Potassium and sodium absorption related traits and QTL mapping at the seedling stage of wheat

Accumulation of K in vacuoles creates necessary osmotic potential for cell extension. Rapid cell extension requires high mobility of osmotic pressure. Na is one of the few other ions which can replace K in this role. To further understand correlation and genetic characteristics of potassium (K) and sodium (Na) absorption and utilization at wheat seedling stage, a hydroponics experiment was conducted with different K and Na treatments in greenhouse using a recombinant inbred lines (RILs). Variance and correlation analysis were conducted for shoot and root biomass, K and Na accumulation respectively. QTL mapping for twenty related traits including the biomass and K/Na related traits was also conducted. The results show that the accumulations of K and Na in wheat seedlings are closely related to each other. Compared with the K deficiency treatment, the Na/K ratio is significantly increased when supplied with Na, but the biomass of wheat seedlings is not increased, so Na has poor ability to replace K when K is deficient. On the other hand, when K is efficient, the Na+ treatments can significantly promote K+ accumulation, but decrease shoot biomass. Therefore, excess amounts of K, Na accumulation are not conducive to the formation of the biomass at the seeding stage of wheat. Total 141 QTLs distributed on all the 21 chromosomes are detected for the tested 20 traits. Fourteen important QTL clusters which including 104 QTLs are identified, and in which, 11 QTL clusters are colocated with K and Na related traits. Eight high frequency QTLs (RHF-QTLs) which could be detected simultaneously in different treatments are also identified in this experiment. These important QTL sites provide important references for further investigation of K and Na relations in plant nutrition and their genetic control.