Effects of Arbuscular Mycorrhizal Fungi on the Heat Resistance of

Dianthus hybridus Seedlings

Yunxin Tang

1,#

, Jia Huang

1,#

, Yunjian Guo

, Yongliang Luo

, Chunwen Li

, Zhongqun He

1,*

and Xiaoting Zhou

1,*

College of Horticulture, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China

People’s Government of Pidu District, Chengdu, Sichuan, 611730, China

Chengdu Jinping Flower Seedling Limited Liability Company, Chengdu, Sichuan, 611730, China

These authors contributed equally to this work

Keywords:

Dianthus hybridus, Arbuscular Mycorrhizal Fungi, High Temperature Stress.

Abstract:

In order to explore whether AMF can inoculation enhance heat resistance of Dianthus hybridus seedlings

under high temperature, growth indexes and gas exchange parameters chlorophyll fluorescence parameters as

well as the main heat resistance evaluation indexs were tested. The results showed that the plant height and

stem diameters of AMF-inoculated plants were significantly greater than those of non-inoculated plants. AMF

treatment also increased the net photosynthetic rate. Under high temperature stress, AMF treatment plants

decreased the MDA content, while it increased the activities of SOD, POD and CAT as well as proline content.

Under high temperature stress, AMF treatment plants suppressed the decrease of Fv'/Fm', Y(II) and qP to the

control level, and also reduced NPQ. Thus, application of AMF inoculation can promote both the plant growth

and heat resistance in Dianthus hybridus seedlings.

1 INTRODUCTION

Dianthus hybridus is an important material for

arranging flower beds and flower borders. To ensure

the production of Dianthus hybridus around the year,

seedling raising is often used. However, high

temperature is one of the limited factors of seedling

raising in Dianthus hybridus in summer, due to its

sensitivity to heat. Under high temperature stress, the

combination of strong sunlight and rapid

transpiration will lead to plant protoplast dehydration

and protein solidification, plant growth weakening,

leaf color fading, wilting and yellow, and lead to the

increase of deformed flowers. Therefore, it is

important to carry out the research on the Dianthus

hybridus of heat resistance. Therefore, it is important

to carry out the research on the Dianthus hybridus of

heat resistance. Arbuscular mycorrhizal fungi (AMF)

is a kind of soil microorganism (Liu 2009), which can

form a symbiotic relationship with more than 90%

plant (Ma 2015). Studies have shown that AMF

inoculation can promote growth of plant (Liu 2015,

Ma 2014), improve the ability of plants to resist

continuous cropping obstacles (Chen 2013), and

enhance plant stress resistance (Liu 2011, Zhang

2016, Guo 2011, Sun 2012, Ye 2019). AMF can

regulate the formation of secondary metabolites in the

host plant by changing the root morphology of the

plant, so as to improve the physical and chemical

properties of the root environment. It also changes the

microbial community structure around the root,

activates and induces a variety of mechanisms in the

process of infecting the host, increase the regulation

of plant defensive enzyme activity and gene

expression, as a result of improving plant abiotic

stress tolerance. However, the effect of AMF

inoculation on the heat resistance of Dianthus

hybridus has not been reported.

This study was based on the inoculated AMF,

measuring the growth indexes and gas exchange

parameters of the leaves of Dianthus hybridus. The

effect of AMF on the heat resistance of Dianthus

hybridus seedlings under high temperature stress

were also discussed. This authors tried to explore the

effect of AMF inoculation on the growth of Dianthus

hybridus, so as to provide a theoretical basis for the

popularization and application of AMF in the

production practice of Dianthus hybridus.

1260

Tang, Y., Huang, J., Guo, Y., Luo, Y., Li, C., He, Z. and Zhou, X.

Effects of Arbuscular Mycorrhizal Fungi on the Heat Resistance of Dianthus hybridus Seedlings.

DOI: 10.5220/0011507800003443

In Proceedings of the 4th International Conference on Biomedical Engineering and Bioinformatics (ICBEB 2022), pages 1260-1263

ISBN: 978-989-758-595-1

2 MATERIALS AND METHODS

2.1 Materials

Dianthus hybridus cv. Fanxing was used in this work,

the seeds were provided by Jinping flower seedling

limited liability company. AMF products (including

mixed bacterial agents such as Glomus mosseae,

Acaulospora morrowiae and Gigaspora gigantean)

were provided by Huai'an chaimihe agricultural

science and technology development limited

company. A commercial substrate was used for

seedling raising, with pH5.5-6.5.

