title: A reduction of sucrose phosphate synthase (SPS) activity affects sucrose/starch ratio in leaves but does not inhibit normal plant growth in rice.
abstract: Sucrose phosphate synthase (SPS) has been shown to mediate sucrose/starch ratio in plant leaves through studies of 'starch leaf' species that mainly accumulate starch in their leaves. However, the contribution of SPS to sucrose/starch ratio in rice leaves, which mainly accumulate sucrose (i.e., 'sugar leaf'), has not been confirmed due to inconsistencies in the results of previous studies. In this study, we analyzed mutant lines with reduced SPS activity, which were generated using Tos17 insertion, RNAi, and the CRISPR/Cas9 system. The knockdown and knockout mutants of OsSPS1 showed a 29-46% reduction in SPS activity in the leaves, but the carbohydrate content in the leaves and plant growth were not significantly different from those of wild-type plants. In a double knockout mutant of OsSPS1 and OsSPS11 (sps1/sps11), an 84% reduction in leaf SPS activity resulted in higher starch accumulation in the leaves than in the wild-type leaves. However, the sps1/sps11 plants grew normally, which is in contrast to the inhibited growth of SPS mutants of Arabidopsis thaliana, a typical starch leaf plant. These results suggest that SPS has a smaller effect on the sucrose/starch ratio in leaves and growth of rice than on starch leaf species.
authors.affiliation: Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Hashida
authors.affiliation: Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan; Central Region Agricultural Research Center, NARO, 1-2-1 Inada, Joetsu, Niigata 943-0193, Japan.
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Hirose
authors.affiliation: Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Okamura
authors.affiliation: Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Ken-Ichiro
authors.initials: KI
authors.lastname: Hibara
authors.affiliation: Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Ryu
authors.initials: R
authors.lastname: Ohsugi
authors.affiliation: Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan. Electronic address: aaokin@mail.ecc.u-tokyo.ac.jp.
authors.forename: Naohiro
authors.initials: N
authors.lastname: Aoki
mesh_terms: D001483:Base Sequence; D050260:Carbohydrate Metabolism; D064112:Clustered Regularly Interspaced Short Palindromic Repeats; D005964:Glucosyltransferases / Q000378:metabolism*; D008969:Molecular Sequence Data; D012275:Oryza / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D063245:Plant Development; D034622:RNA Interference
chemical_list: D005964:Glucosyltransferases; C022698:sucrose-phosphate synthase
keywords: CRISPR/Cas9; Carbon partitioning; Oryza sativa L; Sucrose phosphate synthase