Exogenous DCPTA Ameliorates Simulated Drought Conditions by Improving the Growth and Photosynthetic Capacity of Maize Seedlings

Tenglong Xie,Jing Li,Wanrong Gu,Shi Wei,Yao Meng,Danyang Qu,Lijie Li,Yongchao Wang

doi:10.1038/s41598-017-12977-1

Abstract

Previous reports have indicated that 2-(3,4-dichlorophenoxy)triethylamine (DCPTA) can promote the growth and photosynthetic capacity of plants. However, only a small number of these studies have focused on crops, and few reports have focused on whether DCPTA affects stress tolerance. In this study, maize (Zea mays L.) seedlings were pretreated with or without DCPTA and then exposed to drought stress in a controlled growth room for 7 days, and the growth and photosynthesis indexes of the seedlings were investigated. The DCPTA treatment partly counteracted the observed decreases in biomass, net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), effective photochemical efficiency of photosystem II (ΦPSII), maximum photochemical efficiency of PSII (Fv/Fm), non-photochemical quenching (NPQ), and photosynthetic pigment content and increased the minimal fluorescence (Fo) induced by drought stress. The DCPTA treatment also alleviated the damage induced by drought stress in the photosynthetic apparatus. In addition, DCPTA pretreatment simultaneously increased the root size (e.g., the length, surface area, and volume) and root hydraulic conductivity, which promoted the maintenance of higher relative leaf water contents (RLWCs) under stress conditions. These results indicate that exogenous DCPTA ameliorates simulated drought conditions by improving the growth and photosynthetic capacity of maize seedlings.

Highlights

In NADP-malic enzyme (NADP-ME)-type C4 species, atmospheric CO2 is primarily fixed into oxaloacetate through the carboxylation of phosphoenolpyruvate via phosphoenolpyruvate carboxylase (PEPCase) in mesophyll cells, and oxaloacetate is transported to the mesophyll cell chloroplasts
The simulated drought conditions induced by the 15% polyethylene glycol (PEG)-6000 treatment significantly inhibited seedling growth; the decrease in growth was partially recovered by DCPTA, and this effect was more pronounced at 15 mg/L
The shoot fresh weight, root fresh weight, shoot dry weight, root dry weight and total leaf area on the 7th day increased by 8.90%, 8.88%, 5.75%, 13.46% and 8.20% in the 25 mg/L DCPTA treatment group, respectively; decreased by 45.50%, 39.80%, 37.93%, 32.69% and 28.90% in the 15% PEG-6000 treatment group, respectively; and decreased by 30.99%, 23.44%, 25.28%, 15.38% and 19.97% in the 15% PEG-6000+15 mg/L DCPTA treatment group, respectively

Summary

Introduction

In NADP-ME-type C4 species, atmospheric CO2 is primarily fixed into oxaloacetate through the carboxylation of phosphoenolpyruvate via phosphoenolpyruvate carboxylase (PEPCase) in mesophyll cells, and oxaloacetate is transported to the mesophyll cell chloroplasts. The tertiary amine bioregulator 2-(3,4-dichlorophenoxy) triethylamine (DCPTA) has been reported to increase the dry weight of leaves, stems, and roots in tomatoes[16], increase the root development and leaf areas of radishes and beets[17], and increase the chloroplast volume and ribulose-1,5-bisphosphate activity in the mature leaves of sugar beets[18]. This compound promotes CO2 fixation in cotton[19], accelerates seedling growth and enhances chlorophyll biosynthesis in blue spruce[20] and guayule[21], and stimulates carotenoid biosynthesis in citrus[22]. The present study was performed to investigate the effects and underlying mechanisms of DCPTA on maize under non-stressed and simulated drought conditions

Methods

Results

Discussion

Conclusion