Physiological and molecular basis of susceptibility and tolerance of rice plants to complete submergence.
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ABSTRACT:
SUBMITTER: Jackson MB
PROVIDER: S-EPMC4244997 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Flash flooding of young rice plants is a common problem for rice farmers in south and south-east Asia. It severely reduces grain yield and increases the unpredictability of cropping. The inheritance and expression of traits associated with submergence stress tolerance at the seedling stage are physiologically and genetically complex. We exploited naturally occurring differences between certain rice lines in their tolerance to submergence and used quantitative trait loci (QTL) mapping to improve understanding of the genetic and physiological basis of submergence tolerance. Three rice populations, each derived from a single cross between two cultivars differing in their response to submergence, were used to identify QTL associated with plant survival and various linked traits. These included total shoot elongation under water, the extent of stimulation of shoot elongation caused by submergence, a visual submergence tolerance score, and leaf senescence under different field conditions, locations and years. Several major QTL determining plant survival, plant height, stimulation of shoot elongation, visual tolerance score and leaf senescence each mapped to the same locus on chromosome 9. These QTL were detected consistently in experiments across all years and in the genetic backgrounds of all three mapping populations. Secondary QTL influencing tolerance were also identified and located on chromosomes 1, 2, 5, 7, 10 and 11. These QTL were specific to particular traits, environments, or genetic backgrounds. All identified QTL contributed to increased submergence tolerance through their effects on decreased underwater shoot elongation or increased maintenance of chlorophyll levels, or on both. These findings establish the foundations of a marker-assisted scheme for introducing submergence tolerance into agriculturally desirable cultivars of rice.
| S-EPMC4244984 | biostudies-literature
Project description:Background and aimsRice ecosystems in the tropical coastal areas are subject to two types of flooding stress: transient complete submergence and long-term water stagnation (stagnant flooding). Here, we aimed to dissect the mechanisms for stagnant flooding tolerance of rice genotypes carrying SUB1, a quantitative trait locus for submergence tolerance.MethodsWe screened 80 elite genotypes under stagnant flooding stress in the lowland rice fields in the wet and dry seasons, and examined the tolerance mechanisms of promising genotypes for the two following seasons.Key resultsYield reduction under stagnant flooding averaged 48 % in the dry season and 89 % in the wet season. Elite genotypes carrying SUB1 showed 49 % lower yield than those without SUB1 under stagnant flooding, with no differences under shallow water conditions. However, we identified a few high-yielding Sub1 genotypes that were as tolerant of stagnant flooding as a reference genotype that lacked SUB1. These genotypes had intermediate stature with more shoot elongation in response to rising water than a moderately tolerant Sub1 reference variety, resulting in greater canopy expansion and higher yield. It was important to increase lodging resistance, since plant height >140 cm increased lodging under stagnant flooding. The culm diameter was closely associated with culm strength; reduced aerenchyma formation and increased lignin accumulation in the culm should increase lodging resistance.ConclusionsThe study demonstrated a successful combination of submergence and stagnant flooding tolerance in a rice breeding programme, and identified elite Sub1 genotypes that also tolerate stagnant flooding. Our results will support genetic improvement of Sub1 varieties for stagnant flooding tolerance.
| S-EPMC6944782 | biostudies-literature
Project description:Salinity threat is estimated to reduce global rice production by 50%. Comprehensive analysis of the physiological and metabolite changes in rice plants from salinity stress (i.e. tolerant versus susceptible plants) is important to combat higher salinity conditions. In this study, we screened a total of 92 genotypes and selected the most salinity tolerant line (SS1-14) and most susceptible line (SS2-18) to conduct comparative physiological and metabolome inspections. We demonstrated that the tolerant line managed to maintain their water and chlorophyll content with lower incidence of sodium ion accumulation. We also examined the antioxidant activities of these lines: production of ascorbate peroxidase (APX) and catalase (CAT) were significantly higher in the sensitive line while superoxide dismutase (SOD) was higher in the tolerant line. Partial least squares discriminant analysis (PLS-DA) score plots show significantly different response for both lines after the exposure to salinity stress. In the tolerant line, there was an upregulation of non-polar metabolites and production of sucrose, GABA and acetic acid, suggesting an important role in salinity adaptation. In contrast, glutamine and putrescine were noticeably high in the susceptible rice. Coordination of different strategies in tolerant and susceptible lines show that they responded differently after exposure to salt stress. These findings can assist crop development in terms of developing tolerance mechanisms for rice crops.
