Covarrubias María Paz, Uribe Felipe, Arias-G Daniela, Cabedo Pamela, Handford Michael
Centro de Biología Molecular Vegetal, Department of Biology, Faculty of Sciences, University of Chile, Santiago, Chile.
Front Plant Sci. 2025 May 19;16:1545011. doi: 10.3389/fpls.2025.1545011. eCollection 2025.
Lipoic acid (LA) is a key, yet overlooked player in primary metabolism, due to its role as a cofactor for various multi enzymatic complexes such as the E2 subunits of pyruvate dehydrogenase (PDH) and alpha-ketoglutarate dehydrogenase (kGDH). In recent years, this molecule has seen renewed interest given its strong antioxidant properties and its applications as a dietary supplement. The mechanisms behind the synthesis of LA in vivo have been elucidated, identifying lipoyl synthase (LIP1) as the key enzyme required for this process.
Therefore, in this work, we used the fruit-specific polygalacturonase (PG) promoter to guide (tomato) () overexpression in stably transformed tomatoes.
The resulting plants presented higher transcript levels of in a fruit-specific manner, accumulated more bound and unbound LA yet lacked major phenotypic defects at both the vegetative and reproductive growth stages. Furthermore, changes in the expression of genes related to LA synthesis were explored and a metabolomic study was carried out. Specific metabolite patterns were clearly distinguishable between untransformed and stably transformed lines. For instance, trehalose 6-phosphate, GABA and proline levels were generally higher, whilst glucose 6-phosphate and UDP-glucose levels were lower in fruits of the transformants.
In addition, as the overexpression of results in lower transcript levels of and , and enhanced amounts of LA-bound targets, we speculate that the proportion of unlipoylated E2 subunits of PDH and kGDH may have decreased. This work could assist in obtaining crops with a higher LA content and therefore improved health benefits.
硫辛酸（LA）是初级代谢中的一个关键但常被忽视的参与者，因为它作为多种多酶复合物的辅因子发挥作用，如丙酮酸脱氢酶（PDH）和α-酮戊二酸脱氢酶（kGDH）的E2亚基。近年来，鉴于其强大的抗氧化特性及其作为膳食补充剂的应用，这种分子重新引起了人们的关注。体内LA合成背后的机制已得到阐明，确定硫辛酰胺合成酶（LIP1）是这一过程所需的关键酶。
因此，在这项工作中，我们使用果实特异性多聚半乳糖醛酸酶（PG）启动子来引导（番茄）（）在稳定转化的番茄中过表达。
所得植株以果实特异性方式呈现出更高的转录水平，积累了更多结合态和游离态的LA，但在营养生长和生殖生长阶段均未出现主要的表型缺陷。此外，还探索了与LA合成相关基因的表达变化，并进行了代谢组学研究。未转化和稳定转化株系之间的特定代谢物模式明显可区分。例如，在转化体的果实中，6-磷酸海藻糖、γ-氨基丁酸和脯氨酸水平通常较高，而6-磷酸葡萄糖和尿苷二磷酸葡萄糖水平较低。
此外，由于的过表达导致和的转录水平降低，以及与LA结合的靶标量增加，我们推测PDH和kGDH未脂酰化的E2亚基比例可能降低。这项工作有助于获得LA含量更高、对健康有益的作物。
