Fig. 1. Sucrose transporter (SUT) genes regulate rice yield and quality. A, Relative expression levels of five OsSUT genes (OsSUT1, OsSUT12, OsSUT13, OsSUT4, and OsSUT5). RNA was isolated from root, stem, leaf, and young panicle of Nipponbare at the heading stage, and grains at 5, 10, 15, and 20 d after pollination. Ubiquitin gene (Os03g0234350) serves as the internal control. B, Subcellular localization pattern of OsSUT-GFP in rice protoplasts. The MCA1 protein fused with RFP is a cell membrane-specific marker. The TIP1 (used to represent TIP1;1) protein fused with RFP is a tonoplast-specific marker. GFP, Green fluorescent protein; RFP, Red fluorescent protein. Scale bars, 5 μm. C, Plant phenotypes of wild type (WT) and ossut mutants after heading. Scale bars, 12 cm. D, Grains from one plant of WT and ossut mutants. Scale bars, 5 cm. E, Grain appearance of WT and ossut mutants. Scale bars, 1 cm. F-J, Tiller number per plant (F), grain number per panicle (G), seed-setting rate (H), 1000-grain weight (I), and grain yield per plant (J) of WT and ossut mutants. K-O, Chalky grain rate (K), total starch content (L), amylose content (M), protein content (N), and soluble sugar content (O) of WT and ossut grains. P-R, Non-structural carbon (NSC) content (P), starch content (Q), and sucrose content (R) in the stem of WT and ossut mutants. S-U, Relative expression levels of OsSUT1 (S), OsSUT2 (T), and OsSUT4 (U) in the stem of WT, ossut2-1, ossut3-1, ossut4-1, and ossut5-1. RNA was isolated from the stem of Nipponbare, ossut2-1, ossut3-1, ossut4-1, and ossut5-1 at 10 d after pollination. Ubiquitin gene (Os03g0234350) serves as the internal control. Data are Mean ± SD (n = 10 in F-H and J; n = 3 in A, I, and K-U). Different lowercase letters indicate significant differences at P < 0.05 by two-stage step-up method.