Drought Tolerant Rice Varieties Research Articles

Superior haplotypes of key drought-responsive genes reveal opportunities for the development of climate-resilient rice varieties

Haplotype-based breeding is an emerging and innovative concept that enables the development of designer crop varieties by exploiting and exploring superior alleles/haplotypes among target genes to create new traits in breeding programs. In this regard, whole-genome re-sequencing of 399 genotypes (landraces and breeding lines) from the 3000 rice genomes panel (3K-RG) is mined to identify the superior haplotypes for 95 drought-responsive candidate genes. Candidate gene-based association analysis reveals 69 marker-trait associations (MTAs) in 16 genes for single plant yield (SPY) under drought stress. Haplo-pheno analysis of these 16 genes identifies superior haplotypes for seven genes associated with the higher SPY under drought stress. Our study reveals that the performance of lines possessing superior haplotypes is significantly higher (p ≤ 0.05) as measured by single plant yield (SPY), for the OsGSK1-H4, OsDSR2-H3, OsDIL1-H22, OsDREB1C-H3, ASR3-H88, DSM3-H4 and ZFP182-H4 genes as compared to lines without the superior haplotypes. The validation results indicate that a superior haplotype for the DREB transcription factor (OsDREB1C) is present in all the drought-tolerant rice varieties, while it was notably absent in all susceptible varieties. These lines carrying the superior haplotypes can be used as potential donors in haplotype-based breeding to develop high-yielding drought-tolerant rice varieties.

A participatory framework for prioritizing climate-smart agriculture innovations in rice-based systems: A case study of Mali

Alleviating the climate-related constraints faced by agri-food systems in sub-Saharan Africa requires an accelerated adoption of climate-smart agriculture (CSA) innovations by farmers. However, little is known about the best-bet (most appropriate) CSA innovations, and the enabling conditions for their widespread adoption in a given biophysical and socioeconomic context. The objectives of this study were to identify the best-bet CSA innovations and the barriers, incentive mechanisms, and roles of institutions in widespread adoption in the four rice growing environments in Mali (irrigated lowlands, rainfed lowlands, rainfed uplands, and submergence systems). Data were collected from stakeholder's consultations to assess CSA innovations using four climate-smart performance indicators (productivity, income, adaptation, and mitigation) and four implementation feasibility indicators (technology cost, technical feasibility, gender inclusivity, and market demand). The best-bet CSA innovations included drought- and submergence-tolerant rice varieties, perennial rice, and rice-vegetable rotation in irrigated lowlands; drought-tolerant rice varieties, rice-tuber, rice-vegetable, and rice-legume rotations in rainfed lowlands; drought-tolerant rice varieties and mulching in rainfed uplands; and submergence-tolerant rice varieties, perennial rice, and integrated rice-fish in submergence systems. The average perceived adoption level of CSA innovations by farmers in the rice-growing environments was low, ranging from 7 to 19 % due to the lack of finance, technical knowledge, machinery, fertilizer, and quality seeds. Governments, farmers’ organizations, and research and academic institutions were identified as critical actors in the wide spread adoption of CSA innovations. The framework used in this study can be used to identify and invest into locally relevant best-bet CSA innovation packages.

Physiological Insights of Melatonin Hormone for Alleviation of Drought Stress in Rice

Drought stress significantly hampers crop growth and yield by negatively impacting various biochemical and physiological plant processes. This study aimed to assess drought tolerance in traditional rice varieties using Poly Ethylene Glycol 6000 (PEG 6000) and focused on the effectiveness of melatonin applied through both seed treatment and foliar spray in mitigating the effects of drought stress. The optimal drought screening conditions were determined at a PEG concentration of -4 bars. As the PEG concentration increased, key factors such as germination percentage, vigor index, root length, and shoot length decreased. This indicates that PEG can be a useful tool for early selection of drought tolerant rice varieties. Melatonin (N-acetyl-5-methoxytryptamine), known for alleviating abiotic stress, showed positive effects on seed germination at 200 ppm concentration. The study observed that stomatal closure is a natural response to drought stress, but melatonin application induced partial stomatal opening. Notably, a foliar spray of 100 ppm melatonin demonstrated better recovery from drought stress compared to the 200 ppm concentration. In conclusion, the research suggests that seed treatment with 200 ppm melatonin and foliar spraying with 100 ppm melatonin are the most effective approaches for reducing the adverse effects of drought stress in rice plants.

