The Impact of Piriformospora indica on plant heat and drought tolerance

Abstract

In recent years, the global rise in temperatures has led to drought and heat becoming major environmental stresses that limit plant growth. Previous research has demonstrated the potential of Piriformospora indica in augmenting plant stress resistance. However, specific studies on its effects and underlying mechanisms in cuttings of Rosa chinensis, Jasminum sambac, and Rhododendron simsii Planch are relatively limited. The objective of this study is to explore the effects and mechanisms of P. indica on cuttings and tissue-cultured seedlings of these plants under conditions of drought and high-temperature stress. The experiment involved subjecting P. indica-inoculated and non-inoculated plants to drought (one week without watering) and high-temperature (24-hour exposure to 45°C) stress in a controlled environment chamber. Indicators such as chlorophyll content, chlorophyll fluorescence parameter Fv/Fm, and antioxidant enzyme activity were measured. The results showed that inoculation with P. indica significantly increased the survival rate of the three types of plant cuttings under drought conditions by 13%, 17%, and 16.6% respectively, and resulted in a substantial decrease in malondialdehyde content alongside an increase in chlorophyll content. Under high-temperature stress at 45°C, the chlorophyll fluorescence parameter Fv/Fm values increased by 27.3%, 10.3%, and 51.1% compared to the control group. Furthermore, heat tolerance tests at 42°C showed a 2% higher survival rate in the P. indica inoculated Rhododendron tissue-cultured seedlings than in the control group, with a positive effect observed on the activities of superoxide dismutase and peroxidase. These findings demonstrate that inoculation with P. indica significantly enhances the resistance of Rhododendron, Jasminum sambac, and Rosa to drought and high-temperature stresses, providing insights for sustainable agricultural development and the comprehensive exploitation of the potential value of P. indica.

Keywords: Piriformospora indica; climatic change; drought stress; high-temperature stress; stress resistance.

Figure 1

Results of Trypan Blue Dyeing. (A) Root system of wild-type Rhododendron. (B) Root system of Rhododendron simsii inoculated with Pi. (C) Root system of wild-type Jasminum sambac. (D) Root system of Jasminum sambac inoculated with Pi. (E) Root system of wild-type Rosa chinensis cuttings. (F) Root system of Rosa chinensis inoculated with Pi Arrow: Spores.

Figure 2

Statistics of leaf wilting rate before and after drought stress. The small letters (such as 'a' and 'b') in the bar graphs of your figures typically indicate statistical significance among the treatments, which is often determined through post-hoc analysis after ANOVA testing, such as Tukey's test or LSD (Least Significant Difference) test.

Figure 3

Phenotypic difference of Rhododendron cuttings before and after drought stress and leaf wilting rate. (A) Before drought stress of cuttings inoculated with Piriformospora indica: (B) After drought stress of cuttings inoculated with Piriformospora indica for 7 days: (C) Before the drought stress of the cuttings inoculated with Piriformospora indica 7 days: (D) After the drought stress of the cuttings inoculated with Piriformospora indica for 7 days.

Figure 4

Phenotypic difference of Jasminum sambac cuttings before and after drought stress and leaf wilting rate. (A) Before drought stress of cuttings inoculated with Piriformospora indica: (B) After drought stress of cuttings inoculated with Piriformospora indica for 7 days: (C) Before the drought stress of the cuttings inoculated with Piriformospora indica 7 days: (D) After the drought stress of the cuttings inoculated with Piriformospora indica for 7 days.

Figure 5

Phenotypic difference of Rosa chinensis cuttings before and after drought stress and leaf wilting rate. (A) Before drought stress of cuttings inoculated with Piriformospora indica. (B) After drought stress of cuttings inoculated with Piriformospora indica for 7 days. (C) Before the drought stress of the cuttings inoculated with Piriformospora indica 7 days. (D) After the drought stress of the cuttings inoculated with Piriformospora indica for 7 days.

