Tissue-Specific and Developmental Pattern of Expression of the Rice sps1 Gene

Abstract

Sucrose-phosphate synthase (SPS) is one of the key regulatory enzymes in carbon assimilation and partitioning in plants. SPS plays a central role in the production of sucrose in photosynthetic cells and in the conversion of starch or fatty acids into sucrose in germinating seeds. To explore the mechanisms that regulate the tissue-specific and developmental distribution of SPS, the expression pattern of rice (Oryza sativa) sps1 (GenBank accession no. U33175) was examined by in situ reverse transcriptase-polymerase chain reaction and the expression directed by the sps1 promoter using the ␤-glucuronidase reporter gene. It was found that the expression of the rice sps1 gene is limited to mesophyll cells in leaves, the scutellum of germinating seedlings, and pollen of immature inflorescences. During leaf development, the sps1 promoter directs a basipetal pattern of expression that coincides with the distribution of SPS activity during the leaf sink-to-source transition. It was also found that during the vegetative part of the growth cycle, SPS expression and enzymatic activity are highest in the youngest fully expanded leaf. Additionally, it was observed that the expression of the sps1 promoter is regulated by light and dependent on plastid development in photosynthetic tissues, whereas expression in scutellum is independent of both light and plastid development.

Rice Cultivars with Higher Sucrose Synthase Activity Develop Longer Coleoptiles under Submerged Conditions

“…Sucrose is synthesized in the scutellum by sucrose phosphate synthase (Nomura et al, 1969;Chávez-Bárcenas et al, 2000) and transported to the embryo and coleoptile through the phloem. The activity of sucrose synthesis in the scutellum and the sucrose loading to the phloem may affect sucrose content of the shoot.…”

Expression of Photosynthesis-Related Genes during the Leaf Development of a C3Plant Rice as Visualized byIn SituHybridization

“…5C). It was reported that sps1 (a gene encoding sucrose phosphate synthase) expression shows transversal gradient in sheathed leaves, being higher in the outermost and lower in the innermost (Chávez-Bárcenas et al, 2000). These authors suggested that light, in part, has a major infl uence on the pattern of sps1 expression during leaf development.…”

Microarray Analysis of Sink-Source Transition in Rice Leaf Sheaths

“…Because clear induction of the genes for α-amylase3D and SPS was reported in germinating seeds (Chavez-Barcenas et al 2000, Nanjo et al 2004, we considered them as representative genes being expressed when/where starch degradation and sucrose biosynthesis occurred. However, both genes showed unexpected expression patterns in the leaf sheaths of the first leaves below the flag leaves ( Fig.…”