Profitability and productivity of drought tolerant rice variety Binadhan-21 in some selected areas of Bangladesh

The study was conducted in five major BINA developed Aus rice growing areas of Bangladesh, namely Mymensingh, Rangpur, Kushtia, Chapai Nawabganj and Magura district. The study focused on the profitability and productivity of Binadhan-21; and the major constraints to Binadhan-21 production. Simple random sampling technique was followed for this study. A total of 100 farmers were randomly selected as sample size in the study areas, 20 from each district. Data were collected from Aus rice growers through interview schedule. Collected data were edited, summarized, tabulated and analyzed to fulfill the objectives. Some descriptive statistics were used. Binadhan-21 production is highly profitable in the study area. The average yield was 4.86 t ha-1 in Aus season and undiscounted BCR was 1.93. Therefore, Binadhan-21 farmers received high return on its investment. The farmers in the study areas encountered some constraints to Binadhan-21 production. The first ranked was unavailability of seeds in all areas. Other constraints were lack of training (70.83%), crop lost by bird and animal (56.61%), and natural calamities (19.30%). Bangladesh J. Nuclear Agric, 37(1): 111-116, 2023

RICE RESILIENCE IN THE FACE OF CLIMATE CHALLENGES EXPLORING DROUGHT RESPONSE IN RICE GENOTYPES

Climate change is posing significant challenges to agriculture, threatening global food security. Among these challenges, drought stress is a formidable obstacle to rice production, a staple food for billions. Drought stress disrupts vital physiological processes, causing yield losses and impacting grain quality. Developing drought-tolerant rice varieties is essential to ensure food production and farmers' livelihoods. This study explores the drought tolerance potential of six Basmati rice genotypes: Basmati 198 (G1), Basmati 385 (G2), Rachna basmati (G3), Super Basmati (G4), Shaheen basmati (G5), and Basmat 2000 (G6). These genotypes have previously demonstrated submergence tolerance. By subjecting them to drought stress, we aim to assess their adaptability to multiple stressors, crucial in changing climates. A Randomized Complete Block Design was employed, ensuring methodological rigor. Seedlings were transplanted into the field, and drought stress was induced during the booting stage. We monitored various traits, including plant height, productive tillers, panicle length, spikelet numbers, fertility, branches, biological yield, grain yield, and harvest index. Statistical analyses revealed significant genotype-specific responses to drought. Results showed significant differences among genotypes under both control and drought conditions, underscoring genetic variability. Drought stress significantly impacted most traits. Basmat 2000 (G6) demonstrated superior performance under drought conditions. Clustering analysis revealed genetic diversity among genotypes, offering insights for breeding programs. Correlation analysis highlighted the importance of specific traits for grain yield. In conclusion, this study contributes to understanding genetic diversity among Basmati rice genotypes under drought stress. The findings emphasize the need for developing drought-tolerant rice varieties and offer valuable insights for sustainable rice cultivation in changing climates.

