Characterizing the saltol quantitative trait locus for. In general, rice can tolerate a small amount of saltwater without compromising the growth and. Singh 1,4 1plant breeding, genetics and biotechnology division, international rice research institute, dapo box 7777, metro manila, philippines. Forno d a, cock j h and gomes k a 1976 laboratory manual for physiological studies for rice. Pdf evaluation of salinity tolerance in rice genotypes. In spite of considerable effort, through both international and national breeding programmes, progress in. The levels of the antioxidant enzymes cat and apx and the accumulation of proline may play important roles in salinity tolerance. Response regulators 9 and 10 negatively regulate salinity. Dca1 acts as a transcriptional coactivator of dst and. Pdf improvement of salinity stress tolerance in rice.
Rice is rated as a salt sensitive crop, especially at early seedling and reproductive stages 1, 2. However, mr211, mr232 and ir20 performed better based on dry matter. Characterizing the saltol quantitative trait locus. Salinity is a major abiotic stress limiting growth and productivity of plants in many areas of the world due to increasing use of poor quality of water for irrigation and soil salinization.
Modifying sodium transport to improve salinity tolerance of. The following cycles were used in the abi 7500 fast system 96 wells plates. But the concentrations of na, zn, cu and mn increased. Genomic and transcriptomic analysis reveal molecular basis. The effect of salinity on dry matter production varied from cultivar to cultivar. Pdf characterizing the saltol quantitative trait locus. The narrow genetic pool of japonica germplasm for salinity tolerance and the extent of the salinity challenge are. Sep 16, 2010 this study characterized pokkaliderived quantitative trait loci qtls for seedling stage salinity tolerance in preparation for use in markerassisted breeding. Mechanisms of salinity tolerance in plants have been extensively studied and in the recent years these studies focus on the function of key enzymes and plant morphological traits. Pdf salinity is considered as one of important physical factors influencing rice oryza sativa l. Free proline content was measured by a colorimetric assay as described by bates et al. Salinity is a major constrain to high yield of rice oryza sativa l. Rhoades, usda ars salinity laboratory, riverside, california.
Considerable genetic variation in salt tolerance among rice varieties exists. A panel of ethanemethylsulfonatemutagenized japonica rice lines was grown in the presence of salinity in order to identify genes required for the expression of salinity tolerance. An endophyte from saltadapted pokkali rice confers salttolerance. Gregorio and others published screening rice for salinity tolerance, vol 22, irri discussion paper series find, read and cite all the research you need on researchgate. The validity of this technique was tested by conducting experiments in salinised soil pot culture and in salt affected field where 9 rice lines were grown up to maturity and absolute paddy yield was considered as the criterion for salt tolerance. Significant varietal differences were found in relation to salinity tolerance. Molecular characterization and identification of new. Susceptibility or tolerance of rice plants to high salinity is a coordinated action of. Screening for salt tolerance in the field is difficult as soil salinity is dynamic. Salt stress tolerance is a complex trait, so the qtls related with salt tolerance have significant role in understanding the stress response and generating stresstolerant plants gorantla et.
Improvement of salt tolerance in rice oryza sativa l. School of biosciences the university of birmingham august, 20. On the basis of tolerance ability toward salinity, rice is considered as salt sensitive crop, and growth and yield of rice are. Course material from the usda nrcs training course, management of saline and sodic soils 1991, a series of five training notes by dr. The next frontierthe use of genome editing for integration free. Susceptibility and tolerance of rice crop to salt threat plos. Salt tolerance behaviour of cultivars based on different selection criteria was compared. Despite many attempts using different strategies to improve salinity tolerance in rice, the. Salttolerant and plantgrowthpromoting bacteria isolated. Since members of brassicaceae are important contributor to total oilseed production, there is an. Salt stress is one of the major factors limiting rice oryza sativa production globally. Aris hairmansis a thesis submitted for the degree of doctor of philosophy school of agriculture, food and wine faculty of sciences the university of adelaide february 2014. Although several transporters involved in salt tolerance have been identified in rice, the mechanisms regulating their transport activity are still poorly understood.
