Abstract
BackgroundTriticum aestivum (wheat) is one of the world’s oldest crops and has been used for >8000 years as a food crop in North Africa, West Asia and Europe. Today, wheat is one of the most important sources of grain for humans, and is cultivated on greater areas of land than any other crop. As the human population increases and soil salinity becomes more prevalent, there is increased pressure on wheat breeders to develop salt-tolerant varieties in order to meet growing demands for yield and grain quality. Here we developed a mutant wheat population using the moderately salt-tolerant Bangladeshi variety BARI Gom-25, with the primary goal of further increasing salt tolerance.ResultsAfter titrating the optimal ethyl methanesulfonate (EMS) concentration, ca 30,000 seeds were treated with 1% EMS, and 1676 lines, all originating from single seeds, survived through the first four generations. Most mutagenized lines showed a similar phenotype to BARI Gom-25, although visual differences such as dwarfing, giant plants, early and late flowering and altered leaf morphology were seen in some lines. By developing an assay for salt tolerance, and by screening the mutagenized population, we identified 70 lines exhibiting increased salt tolerance. The selected lines typically showed a 70% germination rate on filter paper soaked in 200 mM NaCl, compared to 0–30% for BARI Gom-25. From two of the salt-tolerant OlsAro lines (OA42 and OA70), genomic DNA was sequenced to 15x times coverage. A comparative analysis against the BARI Gom-25 genomic sequence identified a total of 683,201 (OA42), and 768,954 (OA70) SNPs distributed throughout the three sub-genomes (A, B and D). The mutation frequency was determined to be approximately one per 20,000 bp. All the 70 selected salt-tolerant lines were tested for root growth in the laboratory, and under saline field conditions in Bangladesh. The results showed that all the lines selected for tolerance showed a better salt tolerance phenotype than both BARI Gom-25 and other local wheat varieties tested.ConclusionThe mutant wheat population developed here will be a valuable resource in the development of novel salt-tolerant varieties for the benefit of saline farming.
Highlights
Triticum aestivum is one of the world’s oldest crops and has been used for >8000 years as a food crop in North Africa, West Asia and Europe
We developed and used a mutagenized Bangladesh Agriculture Research Institute (BARI) Gom-25 population to screen and identify 70 individual lines with a level of salt tolerance high enough to allow them to germinate at 200 mM NaCl
Development of a mutant wheat population To determine the amount of ethyl methanesulfonate (EMS) needed to achieve the highest mutation rate without killing all the seeds due to the toxicity of the compound, an EMS titration curve was established (Fig. 1)
Summary
Triticum aestivum (wheat) is one of the world’s oldest crops and has been used for >8000 years as a food crop in North Africa, West Asia and Europe. As the human population increases and soil salinity becomes more prevalent, there is increased pressure on wheat breeders to develop salt-tolerant varieties in order to meet growing demands for yield and grain quality. Wheat is the world’s second most important crop, with a harvest of ca 735 million metric tons during 2018 (www.fao.org). Wheat is grown for its high yield and nutritional benefits, in particular protein, carbohydrates, fiber, fats, minerals and B-group vitamins [1]. It is the major ingredient in staple foods such as pasta, biscuits, bread, and confectionery products used worldwide and constitutes 21% of the total cereal-based production by the food industry [1, 2]. Wheat yield needs to be increased by 70% within the 40 years in order to meet global demands (www.fao.org) [2, 3]
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