Physicochemical properties of endosperm starches in milled rice determine its cooking and eating quality. Amylose is synthesized by granule-bound starch synthase I (GBSSI), whilst amylopectin is synthesized by the synergistic activities of starch synthases (SSs), branching enzymes (BEs) and debranching enzymes (DBEs). However, the complexes formed by starch biosynthetic enzymes are not well characterized. Gene expression profiles and protein complexes were determined in white-core (GM645) and waxy (GM077) mutants derived from a high amylose indica rice Guangluai 4 (GLA4). In GM645, genes including AGPS1, GBSSI, SSIIa, BEI, BEIIa, BEIIb, PUL, ISA1 and SP were significantly downregulated during seed development. In GM077, the expression levels of AGPL2, AGPS1, AGPS2b, SSIIIa, BEI, PUL and ISA1 were significantly upregulated. Co-immunoprecipitation assays revealed interactions of SSs-BEs, SSs-PUL and BEs-PUL in developing seeds. However, weak SSI-SSIIa interaction was detected in GM077, whilst SSI-PUL interaction was absent. Weak interaction signals for SSI-SSIIa, SSIIa-BEI, SSIIa-BEIIb, BEI-BEIIb and SSI-BEI were also observed in GM645. These results suggest that the protein-protein interactions for starch biosynthesis are modified in mutants, which provides insight into the mechanisms of starch biosynthesis, particularly in indica rice.

精米中胚乳淀粉的理化特性决定了其蒸煮和食用质量。直链淀粉由结合颗粒的淀粉合酶I（GBSSI）合成，而支链淀粉则由淀粉合酶（SSs），支化酶（BEs）和脱支酶（DBEs）的协同活性合成。但是，由淀粉生物合成酶形成的复合物不能很好地表征。基因表达谱和蛋白复合物中的白芯（测定GM645）和蜡质（GM077）突变体从高直链衍生籼稻稻广陆矮4（GLA4）。在GM645中，基因包括AGPS1，GBSSI，SSIIa，BEI，在种子发育过程中，BEIIa，BEIIb，PUL，ISA1和SP明显下调。在GM077中，AGPL2，AGPS1，AGPS2b，SSIIIa，BEI，PUL和ISA1的表达水平显着上调。免疫共沉淀测定揭示了正在发育的种子中SSs-BEs，SSs-PUL和BEs-PUL的相互作用。但是，在GM077中检测到弱的SSI-SSIIa相互作用，而没有SSI-PUL交互。在GM645中也观察到了SSI-SSIIa，SSIIa-BEI，SSIIa-BEIIb，BEI-BEIIb和SSI-BEI的弱相互作用信号。这些结果表明，淀粉生物合成的蛋白质-蛋白质相互作用中的突变体被修改，其提供了洞察淀粉生物合成的机制，特别是在籼稻大米。