In rice we have shown that sodium must enter into the cytosol before a. Modifying sodium transport to improve salinity tolerance. Dissecting the genetic loci controlling salt tolerance in rice for improving productivity, especially at the flowering stage, remains challenging. Effect of salinity on germination, seedling growth and. Breeding for salt tolerance is a major goal for rice breeders for which screens are required to select out tolerant lines for breeding. Enhancing trehalose biosynthesis improves yield potential.
The narrow genetic pool of japonica germplasm for salinity tolerance and the extent of the salinity challenge are common to many ricegrowing regions. Salinity has a significant impact on rice production in coastal, arid and semiarid areas in many countries, including countries growing temperate rice, such as kazakhstan. Salinity caused a significant reduction on root length and shoot length. 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. Effects of salt stress on rice growth, development characteristics, and. Result of phenotypic response of rice genotypes to salinity stress at seedling stage indicated varied genotypic response.
The tolerance of salinity in rice requires the presence of. Effect of salinity stress on growth, sugar content. A soil is termed saline if its osmotic pressure is approximately 0. Salt stress, a major plant environmental stress, is a critical constraint for rice productivity. The impact of river salinity is more costly on high value enterprises. Rice intermediate lament, osif, stabilizes photosynthetic machinery and yield under salinity and heat stress neelam soda1, brijesh k. 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. The yields of some particularly sensitive plants, such as rice and horticultural crops, are affected by saline water at levels as low as 700 ec8. A project on physiological, biochemical and molecular responses of plants to salinity stress started in 2003. Genomewide association study for salinity tolerance at. Na, ca, mg, cl, and so4 are the major ions involved. In very slowdraining soils, such as the medium to heavy clays of the rice growing regions, tolerances can be down to about half the levels shown. Present report deals with the effect of varying 0 200 mm nacl salt stress on two popular scented non basmati type indica rice cultivars, namely indrayani and. It was observed that salinity stress caused a significant decrease in shoot lengths, fresh and dry weights of all rice varieties.
Salinity is considered to be a major abiotic stress affecting germination, seedling growth, and crop. This study aimed to explore the changes in morphological, physiological and biochemical characteristics of lettuce lactuca sativa l. Modelling the soil plantwater balance of rainfed lowland rice. The ratios of lengthwidth grain dimension were significantly reduced in t genotypes even at low electrical conductivity ec, 4 mscm. Rice production is limited by soil salinity problems in many tropical. Effects of salt stress on growth, mineral nutrition and. Evaluating rice for salinity using potculture provides a systematic tolerance assessment at the seedling stage naqeebullah kakar1, salah h. Exposure of wildtype rice to salinity upregulated fln2, while a crisprcas9generated fln2. Increased tolerance to salt stress in opdadeficient rice. A highly nontolerant selection proved to harbor a mutation in fln2, a gene which encodes fructokinaselike protein2. Genomewide association study of seedling stage salinity. Rnai mediated drought and salinity stress tolerance in plants. Susceptibility and tolerance of rice crop to salt threat plos.
Varietal characteristics and soil management to reduce drought stress. Salinity is a major yieldreducing factor in coastal and arid, irrigated rice production systems. As a result, finding suitable donors of genes and traits for. We evaluated the salinity tolerance of a panel of 235 temperate japonica rice accessions genotyped with 30,000 snp markers. Gupta2, khalid anwar1, ashutosh sharan1, govindjee3, sneh l. An endophyte from saltadapted pokkali rice confers salt. In the present study, 7 days old rice plants were exposed to 0 control and 100 mm. The seedlings were subjected to five different concentrations 0 mm, 50 mm, 100 mm, 150 mm, and 200 mm of nacl for three weeks. Modifying sodium transport to improve salinity tolerance of commercial rice cultivars oryza sativa l. Salinity effects on seedling growth and yield components. In the present study, rice seedlings showed growth reduction when exposed salinity. 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.
