Disruption ofAtHAK/KT/KUP9enhances plant cesium accumulation under low potassium supply

Abstract

11Understanding molecular mechanisms which underlie transport of cesium (Cs + ) in plants is important 12 to limit entry of its radioisotopes from contaminated area to the food chain. The potentially toxic 13 element Cs + , which is not involved in any biological process, is chemically closed to the macronutrient 14 potassium (K + ). Among the multiple K + carriers, the high-affinity K + transporters family HAK/KT/KUP is 15 thought to be relevant in mediating opportunistic Cs + transport. On the 13 KUP identified in 16Arabidopsis thaliana, only HAK5, the major contributor to root K + acquisition under low K + supply, has 17 been functionally demonstrated to be involved in Cs + uptake in planta. In the present study, we showed 18 that accumulation of Cs + increased by up to 30% in two A. thaliana mutant lines lacking KUP9 and 19 grown under low K + supply. Since further experiments revealed that Cs + release from contaminated 20 plants to the external medium is proportionally lower in the two kup9 mutants, we proposed that KUP9 21 disruption could impair Cs + efflux. By contrast, we did not measure significant impairment of K + status 22 in kup9 mutants suggesting that KUP9 disruption does not alter substantially K + transport in 23 experimental conditions used here. Putative primary role of KUP9 in plants is further discussed. 24 2

Genotypic Variation of Nitrogen Use Efficiency and Amino Acid Metabolism in Barley

“…Earliness of maturity (Badraoui et al, 2009;Noaman et al, 2007;Mlaouhi et al, 2020;Saidi et al, 2005) Disease resistance (Badraoui et al, 2009;Noaman et al, 2007;Saidi et al, 2005) Year of release most care was taken to design the mineral composition of the nutritional solution so that there is no other major deficiency or toxicity. Most importantly, the K levels are not limiting both under LN and HN (Epstein et al, 1963;Gierth and Mäser, 2007;Genies et al, 2021) To determine 15 N uptake over 24 h before harvesting, thus on day 13 after sowing, a 15 N labeling was performed. On day 13 after sowing, the unlabeled watering solution was replaced by a 15 N-containing solution that had the same nutrient composition as the Low N and High N solutions except that the natural 14 NO 3 − was replaced by nitrate with 10% 15 NO 3 − enrichment (w/w).…”