Drought Resistance In Rice Research Articles

Research Profile: Markers for drought resistance in rice

ADVERTISEMENT RETURN TO ISSUEPREVNEWSNEXTResearch Profile: Markers for drought resistance in riceKatie CottinghamCite this: J. Proteome Res. 2006, 5, 2, 228Publication Date (Web):February 3, 2006Publication History Published online3 February 2006Published inissue 1 February 2006https://doi.org/10.1021/pr062692hRIGHTS & PERMISSIONSArticle Views381Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (71 KB) Get e-AlertsSUBJECTS:Plant derived food Get e-Alerts

Fungus-and Drought-Resistant Rice: Impact on Agronomics and Food Security

Fungus-and Drought-Resistant Rice: Impact on Agronomics and Food Security

Genetic analysis for drought resistance of rice at reproductive stage in field with different types of soil

Drought resistance of rice is a complex trait and is mainly determined by mechanisms of drought avoidance and drought tolerance. The present study was conducted to characterize the genetic basis of drought resistance at reproductive stage in field by analyzing the QTLs for drought response index (DRI, normalized by potential yield and flowering time), relative yield, relative spikelet fertility, and four traits of plant water status and their relationships with root traits using a recombinant inbred population derived from a cross between an indica rice and upland rice. A total of 39 QTLs for these traits were detected with individual QTL explained 5.1-32.1% of phenotypic variation. Only two QTLs for plant water status were commonly detected in two environments, suggesting different mechanisms might exist in two types of soil conditions. DRI has no correlation with potential yield and flowering time under control, suggesting that it can be used as a good drought resistance index in field conditions. The co-location of QTLs for canopy temperature and delaying in flowering time suggested a usefulness of these two traits as indexes in drought resistance screening. Correlation and QTL congruence between root traits and putative drought tolerance traits revealed that drought avoidance (via thick and deep root traits) was the main genetic basis of drought resistance in sandy soil condition, while drought tolerance may play more role in the genetic basis of drought resistance in paddy soil condition. Therefore, both drought mechanisms and soil textures must be considered in the improvement of drought resistance at reproductive stage in rice.

HVA1, a LEA gene from barley confers dehydration tolerance in transgenic rice ( Oryza sativa L.) via cell membrane protection

Drought is by far the leading environmental stress-limiting crop yields world-wide. Genetic engineering techniques hold great promise for developing crop cultivars with drought tolerance. Transgenic rice plants have been developed by engineering a wide variety of genes and were shown to be drought tolerant. Understanding the mechanism of stress tolerance in these transgenic plants under agronomically realistic stress conditions would further hasten breeding for drought resistance in rice. In this study, transgenic rice lines expressing the barley HVA1 gene were tested under prolonged drought stress cycle to understand the mechanism of dehydration tolerance. Transgenic plants maintained higher leaf relative water content (RWC) and showed lesser reduction in plant growth under drought stress as compared to non-transgenic (NT) plants. Maintenance of higher plant water status delayed wilting by more than 2 weeks in transgenic plants as compared to NT plants. Transgenic lines had relatively better cell membrane protection than NT line 28 days after stress. Both transgenic and NT lines had similar but low levels of osmotic adjustment (OA) under drought stress. The results indicated that the production of HVA1 proteins might have helped in better performance of transgenic rice plants by protecting cell membrane from injury under drought stress.

QTL mapping of the root traits and their correlation analysis with drought resistance using DH lines from paddy and upland rice cross

