Molecular and Physiological Responses of Rice and Weedy Rice to Heat and Drought Stress (original) (raw)
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Agronomic and genetic approaches for enhancing tolerance to heat stress in rice: a review
Notulae Botanicae Horti Agrobotanici Cluj-Napoca
Rice is an important cereal crop worldwide that serves as a dietary component for half of the world’s population. Climate change, especially global warming is a rising threat to crop production and food security. Therefore, enhancing rice growth and yield is a crucial challenge in stress-prone environments. Frequent episodes of heat stress threaten rice production all over the world. Breeders and agronomists undertake several techniques to ameliorate the adverse effects of heat stress to safeguard global rice production. The selection of suitable sowing time application of plant hormones, osmoprotectants and utilization of appropriate fertilizers and signaling molecules are essential agronomic practices to mitigate the adverse effects of heat stress on rice. Likewise, developing genotypes with improved morphological, biochemical, and genetic attributes is feasible and practical way to respond to this challenge. The creation of more genetic recombinants and the identification of trai...
Physiological and molecular profiling of rice genotypes under drought stress
Water availability is one of the major limiting factors that seriously influence rice production in the rainfed ecologies and rice genotypes exhibit differential response to drought stress. With an objective to understand the physiological factors and the genomic loci that influence the tolerance to drought stress in rice, five weeks old seedlings of thirty eight rice genotypes were subjected to drought stress for 5, 7 and 9 days. Significant variation was observed for traits like shoot length, root length and tiller number/plant in all the treatments studied and fourteen genotypes displayed higher levels tolerance similar to controls. Among the physiological traits, high relative water content (> 75%) under severe drought stress, was recorded in ten genotypes while ten genotypes recorded higher levels of proline accumulation under stress. From the pooled data, it can be concluded that eight genotypes and CR-143-2-2 (control) possess high levels of tolerance to drought stress. In the molecular analysis with thirty microsatellite (SSR) markers linked to different drought tolerance QTLs, twelve markers confirmed the association of the markers with the associated drought tolerance traits in these tolerant genotypes
Frontiers in Plant Science
Productivity of rice, world's most important cereal is threatened by high temperature stress, intensified by climate change. Development of heat stress-tolerant varieties is one of the best strategies to maintain its productivity. However, heat stress tolerance is a multigenic trait and the candidate genes are poorly known. Therefore, we aimed to identify quantitative trait loci (QTL) for vegetative stage tolerance to heat stress in rice and the corresponding candidate genes. We used genotyping-by-sequencing to generate single nucleotide polymorphic (SNP) markers and genotype 150 F 8 recombinant inbred lines (RILs) obtained by crossing heat tolerant "N22" and heat susceptible "IR64" varieties. A linkage map was constructed using 4,074 high quality SNP markers that corresponded to 1,638 recombinationally unique events in this mapping population. Six QTL for root length and two for shoot length under control conditions with 2.1-12% effect were identified. One QTL rlht5.1 was identified for "root length under heat stress," with 20.4% effect. Four QTL were identified for "root length under heat stress as percent of control" that explained the total phenotypic variation from 5.2 to 8.6%. Three QTL with 5.3-10.2% effect were identified for "shoot length under heat stress," and seven QTL with 6.6-19% effect were identified for "shoot length under heat stress expressed as percentage of control." Among the QTL identified six were overlapping between those identified using shoot traits and root traits: two were overlapping between QTL identified for "shoot length under heat stress" and "root length expressed as percentage of control" and two QTL for "shoot length as percentage of control" were overlapping a QTL each for "root length as percentage of control" and "shoot length under heat stress." Genes coding 1,037 potential transcripts were identified based on their location in 10 QTL regions for vegetative stage heat stress tolerance. Among these, 213 transcript annotations were reported to be connected to stress tolerance in previous research in the literature. These putative candidate genes included transcription Kilasi et al. Heat Stress Tolerance in Rice (Oryza sativa) factors, chaperone proteins (e.g., alpha-crystallin family heat shock protein 20 and DNAJ homolog heat shock protein), proteases, protein kinases, phospholipases, and proteins related to disease resistance and defense and several novel proteins currently annotated as expressed and hypothetical proteins.
PLOS ONE, 2016
Rice exhibits enormous genetic diversity, population structure and molecular marker-traits associated with abiotic stress tolerance to high temperature stress. A set of breeding lines and landraces representing 240 germplasm lines were studied. Based on spikelet fertility percent under high temperature, tolerant genotypes were broadly classified into four classes. Genetic diversity indicated a moderate level of genetic base of the population for the trait studied. Wright's F statistic estimates showed a deviation of Hardy-Weinberg expectation in the population. The analysis of molecular variance revealed 25 percent variation between population, 61 percent among individuals and 14 percent within individuals in the set. The STRUCTURE analysis categorized the entire population into three sub-populations and suggested that most of the landraces in each sub-population had a common primary ancestor with few admix individuals. The composition of materials in the panel showed the presence of many QTLs representing the entire genome for the expression of tolerance. The strongly associated marker RM547 tagged with spikelet fertility under stress and the markers like RM228, RM205, RM247, RM242, INDEL3 and RM314 indirectly controlling the high temperature stress tolerance were detected through both mixed linear model and general linear model TASSEL analysis. These markers can be deployed as a resource for marker-assisted breeding program of high temperature stress tolerance.
