Proteomic analysis reveals response of differential wheat (Triticum aestivum L.) genotypes to oxygen deficiency stress

Abstract

Background: Waterlogging is one of the main abiotic stresses that limit wheat production. Quantitative proteomics analysis has been applied in the study of crop abiotic stress as an effective way in recent years (e.g. salt stress, drought stress, heat stress and waterlogging stress). However, only a few proteins related to primary metabolism and signal transduction, such as UDP - glucose dehydrogenase, UGP, beta glucosidases, were reported to response to waterlogging stress in wheat. The differentially expressed proteins between genotypes of wheat in response to waterlogging are less-defined. In this study, two wheat genotypes, one is sensitive to waterlogging stress (Seri M82, named as S) and the other is tolerant to waterlogging (CIGM90.863, named as T), were compared in seedling roots under hypoxia conditions to evaluate the different responses at proteomic level.

Results: A total of 4560 proteins were identified and the number of differentially expressed proteins (DEPs) were 361, 640, 788 in S and 33, 207, 279 in T in 1, 2, 3 days, respectively. These DEPs included 270 common proteins, 681 S-specific and 50 T-specific proteins, most of which were misc., protein processing, DNA and RNA processing, amino acid metabolism and stress related proteins induced by hypoxia. Some specific proteins related to waterlogging stress, including acid phosphatase, oxidant protective enzyme, S-adenosylmethionine synthetase 1, were significantly different between S and T. A total of 20 representative genes encoding DEPs, including 7 shared DEPs and 13 cultivar-specific DEPs, were selected for further RT-qPCR analysis. Fourteen genes showed consistent dynamic expression patterns at mRNA and protein levels.

Conclusions: Proteins involved in primary metabolisms and protein processing were inclined to be affected under hypoxia stress. The negative effects were more severe in the sensitive genotype. The expression patterns of some specific proteins, such as alcohol dehydrogenases and S-adenosylmethionine synthetase 1, could be applied as indexes for improving the waterlogging tolerance in wheat. Some specific proteins identified in this study will facilitate the subsequent protein function validation and biomarker development.

Keywords: Hypoxic stress; Proteomics; Triticum aestivum L.; Waterlogging tolerance.

Fig. 1

Effects of hypoxia treatment on the growth of two wheat varieties. X-axis stands for the time of treatment; T and S stand for the tolerant and sensitive varieties, respectively. Different letters indicate significant level (P < 0.05). Means ± SE (n = 30)

Fig. 2

Expression of some water-logging responsive genes at mRNA level during the treatment. Y-axis stands for the relative mRNA level, X-axis stands for the time of treatment

Fig. 3

The statistic and GO annotation of the DEPs in the two wheat varieties. (a) Numbers of differentially expressed proteins (DEPs) in S and T varieties. Y-axis stands for the number of DEPs, X-axis stands for the comparisons between different time of treatment. (b) GO annotation of the whole identified proteins and DEPs in S and T varieties. All stands for the total identified proteins, S and T stand for the DEPs identified in S and T varieties, respectively

Fig. 4

Clustering and the function classification of the DEPs. (a) S variety; (b) T variety. Left, central and right panels show the hotmap, K-means clustering and Mapman functional classification, respectively

Fig. 5

Comparison of common DEPs in S and T varieties. (a) Venn diagram of the DEPs between S (left) and T (right) varieties, and the correlation coefficient between the accumulation of the shared DEPs from the two varieties (right panel). (b) Function classification (Up) and subcellular location of the shared DEPs (Down). (c) Hot map showing the expressional patterns of the shared DEPs in S and T

Fig. 6

Functional categorization of the S and T specific DEPs. (a) S-specific DEPs; (b) T-specific DEPs. Y-axis indicate the number of proteins. Arrows indicate the enriched groups

Fig. 7

Verification of the DEPs encoding genes’ expression at mRNA level. Y-axis stands for the relative mRNA level, X-axis stands for different DEPs