Abstract
In vitro androgenesis process under salt pressure is recognized as being a valuable method for quick production of salt stress tolerant doubled haploid lines, enabling yield improvement of plants cultivated in dry climates. This study aimed to investigate the effect of salt stress on in vitro androgenetic regeneration, and the production of salt tolerant barley doubled haploid lines. Moroccan barley varieties, Arig, Asni and Tamelalt were used as RS0, and after one round of selfing (RS1) or two (RS2). These successive generations made possible to verify genetic stability or possible accidental heterozygosity, and to obtain plants presumably more tolerant to salinity. After culture of 11,340 anthers on induction medium, 2,270 calluses or embryos were generated. According to the induction rate of these formations, the three generations of each variety were not significantly different, pointing out the genetic stability after two selfings. Tamelalt and Arig had similar in vitro response, while for Asni, the three generations behaviour differed from the previous ones and constitute a statistically separate group. After transfer of the formations on regeneration medium either salt free, as control, or supplemented by increasing concentrations of NaCl, ranging from 2.5 to 13 g.L-1, 170 regenerants were produced. Asni (RS1) showed to be the most salt tolerant, bearing the maximal NaCl concentration of 12 g.L-1, but the single regenerated plant obtained was albino, as most of the regenerated plants from any genotype and generation. However, RS1 and RS2 generations of Asni regenerated one green plant each, with NaCl concentration of 5 g.L-1, resulting in two new Asni doubled haploid fertile lines.
Highlights
In arid and semi-arid regions, high soil salinity is one of the many abiotic stresses limiting the agricultural yields of wheat, rice, maize or barley
This study aimed to investigate the effect of salt stress on in vitro androgenetic regeneration, and the production of salt tolerant barley doubled haploid lines
With these experiments, new genotypes such as doubled haploid lines derived from Asni should be suited to salt and drought, and after being tested for their tolerance, able to be used in further breeding trials
Summary
In arid and semi-arid regions, high soil salinity is one of the many abiotic stresses limiting the agricultural yields of wheat, rice, maize or barley. The hypothesis was that direct high level stress submission, as for rice tolerance to Alions (Van Sint Jan et al, 1997) or for barley to sodium chloride salt, i.e. NaCl (Guasmi et al, 2010), will eliminate every sensitive subject and select mainly monogenics mutants easy to revert, while a progressive and sub-lethal action should operate simultaneously gradual modifications at several hereditary levels, more difficult to be reverted (Sibi and Fakiri, 2000) In this experiment, after the successive androgenesis steps, the doubled haploid barley regenerated on medium containing progressively increased NaCl concentrations, will constitute the first stage of a rapid creation of new barley lines for which, afterward, the tolerance to salt and drought will be analyzed, as well as agronomic traits. During this first step, as the responses of the material might well be related to the genotype, three varieties entered the program to be compared during the in vitro phase, and because of the number of seeds necessary to repeat the experiments, three successive generations were made, by the way, the genetic homogeneity of each variety could be tested through the comparisons of the results at the same level, permitting to exclude the hypothesis of accidental residual heterozygosity
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