Aphid Resistance Evaluation and Constitutive Resistance Analysis of Eighteen Lilies

Abstract

Lilies (Lilium spp.) are famous bulb flowers worldwide, with high ornamental value. Aphid damage has seriously constrained the development of the lily industry. In this study, the aphid resistance of 16 lily cultivars and 2 wild lily species was characterized in the field and greenhouse. Leaf color parameters, stomatal density and size, thickness of leaf layers, leaf waxy content, and leaf water content were determined to explore the constitutive resistance of lilies. The results show that there was a significant positive correlation between the number of aphids in the field and in the greenhouse (p ≤ 0.05, r = 0.47). This indicated that the level of aphid infestation in both the field and the greenhouse is generally consistent across different types of lily plants. Among these 18 lilies, 'Palazzo', 'Nymph', 'Cameleon' and L. lancifolium were resistant to A. gossypii, while 'Black Beauty' and 'Magnefique' had poor resistance. The correlation analysis results showed that the number of aphids was negatively correlated with leaf abaxial surface a*, stomatal size, water content, and thickness of leaf palisade tissue and positively correlated with leaf distal axial surface b*, C*, and waxy content. Among them, the correlation between the number of aphids and the thickness of leaf palisade tissue reached a significant level (p ≤ 0.05, r = -0.521). This indicated that the thickness of the palisade tissue of lily leaves might be an important factor influencing the proliferation of aphids. This study not only screened out aphid-resistant lilies but also established a crucial research foundation for the targeted breeding and molecular breeding of lilies with aphid resistance.

Keywords: Aphis gossypii; aphid resistance; lily; palisade tissue.

Figure 1

Aphid numbers on eighteen lilies at 10 days after inoculation. Values are the mean ± SE (n = 5). Different lowercase letters above the columns indicate significant differences among different lilies at the 0.05 level (Duncan’s test). Greenhouse aphid numbers, F = 6.126; df = 17, 72; p < 0.001. Field aphid numbers, F = 2.055; df = 17, 72; p = 0.018.

Figure 2

Phenotypes of eighteen lily plants at ten days after inoculation in the greenhouse. The bottom left image shows the top part of the lily magnified three times. (A) ‘Black Beauty’; (B) ‘Conca D′or’; (C) ‘Palazzo’; (D) ‘Nymph’; (E) ‘Friso’; (F) ‘Eyeliner’; (G) ‘Armandale’; (H) ‘Heartstrings’; (I) ‘Apricot Fudge’; (J) ‘Trendy Havana’; (K) ‘Secret Kiss’; (L) ‘Cameleon’; (M) ‘The Edge’; (N) ‘White Triumph’; (O) ‘Magnefique’; (P) ‘Watch Up’; (Q) Lilium leucanthum; (R) Lilium lancifolium.

Figure 3

Scatterplot of correlation between greenhouse aphid population and field aphid population (Pearson correlation coefficient).

Figure 4

Leaf wax content of eighteen lilies. Values are the mean ± SE (n = 3). Different lowercase letters above the columns indicate significant differences among different lilies, Duncan’s test, alpha = 0.05 (F = 2.606; df = 17, 36; p = 0.008).

Figure 5

Leaf water content of eighteen lilies. Values are the mean ± SE (n = 3). Different lowercase letters above the columns indicate significant differences among different lilies, Duncan’s test, alpha = 0.05 (F = 16.276; df = 17, 36; p < 0.001).

Figure 6

Correlation between the number of greenhouse aphids and biological parameters of lily leaves (Pearson correlation coefficient). Color code ranges from blue = strong negative correlation (r = −1) to white = no correlation (r = 0) to red = positive correlation (r = +1). Labels with “*” indicate the significant correlations at different levels (* p ≤ 0.05; ** p ≤ 0.01).