Impact of different crop establishment techniques on growth and yield of drought tolerant rice varieties

Impact of different crop establishment techniques on growth and yield of drought tolerant rice varieties

Assessment of Bangladeshi rice landraces for drought tolerance under controlled environment

Drought is one of the major challenging abiotic stresses for rice production in Bangladesh. This study investigated 48 rice landraces obtained from different Eco-zones of Bangladesh for their drought tolerance characteristics. Significant variation was observed in morpho-physiological traits such as length of root and shoot, dry weight of root and shoot, leaf stomatal resistance and stomata number. Stomatal conductance, root length, root dry weight showed significant correlation with visual drought score. A cluster analysis based on morpho-physiological characteristics identified six cluster groups and most of the promising drought tolerance landraces were found in cluster VI. Five landraces - Dhapa, Dud Kalam, Dular, Hogla Pata and Keora showed key desired characteristics for dry weight, stomatal conductance, evapotranspiration, water use efficiency and root parameters for drought tolerance. These landraces could be potential sources in breeding program for the development of drought tolerant rice varieties. Bangladesh Rice J. 26 (1): 1-16, 2022

Optimizing the use of submergence and drought tolerant rice varieties to reduce the impact of climate change on swampland

The swamplands are one among the possibe suboptimal land for agriculture. The land consists of tidal swamplands and freshwater land that are wide obstainable in Indonesia. The hydrotopography of tidal swampland is powerfully influenced by tide and neap tide of water, whereas in freshwater land it’s for the most part determined by precipitation. Drought, flooding or deep inundation, and shifts in rainfall patterns as a result of extreme temperature change have an impact on agriculture in decreasing food crop production, significantly for rice in swamplands. One strategy in anticipating the impact of climate change in agriculture, particularly food crops (rice) is to use submergence and drought tolerant varieties still as early maturing rice varieties. Rice varieties tolerant of submergence in swamplands like Inpara 3, Inpara 4, Inpara 5, Inpari 29, and Inpari 30 Ciherang sub1. Whereas drought tolerant varieties such as Inpari 18, Inpari 19, Inpari 20, Inpago 4, Inpago 5, Inpago 6, Inpago-8, and Inpago Lipigo-4. In addition to avoiding drought, early-maturing aged rice varieties such as Hipa 6 Jete, Inpari Si Denuk are often used, Inpari-34 Salin Agritan, Cakra Buana Agritan, Inpari 12 and Inpari 13. The purpose of this paper is to explain how planting submergence and drought-tolerant rice varieties can reduce the effects of climate change on swamp agriculture. It is expected to significantly reduce the effects of climate change for agriculture in swamplands by treating submergence and drought tolerance and early maturing varieties.

Conventional and molecular breeding strategies for improvement of drought tolerance cultivars in rice: Recent approaches and outlooks

Rice is a vital staple food, especially in Asia, but it is highly susceptible to drought, leading to significant yield losses. To ensure food sustainability, drought-tolerant rice varieties are essential. Conventional breeding methods improve drought tolerance by focusing on biometric traits like root depth, avoidance, escape, and tolerance. This involves screening and crossing drought-tolerant varieties with high-yielding ones, followed by selection and evaluation. Techniques such as pedigree selection, recurrent selection, and backcrossing introduce desirable genes to enhance drought tolerance. Induced mutation through radiation exposure is also used. The molecular basis of drought tolerance involves identifying and manipulating genes responsible for rice's response to water stress. Techniques like QTL analysis, transcriptomics, genomics, and proteomics identify genes and QTLs associated with drought tolerance. Important genes involved in drought response include DREB, LEA, and ROS scavenging genes. Identifying QTLs enables the development of molecular markers for efficient screening of drought-tolerant rice genotypes. In conclusion, conventional breeding and molecular approaches are employed to develop drought-tolerant rice varieties. Conventional breeding improves biometric traits, while molecular techniques identify and manipulate specific genes associated with drought tolerance. This combination holds promise for high-yielding and drought-tolerant rice cultivars, contributing to global food security. However, further research is needed to understand the complex genetic mechanisms underlying drought tolerance in rice and enhance breeding precision and efficiency.

QTL mapping and analysis for drought tolerance in rice by genome-wide association study.

