Leiva-Ampuero Andrés, Agurto Mario, Matus José Tomás, Hoppe Gustavo, Huidobro Camila, Inostroza-Blancheteau Claudio, Reyes-Díaz Marjorie, Stange Claudia, Canessa Paulo, Vega Andrea
Millennium Institute for Integrative Biology (iBio), Santiago, Chile.
Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.
PeerJ. 2020 Sep 17;8:e9742. doi: 10.7717/peerj.9742. eCollection 2020.
Carotenoids are essential components of the photosynthetic antenna and reaction center complexes, being also responsible for antioxidant defense, coloration, and many other functions in multiple plant tissues. In tomato, salinity negatively affects the development of vegetative organs and productivity, but according to previous studies it might also increase fruit color and taste, improving its quality, which is a current agricultural challenge. The fruit quality parameters that are increased by salinity are cultivar-specific and include carotenoid, sugar, and organic acid contents. However, the relationship between vegetative and reproductive organs and response to salinity is still poorly understood. Considering this, cv. Micro-Tom plants were grown in the absence of salt supplementation as well as with increasing concentrations of NaCl for 14 weeks, evaluating plant performance from vegetative to reproductive stages. In response to salinity, plants showed a significant reduction in net photosynthesis, stomatal conductance, PSII quantum yield, and electron transport rate, in addition to an increase in non-photochemical quenching. In line with these responses the number of tomato clusters decreased, and smaller fruits with higher soluble solids content were obtained. Mature-green fruits also displayed a salt-dependent higher induction in the expression of , , , and , key genes of the carotenoid biosynthesis pathway, in correlation with increased lycopene, lutein, β-carotene, and violaxanthin levels. These results suggest a key relationship between photosynthetic plant response and yield, involving impaired photosynthetic capacity, increased carotenoid-related gene expression, and carotenoid biosynthesis.
类胡萝卜素是光合天线和反应中心复合体的重要组成部分，在多种植物组织中还负责抗氧化防御、色素沉着及许多其他功能。在番茄中，盐度会对营养器官的发育和生产力产生负面影响，但根据以往研究，盐度也可能增加果实颜色和风味，从而提高其品质，这是当前农业面临的一项挑战。盐度增加的果实品质参数具有品种特异性，包括类胡萝卜素、糖和有机酸含量。然而，营养器官与生殖器官之间的关系以及对盐度的响应仍知之甚少。考虑到这一点，对微型番茄品种的植株在不添加盐分以及添加浓度不断增加的氯化钠的条件下培养14周，评估从营养生长阶段到生殖生长阶段的植株表现。作为对盐度的响应，植株除了非光化学猝灭增加外，净光合作用、气孔导度、PSII量子产率和电子传递速率均显著降低。与这些响应一致，番茄簇的数量减少，获得了可溶性固形物含量更高的较小果实。绿熟果实还表现出类胡萝卜素生物合成途径的关键基因、、、和的表达受盐度依赖性更高的诱导，这与番茄红素、叶黄素、β-胡萝卜素和紫黄质水平的增加相关。这些结果表明光合植物响应与产量之间存在关键关系，涉及光合能力受损、类胡萝卜素相关基因表达增加以及类胡萝卜素生物合成。