2.2 Experimental Design

The experiment was conducted in the laboratory of

college of horticulture, Sichuan Agricultural

University from January 2021 to September 2021.

Before inoculation, the flowerpots were disinfected

with 75% ethanol and ventilated to dry. Two

treatments were set up: (1) CK: without adding AMF

in the substrate; (2) AMF: adding AMF in the

substrate. The Arbuscular mycorrhizal fungal agent

(spore concentration of 120 per gram) was mixed

with the seedling substrate and loaded them into 50-

well plates, with an average dosage of 50 g per plate.

Then the plates were placed in artificial climate

chamber with the temperature of 25℃/18℃

(day/night), and photoperiod 12h/12h (day/dark)

simultaneously, with Hogland nutrition solution

every three days. As for heat stress experiment, the

Dianthus hybridus seedlings were moved into the

artificial climate box for pretreatment (25℃/ 18℃

(day/night)) after 50 days of inoculation, with

photoperiod of 12h/12h (light/dark), and the relative

humidity was 70%. After 3 days, the temperature of

the artificial climate box was changed into 35℃/30℃

(day/night), the light intensity and air humidity

remained unchanged. The mature leaves of the same

growth part of each plant were sampled on the fifth

day after heat stress.

Plant height and stem diameter were measured by

using vernier caliper. The methods described by Lu

et al (Lu 2009) were used for the determination of free

proline, and the methods of measurement of

antioxidant enzyme activities and malondialdehyde

(MDA) content were described by Wang et al (Wang

2021). Gas exchange parameters were measured by

LI-6400XT Portable Photosynthesis System.

Photosynthetic fluorescence parameters were

measured by portable fluorescence parameter meter

(PAM2500).

2.3 Statistical Analyses

Statistical analysis was carried out by using SPSS

18.0 statistical software. The data were analyzed by

one-way ANOVA, with the least significant

difference at the 5% confidence level.

3 RESULTS AND DISCUSSION

3.1 Effects of AMF on Growth Indexes

and Gas Exchange Parameters in

Dianthus hybridus

After 50 days of AMF inoculation, compared with no

inoculation (CK), the AMF treatment significantly

increased the plant height of Dianthus hybridus. At

the same time, after AMF inoculation, the net

photosynthetic rate, stomatal conductance,

intercellular carbon dioxide concentration and

transpiration rate of Dianthus hybridus leaves were

significantly improved. Previous studies have shown

that arbuscular mycorrhizal can improve the strong

seedling index of wheat (Ma 2014). This study found

that AMF treatment also promoted the growth of

Dianthus hybridus, which was consistent with the

research results in Poncirus trifoliata by Zuo et al

(Zuo 2014).

Table 1: Effects of AMF on growth indexes and gas exchange parameters in Dianthus hybridus.

Treatments Plant height

(cm)

Stem

diameter

(

)

(μmol·co

·s

-1

)

(mol H

O·m

-1

)

(μmol·co

·mol

)

(mmol

O·m

-2

-1

)

CK 15.60±1.09b 0.06±0.01b 2.03±0.38b 0.08±0.02b 336.19±1.61b 1.44±0.38b

AMF 20.83±2.86a 0.12±0.02a 6.12±1.07a 0.16±0.02a 355.63±7.93a 3.83±0.78a

Value are means ± standard errors. Means with the same letter within each column are not significantly different at p < 0.05

Effects of Arbuscular Mycorrhizal Fungi on the Heat Resistance of Dianthus hybridus Seedlings

1261

3.2 Effects of AMF on Proline,

Malondialdehyde (MDA) Contents

and Antioxidant Enzyme Activities

in Dianthus hybridus at High

Temperature

It can be seen from the Table 2 that the activities of

antioxidant enzymes including SOD, POD and CAT

were increased on the 5th day of high temperature

stress. And AMF treatment also increased the

activities of antioxidant enzymes. Compared with the

heat stress treatment without AMF inoculation (HT),

SOD, POD and CAT were increased by 18.09%,

7.22% and 29.86% under HT+AMF treatment,

respectively. On the other hand, compared with the

control, the content of proline were increased by

43.98% and 141.43% in HT and HT+AMF,

respectively. HT+AMF treatment significantly

increased the activity of SOD compared with HT.