| S-EPMC5831039 | biostudies-literature
Project description:TDK1 is a popular rice variety from the Lao PDR. Originally developed for irrigated conditions, this variety suffers a high decline in yield under drought conditions. Studies have identified three quantitative trait loci (QTLs) for grain yield under drought conditions, qDTY3.1 , qDTY6.1 , and qDTY6.2 , that show a high effect in the background of this variety. We report here the pyramiding of these three QTLs with SUB1 that provides 2-3 weeks of tolerance to complete submergence, with the aim to develop drought- and submergence-tolerant near-isogenic lines (NILs) of TDK1. We used a tandem approach that combined marker-assisted backcross breeding with phenotypic selection to develop NILs with high yield under drought stress and non-stress conditions and preferred grain quality. The effect of different QTL combinations on yield and yield-related traits under drought stress and non-stress conditions is also reported. Our results show qDTY3.1 to be the largest and most consistent QTL affecting yield under drought conditions, followed by qDTY6.1 and qDTY6.2 , respectively. QTL class analysis also showed that lines with a combination of qDTY3.1 and qDTY6.1 consistently showed a higher tolerance to drought than those in which one of these QTLs was missing. In countries such as Lao PDR, where large areas under rice cultivation suffer vegetative-stage submergence and reproductive-stage drought, these lines could ensure yield stability. These lines can also serve as valuable genetic material to be used for further breeding of high-yielding, drought- and submergence-tolerant varieties in local breeding programs.
| S-EPMC5670188 | biostudies-other
Project description:BackgroundFlooding has negative impact on agriculture. The plant hormone ethylene is involved in plant growth and stress responses, which are important role in tolerance and adaptation regulatory mechanisms during submergence stress. Ethylene signaling crosstalk with gibberellin signaling enhances tolerance in lowland rice (Flood Resistant 13A) through a quiescence strategy or in deepwater rice through an escape strategy when rice is submerged. Information regarding ethylene-mediated priming in submergence stress tolerance in rice is scant. Here, we used 1-aminocyclopropane-1-carboxylic acid, an ethylene precursor, to evaluate the response in submerged rice seedlings.ResultsThe germination rate and mean germination times of rice seeds was higher in seedlings under submergence only when ethylene signaling was inhibited by supplemented with silver nitrate (AgNO3). Reduced leaf chlorophyll contents and induced senescence-associated genes in rice seedlings under submergence were relieved by pretreatment with an ethylene precursor. The ethylene-mediated priming by pretreatment with an ethylene precursor enhanced the survival rate and hydrogen peroxide (H2O2) and superoxide (O2-) anion accumulation and affected antioxidant response in rice seedlings.ConclusionsPretreatment with an ethylene precursor leads to reactive oxygen species generation, which in turn triggered the antioxidant response system, thus improving the tolerance of rice seedlings to complete submergence stress. Thus, H2O2 signaling may contribute to ethylene-mediated priming to submergence stress tolerance in rice seedlings.
| S-EPMC6458221 | biostudies-literature
Project description:Submergence tolerance is an important trait where short term flash flooding damages rice. Tolerant landraces that withstand submergence for 1–2?weeks were identified. Due to the heterogeneity in flood-prone ecosystem many different types of traditional rice cultivars are being grown by the farmers. The local landraces adapted to extremes in water availability could be the sources of genetic variation are to be used to improve the adaptability of rice to excess water stress. Greater genotypic variability was observed for plant height, elongation and survival %, absolute growth rate, non-structural carbohydrate retention capacity, chlorophyll content, different chlorophyll fluorescence parameters (FPs) characteristics, and re-generation growth at re-emergence. Twenty days submergence caused greater damage even in ( introgressed cultivars compared to the 14?days of submergence. The FPs, carbohydrate content and dry weight at the end of submergence showed positive and highly significant association with re-generation growth. The presence of associated primers, either SC3 or ART5, was noticed even in greater elongating types of rice genotypes. These genotypes possess one or more of the adaptive traits required for the flood-prone ecosystem, which range from temporary submergence of 1–2?weeks to long period of stagnant water tolerance.Electronic supplementary materialThe online version of this article (doi:10.1007/s12284-011-9065-z) contains supplementary material, which is available to authorized users.
| S-EPMC5520825 | biostudies-literature
Project description:Flooding is a major threat to agricultural production. Most studies have focused on the lower water storage limit in rice fields, whereas few studies have examined the upper water storage limit. This study aimed to explore the effect of waterlogging at the rice tillering stage on rice growth and yield. The early-ripening late japonica variety Yangjing 4227 was selected for this study. The treatments included different submergence depths (submergence depth/plant height: 1/2 (waist submergence), 2/3 (neck submergence), and 1/1 (complete submergence)) and durations (1, 3, and 5 d). The control group was treated with the conventional alternation of drying and wetting. The effects of waterlogging at the tillering stage on root characteristics, dry matter production, nitrogen and phosphorus accumulation, yield, yield components, and 1-aminocyclopropane-1-carboxylic acid synthase (ACS) gene expression were explored. Compared with the control group, the 1/1 group showed significant increases in yield, seed-setting rate, photosynthetically efficient leaf area, and OS-ACS3 gene expression after 1 d of submergence. The grain number per panicle, dry weight of the aboveground and belowground parts, and number of adventitious roots also increased. Correlation analysis revealed a significant positive correlation between the panicle number and nitrogen content; however, no significant correlation was found for phosphorus content. If a decrease in rice yield of less than 10% is acceptable, half, 2/3, and complete submergence of the plants can be performed at the tillering stage for 1-3 d; this treatment will increase the space available for rice field water management/control and will improve rainfall resource utilization.