A Double Haploid (DH) population, 116 plants, derived from the cross between Japonica upland rice IRAT109 and paddy rice Yuefu, planted in PVC pipe under upland ecosystem in 2001 and 2002, was used in this study. Seven root traits, including basal root thickness (BRT), total root number (RN), maximum root length (MRL), root fresh weight (RFW), root dry weight (RDW), ratio of root fresh weight to shoot fresh weight (RFW/SFW) and ratio of root dry weight to shoot dry weight (RDW/SDW), were studied. Using index of drought resistance (IDR), the ratio of yield under upland ecosystem to yield under lowland ecosystem of DH lines, as the criteria of drought resistance, and correlation analysis between root traits and IDR, showed that BRT, MRL and RN were significantly correlated with IDR. High IDR lines had thicker BRT, longer MRL and less RN than low IDR lines. A molecular linkage map with 94 RFLP markers and 71 SSR markers covering 1535.1 cM was produced. QTLs and GxE interactions for BRT, RN, MRL, RFW, RDW, RFW/SFW and RDW/SDW were obtained based on the constructed molecular linkage map and software QTLmapper version 1.0. A total of 18 additive QTLs and 18 pairs of epistatic QTLs associated with root traits were detected. There were nine additive QTLs and two pairs of epistatic QTLs performed significant interactions with environment. Some QTLs with high general contribution and no GxE interaction were obtained. Two pairs of epistatic QTLsmrl3 andmrl8, brt3 andbrtlla controlling MRL and BRT had high general contributions of 21.51% and 13.03% respectively. An additive QTL and a pair of epistatic QTLs controlling RFW and RDW had high general contributions of 13.50% and 25.64% respectively. Marker assisted selection (MAS) for rice drought resistance based on QTL with high general contribution, low GxE interaction and tightly linkage with IDR were also discussed.

Genetic Analysis of Drought Resistance in Rice by Molecular Markers

Drought stress is the major constraint to rice (Oryza sativa L.) production and yield stability in rainfed ecosystems. Identifying genomic regions contributing to drought resistance will help develop rice cultivars suitable for rainfed regions through molecular marker assisted breeding. Quantitative trait loci (QTLs) linked to plant water stress indicators, phenology and production traits under irrigated and drought stress conditions were mapped by means of a doubled‐haploid (DH) population of 154 rice lines from the cross CT9993‐5‐10‐1‐M/IR62266‐42‐6‐2. The DH lines were subjected to water stress before anthesis in three field experiments at two locations. The DH lines showed significant variation for plant water stress indicators, phenology, plant biomass, yield and yield components under irrigated control and water stress. A total of 47 QTLs were identified for various plant water stress indicators, phenology, and production traits under control and water stress conditions in the field, which individually explained 5 to 59% of the phenotype variation. A region was identified on chromosome 4 that harbored major QTLs for plant height, grain yield, and number of grains per panicle under drought stress. By comparing the coincidence of QTLs with specific traits, we also genetically dissected the nature of association of root traits and capacity for osmotic adjustment with rice production under drought. Root traits had positive correlations with yield and yield components under drought stress. This study demonstrated that the region RG939‐RG476‐RG214 on chromosome 4 identified for root‐related drought resistance component QTLs also had pleiotropic effects on yield traits under stress. Consistent QTLs for drought resistance traits and yield under stress were detected and might be useful for marker‐assisted selection for rainfed rice improvement.

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Upland rice grown in soil-filled chambers and exposed to contrasting water-deficit regimes: I. Root distribution, water use and plant water status

Root morphological characteristics are known to be important in the drought resistance of some rice ( Oryza sativa L.) varieties. As part of a research programme aimed at using molecular marker technology for the improvement of drought resistance in rice, it is necessary to identify quantitative trait loci (QTLs) associated with root morphology and other drought resistance-related traits. Stability across environments is critically important for the identification of root growth QTLs that are valuable in breeding. Here, a mapping population of 140 recombinant inbred lines and the parental varieties Bala and Azucena were screened for root growth in thin glass-sided soil-filled chambers. In each of 2 years, two treatments were used: an early water deficit (WD0) in which seeds were sown into wet soil but received no more water, and a late water deficit (WD49) in which the plants were watered for 49 days and water was withheld for a final 7 days. Plant height, visible root growth, soil moisture at four depths and water use were monitored weekly. After 56 days, shoot mass, relative water content, root mass in four depth sections and adventitious root thickness at two depths were measured. In the WD0 treatment, shoot growth slowed markedly, while maximum root length was increased, indicating major changes in partitioning. This change in partitioning was also revealed as major differences in root mass (total and at depth) and root to shoot ratio between treatments. There were also large differences in partitioning between similar treatments in different years, which may in part reflect plant responses to soil water and nutrient status. In both treatments, water was extracted first from the upper sections of the rooting zone and then from progressively deeper layers. Effective water extraction required a root length density of at least 0.4 cm cm −3 in both treatments, and in the WD49 treatment water extraction at 100 cm depth was also related to shoot size and stomatal conductance. Azucena had thicker roots and more roots at depth compared to Bala, which slowed shoot growth sooner and became less water-stressed than Azucena. Azucena has root traits that potentially contribute to drought resistance, while Bala has a number of shoot-related mechanisms that make it adapted to drought-prone environments. The data presented here have been used to identify QTLs for root growth traits in a companion paper.

