effect of short- and long-time salt treatment on root traits and expression pattern of atls1 gene in barley (hordeum vulgare l.)

Barley (hordeum vulgare l.) as a salt-tolerant crop species has considerable economic importance in salinity-affected arid and semiarid regions of the world. in the present study, three barley genotypes (sahara3771 and an iranian advanced line as salt tolerant and clipper as salt susceptible) were exposed to 100 and 200 mm nacl at the seedling stage and non-nacl treatment was used as check. the root samples were harvested 24 hours, three days and three weeks after salt treatment in three replications. the root length and root fresh and dry weight were measured and expression pattern of atls1 gene was analyzed on root samples by quantitative real-time-pcr. the effects of genotype and sampling time were significant for root characters and with the advancement of salt treatment duration, root length and root fresh and dry weight were significantly reduced. the expression of atls1 gene was significantly affected by nacl level, genotype, sampling time and their interactions. in all three genotypes, with the increase of nacl concentration, expression of atls1 gene was reduced. under 100 mm nacl, mrna level of atls1 was significantly decreased in clipper as compared with the salt tolerant genotypes, sahara3771 and advanced line. in addition, long-term salt treatment (three weeks) significantly reduced the expression of atls1 in all three genotypes. down-regulation of atls1 gene under long term salt treatment indicates that this gene may be involved in response to salinity stress at the beginning of salt stress.