Contrasting Rootstock-Mediated Growth and Yield Responses in Salinized Pepper Plants (Capsicum annuum L.) Are Associated with Changes in the Hormonal Balance

Abstract

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 (Capsicum annuum 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.

Eggplant grafting on a cold‐tolerant rootstock reduces fruit chilling susceptibility and improves antioxidant stability during storage

“…Such effects are highly controlled at the hormonal level, 36 which are in turn known to be altered in response to grafting. 37 Pulp lightness L* was similar in control and grafted plants at the baby and mid-CM stages. However, at late maturity, grafted eggplants maintained a lighter color than the control (Table 1).…”

“…Given the developmental stages, studies of the observed effects could be caused by the alteration in the polarity of cell expansion. Such effects are highly controlled at the hormonal level, 36 which are in turn known to be altered in response to grafting 37 . Pulp lightness L * was similar in control and grafted plants at the baby and mid‐CM stages.…”

Physiological, biochemical, and metabolic changes in diploid and triploid watermelon leaves during flooding

“…Our results agree with previous report which suggests that flooding results in lower chlorophyll contents but triploid watermelon has more chlorophyll as compared to diploid watermelon ( Yan et al., 1996 ; Choudhary and Padmanabhan, 2021 ; He et al., 2022 ). Similarly, root fresh weight and shoot fresh weight are important in terms of a plant’s response to stress ( Pires et al., 2015 ; Gálvez et al., 2021 ; Zhang et al., 2021 ). Our results indicated that 3X watermelon possess higher root and shoot fresh weights as compared to 2X watermelon plants ( Garg et al., 2002 ; Kartik et al., 2021 ).…”

Editorial: Tropical Plant Responses to Climate Change

“…Several studies have demonstrated that grafting vegetable crops onto tolerant rootstocks can improve global plant performance and final productivity under different abiotic stress conditions [6]. To test the role of hormones in this process, Gálvez et al [7] studied rootstock-mediated growth and yield responses in pepper plants, either non-grafted or grafted onto three commercial rootstocks, which were subjected to moderate salinity stress. They showed that developmental and physiological responses of pepper plants were associated with changes in the hormonal balance that helped to improve crop productivity under salinity stress.…”