Fig. 4: ABA-independent PYL-like proteins exist in seed plants.
From: ABA-independent PP2C-binding in PYLs traces to bacterial origins and persists in land plants
a Putative ABA-independent PYL-like proteins in seed plants that differs from ABA receptors at the key lysine and leucine residues were identified. b Sequence alignment of the ABA-binding regions of putative ABA-independent PYL-like proteins in seed plants. Ca, Capsicum annuum; Cb, Capsicum baccatum; Na, Nicotiana attenuata; Ns, Nicotiana sylvestris; Nt, Nicotiana tomentosiformis; Al, Arabidopsis lyrata; Cs, Camelina sativa; Cr, Capsella rubella; Hv, Hordeum vulgare; Ob, Oryza brachyantha; Os, Oryza sativa. The two residues that differ from those in canonical ABA receptors are labeled with asterisks and rectangles. c Induction of ABA-responsive gene expression by putative ABA-independent PYL-like proteins. RD29Bpro:LUC expression was measured in pyl duodecuple mutant protoplasts transformed with PYLs. Transformation with SnRK2.6, ABF2 and RD29Bpro:LUC served as control. Error bars, SEM (n ≥ 5 independent repeats). Two-way ANOVA, ****p < 0.0001. Right panel, two residues critical for ABA binding (black) and the corresponding variant residues (red). Expression data of control was shared among figs. 3a, c, h and 4c. d Relative expression of ABA-independent NaPYL13L in dry seeds, imbibed seeds, and 5-day-old seedlings of Nicotiana attenuata, compared to the expression of the ABA-responsive NaPYL4L and NaPYL8L genes. NaIF5α served as an internal reference. Error bars, SD (n = 3 technical repeats). e Relative expression levels of CsPYL13L2 in different tissues and developmental stages of Camelina sativa. Data source: ePlant Camelina. f Relative expression levels of HORVU.MOREX.r3.3HG0247520.1 in Hordeum vulgare tissues from ePlant Barley v3. The HvPYL13L gene encodes both HvPYL13L1 and HvPYL13L2 shown in c. Error bars, SEM (n = 6 independent repeats). g Expression of OsPYL12 and OsPYL13 in dry seeds, imbibed seeds, and 9-day-old rice seedlings (Nipponbare) was analyzed by RT-PCR. OsPP2AA3 served as an internal reference. DAG, days after germination. h Structural comparison of OsPYL12 (purple, predicted by AlphaFold3) aligned with the ABA–AtPYL1 (gold) complex. ABA and residues within a 5 Å radius are shown. The black dashed line indicates steric hindrance (<2 Å) between ABA and F76 in OsPYL12. i A model illustrating seed-specific expression of ABA-independent PYL-like proteins in dicot seed plants. Source data are provided as a Source Data file.