Tagging quantitative trait loci associated with grain yield and root morphological traits in rice (Oryza sativa L.) under contrasting moisture regimes

Plant breeding for drought-prone habitats envisages a favorable combination of grain yield and drought resistance. Though several components enhancing drought resistance have been identified in rice,their association with grain yield, under low-moisture stress, has been established in very few instances. We attempt to study the associations between rice grain yield and root system parameters both at phenotypic and genotypic levels. The doubled haploid population of IR64/Azucena was evaluated for root related traits at peak vegetative stage and grain yield related traits under both low-moisture stress and non stress conditions. ‘Mean environment’ was computed for yield related traits. Correlation and QTL mapping was attempted to find out the associations. The correlation between maximum root length and grain yield was positive under stress and negative in non stress. Genotypes with thicker and deeper roots, manifested higher biomass and grain yield under stress. Only one QTL found to increase days to flowering in non stress was also found to influence root volume and dry weight negatively under stress. The study suggests that loci enhancing grain yield and related traits were not pleiotropic with loci for desirable root morphological traits studied under low-moisture stress at vegetative stage, in the genetic material used in the study. It is thus possible to combine higher grain yield and desirable root morphological traits, favorably, to enhance productivity of rice under low-moisture stress. In rainfed ecologies, where deep roots contribute to enhanced drought resistance in rice, the results indicate the possibility of combining drought resistance with higher levels of grain yield.

Locating genomic regions associated with components of drought resistance in rice: comparative mapping within and across species

Direct and indirect economic loss in the agricultural sector due to drought is huge. With the advent of molecular-marker technology, research on drought resistance in crop plants has shifted from physiological descriptions of the phenomenon to genetic dissection of the mechanisms involved. Here, we report a comprehensive study of mapping the drought resistance components (osmotic adjustment and root traits) in a doubled-haploid rice (Oryza sativa L.) population of 154 lines. A genetic linkage map consisting of 315 DNA markers was constructed. A total of 41 quantitative trait loci (QTLs) were identified for osmotic adjustment and root traits, and individually explained 8–38% of the phenotypic variance. A region on chromosome 4 harbored major QTLs for several root traits. Consistent QTLs for drought responses across genetic backgrounds were detected and should be useful for marker-assisted selection towards the incorporation of a trait of interest into an elite line. Comparative mapping identified three conserved genomic regions associated with various physiological responses to drought in several grass species. These results suggest that these regions conferring drought adaptation have been conserved across grass species during genome evolution and might be directly applied across species for the improvement of drought resistance in cereal crops.

Variation in root penetration ability, osmotic adjustment and dehydration tolerance among accessions of rice adapted to rainfed lowland and upland ecosystems

AbstractDrought is the major constraint limiting rainfed rice production. The ability of rice roots to penetrate compacted soils and therefore to increase water extraction capacity, osmotic adjustment and dehydration tolerance of leaves enables the plant to tolerate drought. Experiments were conducted to determine the extent of genetic variation in root penetration index, osmotic adjustment and dehydration tolerance among indica accessions adapted to rainfed lowlands as well as traditional varieties from rainfed uplands. Root penetration index was evaluated in a system using wax–petrolatum layers to simulate soil compaction. Osmotic adjustment and dehydration tolerance were studied under slow development of water stress. Substantial genetic variation was found for root penetration index, osmotic adjustment and dehydration tolerance among indica ecotypes from lowlands, and the study of several traditional varieties from uplands showed variation in root penetration index and related root traits. An indica accession, IR58821‐23‐B‐1‐2‐1 had a high root penetration index of 0.38. The accessions, IR61079‐33‐1‐2‐2‐3, IR62266‐42‐6‐2 and IR63919‐38‐B‐1 had high osmotic adjustment capacities (1.91, 1.90 and 1.78 MPa, respectively); IR61079‐33‐1‐2‐2‐3 also had high dehydration tolerance. Good osmotic adjustment and dehydration tolerance were associated with poor root system. The traditional varieties ‘Kallurundaikar’ and ‘Norungan’ had higher root penetration indices (0.46 and 0.43, respectively), than even the japonica accessions. The study identified indica accessions and traditional varieties with superior root‐ and shoot‐related drought resistance traits that could be used in breeding for drought resistance in rice.

