Effects of Exogenous Ethylene and Cobalt Chloride on Root Growth of Chinese Fir Seedlings under Phosphorus-Deficient Conditions

Hui Zhang,Shanshan Zheng,Xiangqing Ma,Min Chen,Nemin Wang,Pengfei Wu

doi:10.3390/f12111585

Abstract

Studying the effects of different concentrations of ethephon on morphological and physiological changes in the roots of Chinese fir (Cunninghamia lanceolata Lamb. Hook.) seedlings under P deficiency can reveal the internal adaptive mechanisms of these plants under nutrient stress. Herein, we investigated the effects of different ethephon and cobalt chloride concentrations under normal P supply and P deficiency. A significant effect (p < 0.05) of exogenous additive application was observed on the development of Chinese fir root length, surface area, and volume. These root development indices showed maximum values when the ethephon concentration was 0.01 g kg−1 under normal P supply and P deficiency, and they were significantly different from those under 0.04 g kg−1 ethephon treatment. Similarly, the indices showed maximum values when CoCl2 concentration was 0.01 g kg−1 under P deficiency and was significantly different (p < 0.01) from those under 0.2 g kg−1 CoCl2 treatment. Under normal P supply, an increase in ethephon concentration caused superoxide dismutase (SOD; E.C. 1.15.1.1) activity to decrease and peroxidase (POD; E.C. 1.11.1.X) activity to increase gradually. Conversely, CoCl2 addition (0.01 g kg−1) promoted SOD and POD activities under P deficiency. There were no significant differences (p > 0.05) in malondialdehyde content of seedlings among ethephon or CoCl2 treatments. In conclusion, ethylene plays a significant role in adaptative mechanisms underlying stress resistance in plants, prompting them to respond to P starvation and improving seedlings’ tolerance to P-deficient conditions.

Highlights

Plants are subjected to different biotic and abiotic stress conditions during their growth and development
We propose the following hypotheses: (1) application of low concentrations of ethylene can promote morphological and physiological development of Chinese fir under P-stress conditions, and (2) application of cobalt chloride (CoCl2 ) can inhibit the synthesis of ethylene under both normal P supply and P stress; at low concentrations, CoCl2 can promote the growth of the root system of Chinese fir under P-stress conditions, whereas, in high concentrations, CoCl2 inhibits root growth
The Chinese fir seedlings for our study were selected from 1.5 generations of a seed orchard at the state-owned forest farm in Zhangping, Fujian Province, SE China; they belonged to family no. 32, and according to a previously conducted study, these seedlings were of the “root proliferative” type, i.e., their root phenotype changed significantly under various experimental conditions [15]

Summary

Introduction

Plants are subjected to different biotic and abiotic stress conditions during their growth and development. When plants encounter adversity or stress, their hormone levels change; this enables the plants to initiate and regulate the physiological and biochemical processes related to adversity adaptation, thereby coordinating plant growth and development, and inducing the formation of stress resistance [1]. As a part of the hormone regulatory network in plants, the signal transmission of ethylene has an important role in a variety of stress conditions due to its diffusibility and sensitivity; ethylene is a rapid response factor in plants [2]. In addition to having a significant role in the growth and development of plants, many stressful situations can induce the increased secretion of ethylene. The role of ethylene in the development of stress resistance in plants is a significant area of research. Numerous studies have shown that ethylene plays an important role in salt [3]

Methods

Results

Conclusion