Comparative adaptations of high-tolerant species and broccoli cultivars to salinity stress during germination and early development stages

Abstract

Salinity imposes significant physiological and biochemical challenges on plants, disrupting key processes such as germination, involving growth, and water balance. Under saline conditions, plants activate various defense mechanisms to mitigate salinity-induced damage. While many of these mechanisms are well-characterized in mature plants, their role during germination and early seed development remains largely unexplored. In this work, we studied four pre-commercial broccoli (Brassica oleracea L. var. italica) cultivars previously selected for their enhanced salinity tolerance and compared to the high tolerant Eruca vesicaria subsp. sativa. The results provide insights into key mechanisms involved in salinity tolerance, including osmotic potential regulation, mineral homeostasis, antioxidant enzymatic activity and ATP concentration. The ATP availability and utilization emerged as critical determinants of the stress response profiles of the seeds during germination. Notably, the BQ1 cultivar demonstrated the most efficient ATP utilization, suggesting a broader, more sustained, and effective response under saline conditions. These findings highlight ATP as a crucial factor in salinity tolerance during early seeds development.

Keywords: ATP; Antioxidant; Broccoli; Development; Germination; Salinity.

Fig. 1

Physiological parameters in broccoli cultivars BG1, BH1, BX1 and BQ1, as well as E. vesicaria under control, 50 mM, 100 mM, and 150 mM NaCl conditions. (A) Germination rates (n = 100). (B) Sprout length (n = 6). (C) Sprout weight (n = 6). (D) Growth rate (n = 6). Different letters indicate significant differences according to one-way ANOVA followed by a post hoc Tukey´s test (p < 0.05) between treatments within the same species. Each bar represents the mean ± SE

Fig. 2

Osmotic potential value measured in BG1, BH1, BX1 and BQ1 broccoli cultivars and E. vesicaria under control, 50 mM, 100 mM, and 150 mM NaCl conditions. Different letters indicate significant differences determined by one-way ANOVA followed by Tukey´s post hoc test (p < 0.05) between treatments within the same species. Each bar represents the mean ± SE (n = 3)

Fig. 3

ATP concentration in ng per sprouts in BG1, BH1, BX1 and BQ1 broccoli cultivars and E. vesicaria under control, 50 mM, 100 mM, and 150 mM NaCl conditions. Different letters indicate significant differences according to one-way ANOVA followed by Tukey´s post hoc test (p < 0.05) between treatments within the same species. Each bar represents the mean ± SE (n = 3)

Fig. 4

Macronutrient concentration (g/100 g) in BG1, BH1, BX1 and BQ1 broccoli cultivars and E. vesicaria under control, 50 mM, 100 mM, and 150 mM conditions. Different letters indicate significant differences according to one-way ANOVA followed by a post hoc Tukey´s test (p < 0.05) between treatments within the same species. Each bar represents the mean ± SE (n = 3)

Fig. 5

(A) Na/K ratio in BG1, BH1, BX1 and BQ1 broccoli cultivars and E. vesicaria expressed in molar values under control, 50 mM, 100 mM, and 150 mM conditions. (B) Principal Component Analysis (PCA) of macro- and micronutrients in BG1, BH1, BX1 and BQ1 broccoli cultivars and E. vesicaria under control, 50 mM, 100 mM, and 150 mM conditions. Different letters indicate significant differences according to one-way ANOVA followed by a post hoc Tukey´s test (p < 0.05) between treatments within the same species. Each bar represents the mean ± SE (n = 3)

Fig. 6

Enzymatic activity and lipid damage measure in BG1, BH1, BX1 and BQ1 broccoli cultivars and E. vesicaria under control and 100 mM conditions. (A) Ascorbate peroxidase activity. (B) Glutathione reductase activity. (C) Catalase activity. (D) Lipid oxidative damage. Different letters indicate significant differences according to one-way ANOVA followed by a post hoc Tukey´s test (p < 0.05) between species within same treatment. Asterisks (*) indicate significant differences between treatments within the same cultivar or species according to one-way ANOVA followed by a post hoc Tukey´s test (p < 0.05). Each bar represents the mean ± SE (n = 3)