Coupling physiological analysis with proteomic profile to understand the photosynthetic responses of young Euterpe oleracea palms to drought

Proteomics analysis of the effects for different salt ions in leaves of true halophyte Sesuvium portulacastrum

Sesuvium portulacastrum is a true halophyte and shows an optimal development under moderate salinity with large amounts of salt ions in its leaves. However, the specific proteins in response to salt ions are remained unknown. In this study, comparative physiological and proteomic analyses of different leaves subject to NaCl, KCl, NaNO₃ and KNO₃ were performed. Chlorophyll content was decreased under the above four kinds of salt treatments. Starch and soluble sugar contents changed differently under different salt treatments. A total of 53 differentially accumulated proteins (DAPs) were identified by mass spectrometry. Among them, 13, 25, 26 and 25 DAPs were identified after exposure to KCl, NaCl, KNO_3, and NaNO₃, respectively. These DAPs belong to 47 unique genes, and 37 of them are involved in protein-protein interactions. These DAPs displayed different expression patterns after treating with different salt ions. Functional annotation revealed they are mainly involved in photosynthesis, carbohydrate and energy metabolism, lipid metabolism, and biosynthesis of secondary metabolites. Genes and proteins showed different expression profiles under different salt treatments. Enzyme activity analysis indicated P-ATPase was induced by KCl, NaCl and NaNO₃, V-ATPase was induced by KCl and NaCl, whereas V-PPase activity was significantly increased after application of KNO₃, but sharply inhibited by NaCl. These results might deepen our understanding of responsive mechanisms in the leaves of S. portulacastrum upon different salt ions.

Salicylic acid alleviated the effect of drought stress on photosynthetic characteristics and leaf protein pattern in winter wheat

Salicylic acid (SA) is a promising compound to increase plant tolerance to drought stress, and it can affect many aspects of physiological and biochemical processes. This study was focused on the changes in proteins, photosynthesis, and antioxidant system of Sardari wheat ecotypes leave in response to the application of SA under drought stress conditions. Treatments included Sardari wheat ecotypes (Baharband, Kalati, Fetrezamin, Gavdareh, Telvar, and Tazehabad), salicylic acid at 0.5 mM (controls were untreated), and drought stress (30% of the field capacity). The results showed that membrane electrolyte leakage, and lipid peroxidation of all six ecotypes, were obviously increased under drought stress conditions. On the other hand, drought stress decreased leaf chlorophyll content, photosynthetic rate, stomatal conductance, carboxylation efficiency, and transpiration rate. The results of SDS-PAGE indicated that the abundance of some protein spots was downregulated when the plants were exposed to drought stress, while other protein spots' abundance was upregulated in such a situation. Under stress conditions, the highest antioxidant enzymatic activity, photosynthetic performance, cell membrane stability, and numbers of protein bands were observed in Baharband and Telvar, while the lowest was related to Fetrezamin. Salicylic acid treatments effectively ameliorated the negative effects of drought stress on Sardari ecotypes through improving the photosynthetic performance, keeping membrane permeability, induction of stress proteins, and enhancing the activity of antioxidant enzymes. The above findings suggest that ecotype ability to maintain photosynthetic performance was important to cope with drought stress.

Dynamic proteomic analysis of Phanerochaete chrysosporium under copper stress

The model white rot fungus Phanerochaete chrysosporium is frequently preferred for heavy metal accumulation studies due to its high resistance to heavy metals, including copper (Cu). Here, the response of P. chrysosporium under Cu stress at different time points was investigated for the first time by a detailed proteomic analysis using 2DE MALDI-TOF/MS and nanoLC-MS/MS techniques. A total of 123 Cu-responsive protein spots were determined using 2DE approach, and 104 of them were corresponded to 73 distinct open reading frames (ORFs). Of identified ones, 88 spots were over-, and 16 spots were underrepresented. The majority of these proteins showed to the strongest response at 8th h of Cu exposure. Using nanoLC-MS/MS analysis, a total of 167 differentially produced proteins were identified from Cu-exposed cultures after enrichment of the membrane proteins followed by SILAC. Seventy four, 66, and 69 overrepresented, and 56, 71, and 64 underrepresented proteins were identified at 2 h, 4 h, and 8 h of Cu exposure, respectively. The bioinformatic analysis of these proteins revealed that intracellular trafficking proteins such as Ran GTPase and a p24 family protein, and certain proteins involved in posttranslational modification, protein turnover and folding were Cu-responsive. Three important transcription factors (TFs), NAC, BTF3, and homeobox TFs, 40S and 60S ribosomal proteins, chaperones such as Hsp26/Hsp42 and mortalin, as well as 20S proteasome, 14-3-3 proteins and Hsp90 involve in Cu-stress response of P. chrysosporium. Moreover, certain elements of translation machinery, the proteins related with aspartate, methionine, and pyruvate metabolisms, transketolase, and trehalase related with carbohydrate metabolism, citrate synthase, fumarase, V-ATPase, and F0F1-type ATPase playing role in energy production and conversion, transport proteins such as multidrug resistance and p24 family proteins as well as actin-related proteins involved in cytoskeleton remodeling were determined to be Cu-responsive. The present proteome analysis revealed that P. chrysosporium mainly regulates translational and posttranslational processes, certain transport processes, many metabolic pathways and cytoskeleton to overcome the Cu-induced oxidative stress.