Physiological and proteomic analyses of the drought stress response in Amygdalus Mira (Koehne) Yü et Lu roots

Abstract

Background: Plants are oftentimes exposed to many types of abiotic stresses. Drought is one of the main environmental stresses which limits plant growth, distribution and crop yield worldwide. Amygdalus mira (Koehne) Yü et Lu is an important wild peach, and it is considered an ideal wild peach germplasm for improving cultivated peach plants. Because of the loss of genetic variation, cultivated peach plants are sensitive to biotic and abiotic stresses. Wild peach germplasm can offer many useful genes for peach improvement. Responses to drought by withholding water have been studied in Amygdalus mira (Koehne) Yü et Lu roots. In this study, plants were divided into well-watered (control) and water-stressed (treatment) groups, and the treatment group did not receive water until the recovery period (day 16).

Results: Several physiological parameters, including root water content and root length, were reduced by drought stress and recovered after rewatering. In addition, the relative conductivity, the levels of proline, MDA and H₂O₂, and the activities of ROS scavenging enzymes (POD, APX and CAT) were increased, and none of these factors, except the level of proline, recovered after rewatering. In total, 95 differentially expressed proteins were revealed after drought. The identified proteins refer to a extensive range of biological processes, molecular functions and cellular components, including cytoskeleton dynamics (3.16% of the total 95 proteins), carbohydrate and nitrogen metabolism (6.33% of the total 95 proteins), energy metabolism (7.37% of the total 95 proteins), transcription and translation (18.95% of the total 95 proteins), transport (4.21% of the total 95 proteins), inducers (3.16% of the total 95 proteins), stress and defense (26.31% of the total 95 proteins), molecular chaperones (9.47% of the total 95 proteins), protein degradation (3.16% of the total 95 proteins), signal transduction (7.37% of the total 95 proteins), other materials metabolism (5.26% of the total 95 proteins) and unknown functions (5.26% of the total 95 proteins). Proteins related to defense, stress, transcription and translation play an important role in drought response. In addition, we also examined the correlation between protein and transcript levels.

Conclusions: The interaction between enzymatic and non-enzymatic antioxidants, the levels of proline, MDA, H₂O₂ and the relative conductivity, and the expression level of proteins in drought-treated plants all contribute to drought resistance in Amygdalus mira (Koehne) Yü et Lu.

Keywords: Amygdalus mira (Koehne) Yü et Lu; Drought; Physiological; Proteomics; Wild peach.

Fig. 1

Changes of morphological (a), 2-DE master gel of roots (b), soil water content, root water content and root length (c) of Amygdalus mira (Koehne) Yü et Lu roots during drought stress and recovery period

Fig. 2

Changes in Pro (a), MDA (b), H₂O₂ (c), and relative conductivity (d) during drought treatment and recovery

Fig. 3

Changes in POD (a), APX (b), and CAT (c) during drought treatment and recovery

Fig. 4

Hierarchical clustering of the 95 differentially expressed proteins

Fig. 5

Functional category distribution of the 95 identified proteins

Fig. 6

Relative gene expression analyses of 11 differentially expressed proteins by quantitative real-time PCR