Modifying sodium transport to improve salinity tolerance of commercial rice cultivars oryza sativa l. In this study, 305 bacteria were isolated from paddy soil in taoyuan, china. Markerfree transgenic rice plant overexpressing pea lecrlk. Pdf screening rice for salinity tolerance, vol 22, irri. New phenotyping technique for salinity tolerance at reproductive stage in rice. It was thus possible to improve the genetic tolerance of rice varieties to salinity by adopting various breeding methods. A rapid screening technique for salt tolerance in rice.
Plant adaptation or tolerance to salinity stress involves complex physiological traits, metabolic pathways, and molecular or gene networks. Effects of salinity stress on growth, chlorophyll content and ion accumulation in two indica rice oriza sativa l. As the transcription levels of osrr9 and osrr10 altered under several abiotic stresses, we first characterized their role in salinity tolerance. Here, we show that transcription factor osmads25 positively regulates the root system development and tolerance to salinity and oxidative stress in rice plants. It is a complex quantitative trait having different components, which can be dissected effectively by genomewide association study gwas. To understand the molecular basis of salt tolerance in cmg, we performed bsaseq for two extreme bulks derived from the cross between cmg and a cultivar sensitive to salt, zhefu802. Stress and disease tolerance irri rice knowledge bank. Plants differ greatly in their tolerance of salinity, as re. However, rice is very sensitive to salinity and is the most salt sensitive cereal crop with a threshold of 3 dsm. Evaluation of salt tolerance in rice genotypes by multiple. Effect of salinity stress on growth and carbohydrate.
The objective of this study was to develop a new salttolerant rice germplasm using speedbreeding. However, information regarding the improvement of salt tolerance in cultivated rice using wild rice genes is limited. Biomolecules free fulltext the tolerance of salinity in. New phenotyping technique for salinity tolerance at. Modifying sodium transport to improve salinity tolerance.
Mohammad rashed hossain a thesis submitted to the university of birmingham for the degree of doctor of philosophy. Here, we provide an updated overview of salt tolerant mechanisms in glycophytes with a particular interest in rice oryza sativa plants. Drought and salt are two of the most serious threats to food production worldwide, and research on stress tolerance in crops is important for future food security. Frontiers improvement of salt tolerance using wild rice.
In addition to conventional breeding, other innovative breeding techniques such as tissue culture, induced mutations and wide crosses needed to be explored. A highly nontolerant selection proved to harbor a mutation in fln2, a gene which encodes fructokinaselike protein2. Testing method for salinity tolerance is performed in a greenhouse by transplanting 14 daysold seedling on soil salinized with 4000 ppm nacl. Variability for salt tolerance among some rice varieties.
This method controls soil heterogeneity by using pure sand as a growth medium and minimizes unexpected extreme weather. Pdf shaheen basmati was evolved as a salt tolerant fine rice variety by the soil salinity research institute, pindi bhattian, pakistan. Under the abiotic stress, reactive oxygen species ros and free. Salt stress tolerance is a complex trait, so the qtls related with salt tolerance have significant role in understanding the stress response and generating stresstolerant plants gorantla et al. To this end, threeleafstage rice seedlings wild type and osrr9osrr10 mutant were exposed to 150. Evaluating rice for salinity using potculture provides a. The threshold for salt stress in rice is 3 dsm, with a 12% reduction in yield for each unit increase in dsm beyond this value 3. However, some salt tolerant bacteria improve the health of plants under saline stress. Genetic analysis of salt tolerance at seedling and reproductive stages in rice oryza sativa rezamohammadi 1,3,merlyns. Here, we implemented gwas to identify loci controlling salinity tolerance in rice.
Electro physiologically, increasing salinity reducedthe electrical pd of plant leaves. Information on the relative tolerance of different. Therefore, the improvement of salinity tolerance in rice has come to the fore. Rice varieties mr211, ir20, br40 and mr232 showed greater salt tolerance during germination germinated at 12 ds m 1 salinity. We also provide strong evidence that osmads25 increases. Rice salinity tolerance is complex, both genetically and physiologically.
Molecular characterization and identification of new sources. Assessing trait contribution and mapping novel qtl for. Accordingly, there was a major difference in the salt tolerance of the three wheat organs, root was the most salt sensitive organ while spikes was the most salt. Worldwide rice is grown on some 400 million hectares of salt affected land.
