Evaluation of Rice Germplasm under Salt Stress at the Seedling Stage through SSR Markers

Twenty eight rice germplasms were used for identification of salt tolerant rice genotypes at the seedling stage at the experimental farm and Biotechnology laboratory of the Bangladesh Institute of Nuclear Agriculture (BINA), Mymensingh during February 2009 to October 2009. Phenotyping for salinity screening of the rice genotypes was done using salinized (EC level 12 dS m-1) nutrient solution in hydroponic system. Genotypes were evaluated for salinity tolerance on 1-9 scale based on seedling growth parameters following modified Standard Evaluation Scoring (SES) of IRRI. Phenotypically, on the basis of SES and % total dry matter (TDM) reduction of the genotypes viz. PBSAL-614, PBSAL-613, PBSAL-730, Horkuch, S-478/3 Pokkali and PBSAL (STL)-15 were found to be salt tolerant; on the other hand Iratom-24, S-653/32, S-612/32, S-604/32, S-633/32, Charnock (DA6), BINA Dhan-6 and S-608/32 were identified as salt susceptible. For genotyping, ten SSR markers were used for polymorphism, where 3 primers (RM127, RM443 and RM140) were selected for evaluation of salt tolerance. In respect of Primer RM127, 7 lines were found salt tolerant and 11 lines were moderately tolerant and 10 lines were susceptible. Nine tolerant, 9 moderately tolerant and 10 susceptible lines were found when the primer RM140 was used and primer RM443 identified 8 lines as tolerant, 9 lines as moderately tolerant and 11 lines as susceptible. Thus, the salt tolerant lines can be used in further evaluation for salinity tolerance and the SSR markers used in this study are proving valuable for identifying salt tolerant genes in marker assisted breeding. Int. J. Agril. Res. Innov. & Tech. 3 (1): 52-59, June, 2013 DOI: http://dx.doi.org/10.3329/ijarit.v3i1.1609

Microsatellite (SSR) markers assisted characterization of rice (Oryza sativa L.) genotypes in relation to salt tolerance

151-163Under present investigation a total of 18 rice genotypes with diverse genetic background were taken for screening at seedling stage and its molecular characterization using SSR markers. Selected rice genotypes were exposed to five salinity levels (0, 2, 4, 6 and 8 dSm-1) at seedling stage. Modified standard evaluation score (SES) at seedling stage identified 7 highly tolerant, 2 tolerant and 8 moderately tolerant genotypes. The susceptible genotype was IR64 with score 7. Considering 4 other morpho-physiological characters (germination percent, K/Na ratio, shoot and root length, shoot and root fresh weight, shoot and root dry weight) studied at seedling stage, the genotype CSR2K-262 showed greater tolerance among all the 18 genotypes. For molecular characterization a total of 44 SSR markers were selected. The average number of alleles per locus was 9.3 indicating greater magnitude of diversity among plant materials. The average PIC value 0.767 confirmed that the markers used were highly informative. The cluster analysis grouped the 18 genotypes into three major clusters. Cluster I was the largest with 9 genotypes with all highly tolerant and tolerant genotypes, Cluster II comprised 8 genotypes with all tolerant and moderately tolerant and Cluster III comprised of 1 genotype (IR64) identified as susceptible one

Genetic Improvement of Rice for Multiple Stress Tolerance in Unfavorable Rainfed Ecology

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EVALUATION OF THE RESPONSES OF EIGHT RICE (Oryza sativa, L.) GENOTYPES TO VARIOUS CONCENTRATIONS OF NaCl IN A CONTROLLED ENVIRONMENT

Salinity is an ever increasing problem that reduces rice yield in many rice fields around the world. Developing salt tolerant rice (Oryza sativa L.) genotype is one of the solutions to the problem of salinity. This experiment was carried out in the Department of Crop Science and Horticulture at SUA to assess the salinity tolerance of 8 rice genotypes at the seedling stage. Ion accumulation in plants and dry matter content along with molecular markers were used to evaluate the tolerance of each rice genotype. The genotypes were IRRI 112, IRRI 124, FL 478, IRRI 113, IR65912-4B-10-3, IRRI 128, NERICA-L-19 and SUAKOKO-10. In this experiment, the genotypes were exposed to three salinity levels in a randomized complete block design arranged in factorial with three replications. The salinity levels were 100 mM NaCl, 50 mM NaCl and 0 mM NaCl. The homogenous mixture of sand, farm yard manure and rice husk (ratio of 6:2:10 respectively) was used as the planting medium for all rice genotypes. The soil texture was sandy clay-loam. The growth of the genotypes, ion accumulation and dry matter contents were significantly (p ≤ 0.05) affected by increase in NaCl concentration. Two Saltol SSR markers (RM7075 and RM562) were used to determine the presence of salinity tolerance (saltol) gene in rice genotypes.  Based on the SSR markers, ion accumulation and dry weight of plants, two genotypes (IR65192-4B-10-3, and IRRI112) along with FL478 were selected as salt tolerant while two (IRRI-113 and IRRI-128) were moderately tolerant, and three (NERICA-19, SUAKOKO-10 and IRRI-124) were the most susceptible genotypes.  Therefore, two susceptible parents (NERICA-19 and SUAKOKO-10) were selected and two donor parents (FL478 and IR65192-4B-10-3) were selected. Keywords: salinity stress; NaCl concentration; genotypes; markers; seedling stage; Oryza sativa;

Genetic variation among the salinity tolerant breeding lines identified from two multi-parent advanced generation introgression line populations in rice (Oryza sativa)

