Assessing salt-stress tolerance in barley

Artículos Assessing salt-stress tolerance in barley Determinación de la Tolerancia al estrés por salinidad en la cebada Determinação da tolerância ao estresse por salinidade na cevada Somasundaram Rajeswari1  *  , Neeru Sood1  , Trupti Gokhale Swarup1  , Ramachandran Subramanian1  ; Juan Carlos Salcedo-Reyes, Edited by 1  1Birla In itute of Technology and Sciences, Pilani, Department of Biotechnology, Dubai Campus. Abstract Identifying naturally existing abiotic-stress tolerant accessions in cereal crops is central to understanding plant responses towards stress. Salinity is an abiotic stressor that limits crop yields. Salt stress triggers major physiological changes in plants, but individual plants may perform differently under salt stress. In the present study, 112 barley accessions were grown under controlled salt stress conditions (1 Sm-1 salinity) until harvest. The accessions were then analyzed for set of agronomic and physiological traits. Under salt stress, less than 5 % of the assessed accessions (CIHO6969, PI63926, PI295960, and PI531867) displayed early flowering. Only two (< 2 %) of the accessions (PI327671 and PI383011) attained higher fresh and dry weight, and a better yield under salt stress. Higher K+ /Na+ ratios were maintained by four accessions PI531999, PI356780, PI452343, and PI532041. These top-performing accessions constitute naturally existing variants within barley's gene pool that will be instrumental to deepen our understanding of abiotic-stress tolerance in crops. Key words: Agronomic trait; barley; salt stress; yield parameters. Resumen La identificación de accesiones existentes en condiciones naturales que sean tolerantes al estrés abiótico en cultivos de cereales es fundamental para entender las respuestas al estrés. La salinidad es un factor de estrés abiótico que limita el rendimiento de los cultivos. El estrés por salinidad desencadena importantes cambios fisiológicos en las plantas, pero plantas individuales pueden comportarse diferencialmente bajo este tipo de estrés. En el presente estudio se hicieron crecer 112 accesiones de cebada bajo condiciones controladas de estrés por salinidad (1 Sm-1 salinidad) hasta la cosecha. Posteriormente las accesiones se analizaron para determinar sus caracteres agronómicos y fisiológicos. Bajo condiciones de estrés por salinidad, menos del 5 % de las accesiones estudiadas (CIHO6969, PI63926, PI295960 y PI531867) mostraron floración temprana. Solamente dos (< 2 %) de las accesiones (PI327671 y PI383011) alcanzaron mayores pesos fresco y seco y un mayor rendimiento bajo estrés por salinidad. Se mantuvieron mayores proporciones K+/Na+ en cuatro accesiones PI531999, PI356780, PI452343 y PI532041. Estas accesiones que tuvieron el mejor rendimiento constituyen las variantes existentes en condiciones naturales dentro del acervo genético de la cebada, que pueden ser instrumentos para profundizar en nuestro entendimiento de la tolerancia de los cultivos al estrés abiótico. Palabras-clave: caracteres agronómicos; cebada; estrés por salinidad; parámetros de rendimiento Resumo A identificação de acessões existentes em condições naturais que sejam tolerantes ao estresse abiótico em culturas de cereais é fundamental para entender a resposta ao estresse. A salinidade é um fator de estresse abiótico que limita o rendimento das culturas. O estresse por salinidade desencadeia importantes mudanças fisiológicas nas plantas, no entanto, plantas individuais podem se comportar diferentemente sob este tipo de estresse. No presente estudo 112 acessões de cevada foram cultivadas sob condições controladas de estresse por salinidade (1 Sm-1 salinidade) até a colheita. Porteriormente, as acessões foram analizadas para determinar suas características agronômicas e fisiológicas. Sob condições de estresse por salinidade, menos de 5 % das acessões estudadas (CIHO6969, PI63926, PI295960 e PI531867) mostraram floração prematura. Somente duas (< 2 %) acessões (PI327671 e PI383011) atingiram maiores pesos frescos e secos e um maior redimento sob estresse por salinidade. As maiores proporções K+/Na+ foram mantidas em quatro acessões PI531999, PI356780, PI452343 e PI532041. As acessões com maior rendimento constituem as variantes existentes em condições naturais dentro do fundo genético da cevada, que podem ser instrumentos para aprofundar no nosso entendimento da tolerância dos cultivos ao estresse biológico. Palavras-Chave: caracteres agronómico; cevada; estresse por salinidad; parâmetros de redimento. Introduction Salinity affects crops worldwide. In arid and semi-arid environments, salinity's negative effects on crops are exacerbated by high temperature and inadequate water supply. FAO estimated that approximately 20 % of the world's agricultural land is saline [1]. Further, inadequate agricultural practices lead to salinization of approximately 2 000 hectares of land in arid and semi-arid areas per day [2]. Salinity alters a plant's water and mineral nutrient (osmotic and ionic) balance, and prolonged exposure to salinity leads to changes in the molecular and biochemical mechanisms controlling plant development, growth and reproduction [3]. Salinity-induced changes in plants, are modulated by changes in gene expression [4]. Facing an unrelenting salinization of agricultural land, the best way to increase crop production is by planting salt-tolerant and high yielding accessions [5, 6]. To this end, we must first identify, by reliable screening procedures, naturally existing salt-tolerant accessions in crop gene pools. Barley (Hordeum vulgare) is the most salt tolerant cereal crop [7], and it is the fourth most important cereal crop grown worldwide due to its nutritional and health benefits [8]. Barley is also a model crop because of its agronomic, molecular and genetic diversity, which has been exploited and developed since ancient times [9]. Barley is copious in genetic diversity entailed in many landraces and progenitor species. Thus, barley exhibits variation for traits of agricultural importance, such as high yield, resistance to infections, tolerance to abiotic stressors like drought, salt, cold etc. As environmental conditions become more limiting for agriculture, the natural adaptability of cereal crops, like barley ought to be constantly assessed. In the present study, the agronomic, biochemical and yield attributes of 112 barley accessions obtained from USDA were evaluated for salt stress tolerance under field condition in Dubai to find the salt tolerant accessions. Materials and methods Controlled salt stress experiments were carried out in the field at BITS Pilani, Dubai Campus (25.2048 latitude north, 55.2708 east) in the United Arab Emirates. Dubai is classified as an arid environment. The study was conducted during the 2015-16 winter season (Nov-Feb). The experimental growth field, of size 120 m, was prepared to maintain suitable condit (...truncated)