ATXR2 as a core regulator of de novo root organogenesis.

Tissue identity is plastically regulated in plants, and chromatin modifiers/remodelers are main players of cell fate changes. Callus formation is an intriguing example of cell fate transition. Leaf explants can form callus tissues, which resemble lateral root primordium, on callus-inducing medium (CIM). We recently demonstrated that the ARABIDOPSIS TRITHORAX-RELATED 2 (ATXR2) protein, which deposits H3K36me3 at genomic level, regulates callus formation on CIM. Consistent with the role of ATXR2 in conferring root identity, lateral root formation was significantly reduced in atxr2-deficient mutants. Furthermore, atxr2 mutants also displayed defects in adventitious root formation from wounded leaf tissues on hormone-free medium. Our findings indicate that ATXR2 is a genuine regulator of de novo root organogenesis.