Carbon isotope discrimination and yield of upland rice as affected by drought at flowering

Field experiments involving upland rice genotypes, sown in various dates in late season, were carried out to assess the relationship of carbon isotope discrimination with grain yield and drought resistance. In each one of the three years, one trial was kept under good water availability, while other suffered water shortage for a period of 18-23 days, encompassing panicle emergence and flowering. Drought stress reduced carbon isotope discrimination measured on soluble sugars (deltas) extracted from stem uppermost internode at the end of the imposition period, but had relatively less effect on bulk dry matter of leaves, sampled at the same period, or that of uppermost internodes and grains, sampled at harvest. The drought-induced reduction in deltas was accompanied of reduced spikelet fertility and grain yield. In the three trials subjected to drought, genotypes with the highest yield and spikelet fertility had the lowest deltas. However, this relationship was weak and it was concluded that deltas is not a sufficiently reliable indicator of rice drought resistance to be useful as a screening test in breeding programs. On the other hand, grain yield and spikelet fertility of genotypes which were the soonest to reach 50% flowering within the drought imposition period, were the least adversely affected by drought. Then, timing of drought in relation to panicle emergence and to flowering appeared to be a more important cause of yield variation among genotypes than variation in deltas.

A combined RFLP and AFLP linkage map of upland rice (Oryza sativa L.) used to identify QTLs for root-penetration ability

Acombined RFLP and AFLP linkage map of an F6 recombinant inbred population, which was derived from a previously mapped F2 of a cross between the two drought resistant upland rice varieties Bala and Azucena, is presented. The map contains 101 RFLP and 34 AFLP markers on 17 linkage groups covering 1680 cM. Also presented is the approximate mapping position of a further four RFLP and 75 AFLP markers, which either could not be given a unique place on the map or for which the available data is not sufficient to allow confident positioning, and the result of quantitative trait locus (QTL) mapping of traits related to root-penetration ability. Root penetration was assessed by counting the number of root axes that penetrated a 3 mm-thick layer consisting of 80% wax and 20% white soft paraffin. Good root penetration would be expected to increase drought resistance where soil strength is high. Single-marker analysis revealed seven QTLs for the number of roots which penetrate the wax layer. In identical locations were seven QTLs for the ratio of penetrated to the total number of roots. Transgressive inheritance of positive alleles from Bala explained four of these QTLs. Comparison of the QTLs identified here with previous reports of QTLs for root morphology suggest that alleles which improve root penetration ability may also either make the roots longer or thicker.

Mapping QTLs associated with drought resistance in rice: Progress, problems and prospects

The use of molecular markers in the mapping of traits of agronomic importance holds great promise for speeding the development of improved plant varieties and increasing our understanding of the physiological or molecular mechanisms behind biological phenomena. The technique is now being applied to drought resistance in rice (Oryza sativa L.). Drought is important because a considerable proportion of the world rice area is not irrigated and can be prone to water deficit. A large number of people, particular some of the poorest rice farmers, stand to gain if new varieties which combine high yield and drought resistance can be developed. Rice should be particularly useful for the molecular genetic analysis of drought resistance because of its growing role as a model monocot species and the diversity of drought resistance mechanisms which are found in the germplasm. We briefly review the traits which might be considered important in improving drought resistance in rice, before explaining the molecular mapping approach. We review progress at locating quantitative trait loci (QTLs) for individual mechanisms of drought resistance in controlled environment conditions. This includes a detailed comparison of reported QTLs related to root morphological characters. The search for QTLs associated with field performance under drought stress is analysed and the problems associated with understanding the genetic control of a complex physical and physiological phenomenon under conditions of substantial environmental variation are highlighted. We emphasise that the use of near isogenic lines in overcoming some of the problems offers considerable promise for the future.

