Comparison of root tolerance to drought and aphid (Myzus persicae Sulzer) resistance among different potato (Solanum tuberosum L.) cultivars

Abstract

This study was conducted to determine the root system architecture and biochemical responses of three potato (Solanum tuberosum L.) cultivars to drought and aphid (Myzus persicae Sulzer) infestation under greenhouse conditions. A factorial experiment comprising three potato cultivars (Qingshu 9, Longshu 3, and Atlantic), two levels of water (Well watered and drought) application and aphid infestation (Aphids and no aphids) was conducted. The results show that drought stress and aphid infestation significantly increased the root-projected area, root surface area, number of root tips, and number of root forks of all cultivars, relative to their corresponding control plants. The least root projected area, root surface area, number of root tips, and number of root forks occurred on DXY under both drought and aphid infestation. Nevertheless, the greatest root projected area, root surface area, number of root tips and number of root forks occurred on QS9 plants. Moreover, increased SOD, CAT, and POD activities were observed across all cultivars, under drought and aphid stress. The highest SOD, POD, and CAT activities occurred in QS9; under drought and aphid stress, while the least SOD, POD, and CAT activities was observed in DXY. The Atlantic cultivar, which possesses a root system sensitive to water deficit, demonstrated greater resistance to aphid infestation under well-watered and drought-stressed conditions. Conversely, Qingshu 9, which possesses a root system tolerant to water deficit, was highly susceptible to aphids. This study shows that the root architectural and biochemical traits that enhance potato tolerance to drought do not necessarily correlate to a plant's tolerance to aphids.

Figure 1

Changes in aphid population abundance in three potato genotypes under two levels of water availability and two levels of aphid infestation. Data represent the mean ± SD of three replicates.

Figure 2

Aphid fresh weight (a), dry weight (b), and mortality rate (c) in three potato genotypes under two levels of water availability and two levels of aphid infestation. Data represent the mean ± SD of three replicates. Lowercase letters indicate means that are significantly different according to the LSD test (P < 0.05).

Figure 3

Total root length (a), root volume (b), average root diameter (c), and root crossings (d) of three potato genotypes under two levels of water availability and two levels of aphid infestation. Data represent the mean ± SD of three replicates. Lower case letters indicate statistically significant differences between cultivars within the same water treatment and aphid treatment by LSD test (P < 0.05).

Figure 4

Root projected area (a), root surface area (b), number of root tips (c), and number of root forks (d) of three potato genotypes under two levels of water availability and two levels of aphid infestation. Data represent the mean ± SD of three replicates. Lower case letters indicate statistically significant differences between cultivars within the same water treatment and aphid treatment by LSD test (P < 0.05).

Figure 5

Scan images of the root system of three potato genotypes at 60 days after drought and aphid infestation treatments. Digital images of the root system were produced with a root scanner (STD 4800, EPSON, Quebec City, Canada).

Figure 6

Root fresh weight (a), dry weight (b), moisture content (c), and mass fraction (d), of three potato genotypes under two levels of water availability and two levels of aphid infestation. Data represent the mean ± SD error of three replicates. Lower case letters indicate statistically significant differences between cultivars within the same water treatment and aphid treatment by LSD test (P < 0.05).

Figure 7

Biomass response to drought (a), aphids (b), and drought and aphids (c) in comparison to the control for three potato genotypes under two levels of water availability and two levels of aphid infestation. Data represent the mean ± SD of three replicates. Lowercase letters indicate means that show statistically significant differences between treatments according to the LSD test (P < 0.05).

Figure 8

H₂O₂ content (a), MDA content (b), Pro content (c), SOD activity (d), POD activity (e), and CAT activity (f) of three potato genotypes under two levels of water availability and two levels of aphid infestation. Data represent the mean ± SD of three replicates. Lower case letters indicate statistically significant differences between cultivars within the same water treatment and aphid treatment by LSD test (P < 0.05).