Reduction in SBPase Activity by Antisense RNA in Transgenic Rice Plants: Effect on Photosynthesis, Growth, and Biomass Allocation at Different Nitrogen Levels

Abstract

Rice cultivar zhonghua11 (Oryza sativa L. ssp. japonica) plants with decreased sedoheptulose-1, 7-bisphosphatase (SBPase) were obtained by transformation with the rice SBPase antisense gene under the control of the maize ubiquitin promoter. The transgenic and wild-type plants were grown at different nitrogen levels (0.1, 1, or 10 mM NH 4 NO 3 ). Growth rates of the seedlings were measured by the changes in dry weight, and the photosynthetic carbon reduction activities and the potential efficiency of photosystem II were measured by CO 2 assimilation and F v /F m , respectively. At low N, there are strong effects on growth and photosynthesis when SBPase was reduced by genetic manipulation. Decreased SBPase activity led to a decrease in the amount of starch accumulated in the leaves at all N levels and the decrease was much more prominent in low N than that in high N, but the starch allocation between shoot and root was unaltered. The analysis of chlorophyll fluorescence and SBPase activity indicated that the decrease of growth and photosynthesis at different N levels were not related to the function of PSII but to the activity of SBPase. Western blot analysis showed the content of SBPase in thylakoid membranes was much more than in the stroma fractions in transgenic plants at low N. Results suggested that low N in addition to a 34% decrease in SBPase activity is sufficient to diminish photosynthesis and limit biomass production. Decreased SBPase activity may reduce the N use efficiency of photosynthesis and growth and alter biomass allocation.

Increased SBPase activity improves photosynthesis and grain yield in wheat grown in greenhouse conditions

“…The importance of SBPase in the control of the regenerative phase of the Calvin cycle has been shown by several studies; modelling and simulation studies have shown that SBPase exerts control over the rate of RuBP regeneration [ 23 , 24 ]. In studies that decreased SBPase levels in tobacco plants, reduced photosynthesis and growth were observed [ 25 – 27 ], with similar results found for rice [ 28 ]. Conversely, increases in the activity levels of SBPase led to increased photosynthesis and biomass in tobacco under controlled conditions [ 29 ] as well as in the field under elevated [CO 2 ] [ 30 ].…”

Comparative Proteomics of Leaves from Phytase-Transgenic Maize and Its Non-transgenic Isogenic Variety

“…The enzyme SBPase participates in the final regenerative phase of the Calvin cycle by catalyzing the dephosphorylation of sedoheptulose 1,7-bisphosphate to produce the CO 2 acceptor molecule RubP for the continued functions (Raines et al, 1999 ). This enzyme is unique to the Calvin cycle, and its activity affects photosynthesis, growth, and biomass allocation (Feng et al, 2009 ). It has been reported that decreased activity of SBPase can result in a significant reduction in the rate of light- and CO 2 -saturated photosynthesis (Harrison et al, 1998 ), and over-expression of SBPase can enhance carbon assimilation and crop yields (Rosenthal et al, 2011 ; Jessica et al, 2013 ).…”

Overexpression of bifunctional fructose-1,6-bisphosphatase/sedoheptulose-1,7-bisphosphatase leads to enhanced photosynthesis and global reprogramming of carbon metabolism in Synechococcus sp. PCC 7002

“…These enzymes catalyze the dephosphorylation of fructose-1,6-bisphosphate and sedoheptulose-1,7-bisphosphate in the so-called regeneration phase of the Calvin Benson cycle (Cotton et al, 2015;Feng et al, 2014;Tamoi et al, 1996). RuBisCO and SBPase, along with aldolase, have been identified as ratelimiting enzymes in the Calvin cycle (Ding et al, 2016;Feng et al, 2009;Harrison et al, 1997Harrison et al, , 2001; Hudson et al, 1992;Haake et al, 1998Haake et al, , 1999Izumi et al, 2012;Lauerer et al;Lawson et al, 2006;Olçer et al, 2001;Raines, 2003;Zhu et al, 2007). Additionally, cyanobacteria possess a carbon concentrating mechanism (CCM) that can concentrate inorganic carbons in the cytosol through energy consuming processes coupled to Na + gradients, ATP hydrolysis, and/or oxidation of NAD(P)H (Rae et al, 2013).…”