Plastidic phosphoglucose isomerase is an important determinant of starch accumulation in mesophyll cells, growth, photosynthetic capacity, and biosynthesis of plastidic cytokinins in Arabidopsis.
Plastidic phosphoglucose isomerase is an important determinant of starch accumulation in mesophyll cells, growth, photosynthetic capacity, and biosynthesis of plastidic cytokinins in Arabidopsis.
复制标题
DOI：
10.1371/journal.pone.0119641
复制
发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Pozueta-Romero J
中科院分区：
文献类型：
--
作者：
Bahaji A;Sánchez-López ÁM;De Diego N;Muñoz FJ;Baroja-Fernández E;Li J;Ricarte-Bermejo A;Baslam M;Aranjuelo I;Almagro G;Humplík JF;Novák O;Spíchal L;Doležal K;Pozueta-Romero J
磷酸葡萄糖异构酶(PGI)催化葡萄糖-6-磷酸和果糖-6-磷酸的可逆异构化。它参与糖酵解和氧化戊糖磷酸途径(OPPP)中葡萄糖-6-P分子的再生。在受光照的叶肉细胞的叶绿体中，PGI还将Calvin-Benson循环与淀粉生物合成途径联系起来。在这项工作中，我们分离到了pgi1-3，这是一个由于PPGI编码基因PGI1内含子剪接异常而完全缺乏PPGI活性的突变体。Pgi1-3源叶的淀粉含量约为野生型的10-15%，与T-DNA插入PPGI缺失突变体pgi1-2的淀粉含量相近。通过引入阻止β-淀粉分解的Sex1零突变，可以逆转pgi1叶片的淀粉缺乏。虽然先前的研究表明pgi1-2叶片的淀粉颗粒仅限于靠近叶肉的束鞘细胞和气孔保卫细胞，但本工作进行的显微镜分析表明，pgi1-2和pgi1-3叶肉细胞的叶绿体中都存在淀粉颗粒。RT-PCR法分析表明，β-淀粉酶编码基因在pGI1叶片中高水平表达，同时伴随着β-淀粉酶活性的增强。Pgi1-2和pgi1-3突变体即使在连续光照条件下也表现出生长缓慢和光合作用能力降低的表型。代谢分析表明，pgi1叶片的腺苷酸能荷值和NAD(P)H/NAD(P)比值均低于对照叶片。这些分析还表明，pgi1叶片中的可塑性2-C-甲基-D-赤藓糖醇4-磷酸(MEP)途径衍生的细胞分裂素(CKs)的含量极低。值得注意的是，外源CKS在很大程度上逆转了pgi1叶片低淀粉含量的表型。总体而言，PPGI是叶肉细胞光合作用、能量状态、生长和淀粉积累的重要决定因素，可能是因为它参与了OPPP/糖酵解中间产物的产生，这些中间产物是合成可塑性MEP途径衍生激素如CKS所必需的。
Phosphoglucose isomerase (PGI) catalyzes the reversible isomerization of glucose-6-phosphate and fructose-6-phosphate. It is involved in glycolysis and in the regeneration of glucose-6-P molecules in the oxidative pentose phosphate pathway (OPPP). In chloroplasts of illuminated mesophyll cells PGI also connects the Calvin-Benson cycle with the starch biosynthetic pathway. In this work we isolated pgi1-3, a mutant totally lacking pPGI activity as a consequence of aberrant intron splicing of the pPGI encoding gene, PGI1. Starch content in pgi1-3 source leaves was ca. 10-15% of that of wild type (WT) leaves, which was similar to that of leaves of pgi1-2, a T-DNA insertion pPGI null mutant. Starch deficiency of pgi1 leaves could be reverted by the introduction of a sex1 null mutation impeding β-amylolytic starch breakdown. Although previous studies showed that starch granules of pgi1-2 leaves are restricted to both bundle sheath cells adjacent to the mesophyll and stomata guard cells, microscopy analyses carried out in this work revealed the presence of starch granules in the chloroplasts of pgi1-2 and pgi1-3 mesophyll cells. RT-PCR analyses showed high expression levels of plastidic and extra-plastidic β-amylase encoding genes in pgi1 leaves, which was accompanied by increased β-amylase activity. Both pgi1-2 and pgi1-3 mutants displayed slow growth and reduced photosynthetic capacity phenotypes even under continuous light conditions. Metabolic analyses revealed that the adenylate energy charge and the NAD(P)H/NAD(P) ratios in pgi1 leaves were lower than those of WT leaves. These analyses also revealed that the content of plastidic 2-C-methyl-D-erythritol 4-phosphate (MEP)-pathway derived cytokinins (CKs) in pgi1 leaves were exceedingly lower than in WT leaves. Noteworthy, exogenous application of CKs largely reverted the low starch content phenotype of pgi1 leaves. The overall data show that pPGI is an important determinant of photosynthesis, energy status, growth and starch accumulation in mesophyll cells likely as a consequence of its involvement in the production of OPPP/glycolysis intermediates necessary for the synthesis of plastidic MEP-pathway derived hormones such as CKs.
登录
查看更多内容
影响因子：
4.1
作者：
Fox, SR;Hill, LM;Hills, MJ
通讯作者：
Hills, MJ
影响因子：
7.4
作者：
Eicks, M;Maurino, V;Fischer, K
通讯作者：
Fischer, K
影响因子：
56.9
作者：
ARNON, DI
通讯作者：
ARNON, DI
影响因子：
7.2
作者：
Clough, SJ;Bent, AF
通讯作者：
Bent, AF
影响因子：
7.4
作者：
Edner, Christoph;Li, Jing;Ritte, Gerhard
通讯作者：
Ritte, Gerhard