Analysis of a Triose Phosphate/Phosphate Translocator-Deficient Mutant Reveals a Limited Capacity for Starch Synthesis in Rice Leaves

Abstract

Reduction of the cytosolic fructose-1,6-bisphosphatase in transgenic potato plants limits photosynthetic sucrose biosynthesis with no impact on plant growth and tuber yield. Plant J. 9, 671-681.

Plastidic phosphoglucomutase and ADP-glucose pyrophosphorylase mutants impair starch synthesis in rice pollen grains and cause male sterility

“…Unlike Arabidopsis, however, rice leaves normally accumulate relatively little starch. Our mutant analyses of the rice cytosolic fructose 1,6 bis phosphatase and the plastidic triose phosphate/phosphate translocator demonstrated that rice has a limited capacity for starch synthesis in the source leaf ( Lee et al , 2008 , 2014 ). Hence, the impairment of the synthesis of transitory leaf starch mediated by mutations in apl1 , an OsAGPL3 mutant, and osagps2 , an OsAGPS2 mutant, would not be expected to disrupt normal plant growth ( Lee et al , 2007 ; Rösti et al , 2007 ).…”

“…No visible phenotypic differences in vegetative growth were observed for the starchless rice mutants, osagps2 and apl1 ( Lee et al , 2007 ; Rösti et al , 2007 ). The absence of any effect on growth and development by leaf starch deficiency in rice may simply be due to the fact that this plant has limited starch synthesis capacity and that its growth relies more on the synthesis of sucrose ( Lee et al , 2008 , 2014 ).…”

Alternative electron transport pathways in photosynthesis: a confluence of regulation

“…Mutants can use this transient starch pool as a buffer, but it becomes saturated in high light [36,37]. The rice Ostpt1 mutant is unable to sustain such a compensatory pathway and has a stunted growth phenotype at all light regimes [38]. The balance of phosphorylated sugars inside and outside the chloroplast has a regulatory role in acclimation [39]: arresting either chloroplast export of triose-P in tpt mutants or translocation of glucose-6-phosphate (via GPT2) into the chloroplast in gpt2 mutants and are both associated with a defective acclimation response.…”

Spectacular Oscillations in Plant Isoprene Emission under Transient Conditions Explain the Enigmatic CO2 Response

“…feedback-inhibited conditions, the reactions of triosephosphate transport and consumption cannot keep up with the rate of photosynthetic triose phosphate production, and it is well established that such conditions ultimately lead to a reduced rate of ATP and NADPH synthesis due to low stromal P i (Sharkey, 1985a;Sharkey and Vanderveer, 1989;Sharkey and Vassey, 1989;Lee et al, 2014). Under such conditions, the sensitivity of photosynthesis to changes in CO 2 and O 2 concentrations decreases, and the photosynthesis might eventually even respond negatively to increases in CO 2 concentration and decreases in O 2 concentration (Sharkey, 1985a(Sharkey, , 1985b(Sharkey, , 1986.…”