PDF1.5 Enhances Adaptation to Low Nitrogen Levels and Cadmium Stress.

Zhimin Wu,Dong Liu,Jinsong Luo,Ningyan Yue,Zhenhua Zhang,Haixing Song

doi:10.3390/ijms221910455

Abstract

Environmental acclimation ability plays a key role in plant growth, although the mechanism remains unclear. Here, we determined the involvement of Arabidopsis thaliana PLANT DEFENSIN 1 gene AtPDF1.5 in the adaptation to low nitrogen (LN) levels and cadmium (Cd) stress. Histochemical analysis revealed that AtPDF1.5 was mainly expressed in the nodes and carpopodium and was significantly induced in plants exposed to LN conditions and Cd stress. Subcellular localization analysis revealed that AtPDF1.5 was cell wall- and cytoplasm-localized. AtPDF1.5 overexpression significantly enhanced adaptation to LN and Cd stress and enhanced the distribution of metallic elements. The functional disruption of AtPDF1.5 reduced adaptations to LN and Cd stress and impaired metal distribution. Under LN conditions, the nitrate transporter AtNRT1.5 expression was upregulated. Nitrate transporter AtNRT1.8 expression was downregulated when AtPDF1.5 was overexpressed, resulting in enhanced transport of NO3− to shoots. In response to Cd treatment, AtPDF1.5 regulated the expression of metal transporter genes AtHMP07, AtNRAMP4, AtNRAMP1, and AtHIPP3, resulting in higher Cd accumulation in the shoots. We conclude that AtPDF1.5 is involved in the processing or transmission of signal substances and plays an important role in the remediation of Cd pollution and LN adaptation.

Highlights

Environmental acclimation ability plays a crucial role in plant growth, and nutrient element transport is a key factor in environmental acclimation [1,2,3]
When Col-0 plants were grown under low nitrogen (LN) conditions, the expression of AtPDF1.5 was upregulated in both shoots and roots (Figure S1a,c), whereas in plants treated with Cd, AtPDF1.5 was highly upregulated in roots, but not significantly in shoots (Figure S1b,d)
To determine the mechanisms underlying the observed differences in metal distribution, we examined the expression of selected metal transporter genes (AtHMP07, AtNRAMP4, AtNRAMP1, and AtHIPP3) in Arabidopsis seedlings subjected to the CK, LN, and Cd treatments (Figure 8)

Summary

Introduction

Environmental acclimation ability plays a crucial role in plant growth, and nutrient element transport is a key factor in environmental acclimation [1,2,3]. Shoots are the main sites of photosynthesis and metabolism in plants [5,6], and the translocation of NO3− from roots to shoots has been reported to be one of the main processes contributing to plant growth and higher nitrogenuse efficiency [7]. Metallic elements play vital roles in plant growth and stress resistance [12,13], with different metals having specific functions [14]. Potassium (K) can promote the activation of enzymes and enhance photosynthesis, sugar metabolism, and protein synthesis, thereby enhancing the ability of plants to resist drought, cold, salt, alkaline stresses, diseases, and pests [15,16]. Cu is a component of enzymes such as cytochrome oxidase, phenoloxidase, ascorbic acid oxidase, polyamine oxidase, and peroxide dismutase involved in respiratory metabolism [21,22]

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