The use of seedling leaf death score for evaluation of drought resistance of rice

Leaf death (drought score) of seedlings has been extensively used in rice breeding programs as a selection index for drought resistance. This paper investigates the factors that affect the drought score of rice cultivars exposed to water stress during the vegetative stage and the relationship between drought score and yield. Two upland experiments consisting of 21 and 8 cultivars, respectively, were subjected to water deficit during vegetative growth. In the first experiment, the plants were grown under three stress conditions and pre-dawn leaf water potential, epidermal conductance, canopy light interception and drought score were determined during the stress period. In the second experiment leaf area, water use, dry matter growth and grain yield were also examined. Large genotypic variation in plant size existed in both experiments and this affected development of water stress and drought score. The cultivars with large plant size tended to have high drought score. A significant positive correlation ( r = 0.74∗∗, n = 63) existed between drought score and light interception. However, analysis of covariance indicated that genotypic variation in drought score existed after the effect of plant size was taken into account. Significant genotypic variation in leaf water potential existed and this was negatively correlated with drought score ( r = 0.75∗∗, n = 42). Cultivars with large leaf area tended to lose more green leaves during the stress period, but this did not result in reduced dry matter growth during or after the stress period. Green leaf area remaining after the stress period, and not amount of dead leaf (drought score) determined subsequent dry matter growth ( r = 0.45∗∗, n = 32), and there was no correlation between drought score of seedlings and grain yield. Thus for use in a vegetative screening program for drought resistance, estimates of drought score should be accompanied by estimates of plant size.

Growth Responses of Drought Resistant Rice Cultivars to Soil Compaction under Irrigated and Succeeding Non-irrigated Conditions during the Vegetative Stage

We investigated whether drought resistant rice cultivars exhibit higher dry-matter production under wet and dry compacted soil conditions in the vegetative stage and determined the dominant factors governing resistance to soil compaction. Three rice cultivars, a drought-sensitive Nipponbare, and drought-resistant Senshou and Dular, were grown in pots at four soil bulk densities (SBD) ranging from 1300 to 1600 dry soil kg m−3. Root and shoot dry matter productions was slightly smaller in Nipponbare over the 29 days after sowing under irrigated conditions than in the other cultivars at all SBDs. Senshou and Dular also maintained a higher dry matter production, both in relative and absolute values, than Nipponbare under the condition of withheld irrigation from days 29 — 39 after sowing. The higher stomatal conductance and leaf water potential of these two cultivars were supported by a larger root system which was mostly accompanied by lower top-root ratios in the irrigated and compacted soils. The higher plant growth rate under the non-irrigated condition might have been a result of both the higher water absorption rate and water use efficiency, which in turn were supported by the larger root biomass. We conclude that the ability of rice to rapidly develop a root system in the early vegetative phase under compacted soils facilitates plant production under subsequent soil desiccated conditions.

Breeding for Drought Resistance in Rice: Physiology and Molecular Genetics Considerations

Drought stress is a major constraint to rice (Oryza sativa L.) production and yield stability in many rainfed regions of Asia, Africa, and South America. The genetic improvement of adaptation to drought is addressed through the conventional approach by selecting for yield and its stability over locations and years. Because of low heritability of yield under stress and inherent variation in the field, such selection programs are expensive and slow in attaining progress. The objective of this paper is to review the current knowledge in physiology and molecular genetics which have implications in breeding for drought resistance in rice. The ability of root systems to provide for evapotranspirational demand from deep soil moisture and capacity for osmotic adjustment are considered major drought resistance traits in rice. However, selection for these traits still entail extensive investments in field nurseries or greenhouse facilities and is prone to problems of repeatability because of environmental variability. Recent development of molecular linkage maps of rice and other advances in molecular biology offer new opportunities for drought resistance breeding. Molecular markers linked to root traits and osmotic adjustment are being identified, which should lead to marker‐assisted selection. Transgenic rice plants having tolerance to water deficit and osmotic stresses have been reported. Work on genetic engineering of osmoprotectants, such as proline and glycine betaine, into the rice plant for drought tolerance improvement is in progress. Close collaboration between molecular geneticists, plant physiologists, and breeders is needed to critically assess the contribution of specific genes and application of molecular genetics to breeding for drought resistance in rice and other crops.

