Institute for Agri-Food Research and Technology of Murcia (IMIDA), Department of Plant Production and Agrotechnology, c/Mayor s/n, E-30150 Murcia, Spain.
Centro de Edafología y Biología Aplicada del Segura (CEBAS-CSIC), Department of Plant Nutrition, Campus Universitario de Espinardo, E-30100 Murcia, Spain.
Int J Mol Sci. 2021 Mar 24;22(7):3297. doi: 10.3390/ijms22073297.
Salinity provokes an imbalance of vegetative to generative growth, thus impairing crop productivity. Unlike breeding strategies, grafting is a direct and quick alternative to improve salinity tolerance in horticultural crops, through rebalancing plant development. Providing that hormones play a key role in plant growth and development and stress responses, we hypothesized that rootstock-mediated reallocation of vegetative growth and yield under salinity was associated with changes in the hormonal balance. To test this hypothesis, the hybrid pepper variety ( L. "Gacela F1") was either non-grafted or grafted onto three commercial rootstocks (Creonte, Atlante, and Terrano) and plants were grown in a greenhouse under control (0 mM NaCl) and moderate salinity (35 mM NaCl) conditions. Differential vegetative growth versus fruit yield responses were induced by rootstock and salinity. Atlante strongly increased shoot and root fresh weight with respect to the non-grafted Gacela plants associated with improved photosynthetic rate and K homeostasis under salinity. The invigorating effect of Atlante can be explained by an efficient balance between cytokinins (CKs) and abscisic acid (ABA). Creonte improved fruit yield and maintained the reproductive to vegetative ratio under salinity as a consequence of its capacity to induce biomass reallocation and to avoid Na accumulation in the shoot. The physiological responses associated with yield stability in Creonte were mediated by the inverse regulation of CKs and the ethylene precursor 1-aminocyclopropane-1-carboxylic acid. Finally, Terrano limited the accumulation of gibberellins in the shoot thus reducing plant height. Despite scion compactness induced by Terrano, both vegetative and reproductive biomass were maintained under salinity through ABA-mediated control of water relations and K homeostasis. Our data demonstrate that the contrasting developmental and physiological responses induced by the rootstock genotype in salinized pepper plants were critically mediated by hormones. This will be particularly important for rootstock breeding programs to improve salinity tolerance by focusing on hormonal traits.
盐度会引起营养生长与生殖生长的失衡，从而降低作物的生产力。与选育策略不同，嫁接是一种直接而快速的替代方法，可以通过重新平衡植物的发育来提高园艺作物的耐盐性。由于激素在植物的生长和发育以及应激反应中起着关键作用，我们假设，在盐胁迫下，根砧介导的营养生长和产量的再分配与激素平衡的变化有关。为了验证这一假设，我们将杂交辣椒品种（L. "Gacela F1"）非嫁接或嫁接在三种商业根砧（Creonte、Atlante 和 Terrano）上，并在温室中控制（0 mM NaCl）和中度盐胁迫（35 mM NaCl）条件下生长。根砧和盐度诱导了不同的营养生长与果实产量的响应。Atlante 相对于非嫁接的 Gacela 植株强烈地增加了地上部和根的鲜重，同时提高了光合速率和 K 稳态，这与盐胁迫下的 ABA 有关。 Atlante 的这种刺激作用可以通过细胞分裂素（CKs）和脱落酸（ABA）之间的有效平衡来解释。Creonte 提高了果实产量，并在盐胁迫下维持了生殖与营养的比例，这是由于其在重新分配生物量和避免 shoot 中 Na 积累方面的能力。Creonte 与产量稳定性相关的生理响应是通过 CKs 和乙烯前体 1-氨基环丙烷-1-羧酸的反向调节来介导的。最后，Terrano 限制了 shoot 中赤霉素的积累，从而降低了植物的高度。尽管 Terrano 诱导了接穗的紧凑性，但通过 ABA 介导的对水关系和 K 稳态的控制，在盐胁迫下仍然维持了营养和生殖生物量。我们的数据表明，在盐胁迫下，根砧基因型诱导的辣椒植株的发育和生理响应的差异是由激素决定的。这对于根砧选育计划通过聚焦于激素特性来提高耐盐性尤为重要。
