prn1 mutants accumulate excess quercetin, and can survive UV-C irradiation that kills WT.

A. prn1 mutants accumulate more quercetin compared to WT seedlings. 6-d-old dark-grown seedlings were treated with a brief pulse of UV (317 nm), returned to darkness, then harvested 6 h later to determine the total extractable quercetin (Q) or kaempferol (K) in WT or prn1 seedlings (WT-Q; prn1-Q; WT-K; prn1-K). The levels of Q and K are indicated for prn1 and WT and SD are shown. n = 4 B & C. prn1 mutants survive a UV-C radiation treatment that kills WT seedlings. Seedlings grown in complete darkness as described in methods. UV-C treatments were administered on d 6 as described [30], with 4 min (B) or 8 min (C) of 254 nm (UV-C) radiation. Seedlings were returned to complete darkness for 24 h. UV-C killing doses for adt3 or WT were determined by prior ‘titration’ experimentation [30]. Seedlings were photographed from the side. n = 4. D. prn1 seedlings transformed with PRN1::PRN1-GFP construct are killed by 8 min of UV-C, similar to WT. Seeds (30) of WT, prn1 or prn1 transformed with PRN1::PRN1-GFP (PRN1::PRN1-GFP prn1) were sown, then seedlings grown in complete darkness. UV-C treatments were administered on d 6 as described [30], with an 8 min dose of 254 nm (UV-C) radiation. Seedlings were returned to complete darkness for 24 h. Seedlings were photographed from the side. n = 4.