Genetic dissection of root growth in rice (Oryza sativa L.). II: mapping quantitative trait loci using molecular markers

Drought is a major abiotic stress of upland rice, and good root growth has been associated with drought avoidance. We report on the genetic mapping of root growth traits in an F2 population derived from two drought-resistant rice varieties, ‘Bala’ and ‘Azucena’. Restriction fragment length polymorphism (RFLP) between the parents was 32%, and a molecular map with 71 marker loci and 17 linkage groups covering 1280 cM was produced. Quantitative trait loci (QTLs) for eight root growth characteristics were mapped using phenotype data obtained in a hydroponic screen previously described in a companion paper. Using a significance threshold of LOD 2.4, we observed one QTL for maximum root length after 28 days growth on chromosome 11. It had a LOD score of 6.9, explained nearly 30% of the variation and appeared to be largely additive in effect. QTLs for maximum root length after 3, 7, 14 and 21 days of growth were also revealed. Some root-length QTLs, including that on chromosome 11, varied greatly with developmental stage. One QTL for root volume and two QTLs for adventitious root thickness were detected. No QTLs were detected for the length of cells in the mature (fully expanded) zone of adventitious root tips. The results obtained are discussed in the context of previous reports on mapping root growth parameters in rice.

Gas Exchange, Water Loss and Biomass Production in Rice and Wild Oryza Species in Well‐Watered and Water‐Limiting Growth Conditions

Abstract:A major reason for the drought susceptibility of cultivated rice is the inability to regulate water loss as effectively as other cereals. We report studies of growth and gas exchange under well‐watered and water‐limiting conditions on selected species of Oryza and seek to relate this physiological information to the ecology of the genus. The immediate ancestor of the Oryza sativa cultigen is native to swamps and marshes, and wet habitats are typical for the genus as a whole. However, the ecological range of some species does extend to habitats that dry out seasonally. In all species studied growth was reduced by water deficit. In all species studied leaves had small absolute water contents and began to roll at a relative water content above 90%. However, there were species differences in leaf rolling and the response of stomatal conductance to an increase in vapour pressure deficit. Following re‐watering, there were persistent reductions in stomatal conductance in most of the species tested, but the assimilation rate was not reduced in all of these cases. Where there was a persistant reduction in assimilation rate, there was also a reduction in carboxylation efficiency. It was a frequent observation that plants had a stomatal conductance greater than expected for their carbon assimilation rate; that is in the range where substantial changes in conductance have little effect upon photosynthesis. It is suggested that a reason for this may be the cooling of leaves which have a small thermal capacity in environments which often combine high temperature, humidity and irradiance. Large conductances combined with small water contents may be no disadvantage in the natural habitats of Oryza, but provide some reasons for the poor regulation of water loss in cultivated rice. Although there were significant differences in gas exchange amongst species the advantages that were observed over O. sativa were not of a magnitude likely to justify wide hybridisation. This implies that improvement in the drought resistance of rice is more likely to come from increasing water acquisition than from decreasing water loss.

Effect of zinc on grain characteristics of draught-resistant rice mutants

Through the use of Instrumental Neutron Activation Analysis (INAA), zinc concentration was determined in kernels resulted on plants of six drought-resistant rice mutant lines fertilized with zinc sulphate. It was found that zinc fertilization increased zinc residues in the kernels with varying concentrations depending on the line, each line reacted and responded to zinc independently. Zinc content in the kernels ranged from 5.63 to 91.4 ppm in the unfertilized control lines. This range was enlarged due to zinc fertilization of the plants to be from 93.51 to 554.53 ppm. It was also noticed that zinc fertilization increased seed heaviness in varying degrees depending on the line itself. This increase may be due to the increase in kernel thickness rather than in kernel width or length.