Figure 6

Malondialdehyde Content after drought stress. (A) Malondialdehyde content in Rhododendron seedlings after drought stress; (B) Malondialdehyde content in Jasminum sambac seedlings after drought stress; (C) Malondialdehyde content in Rosa chinensis seedlings after drought stress. The small letters (such as 'a' and 'b') in the bar graphs of your figures typically indicate statistical significance among the treatments, which is often determined through post-hoc analysis after ANOVA testing, such as Tukey's test or LSD (Least Significant Difference) test.

Figure 7

Chlorophyll content after drought stress. (A) Chlorophyll content in Rhododendron seedlings after drought stress: (B) Chlorophyll content in Jasminum sambac seedlings after drought stress: (C) Chlorophyll content in Rosa chinensis seedlings after drought stress. The small letters (such as 'a' and 'b') in the bar graphs of your figures typically indicate statistical significance among the treatments, which is often determined through post-hoc analysis after ANOVA testing, such as Tukey's test or LSD (Least Significant Difference) test.

Figure 8

3,3’-Diaminobenzidine (DAB) and Nitroblue Tetrazolium (NBT) staining results of Rhododendron, Rosa chinensis, and Jasminum sambac cuttings. (A) DAB staining results of Rhododendron cuttings (a). Rosa chinensis cuttings (b), and Jasminum sambac cuttings (c). (B) DAB staining results of Rhododendron cuttings inoculated with Piriformospora indica (a), Rosa chinensis cuttings inoculated with Piriformospora indica (b), and Jasminum sambac cuttings inoculated with Piriformospora indica (c). (C) NBT staining results of Rhododendron cuttings (a), Rosa chinensis cuttings (b), and Jasminum sambac cuttings (c). (D) NBT staining results of Rhododendron cuttings inoculated with Piriformospora indica (a), Rosa chinensis cuttings inoculated with Piriformospora indica (b), and Jasminum sambac cuttings inoculated with Piriformospora indica (c).

Figure 9

Fv/Fm chlorophyll fluorescence images of cutting seedlings before and after high temperature stress. The first two are rhododendron leaves, the middle two are moon leaves, and the last two are Jasminum sambac leaves.The color scale beneath the figures ranges from 0 (black) to 100 (pink), indicating the degree of leaf damage from high to low.

Figure 10

The effect of high temperature stress on FV/Fm cutting seedling. (A) FV/Fm ratio of Rhododendron cuttings after heat stress: (B) FV/Fm ratio of Jasminum sambac cuttings after heat stress: (C) FV/Fm ratio of Rosa chinensis cuttings after heat stress. The small letters (such as 'a' and 'b') in the bar graphs of your figures typically indicate statistical significance among the treatments, which is often determined through post-hoc analysis after ANOVA testing, such as Tukey's test or LSD (Least Significant Difference) test.

Figure 11

Tissue Culture seedlings of Rhododendron under high temperature stress. (A, I) Tissue cultured seedlings of Rhododendron before high temperature stress: (B, J) Tissue cultured seedlings of Rhododendron inoculated with P. indica before high temperature stress: (E, M) Tissue cultured seedlings of Rhododendron after high temperature stress: (F, N) Tissue cultured seedlings of Rhododendron inoculated with P. indica after high temperature stress: (C, D, K, L) Detail picture before high temperature stress: (G, H, O, P) Detail picture after high temperature stress.

Figure 12

Survival rate of Rhododendron plantlets inoculated and uninoculated with Piriformospora indica at 42°C. The small letters (such as 'a' and 'b') in the bar graphs of your figures typically indicate statistical significance among the treatments, which is often determined through post-hoc analysis after ANOVA testing, such as Tukey's test or LSD (Least Significant Difference) test.

Figure 13

DAB (3,3’-Diaminobenzidine) and Nitroblue Tetrazolium (NBT) staining results of Rhododendron tissue culture seedlings. (A) DAB staining results showing the presence of reactive oxygen species (ROS) in Rhododendron tissue culture seedlings without Piriformospora indica inoculation (top panel) and with Piriformospora indica inoculation (bottom panel). (B) NBT staining results indicating the accumulation of superoxide in Rhododendron tissue culture seedlings without Piriformospora indica inoculation (top panel) and with Piriformospora indica inoculation (bottom panel).

Figure 14

Effects on the physiological characteristics of plants inoculated with Piriformospora indica under high temperature and drought stress conditions.