Protein lysine acetylation is a reversible and dynamic post-translational modification. It plays an important role in regulating diverse cellular processes including chromatin dynamic, metabolic pathways, and transcription in both prokaryotes and eukaryotes. Although studies of lysine acetylome in plants have been reported, the throughput was not high enough, hindering the deep understanding of lysine acetylation in plant physiology and pathology. In this study, taking advantages of anti-acetyllysine-based enrichment and high-sensitive-mass spectrometer, we applied an integrated proteomic approach to comprehensively investigate lysine acetylome in strawberry. In total, we identified 1392 acetylation sites in 684 proteins, representing the largest dataset of acetylome in plants to date. To reveal the functional impacts of lysine acetylation in strawberry, intensive bioinformatic analysis was performed. The results significantly expanded our current understanding of plant acetylome and demonstrated that lysine acetylation is involved in multiple cellular metabolism and cellular processes. More interestingly, nearly 50% of all acetylated proteins identified in this work were localized in chloroplast and the vital role of lysine acetylation in photosynthesis was also revealed. Taken together, this study not only established the most extensive lysine acetylome in plants to date, but also systematically suggests the significant and unique roles of lysine acetylation in plants.

BackgroundHigh Salinity is a major environmental stress influencing growth and development of rice. Comparative proteomic analysis of hybrid rice shoot proteins from Shanyou 10 seedlings, a salt-tolerant hybrid variety, and Liangyoupeijiu seedlings, a salt-sensitive hybrid variety, was performed to identify new components involved in salt-stress signaling.ResultsPhenotypic analysis of one protein that was upregulated during salt-induced stress, cyclophilin 2 (OsCYP2), indicated that OsCYP2 transgenic rice seedlings had better tolerance to salt stress than did wild-type seedlings. Interestingly, wild-type seedlings exhibited a marked reduction in maximal photochemical efficiency under salt stress, whereas no such change was observed for OsCYP2-transgenic seedlings. OsCYP2-transgenic seedlings had lower levels of lipid peroxidation products and higher activities of antioxidant enzymes than wild-type seedlings. Spatiotemporal expression analysis of OsCYP2 showed that it could be induced by salt stress in both Shanyou 10 and Liangyoupeijiu seedlings, but Shanyou 10 seedlings showed higher OsCYP2 expression levels. Moreover, circadian rhythm expression of OsCYP2 in Shanyou 10 seedlings occurred earlier than in Liangyoupeijiu seedlings. Treatment with PEG, heat, or ABA induced OsCYP2 expression in Shanyou 10 seedlings but inhibited its expression in Liangyoupeijiu seedlings. Cold stress inhibited OsCYP2 expression in Shanyou 10 and Liangyoupeijiu seedlings. In addition, OsCYP2 was strongly expressed in shoots but rarely in roots in two rice hybrid varieties.ConclusionsTogether, these data suggest that OsCYP2 may act as a key regulator that controls ROS level by modulating activities of antioxidant enzymes at translation level. OsCYP2 expression is not only induced by salt stress, but also regulated by circadian rhythm. Moreover, OsCYP2 is also likely to act as a key component that is involved in signal pathways of other types of stresses-PEG, heat, cold, or ABA.

BackgroundDespite the heat-related physiology and heat-shock proteins in maize have been extensively studied, little is known about the transcriptome profiling of how the maize varieties with different genotypes responding to high temperatures. Seedling mortality of Xiantian 5 (XT) is significantly lower than that of Zhefengtian (ZF) when exposed to high temperature (42 °C for 6 h) and followed by a recovery growth (25 °C for one week). Therefore, we performed a transcriptome analysis using the total RNA extracted from the leaves of XT and ZF that were previously subjected to heat stress at 42 °C for 0 h, 0.5 h, and 3 h, respectively.ResultsA total of 516 commonly up-regulated and 1,261 commonly down-regulated genes were identified among XT/ZF, XT0.5/ZF0.5 and XT3/ZF3 using transcriptome analysis. Gene Ontology classification of the 516 up-regulated genes showed that their encoded proteins were significantly assigned to 18 cellular components, and were classified into 9 functional categories, and were involved in 9 biological processes. Most of proteins encoded by up-regulated genes were localized in chloroplast and its structural components, and involved in multiple biological processes associated with photosynthesis, indicating that these chloroplast proteins play an important role in increasing heat tolerance in sweet maize. While the proteins encoded by 1,261 down-regulated genes were significantly assigned to 31 cellular components, and were classified into 3 functional categories, and were involved in 9 biological processes. Interestingly, these proteins were involved in a series of biological processes from gene expression to translation, suggesting that lowering these processes may contribute to improved heat resistance in sweet maize. The up-regulated genes were identified to be involved in 36 distinct metabolic pathways, of which the most significant ones was secondary metabolite biosynthetic pathway. While the down-regulated genes were identified to be involved in 23 distinct metabolic pathways, of which the most significant ones were found in ribosome. Quantitative real-time PCR analysis demonstrated that 5 genes involved in the biosynthesis of secondary metabolites and photosynthesis in XT have higher abundance than those in ZF, whereas 5 ribosome genes in XT showed lower abundance than those in ZF. In addition, heat-tolerant sweet maize may keep at lower growth level than heat-sensitive one through dowregulating expression of genes related to zeatin and brassinosteroid biosynthesis to better regulate heat stress responses.ConclusionsComparative transcriptomic profiling reveals transcriptional alterations in heat-resistant and heat-sensitive sweet maize varieties under heat stress, which provides a new insight into underlying molecular mechanism of maize in response to heat stress.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-017-0973-y) contains supplementary material, which is available to authorized users.

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