WRKY6 is involved in the response to boron deficiency in Arabidopsis thaliana

Boron (B) is one of the essential nutrients for plant growth and reproduction. Transcriptome analyses have identified genes regulated by B deficiency, but their function mostly remains elusive. To identify the functions of B deficiency-inducible genes, T-DNA insertion mutants of 10 B deficiency-induced genes were obtained, and their growth properties in response to B conditions were examined. Among the lines examined, mutants of the transcription factor WRKY6 showed growth defect compared with the wild-type under B deficiency, but not under normal conditions. This growth defect was commonly observed among three independently isolated wrky6 mutants. There was no significant difference in B concentration between wrky6-3 and the wild-type. Promoter activity of WRKY6 was induced around the root tip under B deficiency. These results established that WRKY6 is a low-B-induced transcription factor gene that is essential for normal root growth under low-B conditions. Transcriptome analysis around the root tip identified WRKY6-regulated genes under B deficiency. Our findings represent the first identification of a transcription factor involved in the response to B deficiency.