Protective enzyme systems such as SOD, POD and

CAT and ascorbic acid glutathione (AsA-GSH)

cycle

system play an extremely important role in the

process of scavenging reactive oxygen species free

radicals and peroxides. They work synergistically

with peroxidase isozymes and other non enzymatic

systems, so as to regulate membrane permeability,

prevent membrane lipid peroxidation and reduce the

damage of membrane system. In this study, there was

higher antioxidant enzyme activities with the AMF

treatment.

On the other hand, compared with the control, the

content of MDA were increased by 46.88% in HT and

were increased by 31.25% in HT+AMF. The

improvement of antioxidant enzyme activity can

promote the scavenging ability of reactive oxygen

species and improve the stress adaptability. Proline is

an osmotic protective agent, and its accumulation is

positively correlated with the stress resistance of

plants. The results of this study showed that AMF

inoculation could significantly improve the content of

proline in Dianthus hybridus in responce to heat

stress, improving the ability of heat adaptation. The

results were consistent with the results in Lactuca

satica L. by Ma et al (Ma 2015).

Table 2: Effects of AMF on proline, MDA contents and antioxidant enzyme activities of Dianthus hybridus at high

temperature.

Treatments SOD

activity

(

U·

-1

)

POD

activity

(

U·

-1

)

CAT

activity

(

U·

-1

)

MDA

content

(μg

-1

)

Pro

content

(μg

-1

)

8.83±0.66b 11.98±0.90b 3.50±1.04b 0.32±0.03b 15.71±4.34c

HT 10.61±0.75b 14.81±1.04a 5.29±0.47ab 0.47±0.05a 22.62±3.01b

HT+AMF 12.53±1.25a 15.88±1.40a 6.87±1.12a 0.22±0.08b 37.93±2.00a

Value are means ± standard errors. Means with the same letter within each column are not significantly different at p < 0.05.

3.3 Effects of AMF on Chlorophyll

Fluorescence Parameters of

Dianthus hybridus Under Heat

Stress

High temperature stress significantly decreased

Fv'/Fm', Y(II), qP in chlorophyll fluorescence

parameters of Dianthus hybridus leaves, but

significantly increased NPQ, indicating that high

temperature inhibited the potential activity of

photosynthetic reaction center II and hindered cyclic

photosynthetic electron transfer of Dianthus hybridus

leaves. Compared with HT, HT+AMF could inhibit

the decreases of Fv'/ Fm', Y (II) and qP under high

temperature, indicating that the inhibitory effect of

high temperature on photosynthetic electron transfer

was reduced to a certain extent. In addition, Fv/Fm

did not decrease after 5d of high temperature stress,

indicating that the photosynthetic structure of

Dianthus hybridus leaves were not damaged.

Table 3: Effect of AMF on chlorophyll fluorescence parameters of Dianthus hybridus at high temperature.

Treatment Fv/Fm Fv'/Fm' Y(II) qP NPQ

0.79±0.01a 0.64±0.04a 0.49±0.02a 0.79±0.01a 0.61±0.15b

HT 0.79±0.01a 0.56±0.03b 0.27±0.04b 0.55±0.12b 0.86±0.07a

HT+AMF 0.78±0.01a 0.69±0.02a 0.54±0.02a 0.84±0.03a 0.48±0.02b

Value are means ± standard errors. Means with the same letter within each column are not significantly different at p < 0.05.

ICBEB 2022 - The International Conference on Biomedical Engineering and Bioinformatics

1262

4 CONCLUSION

Comprehensive analysis showed that high

temperature stress had significant effects on the

physiological parameters and chlorophyll

fluorescence parameters of Dianthus hybridus.

Inoculation with AMF can alleviate the damage

caused by high temperature stress to the activity of

antioxidant enzymes, osmotic regulators and

photosynthetic electron transport system, and

improve the heat resistance of Dianthus hybridus to a

certain extent.

ACKNOWLEDGEMENTS

This work was financially supported by Introduction

and breeding of new varieties of European flowers

(NO.2022349001).

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