Several Cu2+-containing LACCASE-like genes were retrieved as target candidates, and 59 RACE analysis in nodulated roots confirmed that a L. japonicus homolog of Arabidopsis LACCASE10 indeed undergoes endonucleolytic cleavage within the miR397 complementary site (Fig. 7D). Collectively, these results strongly suggest that miR397 expression, which correlates with functional symbiosis, is linked to copper homeostasis at the nodule organ and systemic levels, at least in part via posttranscriptional regulation of the LACCASE10 homolog in L. japonicus.