1. WT ospti1a EV 182646 HAstrepII -OsPti1a OsPti1a -HAstrepII OsPti1a CBB WB: anti-HA antibody BA C OsPti1a -HAstrepII 182646 EV ospti1aWT EV HAstrepII -OsPti1a EV ospti1aWT EV Supplemental Figure 1. Complementation test of HAstrepII-OsPti1a or OsPti1a-HAstrepII in the ospti1a mutant background. In (A) and (B), transgenic plants expressing HAstrepII-OsPti1a, OsPti1a-HAstrepII, or empty vector (EV) in the ospti1a mutant were grown under same conditions, respectively. The photograph shows the T0 transgenic plants in the ospti1a background and WT. The numbers indicate independent transgenic plant lines. (C) Immunoblot analysis of total proteins extracted from leaves of these transgenic plants. Lower panels indicate CBB staining of the membrane after immunoblotting.

2. SMSM OsPti1a CBB OsPti1a WT ΔN-OsPti1a Transiently expression assay in N. benthamiana WB:anti-OsPti1a antibody A C Supplemental Figure 2. Transient expression analysis of OsPti1a mutants in N. benthamiana. (A) The cellular localization of OsPti1a expressed after agroinfiltrating Nicotiana benthamiana. N. benthamiana leaves were infiltrated with Rhizobium radiobacter EHA105 containing OsPti1a or ΔN-OsPti1a cDNA. Leaves were harvested 2 days after agroinfiltration. Total proteins were extracted and fractionated into soluble (S) and microsomal (M) fractions. OsPti1a proteins were detected by an anti-OsPti1a antibody. (B) Point mutations in the N-terminal sequence of OsPti1a. (C) Immunoblot analysis of cellular fractions of the mutated OsPti1a proteins expressed after agroinfiltrating N. benthamiana. Mutated variants of OsPti1a were transiently expressed in N. benthamiana. Three days after inoculation, proteins were extracted, fractionated, and subjected to immunoblot analysis using an anti-OsPti1a antibody (upper panel). After immunoblotting, the PVDF membrane was stained with CBB (lower panel). OsPti1a WT OsPti1a C6A OsPti1a C7A OsPti1a C6A/C7A MSCFACCG MSCFAACG MSCFACAG MSCFAAAG B OsPti1a WT OsPti1a C6A OsPti1a C7A OsPti1a C6A/C7A CBB OsPti1a WB: anti-OsPti1a antibody MS MSMSMS

3. Supplemental Figure 3. The size of the OsPti1a complex does not change in response to chitin treatment. Gel filtration fractions of protein extracts from WT suspension cultured cells after chitin treatment were subjected to immunoblot analyses (left panel) using an anti-OsPti1a antibody. The arrows and asterisks indicate the positions of OsPti1a and cross-reacting bands, respectively. The fraction numbers and molecular masses (kDa) are indicated at the top of the figure. After immunoblotting, the PVDF membrane was stained with CBB (right panels). WB: anti-OsPti1a antibody 10 min 180 min 60 min 1718 19 2021232527292224262816 44015866kDa Frac. No. OsPti1a * * * 0 min 1718 19 2021232527292224262816 44015866kDa Frac. No.