At all 3 stages, varieties differed in their degree of tolerance, but the order of tolerance varied considerably between stages. Salt stress causes significant reductions in rice production worldwide. In addition to conventional breeding, other innovative breeding techniques such as tissue culture, induced mutations and wide crosses needed to be. Salt tolerance is an important constrain for rice, which is generally categorized as a typical glycophyte. Rice plants were grown in waterlogged conditions, to represent this aspect of irrigated rice fields that should be included in salinity tolerance studies, as the effects of hypoxia on salinity. Genetic analysis of salt tolerance at seedling and. Tahir nuclear institute for agriculture and biology, faisalabad, pakistan abstract. This study was designed to identify useful agronomic. In this study we identified dca1, a transcriptional coactivator of dst that is conserved in the worlds three major crops. Salinity effects on seedling growth and yield components of rice. Placing all the results together we could deduce osmyb481 to be a novel mybrelated tf of rice for abiotic stress tolerance. Effects of salinity stress on growth, chlorophyll content and. Of the cereals, rice oryza sativa is the most sensitive and barley hordeum vulgare is the most tolerant figure 1. The concentrations of p and k in the tops of rice cultivars decreased with increasing soil salinity.
The purpose of this study was to establish the relative importance of different traits associated with salinity tolerance in rice and to identify new quantitative trait loci qtl conferring tolerance to salinity at seedling stage. Traditional rice landraces of coastal area in bangladesh are distinct regarding their phenotype, response to salt stress and yield attributes. Wild rice germplasm is considered a valuable genetic resource for improving rice cultivars. Shannon flood irrigation practices that are commonly used in california et al. Mar 25, 2014 to our knowledge, it is the first report that mybrelated type tf, osmyb481, involved in drought and salt tolerance in rice. A new salinity tolerance screening technique using rice seedlings in potculture was tested. Breeding for salt tolerance is a major goal for rice breeders for which screens are required to select out tolerant lines for breeding. Genomewide association study of seedling stage salinity. Identification of new qtl for salt tolerance from rice. The vast genetic variability reported in rice in response to salinity makes it amenable to genetic manipulation to further enhance its tolerance akbar et al. Identification of molecular markers tightly linked to salt tolerant genes can serve as land marks for the physical localization of such genes facilitating marker assisted selection mas. Salinity is one of the most widespread abiotic stresses affecting rice productivity worldwide. Shannon abstract reduction were observed scardaci et al. Here, we characterized the rice oryza sativa really interesting new gene ring h2.
Salinity tolerance in rice is highly desirable to sustain production in areas rendered saline due to various reasons. Pihog1, a stress regulator map kinase from the root. Pdf salinity and salt tolerance improvements in thai rice. The study to develop a testing method for salinity tolerance at germination stage was conducted from. Nov 17, 2016 rice plants were grown in waterlogged conditions, to represent this aspect of irrigated rice fields that should be included in salinity tolerance studies, as the effects of hypoxia on salinity. Improvement of salinity stress tolerance in rice mdpi. Genomewide association mapping of salinity tolerance in. Pearson, 1959 and attempts to enhance the salt tolerance in rice through breeding date from the early 1970s akbar et al. Molecular characterization and identification of new sources of tolerance to submergence and salinity from rice landraces of coastal india volume 17 issue 3 r. Identified genomic regions associated with salinity tolerance accelerated molecular.
The rice genotypes differed significantly for salt tolerance at seedling stage. Here, we show evidence that a rice mg transporter osmgt1 is required for salt tolerance probably by regulating transport activity of. A magnesium transporter osmgt1 plays a critical role in. Many qtls have been identified in rice for salinity tolerance contributing traits and majority of them have been reported on chromosome 1. One of the identified endophytic fungus, which was tolerant to high concentrations of salt, was transferred to the saltsensitive rice variety ir64. Genetic variation for salinity tolerance in pakistani rice oryza sativa l. Testing method for salinity tolerance at germination stage on. With characterization of these landraces, suitable candidate genes for salinity tolerance could be identified to introgress into modern rice varieties. Salinity is a serious threat to rice production in southern bangladesh. On the basis of tolerance ability toward salinity, rice is considered as saltsensitive crop, and growth and yield of rice are. An analysis of 100 ssr markers on 140 ir29pokkali recombinant inbred lines rils confirmed the location of the saltol qtl on chromosome 1 and identified additional qtls associated with tolerance. Genetically improving salt tolerance of rice is a highly important objective of rice breeding programs.
