice parental lines. A novel bacterial blight resistance gene, Xa33 has been identified from an accession of the wild rice, O. nivara, fine-mapped and transferred into several elite genetic backgrounds. Novel sources of resistance against bacterial blight and blast diseases have been identified and characterized and major blast resistance have been transferred to several elite genetic backgrounds and a major QTL associated with neck blast resistance has been identified from wild rice. Additionally, genepyramid lines possessing resistance against gall midge have also been developed and a novel and highly effective BPH resistance gene has also been identified and mapped with molecular marker and few promising donors possessing resistance against sheath blight have been identified. A molecular marker-based assay has been designed for rapid and accurate determination of impurities in seed-lots of rice hybrids and their parental lines and functional markers have been developed for the traits relevant to hybrid rice, viz., wide-compatibility, wild-abortive cytoplasmic male sterility and fertility restoration. Functional markers have also been developed for major grain quality determining genes, fgr and GS3 and a major QTL controlling gelatinization temperature has been identified through molecular mapping. The major QTL responsible for low soil phosphorus (P) tolerance, viz., Pup1 has been transferred to Improved Samba Mahsuri, MTU1010 and IR64 and novel, non-Pup1 type donors have been identified for the trait. Four major yield enhancing genes, viz., Gn1a, SCM2, OsSPL14 and GW5 have been transferred to elite rice cultivars, viz., Improved Samba Mahsuri, Swarna, MTU1010 and NDR359.Not Availabl

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Not AvailableBiotechnological tools like molecular markers can add precision to breeding and accelerate breeding efforts. Towards this objective, our research team at ICAR-IIRR has applied marker-assisted breeding (MAB) for improvement of multiple traits like resistance against bacterial blight, blast, gall midge and BPH, heterosis related traits, improvement of low soil P tolerance, grain quality and yield. Through marker-assisted backcross breeding (MABB), a high-yielding, bacterial blight resistant rice variety possessing fine-grain type and low glycemic index (GI), named Improved Samba Mahsuri (ISM) has been developed and released for cultivation by farmers. MABB has also been applied for improving bacterial blight resistance of a few important traditional and evolved Basmati rice varieties and hybrid rice parental lines. A novel bacterial blight resistance gene, Xa33 has been identified from an accession of the wild rice, O. nivara, fine-mapped and transferred into several elite genetic backgrounds. Novel sources of resistance against bacterial blight and blast diseases have been identified and characterized and major blast resistance have been transferred to several elite genetic backgrounds and a major QTL associated with neck blast resistance has been identified from wild rice. Additionally, genepyramid lines possessing resistance against gall midge have also been developed and a novel and highly effective BPH resistance gene has also been identified and mapped with molecular marker and few promising donors possessing resistance against sheath blight have been identified. A molecular marker-based assay has been designed for rapid and accurate determination of impurities in seed-lots of rice hybrids and their parental lines and functional markers have been developed for the traits relevant to hybrid rice, viz., wide-compatibility, wild-abortive cytoplasmic male sterility and fertility restoration. Functional markers have also been developed for major grain quality determining genes, fgr and GS3 and a major QTL controlling gelatinization temperature has been identified through molecular mapping. The major QTL responsible for low soil phosphorus P tolerance, viz., Pup1 has been transferred to Improved Samba Mahsuri, MTU1010 and IR64 and novel, non-Pup1 type donors have been identified for the trait. Four major yield enhancing genes, viz., Gn1a, SCM2, OsSPL14 and GW5 have been transferred to elite rice cultivars, viz., Improved Samba Mahsuri, Swarna, MTU1010 and NDR359.Not Availabl

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Not AvailableStigma exsertion is important in increasing out crossing rate in rice hybrid parental lines. In the present investigation, inheritance pattern of stigma exsertion trait in F3 population developed between IR68897B x BF16B was studied. On phenotyping of 674 F3 plants, it segregated into 91 low, 456 moderate and 127 high stigma exsertion plants based on IRRI-SES scale published by INGER, 2014. Further, subjected to chi square analysis to test their goodness of fit to appropriate Mendelian ratios and showed significant. Thus, stigma exsertion is quantitative trait. Also transgressive segregation observed during phenotyping indicated that complementary gene action with additive effects and dispersed in both the parents. The frequency distribution showed continuous variation signifying that stigma exsertion trait is controlled by polygenes and influenced by environmentDB

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Not AvailableRice is generally shows variable level of sensitivity to salinity during its developmental stages and remarkably sensitive during young seedling stage and early reproductive phase. Quantifying the level of salt tolerance based on salt stress indices is an effective method in identification of tolerant genotypes. In this study, the salt stress indices were used to identify best performing genotypes based on salt susceptibility indices (SSI) and salt response indices (SRI) as relevant parameters. Among the 39 genotypes studied, 29 showed better endurance to salt susceptibility indices, among them Pokkali, IR72132-AC-6-1 and IR70869-B-P-13-2 performed well with least SSI, which refers more tolerance with lesser yield reduction, whereas IR29 was vice-versa to the above. Genotypes IR72593-B-19-2-3-1, IR73104-B-1-1-3-2-1 and IR74802-3R-7-1-2 had a better performance with early flowering and highly responsive to salt stress with lower percent yield reduction. The phenotypic variation is higher than genotypic variation for all traits except for flowering duration and it indicates presence of variability for different traits. High heritability with variability, genetic advance and better salt stress indices indicates involvement of additive gene action and can be manipulated and utilized in further breeding program.Not Availabl