Collection and utilization salt tolerance diversity in wild relatives of bread wheat

Iran is located in dray region in the world and most of it is covered by deserts. So, excluding some limited area in nortb and west, the average of precipitation in the other regions is about 200 mm and less than it. On other band about 23 million's ha of Iran land area is affected by salt stress, and a lot of irrigated lands are affecting by salt slowly, and will be unproductive in feature. However the food production is increased recently, but the demand is increased more than production and at present increasing the cultivated area is impossible, because the health water and fertile soil are limited. Thus the improvement of cultivars with high tolerance to drought and salinity are very important. Also, Iran is a major center of diversity for Triticum species. So 17 species of this genus are found in Iran and some of them have a wide spread distribution throughout the country. This importance has been understood in Gene Bank thus collection and conservation of wild wheat species bad been started in first days of establishment of gene bank. To this direction we have a project on evaluation of wild species for salt tolerance. In this project, a total of 1000 Aegilops sp accessions collected from salt affected area of Iran, were germinated at 0 and 300 mmoUl of salt concentration. Every tow-day the number of germinated seeds was scored. After one week the length of roots and shoots were measured. The none¬germinated seeds were removed and germinated seeds were transferred to hydroponics system containing nutrients and tow level of salinity, 0 and 150 mmoUl. The nutritional solution was changed every week. After 4 weeks length of roots and shoots were measured in live plants, and the 5tb leaf was selected to analyze for k+ and Na+ concentration by flame photometer. Some researchers have suggested that the K/Na ratio in plants have a correlation with salinity tolerance. Then plants were transferred to the pots until maturity to prepare pure lines. The decreasing growth ratio of roots and shoots in saline treatments at germination stage and tillering stage was calculated, and the K+/Na+ ratio of the 5th leaf was calculated too. By ranking the accessions based on three characters, some tolerant populations were selected. Tbose samples have used to interspecific hybridization for introduce salt tolerance genes from Aegilops samples to bread wheat. Some accessions of Ae.tauschii(DD), Ae.umbellulata(UU), Ae.trincialis(CCUU), Ae.columnaris(MMUU), Ae.cylindrica(CCDD) Ae.crassa(DDMM) were used in crosses with Triticum aestivum (AABBDD)Var. Chines Spring, In 15-19 days of pollination the hybrid embryos were extracted from hybrid seeds and planted on the Gamburg's B5 medium by using embryo rescue methods, after germination the plantlets were transformed in the soil. The interspecific compatibility in progamous stage and in embryo genesis was estimated. The Aegilops - Triticum hybrid plants were made in crosses with using Ae.columnaris, Ae.tauschii Ae.trinciaIis and Ae.umbeHulata. The most resultant crosses carried out with using Aegilopses as female and the crosses of Ae.columnaris and Ae. trincialis whit T.aestivum were more resultant than other crosses. The normal differentiation of embryos was observed in crosses of Ae.columnaris, Ae.trincialis, and Ae.umbellulata with T.aestivum. It is possible that the U genome determinate the normal embryo genesis of hybrid plants. The plants were used for making some backcrosses with T.aestivum. The bread wheat var. Chinese spring was planted at experimental farm and hybrid plants were transferred to pots in greenhouse. Hybrid plants were absolutely sterile at flowering and no pollen had been seen on the anthers, but ovary and stigma were normal. The mature pollens were collected from wheat spikes in the field every day. The suitable spikes in hybrid plants were selected and inoculated by T.aestivum pollens. Hundreds backcrosses were made in this wayunfortunately, no seed was produced in these crosses.