Rice drought resistance is a complicated quantitative feature involving a range of biological and agronomic variables, but little is known about the underlying genetics and regulatory mechanisms that regulate drought tolerance. This study used 120 recombinant inbred lines (RILs), derived from a cross between drought tolerant Lvhan 1 and susceptible Aixian 1. The RILs were subjected to drought stress at the first ear stage, and phenotypic data of 16 agronomic and physiological traits under varying conditions were investigated. Genome-wide association study (GWAS) on the drought resistance index of traits was carried out. A total of 9 quantitative trait loci (QTLs) associated with drought-related traits were identified on chromosomes 2, 6, 7, 8, 9, and 10, which includes QTLs for plant height (PH) qPH10.1, effective panicles number (EPN) qEPN6.1, panicle length (PL) qPL9.1, thousand-grain weight (TGW) qTGW2.1, qTGW6.1, qTGW8.1, leaf length (LL) qLL7.1, leaf width (LW) qLW7.1, and leaf area (LA) qLA7.1. The fraction of phenotypic variation explained by individual QTL varied from 10.6% to 13.9%. Except for days to flowering (DTF), the mean values of all traits under normal water management conditions were considerably higher than those under drought conditions. Except for the DTF, the drought resistance index of all rice traits was less than 1, indicating that drought treatment reduced the EPN, FGPP, SSR, PH, and LA, which affected the growth and development of rice. The drought resistance index of DTF was 1.02, indicating that drought prolonged the heading time of rice and diminish the yield parameters. Along with identifying QTLs, the results also predicted ten candidate genes, which are directly or indirectly involved in various metabolic functioning related to drought stress. The identification of these genomic sites or QTLs that effectively respond to water scarcity will aid in the quest of understanding the drought tolerance mechanisms. This study will facilitate the marker-assisted rice breeding and handy in the breeding of drought-tolerant rice varieties.

Genome-Wide Scan for Genetic Signatures Based on the Whole-Genome Resequencing of Salt- and Drought-Tolerant Rice Varieties

Identifying elite stress-tolerant varieties and elucidating the genetic mechanisms mediating stress resistance can help breeders develop and exploit new rice germplasm resources. In this study, we identified five salt-tolerant varieties and five drought-tolerant upland rice varieties by survival rate and drought tolerance grade and constructed variation maps of the resistance using a deep-sequencing approach. Using 116 rice accessions from the 3000 Rice Genomes Project, we characterized the population structure of sequenced varieties. Through comparative genomics and transcriptome analysis, we screened 39 salt-response candidate genes. Natural variation analysis on root length-related drought candidate gene showed that Hap1 and Hap4 were the predominant haplotypes in indica, while Hap5 was the predominant haplotype in japonica. Gene Ontology (GO) analysis showed that carbohydrate metabolic process, defense response, and response to stimulus were the common GO terms associated with salt and drought tolerance. Selective signatures in elite stress-tolerant varieties indicated that multiple important stress tolerance genes, namely OsRac1, Pikp-2, Xa26, OsSIRP4, and wsl1, were selected and utilized in these sequenced rice varieties. These findings may be useful for clarifying the genetic variations among elite stress-tolerant varieties, while also laying the foundation for a more comprehensive investigation of the genetic basis of salt and drought tolerance.

Morphological and Molecular Diversity of Traditional Upland Rice (Oryza sativa L.) Varieties for Drought Tolerance at Seedling Stage

Drought is considered the major threat and most damaging abiotic stress for rice production.However, some traditional upland rice varieties (TURVs) may have some forms of tolerance to various stresses compared to new elite varieties. Two experiments were conducted. Experiment to determine the morpho-physiological response, phenotypic diversity, and similarity of 13 TURVs and 2 check varieties to mild drought stress at the seedling stage (Experiment 1 (E1) and to determine the molecular diversity and genetic similarity of the genotypes using selected simple sequence repeat (SSR) markers ((Experiment 2 (E2). In E1, all TURVs were highly tolerant under mild drought stress for a physiological response. Standardized Shannon-Weaver Diversity Index(H’) showed zero to low phenotypic diversity for qualitative traits. However, the phenotypic diversity of quantitative traits ranged from moderate to high for well-watered conditions, low to high for drought conditions, and moderate to high for re-watered conditions. Cluster analysis through Ward’s minimum variance based on pooled phenotypic data grouped the genotypes into three major clusters at 7 Euclidean distances. For E2, polymorphic information content values from 24 polymorphic SSR markers ranged from slightly informative (RM256) to highly informative (RM206), with a mean of 0.61. Nei’s gene diversity mean was 0.62 and values varied from 0.26 (RM256) to 0.86 (RM206). Based on Jaccard’s similarity coefficient, rice genotypes were grouped into nine minor clusters. The results indicate that TURVs harbor moderate to high allelic diversity and there are potential tolerance genes for mild drought stress that can be utilized in breeding programs for drought-tolerant rice varieties.