Traditional or the folk cultivars of rice have been used as the major donor parent for developing abiotic and biotic stress resistance in different rice hybridization programme. Abiotic stresses including drought, submergence and salinity with other adverse conditions that are frequent constraint to rice production. Genetic resources of tolerance of these stresses are available in traditional rice land races, but complexity of these traits have hindered transfer of the tolerance genes into elite rice cultivars. However, QTL for these traits have been identified and marker assisted breeding strategy has been used for specific QTL introgression into sensitive cultivars. Out of different marker system SSLP or microsatellites are the most recent and frequently used by different workers worldwide for marker assisted selection (MAS) as well as for QTL mapping. In rice, microsatellites are well established spanning the entire genome. A number trait linked rice microsatellite markers (RM) a...
2021
High temperature is a major environmental stress factor limiting rice productivity. The present investigation was carried out to evaluate and identify heat tolerant rice genotypes on the basis of heat indices and SSR markers. Fifteen rice genotypes were designed in Randomized Complete Block Design (RBCD) with three replications under normal and heat stress conditions at two environmentally different sites (Sakha and New Vally) during 2018 and 2019 rice season. Parameters of heat indices were calculated based on grain yield under both conditions. The results indicated that the heat tolerant index (HTI) and mean productivity (MP) index had the highest correlation with yield under two the conditions, Giza178, Giza179, Giza182, Egyptian Yasmin, Egyptian Hybrid1 and N22 were the best genotypes based on indices values, representing high temperature tolerance of these genotypes. Results of variance analysis of yield and other traits in both conditions showed that there was a significant di...
IJBT Vol.20(1) [January 2021], 2021
Global warming is unusually increasing the earth temperature over the past century at an average rate of 0.07 per decade since 1880. The increased temperature exhibit greater impact on grain yield, approximately 5.18 million tons of rice yields due to heat wave. Heat shock factors (HSF) has major role in regulating heat shock proteins which in turn responsible for survival of plants in heat stress by refolding proteins, maintaining functional confirmation, aiding in host defence mechanism. The aim of this research was to analyse phenological, biochemical changes and key genes highly expressed during heat stress at flowering stage in rice. Expression analysis of nine HSF genes had given a differential expression under heat stress as compared to controlled traits. This study suggested OsHSP26.7 as most responsive gene under heat stress and rice line 159, RRF-127, GP-145-103 and Annada with heat tolerant adaptive mechanisms and better performance under high temperatures and was found to be in correlation with the estimated biochemical traits. This can be taken as a base for heat tolerance response of the crop, which may be useful for further validation studies of the candidate genes for heat tolerance in the rice as well as other crop plants.
Frontiers in Plant Science, 2015
In changing climatic conditions, heat stress caused by high temperature poses a serious threat to rice cultivation. A multiple organizational analysis at physiological, biochemical, and molecular levels is required to fully understand the impact of elevated temperature in rice. This study was aimed at deciphering the elevated temperature response in 11 popular and mega rice cultivars widely grown in India. Physiological and biochemical traits specifically membrane thermostability (MTS), antioxidants, and photosynthesis were studied at vegetative and reproductive phases, which were used to establish a correlation with grain yield under stress. Several useful traits in different genotypes were identified, which will be an important resource to develop high temperature-tolerant rice cultivars. Interestingly, Nagina22 emerged as the best performer in terms of yield as well as expression of physiological and biochemical traits at elevated temperature. It showed lesser relative injury, lesser reduction in chlorophyll content, increased super oxide dismutase, catalase and peroxidase activities, lesser reduction in net photosynthetic rate (P N), high transpiration rate (E), and other photosynthetic/fluorescence parameters contributing to least reduction in spikelet fertility and grain yield at elevated temperature. Furthermore, expression of 14 genes including heat shock transcription factors and heat shock proteins was analyzed in Nagina22 (tolerant) and Vandana (susceptible) at flowering phase, strengthening the fact that N22 performed better at molecular level also during elevated temperature. This study shows that elevated temperature response is complex and involves multiple biological processes that are needed to be characterized to address the challenges of extreme conditions of future climate.
2018
High night temperature (HNT) has strong negative effects on rice plant growth and development. HNT also impacts many physiological characteristics of rice which affect the grain quality of rice grown around the world. One potential mechanism of HNT damage is from the induction of ethylene-triggered reactive oxygen species that can lead to increased membrane damage and negatively impact yield and grain quality. In this study, the changes in physiological behavior due to the interaction between HNT and the ethylene-inhibitor 1-MCP was investigated. Furthermore, genome-wide expression analysis under HNT was performed using RNA-Seq to gain insights into the gene functions underlying tolerance to HNT. Plants were grown under ambient night temperature (ANT) (25 °C) or HNT (30 °C) with or without 1-MCP treatment. RNA extraction was performed on two phenotype-contrasting rice cultivars (Antonio and Colorado) from which in-depth RNA-Seq analysis was used to identify differentially expressed genes involved in heat tolerance in these varieties. Results from this experiment showed a total of 25 transcripts derived from analyzing the effects of various comparisons of treatments on the genotypes used in this study. From these findings we conclude that notable transcripts in this subset played a role in molecular mechanisms pertaining to ethylene interaction and HNT. High temperature environments are fairly innocuous for some exotic rice varieties; however, these genetic donors for heat tolerance often have various undesirable traits, including red pericarp, black hulls, and awns. To improve the efficiency of using these exotic accessions in