Tomato Fruit Photosynthesis Is Seemingly Unimportant in Primary Metabolism and Ripening But Plays a Considerable Role in Seed Development
Tomato Fruit Photosynthesis Is Seemingly Unimportant in Primary Metabolism and Ripening But Plays a Considerable Role in Seed Development
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DOI：
10.1104/pp.111.186874
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发表时间：
2011-12-01
期刊：
影响因子：
7.4
通讯作者：
Fernie, Alisdair R.
中科院分区：
文献类型：
--
作者：
Lytovchenko, Anna;Eickmeier, Ira;Fernie, Alisdair R.
番茄果实与其他植物一样，经历了从部分光合作用到真正异养代谢的转变。虽然有大量证据表明番茄幼果的光合作用具有功能性，但碳吸收的速度很少超过二氧化碳释放的速度，这就提出了碳在该组织中的作用的问题。在这里，我们描述了显示谷氨酸1-半醛转氨酶（GSA）表达特异性降低的品系的产生和特性。尽管这些植物含有较少的GSA蛋白，叶绿素水平和光合活性较低，但它们在其他方面几乎没有差异。事实上，它们在果实大小、重量或成熟能力方面几乎没有差异，而且在其他主要或中间代谢物方面几乎没有变化。虽然GSA反义系的特征是光合作用相关基因的表达、细胞壁和氨基酸代谢相关基因的表达发生了显著变化，但这些变化并未在表型水平上表现出来。反义植物的一个显著特征是它们的种子表型：在果实发育的早期阶段，转化体表现出较少的种子集和改变的形态和代谢，尽管这些差异并不影响最终的种子数量或繁殖力。综上所述，这些结果表明，至少在环境条件下，果实的光合作用对果实的能量代谢或发育不是必需的，但对适当时间的种子发育是必不可少的，因此在逆境条件下可能具有优势。
Fruit of tomato (Solanum lycopersicum), like those from many species, have been characterized to undergo a shift from partially photosynthetic to truly heterotrophic metabolism. While there is plentiful evidence for functional photosynthesis in young tomato fruit, the rates of carbon assimilation rarely exceed those of carbon dioxide release, raising the question of its role in this tissue. Here, we describe the generation and characterization of lines exhibiting a fruit-specific reduction in the expression of glutamate 1-semialdehyde aminotransferase (GSA). Despite the fact that these plants contained less GSA protein and lowered chlorophyll levels and photosynthetic activity, they were characterized by few other differences. Indeed, they displayed almost no differences in fruit size, weight, or ripening capacity and furthermore displayed few alterations in other primary or intermediary metabolites. Although GSA antisense lines were characterized by significant alterations in the expression of genes associated with photosynthesis, as well as with cell wall and amino acid metabolism, these changes were not manifested at the phenotypic level. One striking feature of the antisense plants was their seed phenotype: the transformants displayed a reduced seed set and altered morphology and metabolism at early stages of fruit development, although these differences did not affect the final seed number or fecundity. Taken together, these results suggest that fruit photosynthesis is, at least under ambient conditions, not necessary for fruit energy metabolism or development but is essential for properly timed seed development and therefore may confer an advantage under conditions of stress.