However, rice is very sensitive to salinity and is the most salt sensitive cereal crop with a threshold of 3 dsm. Computationally annotated genes have not fully been validated, because ests and fulllength cdnas cannot cover entire transcribed regions. Under salinity stress, changes of chemical contents also differed among phenolic compounds and rice cultivars. Growth reduction is generally observed in plants exposed to salinity stress. Frontiers overexpression of a myb family gene, osmyb6. Carbohydrate metabolism, rice, salinity stress, salt tolerant salinity is a major environmental stress affecting plant. To identify salinitytolerant germplasm and related. Here, we conducted a genomewide association study gwas of salt tolerance based on exome sequencing of the thai rice accessions. Reduction in relative water content rwc and photosynthesis dry matter is a common effect of salinity stress. A good solution would be the development of an efficient screening methodology to identify genotypes possessing genes for salt tolerance. Evaluating rice for salinity using potculture provides a. Salinity tolerance in irrigated crops nsw department of. Rice responses to salinity stress in general, plants that are more salttolerant tend to grow more slowly at low salinity levels than less salttolerant.
The rice damage by salinity becomes more severe in case of a drought in the early or late periods of the rainy season. Salinity stress is one of the most devastating abiotic stresses that affect growth, development and productivity of major crops. Tarom azmoon was exposed to 200 mm nacl for 14 days. Crop salinity tolerances can be up to 50% higher than shown below in welldrained soils such as deep sandy loams where percolation and leaching are rapid. Saltresistant rice cultivars nona bokra and ir 4630 exposed at the seedling stage during one or two weeks to 0, 20, 30, 40 or 50 mm nacl accumulated less na, cl, zn and proline and more k at root and shoot levels than saltsensitive i kong pao and ir 31785. Worldwide rice is grown on some 400 million hectares of salt affected land. Rootspecific transcript profiling of contrasting rice. The effect of salt stress on the germination of maize zea. It has been reported that overexpression of bifunctional fusion of the tps and tpp genes of e. Therefore the role of the central stress signal jasmonate for the salt response was analysed in rice comparing the responses to salt stress for two jasmonic acid ja biosynthesis rice mutants cpm2 and hebiba impaired in the function of allene oxide cyclase aoc and their wild. Effect of salinity stress on growth and carbohydrate. Moreover, a higher solute concentration contributing to osmotic adjustment and the higher antioxidant enzymes activity were observed in shoots of salinity treated giza 178 than those of giza 177. Gene expression analysis associated with salt stress in a.
Wellknown rice landraces like pokkali and nona bokra are highly tolerant to salinity stress damage scores or ses 1 in a scale of 19 at the 2weekold seedling stage. Molecular characterization and identification of new sources of tolerance to submergence and salinity from rice landraces of. In low salt environments, plant cells can take up water and nutrients from the soil solution to support higher osmotic pressures compared to that of the soil solution. Salinity stress represents a global constraint for rice, the most important staple food worldwide. Attempts to develop salinitytolerant rice varieties have had limited success due to the complexity of the salinity tolerance trait, high variation in the stress response and a lack of available donors for candidate genes for cultivated rice. It is the duty of plant physiologists to comprehend the growth, development, and physiological processes of rice plants under stress. The results demonstrated that, response of root length to salt stress was more severe than shoot length figure 2.
The need for salt tolerant rice varieties able to cope with several other stress conditions obviously puts a lot of pressure on breeders who must better comprehend the physiology and genetic control of salt tolerance. Rice has been reported to be relatively tolerant to salinity stress during germination, active tillering and towards maturity, but sensitive during. Microarray technology is limited to monitoring the expression of previously annotated genes that have corresponding probes on the array. All about salinity nsw environment, energy and science. Singh, plant breeder at the international rice research institute, discusses the latest progress in salinty tolerance research in rice. Development of varieties with improved salt tolerance in major field crops is an urgent need to maintain crop productivity in different parts of the world. The r eduction in leaf area table 1 of all 18 rice genotypes under salinity stress plants has been attributed to suppressed cell division. Improvement of salinity stress tolerance in rice mdpi. Using affymetrix rice genomic arrays, salinityinduced transcript profiles were documented recently in shoot tissues of ir29, a saltsensitive indica cultivar, and the.
Alleviation of the adverse effects of salinity stress. Here, mrnaseq an illumina cdna sequencing application was used to monitor whole mrnas of salinity stress. To test the usefulness of microsatellite ssr markers associated with saltol qtl, a collection of 150 diverse rice genotypes were used. Effects of salinity stress on growth and phenolics of rice. Aiwu, a moderately resistant genotype, exhibited an intermediate behaviour. Salinity stress affects global food producing areas by limiting both crop growth and yield.
