Sucrose-phosphate synthase activity and yield analysis of tomato plants transformed with maize sucrose-phosphate synthase

Abstract

Sucrose synthesis is a major element of the interactions between photosynthesis and plant growth and development. Tomato (Lycopersicon esculentum Mill. cv. UC82B) plants transformed with maize sucrose-phosphate synthase (SPS; EC 2.3.1.14) expressed from either a ribulose-1,5-bisphosphate carboxylaseoxygenase (Rubisco) small subunit promoter (SSU) or the cauli¯ower mosaic virus 35S promoter (35S) were used to study eects of increased sucrose synthesis rates on plant growth. The plants were grown in growth chambers, ®eld plots, and open-top chambers. The 35S plants had a 2 to 3-fold increase in young-leaf SPS activity, a 10 to 20-fold increase in young-root SPS activity and no increase in young-fruit SPS activity. The leaf SPS activity in one of the 35S lines fell to control levels by two months of age. The SSU plants had a 4 to 5-fold increase in leaf SPS activity and no signi®cant increase in root or young-fruit SPS activity. One 35S line, which maintained high leaf SPS activity throughout development, yielded 70±80% more than controls at both normal and elevated CO 2 in open-top chambers in the ®eld and 20±30% more than controls in two additional ®eld trials. The other 35S line and the two SSU lines either yielded less or did not dier from controls under several growth conditions. Since only one of four transformed lines showed an increase in yield, we can not yet conclude that increased leaf SPS activity leads to increased yield. However, increased leaf SPS activity appears to result in increased fruit sugar content since all three lines with increased leaf SPS usually also had increased fruit sugars.Key words: Cauli¯ower mosaic virus 35S promoter ± Growth chamber (open topped) Lycopersicon ± Open top chambers ± Ribulose-1,5-bisphosphate carboxylase-oxygenase small subunit promoter ± Sucrose-phosphate synthase ± Yield (transformed tomato) Abbreviations: DAS = days after seeding; SPS = sucrosephosphate synthase; SSU = small subunit of Rubisco Correspondence to: M. Laporte;

Metabolism and Accumulation of Sugars Translocated to Fruit and Their Regulation

“…SPS in leaves regulates partitioning of assimilate. In transgenic tomatoes containing the over-expressed SPS gene, SPS activity increased 3-fold in leaves, but not in fruit, while the sugar contents in fruit increased (Laporte et al, 1997). In other transgenic tomatoes containing the overexpressed SPS gene, the SPS activity increased 2.4-fold, but other enzyme activities did not change, and unloading of sucrose was more active .…”

Improving biomass production and saccharification in Brachypodium distachyon through overexpression of a sucrose-phosphate synthase from sugarcane

“…Therefore, SPS 8 overexpression has been used to modify plant development. Heterologous overexpression of 9 an SPS gene from maize in tomato (Lycopersocum esculentum) resulted in increased fruit 10 yield (Laporte et al, 1997;Micallef et al, 1995) where best results were obtained with an SPS 11 activity in transgenic plants which was approximately twice as high as in wild-type plants 12 (Laporte et al, 2001). Similar to tomato, overexpression of a maize SPS gene increased tuber 13 weight and total yield in transgenic potato (Solanum tuberosum) plants (Ishimaru et al, 2008) 14 as well as increased plant height and biomass production but also delayed flowering in 15 transgenic tobacco (Nicotiana tabacum) lines (Coleman et al, 2010;Park et al, 2008).…”

Tansley Review No. 105.

“…In some lines, the transgenic tomato plants had higher relative growth rates, total biomass accumulation and fruit yield than wild-type plants (Galtier et al, 1993(Galtier et al, , 1995Micallef et al, 1995 ;Laporte et al, 1997). An increase in the shoot\root ratio and early flowering was also reported in some lines.…”