Drought stress in rice: morpho-physiological and molecular responses and marker-assisted breeding.

Rice (Oryza Sativa L.) is an essential constituent of the global food chain. Drought stress significantly diminished its productivity and threatened global food security. This review concisely discussed how drought stress negatively influenced the rice's optimal growth cycle and altered its morpho-physiological, biochemical, and molecular responses. To withstand adverse drought conditions, plants activate their inherent drought resistance mechanism (escape, avoidance, tolerance, and recovery). Drought acclimation response is characterized by many notable responses, including redox homeostasis, osmotic modifications, balanced water relations, and restored metabolic activity. Drought tolerance is a complicated phenomenon, and conventional breeding strategies have only shown limited success. The application of molecular markers is a pragmatic technique to accelerate the ongoing breeding process, known as marker-assisted breeding. This review study compiled information about quantitative trait loci (QTLs) and genes associated with agronomic yield-related traits (grain size, grain yield, harvest index, etc.) under drought stress. It emphasized the significance of modern breeding techniques and marker-assisted selection (MAS) tools for introgressing the known QTLs/genes into elite rice lines to develop drought-tolerant rice varieties. Hence, this study will provide a solid foundation for understanding the complex phenomenon of drought stress and its utilization in future crop development programs. Though modern genetic markers are expensive, future crop development programs combined with conventional and MAS tools will help the breeders produce high-yielding and drought-tolerant rice varieties.

Selection index and agronomic characters of doubled haploid rice lines from anther culture

Abstract. Hadianto W, Purwoko BS, Dewi IS, Suwarno WB, Hidayat P. 2023. Selection index and agronomic characters of doubled haploid rice lines from anther culture. Biodiversitas 24: 1511-1517. Development of superior rice varieties requires selection of the best lines having good agronomic characters and high yields. This study aimed to select high-yielding doubled haploid rice lines obtained from anther culture through index selection and agronomic characters. The study was conducted using a single-factor randomized complete block design (RCBD) with genotype as treatment. Sixty doubled haploid lines and 5 check varieties were evaluated along with three replications, hence, the total experimental unit was 195. Analysis of variance showed that the genotypes had a significant effect on all observed characters, except for the number of productive tillers. The agronomic characters observed had a high broad sense of heritability, except for the number of productive tillers which was in the medium category. Furthermore, index selection was carried out based on productivity, the number of productive tillers, the total number of grains, as well as the percentage of filled grains. Based on the index selection, 29 lines were selected among the 60 doubled haploid rice lines tested. These lines had the range in productivity from 2.95 to 6.77 ton ha-1, the number of productive tillers from 12.3 to 20.8 tillers, the total number of grains from 135 to 275.4 seeds, the filled grain percentage from 53.23 to 87.61%, and the selection index from -1.48 to 7.88. The selected lines will be further tested at the next experimental stage in several locations to produce high-yielding, brown planthopper-resistant, and drought-tolerant rice varieties.

