Growth and antioxidant responses to water stress in eggplant MAGIC population parents, F1 hybrids and a subset of recombinant inbred lines

Abstract

Background: The generation of new eggplant (Solanum melongena L.) cultivars with drought tolerance is a main challenge in the current context of climate change. In this study, the eight parents (seven of S. melongena and one of the wild relative S. incanum L.) of the first eggplant MAGIC (Multiparent Advanced Generation Intercrossing) population, together with four F₁ hybrids amongst them, five S5 MAGIC recombinant inbred lines selected for their genetic diversity, and one commercial hybrid were evaluated in young plant stage under water stress conditions (30% field capacity; FC) and control conditions (100% FC). After a 21-day treatment period, growth and biomass traits, photosynthetic pigments, oxidative stress markers, antioxidant compounds, and proline content were evaluated.

Results: Significant effects (p < 0.05) were observed for genotype, water treatments and their interaction in most of the traits analyzed. The eight MAGIC population parental genotypes displayed a wide variation in their responses to water stress, with some of them exhibiting enhanced root development and reduced foliar biomass. The commercial hybrid had greater aerial growth compared to root growth. The four F₁ hybrids among MAGIC parents differed in their performance, with some having significant positive or negative heterosis in several traits. The subset of five MAGIC lines displayed a wide diversity in their response to water stress.

Conclusion: The results show that a large diversity for tolerance to drought is available among the eggplant MAGIC materials, which can contribute to developing drought-tolerant eggplant cultivars.

Keywords: Breeding; Eggplant; Hybrids; MAGIC population; Oxidative stress; Water stress.

Fig. 1

Eggplant MAGIC materials (parents, F₁ hybrids and a subset of S5 lines) and an F₁ commercial hybrid (Petra) after 21 days of irrigation treatments at 100% (control) and 30% (water stress) of field capacity

Fig. 2

Irrigation applied during the 21 days of water treatment of the eight parents of the MAGIC line and the commercial hybrid Petra under both control (100% FC) and water stress (30% FC) conditions. Different letters in each treatment (uppercase letter for control and lowercase italics for water stress) indicate significant differences between genotypes, determined using the SNK multiple comparison test at a significance level of p < 0.05. The asterisk indicates a significant difference between the control and water stress treatments for each genotype, according to the SNK method for a p-value < 0.05. Vertical bars indicate ± standard error

Fig. 3

Chlorophyll a (A), chlorophyll b (B), total chlorophyll (C) and carotenoids (D) of the eight parents of the MAGIC line and the commercial hybrid Petra under control (100% FC) and water stress (30% FC) conditions. Different letters in each treatment (uppercase letter for control and lowercase italics for water stress) indicate significant differences between genotypes, determined using the SNK multiple comparison test at a significance level of p-value < 0.05. The asterisk indicates a significant difference between the control and water stress treatments for each genotype, according to the SNK method for a p-value < 0.05. Vertical bars indicate ± standard error

Fig. 4

Proline of the eight parents of the MAGIC line and the commercial hybrid Petra under control and water stress conditions. Different letters in each treatment (uppercase letter for control and lowercase italics for water stress) indicate significant differences between genotypes, determined using the SNK multiple comparison test at a significance level of p < 0.05. The asterisk indicates a significant difference between the control and water stress treatments for each genotype, according to the SNK method for a p-value < 0.05. Vertical bars indicate ± standard error

Fig. 5

Correlation matrix coefficients for control (upper right diagonal) and water stress (lower left diagonal) in eighteen genotypes evaluated. Only statistically significant correlations (p-value < 0.001) are shown

Fig. 6

Loading plot (above) and score plot (below) of the principal component analysis (PCA) for the eighteen eggplant genotypes evaluated under control (100% FC) and water stress (30% FC) conditions, based on the first two principal components. The first and second components (PC1 and PC2) represent 60.1% and 13.1% of the variation, respectively