Natural variation in potassium deficiency responses among Arabidopsis thaliana accessions

Potassium (K) is a key nutrient essential for plant growth, and its deficiency induces various adaptative responses in plants; however, the mechanisms underlying these responses remain unclear. In the present study, we explored the natural variation in K deficiency responses among 100 naturally occurring accessions of Arabidopsis thaliana and then performed a genome-wide association study (GWAS) to identify the genetic loci associated with these responses. All 100 Arabidopsis accessions showed significant differences in several traits under K deficiency, including shoot and root growth, photosynthetic activity, and inorganic ion contents. The results indicated that the reduction in K+ content due to K deficiency was correlated more significantly with decreases in the number and total length of lateral roots than with decreases in primary root length and shoot growth. Furthermore, GWAS and subsequent analyses of relevant mutants and transgenic plants suggested that several genes, which have not yet been shown to play a role in the K deficiency response, are associated with the number and/or total length of lateral roots under K deficiency. The identified genes are ROH1, NF-YA3, MAA3, and AtDTX28, which encode an exocyst subunit EXO70A1 interacting protein, an NF-Y type transcription factor, a female gametophyte development-related protein, and a MATE efflux family protein, respectively. These findings provide new insights into the mechanisms underlying K deficiency responses.