Abstract
Cellulose is the most abundant biopolymer in the world, the main load-bearing element in plant cell walls, and represents a major sink for carbon fixed during photosynthesis. Previous work has shown that photosynthetic activity is partially regulated by carbohydrate sinks. However, the coordination of cellulose biosynthesis with carbohydrate metabolism and photosynthesis is not well understood. Here, we demonstrate that cellulose biosynthesis inhibition (CBI) leads to reductions in transcript levels of genes involved in photosynthesis, the Calvin cycle, and starch degradation in Arabidopsis (Arabidopsis thaliana) seedlings. In parallel, we show that CBI induces changes in carbohydrate distribution and influences Rubisco activase levels. We find that the effects of CBI on gene expression and carbohydrate metabolism can be neutralized by osmotic support in a concentration-dependent manner. However, osmotic support does not suppress CBI-induced metabolic changes in seedlings impaired in mechanoperception (mid1 complementing activity1 [mca1]) and osmoperception (cytokinin receptor1 [cre1]) or reactive oxygen species production (respiratory burst oxidase homolog DF [rbohDF]). These results show that carbohydrate metabolism is responsive to changes in cellulose biosynthesis activity and turgor pressure. The data suggest that MCA1, CRE1, and RBOHDF-derived reactive oxygen species are involved in the regulation of osmosensitive metabolic changes. The evidence presented here supports the notion that cellulose and carbohydrate metabolism may be coordinated via an osmosensitive mechanism.
Highlights
Cellulose is the most abundant biopolymer in the world, the main load-bearing element in plant cell walls, and represents a major sink for carbon fixed during photosynthesis
Examples include genes encoding components of the LIGHT-HARVESTING ANTENNA COMPLEX (LHC) of PSI and PSII, RUBISCO ACTIVASE, CHAPERONIN 60b (CPN60B), PLASTID TRANSCRIPTIONALLY ACTIVE14, and GLYCERALDEHYDE-3-PHOSPHATE DEHYDROGENASE B SUBUNIT (GAPB), which are involved in photosynthetic carbon fixation
DCB-treated seedlings exhibited elevated levels of cell death. We found that both mock- and cellulose biosynthesis inhibition (CBI)-treated seedlings exhibit an initial increase in Suc at the start of treatment
Summary
Cellulose is the most abundant biopolymer in the world, the main load-bearing element in plant cell walls, and represents a major sink for carbon fixed during photosynthesis. We demonstrate that cellulose biosynthesis inhibition (CBI) leads to reductions in transcript levels of genes involved in photosynthesis, the Calvin cycle, and starch degradation in Arabidopsis (Arabidopsis thaliana) seedlings. Osmotic support does not suppress CBI-induced metabolic changes in seedlings impaired in mechanoperception (mid complementing activity1 [mca1]) and osmoperception (cytokinin receptor1 [cre1]) or reactive oxygen species production (respiratory burst oxidase homolog DF [rbohDF]). These results show that carbohydrate metabolism is responsive to changes in cellulose biosynthesis activity and turgor pressure. The mechanisms translating environmental perturbation into a response in terms of enzyme activity and/ or adaptation of carbohydrate metabolism are not well understood (Gupta and Kaur, 2005; Kempa et al, 2007; Hey et al, 2010)
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