Vulnerability and ecosystem-based adaptation in the farming communities of droughtprone Northwest Bangladesh

Agriculture is sensitive to climate change as it depends on temperature and rainfall patterns for crop production. Though Bangladesh's recent growth in its agriculture sector is remarkable, the farmer community living in the northwest region of Bangladesh faces drought every year that negatively affects agriculture, ecology, and society. However, studies focusing on farmer communities' vulnerability to drought and adaptation options through a social-ecological lens are limited. The present study used a framework that combines social-ecological vulnerability (i.e., exposure, sensitivity, and lack of resilience) and ecosystem-based adaptation (EbA) strategies and linked them with risk governance (i.e., organization, planning, and implementation) to understand social-ecological risk and adaptation. Data was collected through 50 in-depth interviews and six focus group discussions with the farmer communities of the Tanore sub-district of Rajshahi district, Bangladesh. We found that increased temperature, lack of water availability, change in rainfall pattern, and limited availability of drought-resilient crop seeds increased farmers’ vulnerability to drought. Farmers were shifting from traditional farming practices to more ecosystem-based, integrated farming practices that are less climate-sensitive. Combined agriculture, selecting drought-tolerant rice varieties, and shifting cropping patterns were some strategies that farmers adopted to address risks. However, the adaptation of these strategies was not well-governed. Farmers opined some strategies that could be initiated at the organization (e.g., local government support), planning (e.g., planning farming skill development), and implementation (e.g., restoring water bodies) levels to help the community to reduce risk. The study would aid in framing governance measures to reduce vulnerability and risk in agriculture-dominated social-ecological systems.

Phenotyping for the Seedling Stage of the Drought Stress Tolerance in Rice (Oryza sativa L.)

The ever-increasing demand for rice raises the need to increase productivity by developing drought-tolerant rice varieties. Drought tolerance is a complex polygenic trait that largely depends upon plant developmental stages and showed genotype-specific variability. The experiment was conducted using drought tolerant (Binadhan-19, BRRI dhan83) and drought susceptible (BRRI dhan26, BRRI dhan48) rice genotypes at the glasshouse of Bangladesh Institute of Nuclear Agriculture (BINA), Mymensingh to characterize the seedling stage drought tolerance as well as disclose the variability of the genotypes for morphological and biochemical traits. A completely randomized design (CRD) with three replications and treatments (control and drought stress imposed by 20% PEG) was used for the experiment. Data on shoot length, root length, fresh root weight, fresh shoot weight, dry root weight, dry shoot weight, chlorophyll content (SPAD value), MDA, and H2O2 were recorded and analyzed through appropriate breeding tools. Significant variation (p<0.01) was observed for genotype, treatment, and genotype (G) × treatment (T) interactions viz., shoot length, root length, root fresh weight, shoot fresh weight, root dry weight, shoot dry weight, chlorophyll, H2O2, and MDA. Drought stress leads to a significant decrease in root and shoots growth whereas the level of H2O2 and MDA increased significantly. A greater decrease in root and shoot growth was observed in susceptible genotypes (BRRI dhan28, BRRI dhan48) compared to tolerant genotypes (BRRI dhan71, Binadhan-19). In contrast, a limited increase in H2O2 and MDA was recorded in tolerant genotypes compared to susceptible genotypes. H2O2 showed a significant positive correlation with root and shoot characteristics under control conditions, whereas H2O2 showed a significant negative correlation with chlorophyll content under drought conditions. MDA showed a significant negative correlation with most of the studied traits under well-watered conditions. Considering all of the traits at the seedling stage, the genotype Binadhan-19 is considered a drought-tolerant genotype both under well-watered and drought conditions, and this genotype was selected for further study under direct field conditions as well as for genetic improvement against drought stress.

Tolerance of Upland Rice Genotypes from Deli Serdang North Sumatra to Drought Stress Condition