Salinity is a major environmental constraint affecting rice production in both irrigated and non-irrigated areas and threatening global food security. Development of salt-tolerant rice varieties with desirable agronomic traits is a logical approach to maintain high yield in saline areas. Here, we report development of two multi-parent advanced generation introgression line (MAGIL) rice populations in two US cultivar backgrounds and their physiological and morphological evaluation under salinity stress at germination and seedling stages. From the initial screening of 180 MAGILs in sand culture, 36 tolerant-to-moderately salt-tolerant lines were selected and further confirmed in hydroponics experiment. The selected MAGILs showed lower root and shoot Na+/K+ ratio compared with the recurrent parents. The principal component and cluster-based analysis using 12 morphophysiological traits revealed grouping of the selected lines with tolerant donors. Genotyping results with 100 polymorphic SSR markers indicated a low level of genetic diversity among these lines. Clustering based on molecular marker data separated the MAGILs from the salt tolerance donors in both populations but were grouped with the recurrent parents, suggesting genetic similarity of MAGILs with recurrent parents. The salt-tolerant MAGILs identified in this study are useful resource for investigating molecular and physiological bases of salt-tolerant mechanisms as well as for evaluating their yield potential for release as salt-tolerant rice varieties

Plant Stress Physiology

This book includes ten chapters addressing various aspects of plant stress physiology, including plant responses and tolerance to abiotic and biotic stress. These chapters summarize recent findings on the physiological and molecular mechanisms of stress tolerance. They also discuss approaches to enhancing plant productivity via stress tolerance mechanisms. This book is useful for undergraduate and graduate students, teachers, and researchers in the field of plant physiology and crop science

Morphological, Biochemical and Genetic Variation of Rice (Oryza sativa L.) Genotypes to Vegetative Stage Salinity Stress

Salinity is one of the most serious issues in rice cultivation and production. Salt stress significantly reduced seedling growth performance of rice. This research was conducted to study the effects of vegetative stage salinity stress on morphological, biochemical, molecular and genetic variation of 12 rice genotypes as well as 2 check varieties, MR297 (susceptible) and Pokkali (tolerant). The experiment was arranged in a split-plot design with 3 replications. Normal freshwater at 0 dS m-1 (L1), saline water at 6 dS m-1 (L2) and saline water at 12 dS m-1 (L3) were the main plot and rice genotypes were the sub-plot. In general, morphological and biochemical traits of all genotypes showed an overall reduction of about 47.41% in L3 as compared to L1 except for the tolerant check, Pokkali. The genetics and correlation analysis indicated that plant height, leaf size and standard evaluation system (SES) score might be used as a selection criterion in developing salt tolerant rice. The multivariate analysis revealed that a Malaysian landraces, Jarom Mas was clustered together with Pokkali as tolerant genotype. Screening using tightly linked Simple Sequence Repeat (SSR) markers (RM1287, RM10748, RM493) of salinity tolerant QTL, Saltol indicated that this QTL was absence in Jarom Mas. This finding might indicate the presence of other QTL associated with salinity tolerance in Jarom Mas. Further study on identifying the speculated QTL may be conducted to confirm this postulation

Salt Stress Tolerance in Rice: Emerging Role of Exogenous Phytoprotectants

Excess salinity in soil is one of the major environmental factors that limit plant growth and yield of a wide variety of crops including rice. On the basis of tolerance ability toward salinity, rice is considered as salt-sensitive crop, and growth and yield of rice are greatly affected by salinity. In general, rice can tolerate a small amount of saltwater without compromising the growth and yield. However, it greatly depends on the types and species of rice and their growth stage. Salinity-induced ionic and osmotic stresses reduce rate of photosynthesis and consequently cause oxidative stress, which is also responsible for growth reduction. The negative effects of salt stress that mentioned ultimately reduced yield of most crops including rice, except some halophytes. In recent decades, researchers have developed various approaches toward making salt-tolerant rice varieties. Using phytoprotectants is found to be effective in conferring salt tolerance to rice plants. In this chapter, we reviewed the recent reports on different aspects on salt stress tolerance strategies in light of using phytoprotectants

Genotypic variation in response to salinity in a new sexual germplasm of Cenchrus ciliaris L.

As part of breeding program for new salt- tolerant sexual genotypes of Cenchrus ciliaris L., we evaluated the salt- stress response of two new sexual hybrids, obtained by controlled crosses, at seedling and germination stages.Inst. de Fisiologia y Recursos Genéticos VegetalesFil: Quiroga, Mariana Paola. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Fisiología y Recursos Genéticos Vegetales; ArgentinaFil: Tommasino, Exequiel Arturo. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Fisiología y Recursos Genéticos Vegetales; ArgentinaFil: Griffa, Sabrina Mariana. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Fisiología y Recursos Genéticos Vegetales; ArgentinaFil: Ribotta, Andrea Noemi. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Fisiología y Recursos Genéticos Vegetales; ArgentinaFil: Lopez Colomba, Eliana. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Fisiología y Recursos Genéticos Vegetales; ArgentinaFil: Carloni, Edgardo José. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Fisiología y Recursos Genéticos Vegetales; ArgentinaFil:Grunberg, Karina. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Fisiología y Recursos Genéticos Vegetales; Argentina. Consejo de Nacional Investigaciones Científicas y Técnicas; Argentin

Approaches in Enhancing Antioxidant Defense in Plants

This Special Issue, “Approaches in Enhancing Antioxidant Defense in Plants” published 13 original research works and a couple of review articles that discuss the various aspects of plant oxidative stress biology and ROS metabolism, as well as the physiological mechanisms and approaches to enhancing antioxidant defense and mitigating oxidative stress. These papers will serve as a foundation for plant oxidative stress tolerance and, in the long term, provide further research directions in the development of crop plants’ tolerance to abiotic stress in the era of climate change