| S-EPMC4441388 | biostudies-literature
Project description:Maize is highly sensitive to short term flooding and submergence. Early season flooding reduces germination, survival and growth rate of maize seedlings. We aimed to discover genetic variation for submergence tolerance in maize and elucidate the genetic basis of submergence tolerance through transcriptional profiling and linkage analysis of contrasting genotypes. A diverse set of maize nested association mapping (NAM) founder lines were screened, and two highly tolerant (Mo18W and M162W) and sensitive (B97 and B73) genotypes were identified. Tolerant lines exhibited delayed senescence and lower oxidative stress levels compared to sensitive lines. Transcriptome analysis was performed on these inbreds to provide genome level insights into the molecular responses to submergence. Tolerant lines had higher transcript abundance of several fermentation-related genes and an unannotated Pyrophosphate-Dependent Fructose-6-Phosphate 1-Phosphotransferase gene during submergence. A coexpression network enriched for CBF (C-REPEAT/DRE BINDING FACTOR: C-REPEAT/DRE BINDING FACTOR) genes, was induced by submergence in all four inbreds, but was more activated in the tolerant Mo18W. A recombinant inbred line (RIL) population derived from Mo18W and B73 was screened for submergence tolerance. A major QTL named Subtol6 was mapped to chromosome 6 that explains 22% of the phenotypic variation within the RIL population. We identified two candidate genes (HEMOGLOBIN2 and RAV1) underlying Subtol6 based on contrasting expression patterns observed in B73 and Mo18W. Sources of tolerance identified in this study (Subtol6) can be useful to increase survival rate during flooding events that are predicted to increase in frequency with climate change.
| S-EPMC4373911 | biostudies-literature
Project description:Submergence tolerance of 13 doubled haploid lines of rice and their parents (submergence tolerant FR13A and submergence intolerant CT6241) was assessed using 2-week-old seedlings. Plants were scored for leaf senescence and percentage of seedlings that survived up to 15 d submergence, followed by a 12 d recovery period. Seven lines proved to be submergence tolerant, and six relatively intolerant. In all lines, activity of pyruvate decarboxylase (PDC), extracted from the apical 3-5 cm of root axes, decreased by 46-96 % and 38-76 %, respectively, during 5 or 10 d submergence under natural day/night conditions, compared with pre-submergence values (100 %). However, when the enzyme was extracted at night, submergence increased PDC activity of all rice lines (approx. 112 % on average), compared with pre-submergence values (100 %). The stimulating effect of the dark period on PDC activity was reproduced and amplified by submerging rice seedlings for up to 5 d in continuous darkness in water containing sub-ambient concentrations of oxygen (2.3 mg l(-1)). Such increased PDC activity was also observed in seedlings exposed to anoxia for 6 h (approx. 6-175 % higher than pre-submergence values). Irrespective of tolerance class, submergence decreased soluble protein concentrations under all conditions and sampling times. No positive correlation was found between PDC activity and tolerance of the various rice lines to submergence. However, PDC activity was slightly higher in submergence intolerant lines, compared with tolerant lines, under both dark submergence and anoxia. Such differences in PDC activity between the two groups of rice lines were not observed when they were submerged under the natural diurnal cycle. Increased PDC activity in roots at night demonstrated a probable incidence of tissue hypoxia or anoxia during submergence during each dark period.
| S-EPMC4244983 | biostudies-literature
Project description:Poplar is a major afforestation tree species in flood-prone areas. Here, we compared molecular and physiological responses in the roots of two full-sib poplar clones, LS1 (flood-tolerant) and LS2 (flood-susceptive), subjected to stagnant flooding using transcript and metabolite profiling. LS1 displayed less phenotypic damage and superior leaf gas exchange and plant growth compared with those of LS2. We concluded that three characteristics might contribute to the differences in flood tolerance between LS1 and LS2. First, fermentation was initiated through lactic dehydrogenation in LS1 roots under flooding and subsequently dominated by alcohol fermentation. However, lactic dehydrogenase was persistently active in flooded LS2. Second, 13 differentially expressed genes associated with energy and O2 consumption processes under soil flooding had lower transcript levels in LS1 than those in LS2, which might contribute to better energy-/O2-saving abilities and behaviours in flood-tolerant LS1 than those in flood-susceptible LS2 under hypoxic stress. Third, LS1 possessed increased reactive oxygen species scavenging abilities compared with those of LS2 under edaphic flooding. Our data are a valuable contribution to understanding the mechanisms involved in the flood tolerance of poplar.
| S-EPMC6110812 | biostudies-literature