| In recent years,the area of saline-alkali land in China has increased continuously,with a total area of 99.13 million hm2.The high concentration of saline-alkali in the soil has led to plant ion toxicity,osmotic stress,etc.Nitrogen is the limiting element for plant growth,and the nitrogen metabolism mechanism of plants is affected by external stress and self-regulation ability;Soil salinization limits the nitrogen absorption of crops,resulting in crop yield reduction.In this paper,the saline-alkali tolerance of wild barley（Hordeum brevisubulatum）was studied by the high concentration of saline-alkali stress of 350 m M Na Cl and 350 m M Na HCO3;The effects of saline-alkali stress on nitrogen uptake of wild barley and its relatives were studied by 15N isotope tracer technique;The NRT2 gene family members of wild barley related to nitrogen absorption were identified by means of bioinformatics,and the effects of improved barley on nitrogen absorption under saline-alkali stress were studied by using barley genetic transformation;The hybrid barley（T621）was obtained by crossing wild barley with wheat,and its physiological indexes under salt and alkali stress were measured.The main results are as follows:1.The survival rate of wild barley in saline-alkali ponds was higher than that of Burton barley and cultivated barley;Through pot experiments,it was found that wild barley can withstand 350 m M salt and alkali stress,and can maintain normal growth and development under high concentrations of salt and alkali stress;Barley exhibited higher nitrate uptake efficiency than barley under 150 m M Na Cl and 50 m M Na HCO3salt and alkali stress concentrations.2.By exploring gene resources for efficient nitrogen uptake in wild barley under salt and alkali stress,it was found that the NRT2 gene family members involved in nitrogen uptake in wild barley have significantly expanded compared to related species such as barley and wheat.A cluster of expanded NRT2 genes was significantly induced to express under salt and alkali stress.3.Utilizing the excellent gene resources of wild barley discovered to improve and cultivate barley,the new barley germplasm obtained can maintain nitrate nitrogen content in the upper and lower parts of the ground under salt and alkali stress;Under the same salinity stress concentration,the nitrate reductase activity of the new barley germplasm was significantly increased compared to that of wild type barley,promoting the nitrogen assimilation process of nitrate nitrogen conversion to ammonium nitrogen.4.The biomass of triticale,a hybrid of wild barley related species and wheat,did not significantly decrease under salt and alkali stress;The osmoregulation substances were significantly increased compared to other species of the wheat family;In addition,barley can maintain nitrate nitrogen content in the aboveground and underground parts under salt and alkali stress.In conclusion,compared with barley and wheat,wild barley has better tolerance to salt and alkali and can maintain nitrogen absorption efficiency.Barley and wheat improved by wild barley’s excellent characters can maintain normal biomass under salt and alkali stress,and the nitrate nitrogen content in the aboveground and underground parts is not significantly reduced.Therefore,the utilization of the excellent saline-alkali tolerance characteristics of wild barley can effectively improve the nitrogen absorption of the related crops under saline-alkali stress,thus creating new germplasm with efficient nitrogen absorption,and realizing the effective utilization of saline-alkali land. |