In order to cope with salt stress, plants have evolved high degrees of developmental plasticity, including adaptation via. Pdf effect of salinity on osmolytes and relative water. Effect of salinity on chlorophyll concentration, leaf area. P transport from root to shoot was inhibited in the most. Tfiiiatype zfp252ox rice also showed enhanced salt and drought tolerance with the elevated level of stress defense genes, as compared with zfp252 antisense and nontransgenic plants xu et. Pdf rice oryza sativa l is an important staple crop that feeds more than one half of the worlds population and is the model system for. Recently, the complete genomes of 3000 rice accessions were sequenced through the 3 k rice genome project, and this set included 203 temperate japonica rice accessions. Stress and disease tolerance irri rice knowledge bank. Head rice recovery was reduced by salinity stress whereas it was not affected by alkalinity stress. Rice is considered to be a saltsensitive crop, and excess salt levels adversely affect all the major metabolic activities, causing cell wall damage, cytoplasmic lysis or genomic instability. The implications of river salinity are also costly for agriculture.
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. Effect of salinity on the morphological, physiological and. High salinity stress induces several nac genes in rice as well. Salinity is a major abiotic stress limiting yield in many parts of the world. If this is the first time you use this feature, you will be asked to authorise cambridge core to connect with your account. However, knowledge concerning the involvement of rice myb genes in salinity and drought stress resistance are largely unknown. Rice losses by salinity take place with both highyielding rice in double or triple rice cropping systems and traditional rice in rice shrimp rotational farming system. For rice, soil salinity beyond ece 4 dsm is considered moderate salinity while more than 8 dsm becomes high. Physiological, biochemical and gene expression studies of.
The consequences of all these can ultimately lead to plant death as result of growth arrest and molecular damage mc cure and hanson, 1990. Salinity is defined as the presence of excessive amounts of soluble salts in the soil usually measured as electrical conductivity, ec. The dry matter production and the concentration of nutrients in rice oryza sativa l. In this project the sodium uptake mechanisms in salttolerant and saltsensitive species were studied by use of a new fluorescent dye, specific for sodium, sbfi. Effect of salinity stress on growth, sugar content, pigments and enzyme activity of rice. Soaking rice seeds with 25 mm of trehalose tre could alleviate the harmful effects of salinity stress.
In recent years, the use of recirculating water systems in rice production and the requirement for water holding in the fields without recirculating water systems have increased in areas of the us due to environmental concerns related to the problems caused by drainage into receiving. Tolerance to mild salinity stress in japonica rice. Stress physiology in relation to breeding for drought resistance a case study of rice. Genetic dissection of salt tolerance in rice louisiana. Insights into genomics of salt stress response in rice. Massive parallel sequencing of mrna in identification of. In the present study, we cloned and characterized the osmyb6 gene, which was induced by drought and salinity stress. It is a major agronomic problem in arid and semiarid regions of the world. This work is original and contains no material which has been accepted for the award to the candidate of any other degree or. Salinity tolerance is an important quality for european rice grown in river deltas. Salt stress induces physiochemical alterations in rice grain. Rice responses to salinity stress in general, plants that are more salttolerant tend to grow more slowly at low salinity levels than less salttolerant plants.
Salinity stress negatively affects the quality and quantity of crop production. Similarly, mirna involved in salinity stress was 5. Despite many attempts using different strategies to improve salinity tolerance in rice, the achievements so far are quite modest. Pdf improvement of salinity stress tolerance in rice. Overexpression of salt stress inducible snac1 hu et al. The mechanisms of salinity tolerance in plants are regulated by a set of inherent multigenes and. The panel was exposed to mild salt stress 50 mm nacl. Drought response of dry seeded rice and its modelling. Salinity is an agricultural problem which decreases or restricts crop production worldwide. From rice, salt stress responsive osisap1ox conferred tolerance to salt, cold and dehydration stress in transgenic tobacco mukhopadhyay et al. An overview molecular and physiological traits imparting resistancetolerance and susceptibility to a particular biotic and abiotic stress are important. Correlation and path coefficients for direct and indirect effects of. However, at high salinity stress, ph was reduced significantly for all rice genotypes, ranging from 19. Here we present the most recent data on the salinity effect on rice physiology and stress adaptation, including implications on growth regulation and reproductive development.
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