Table I.

Enzyme activities assayed in extracts from antisense (JT 676, JT 594, JT 654, and JT 595) and sense (JT 1, JT 78, JT 98, and JT 62) AATP-tubers

EnzymesWTJT 676JT 594JT 654JT 595JT 1JT 78JT 98JT 62
Suc synthase1,901 ± 2111,941 ± 1102,261 ± 1432,337 ± 1112,079 ± 3001,626 ± 1302,538 ± 622,253 ± 892,541 ± 200
UDPGlc pyrophosphorylase1,397 ± 701,640 ± 251,668 ± 181,435 ± 511,629 ± 171,318 ± 581,401 ± 311,473 ± 521,389 ± 63
Alkaline invertase25.6 ± 1.135.7 ± 0.657.7 ± 4.360.9 ± 2.951.1 ± 4.124.5 ± 1.527.6 ± 1.928.0 ± 1.230.9 ± 3.5
Acid invertase6.1 ± 0.417.6 ± 2.033.5 ± 4.541.9 ± 8.543.3 ± 12.210.6 ± 5.77.1 ± 1.47.1 ± 1.69.8 ± 1.6
SPS (V max)506 ± 34453 ± 84492 ± 37447 ± 41575 ± 68435 ± 67493 ± 34486 ± 34379 ± 94
SPS (V sel)32.2 ± 8.349.8 ± 5.552.5 ± 6.457.4 ± 3.470.0 ± 1025.9 ± 4.236.2 ± 1424.4 ± 7.127.2 ± 1.0
SPS (V sel/V max)6.0 ± 1.314.6 ± 5.010.5 ± 0.613.1 ± 0.812.3 ± 1.16.6 ± 1.66.9 ± 2.35.3 ± 1.57.2 ± 0.3
Glc6P-dehydrogenase (G6PDH)1,437 ± 1051,383 ± 731,521 ± 81,467 ± 1031,639 ± 411,398 ± 571,319 ± 541,408 ± 1401,939 ± 216
6-Phosphogluconate-DH270 ± 16381 ± 54327 ± 12347 ± 8358 ± 3273 ± 12276 ± 12315 ± 11343 ± 30
Phosphofruktokinase (PFK)101 ± 676 ± 4110 ± 9129 ± 16104 ± 1098 ± 7119 ± 6105 ± 10109 ± 9
Pyrophosphate: Fru-6-phosphate: phosphotransferase (PFP)1,125 ± 69926 ± 91,152 ± 48940 ± 1011,084 ± 601,089 ± 691,112 ± 411,160 ± 1231,265 ± 90
Glycerinaldehydephosphate dehydrogenase (GAP-DH)2,087 ± 2551,616 ± 1152,153 ± 2452,094 ± 2712,209 ± 971,959 ± 2322,049 ± 3041,698 ± 2562,350 ± 346
Pyruvatekinase379 ± 48340 ± 38418 ± 17313 ± 36281 ± 35423 ± 65528 ± 46333 ± 93376 ± 58
PEP carboxylase97 ± 10172 ± 18186 ± 14191 ± 16232 ± 1899 ± 7129 ± 19141 ± 11131 ± 5
PEP phosphatase517 ± 66388 ± 47608 ± 33858 ± 120608 ± 21474 ± 44698 ± 12470 ± 101479 ± 69
ADPGlc pyrophosphorylase893 ± 75723 ± 37686 ± 35812 ± 38680 ± 51857 ± 1521,088 ± 291,024 ± 94998 ± 66

Results (nmol g fresh wt−1 min−1) are the mean ± se (n = 5 separate tubers from different plants). Suc phosphate synthase (SPS) was measured under two different assay conditions: V max assay (12 mm Fru6P, 36 mm Glc6P, and 6 mmUDPGLc), or V sel assay (2 mm Fru6P, 6 mm Glc6P, 6 mm UDPGlc, and 5 mmPi).