natural variants of athkt1 enhance na+ accumulation in two wild populations of arabidopsis自然变异athkt1增强na +积累两种拟南芥野生种群.pdfVIP

Natural Variants of AtHKT1 þ Accumulation in Two Enhance Na Wild Populations of Arabidopsis * Ana Rus, Ivan Baxter, Balasubramaniam Muthukumar, Jeff Gustin, Brett Lahner, Elena Yakubova, David E. Salt Center for Plant Environmental Stress Physiology, Purdue University, West Lafayette, Indiana, United States of America Plants are sessile and therefore have developed mechanisms to adapt to their environment, including the soil mineral nutrient composition. Ionomics is a developing functional genomic strategy designed to rapidly identify the genes and gene networks involved in regulating how plants acquire and accumulate these mineral nutrients from the soil. Here, we report on the coupling of high-throughput elemental profiling of shoot tissue from various Arabidopsis accessions with DNA microarray-based bulk segregant analysis and reverse genetics, for the rapid identification of genes from wild populations of Arabidopsis that are involved in regulating how plants acquire and accumulate Naþ from the soil. Elemental profiling of shoot tissue from 12 different Arabidopsis accessions revealed that two coastal populations of Arabidopsis collected from Tossa del Mar, Spain, and Tsu, Japan (Ts-1 and Tsu-1, respectively), accumulate higher shoot levels of Naþ than do Col-0 and other accessions. We identify AtHKT1, known to encode a Naþ transporter, as being the causal locus driving elevated shoot Naþ in both Ts-1 and Tsu-1. Furthermore, we establish that a deletion in a tandem repeat sequence approximately 5 kb upstream of AtHKT1 is responsible for the reduced root expression of AtHKT1 observed in these accessions. Reciprocal grafting experiments establish that this loss of AtHKT1 expression in roots is responsible for elevated shoot Naþ. Interestingly