Drought is the main problem that is often faced in upland rice cultivation in the dry land. Therefore, drought-tolerant rice varieties are needed, but until now, the number is very limited. It is crucial to produce drought-tolerant rice because Indonesia has a relatively sizeable dry land of 148 million ha. This study aimed to obtain a genotype of upland rice that is tolerant to drought with high productivity and can be developed in the dry land. This research was then continued with drought tolerance testing by giving water below field capacity in a greenhouse. This study was in a factorial form using a Split Plot Design, with the main plot of drought stress treatment consisting of tree levels, namely water availability field capacity water, field capacity water, and field capacity water. The sub-plots were four genotypes of upland rice from Deli Serdang North Sumatra consisting of Sialus, Arias, Silayur, Sirabut and one drought-tolerant variety for comparison is Inpago11. The observed variables included plant height, chlorophyll content, number of tillers, number of productive tillers, age of flowering, harvest period, grain weight per clump, and weight of 100 grains. The heaviest drought stress (FCW) caused a significant decrease in plant height, number of tillers per clump, number of productive tillers, and grain weight per clump and extended the flowering and harvesting ages. Based on the tolerance index criteria, it was found that the Silayur genotype was more tolerant to drought stress than the other upland rice genotypes.

Green Seeker and chlorophyll meter-assisted nitrogen management increased the rice productivity in direct seeded dry rice

Prediction of nutrient requirements is crucial for successful decision-making in crop production. The objective of this experiment was to study the real-time nitrogen management (RTNM) in dry direct-seeded with Green Seeker and SPAD meter in rainfed rice. The experiment was done in a randomized block design with seven treatments viz. T1 : N omission, T2 : N applied as basal and active tillering (AT), T3 : N as basal, AT and panicle initiation (PI), T4 : N as basal and top dressing at NDVI threshold of 0.75, T5 : N as basal and at NDVI threshold of 0.8, T6 : N as basal and SPAD35, and T7 : N as basal and SPAD37.5. An early maturing drought tolerant rice variety Sahbhagi Dhan was drill seeded (dry) for this study. The soil of the site of the experiment was sandy loam, acidic with medium organic carbon, available nitrogen, phosphorus, and potassium. Basal application of 30 kg N ha-1 followed by top dressing of 20 kg N ha-1 two times at 35 and 63 DAS directed by NDVI threshold level of 0.8 (T5 ) was superior compared totherest of the treatment effects in terms of growth, productivity, profitability, nutrient, and energy use efficiency.

Expression Analysis of OsWRKY11 and OsNAC2 Genes in New Malaysian Drought-tolerance Rice Cultivar MR303

Local drought-tolerant rice variety MR303 (Oryza sativa spp. Indica) has higher tolerance towards abiotic stress while maintaining its high yield and grain quality. Expression of OsWRKY11 has shown to be a positive modulator while OsNAC2 is a negative modulator for drought-tolerance in Oryza sativa spp. Japonica. However, these transcription factor (TF) genes regulation are species-specific and its regulation may differ in our local rice variety. Thus, our study aimed to identify the relative expression of these genes and its effects on plant morphology and drought-tolerance capabilities. Our results on relative expression of OsWRKY11 in the MR303 rice variety showed that under drought stress, this gene was highly expressed. This result was similar to previous findings in Oryza sativa spp. Japonica. However, for OsNAC2 gene expression, our results contradict with previous findings where under drought stress, this gene was also highly expressed instead of downregulated. These results suggest that our local rice variety may have different gene regulation under drought stress compared to other rice varieties. Proline assay showed that proline contents in drought-treated plant has increased 10 times compared to control which associated with drought-tolerance activities. Further studies may be conducted to gain better understanding on the roles of these genes in regulating drought-responsive genes in the local variety.

EXPLORING NEW TECHNIQUES AND STRATEGIES FOR ENHANCING RICE DROUGHT TOLERANCE

Drought stress harms rice production and results in significant economic losses. The severity of the global climate change issue is rising. Given the current and projected levels of global food demand, it is imperative to boost agricultural output in rain-fed, drought-prone areas. Because they are crucial to achieving the production goal in rainfed regions, drought-tolerant rice varieties are in great demand. Future research on genetic improvement for drought resistance should be given top priority. A recent study has shown that several genetic and physiological factors affect how well rice manages drought. This information has been used to make better rice varieties that can manage drought. In addition, new techniques like marker-assisted selection and gene editing are being used to make rice even more resistant to drought.