Extended Data Fig. 9: MYB74 plays a role in REC transdifferentiation and cuticle layer formation.

a, Schematic representation of the prMYB74:MYB74-SRDX construct used to express the chimeric repressor MYB74-SRDX. The dark box indicates the SRDX fragment, fused to the MYB74 coding sequence (CDS). Blue arrows indicate the locations of primers used for RT-qPCR analysis of MYB74-SRDX expression. b, Compared to wild-type plants, the relative expression levels of MYB74-SRDX in prMYB74:MYB74-SRDX plants were examined using RT-qPCR assays. Total RNA was extracted from the receptacles of T2 plants from two independent transgenic lines (that is, #5 and #35). UBQ10 was used as an internal control. The error bars indicated mean ± SD from three biological replicates. c, Scanning electron microscope (SEM) images show the AZs and RECs’ surfaces of S17m siliques. In WT, an intact cuticle layer has formed, effectively filling the gaps between RECs. However, epidermis-specific expression of the cutinase gene CUTICLE DESTRUCTING FACTOR1 (CDEF1) impairs cuticle formation, resulting in unfilled gaps (indicated by an arrowhead). This plant line was able to flower but did not produce normal flowers. Scale bars, 50 µm (top) and 5 µm (bottom). d, Dual luciferase assay shows that MYB74 directly regulates GPAT4 promoter activity. A vector containing the multicloning site instead of the MYB74 coding sequence was a control. The error bars showed mean ± SD from three biological replicates. e, Co-expression of MYB74 and GPAT4 in the outermost layer of RECs, which differentiate into epidermal cells. Note the presence of inner RECs expressing only MYB74. Scale bars, 25 µm. f, Altered expression of the epidermal marker gene ATML1 in the RECs of plants carrying prUBQ10 > >MYB74-SRDX and prATML1:nls-GFP following MYB74-SRDX induction via one-day treatment with ß-estradiol. Scale bar, 50 µm.