Molecular dissection of seedling salinity tolerance. Mapping qtls for traits related to salinity tolerance at. Effect of salinity on chlorophyll concentration, leaf area. The typical mechanism of salinity tolerance in rice is the na exclusion or uptake reduction, and increased absorption of k to maintain a good nak balance in the shoot.
Effect of salinity on chlorophyll concentration, leaf area, yield and yield components of rice genotypes grown under saline environment y. Improving salt tolerance in rice therefore is essential for ensuring food. Salinity studies on rice grown in northern california, for example, resulted in a threshold. On the basis of tolerance ability toward salinity, rice is considered as salt sensitive crop, and growth and yield of rice are greatly affected by salinity. Discussion the protective role of proline against naclinduced oxidative. The salt tolerance of several australian and overseas rice varieties was studied at germination, early vegetative growth, and reproductive development in a temperature controlled glasshouse to determine the reliability of screening at any particular stage. However, mr211, mr232 and ir20 performed better based on. Singh, plant breeder at the international rice research institute, discusses the latest progress in salinty tolerance research in rice.
Salinity effects on seedling growth and yield components of rice linghe zeng and michael c. Salinity tolerance loci revealed in rice using high. Therefore, the aim of this experiment was to uncover prospective rice landraces tolerant to salinity. Characterizing the saltol quantitative trait locus for salinity tolerance in rice. Rice is a major staple crop and immensely affected by soil salinity. Study of salt tolerance in wheat triticum aestium l.
These mechanisms can also be further classified into ion exclusion, osmotic tolerance and tissue tolerance roy et al. Protocols for pre field screening of mutants for salt. Dissecting molecular mechanisms underlying salt tolerance in rice. Screening six varieties of rice oryzasativa for salinity. Background salinity is a major abiotic stress limiting yield in many parts of the world. Breeders have long made use of the high level of salinity tolerance in landraces like nona bokra and pokkali. Salt tolerance improvement in rice through efficient snp marker.
It would also be the next frontier for integrationfree. Exposure of wildtype rice to salinity upregulated fln2, while a crisprcas9generated fln2. Investigations of the effects of salinity on rice have been underway for more than 50 years kapp, 1947. Despite many attempts using different strategies to improve salinity tolerance in rice. Rice transcription factor osmads25 modulates root growth and. Tagging and validation of ssr markers to salinity tolerance. Excess salinity in soil is one of the major environmental factors that limit plant growth and yield of a wide variety of crops including rice. Salinity laboratory, usda ars riverside, ca abstract the capability of crops to grow on saline soils varies among species and depends on the concentration of salts presen t in the rootzone and on various environmental and cultural conditions. Soil salinity is one of the most devastating factors threatening cultivable land. Soil salinity is one of the major constraints affecting rice production worldwide, especially in the coastal areas.
Salinity threat is estimated to reduce global rice production by 50%. Progress in rice breeding for salt tolerance, constitutes the identification of the major locus conferring a salt tolerance gene at different growth stages. Four simple sequence repeats ssr markers rm493, rm10793, rm3412 and rm10791 found in the saltol locus in chromosome 1 were used for molecular analysis. Rice plants generally tolerate salt by mainly two mechanisms, ion exclusion and osmotic tolerance munns and tester, 2008. Among the various abiotic stresses limiting the crop productivity, salinity stress is a major problem, which needs to be addressed and answered urgently. Mutants for salt tolerance in rice, wheat and barley.
Author summary plant roots are constantly exposed to a variety of abiotic stresses, and high salinity is one of major limiting conditions that impose constraints on plant growth. Overexpression of rice expansin7 osexpa7 confers enhanced tolerance to salt stress in rice chuluuntsetseg jadamba 1, kiyoon kang 2, namchon paek 2, soo in lee 3, and soocheul yoo 1, 1 crop molecular breeding laboratory, department of plant life and environmental science, hankyong. Among these, 162 strains were tested for salt tolerance. Salinity imposes both ionic toxicity and osmotic stress to plants hasegawa et al. Many qtls have been identified in rice for salinity tolerance contributing traits and majority of. Oryza sativa, genotyping by sequencing, quantitative trait locus, salt tolerance, candidate gene.
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