Quantitative analysis of the grain amyloplast proteome reveals differences in metabolism between two wheat cultivars at two stages of grain development

Abstract Background Wheat (Triticum aestivum L.) is one of the world’s most important grain crops. The amyloplast, a specialized organelle, is the major site for starch synthesis and storage in wheat grain. Understanding the metabolism in amyloplast during grain development in wheat cultivars with different quality traits will provide useful information for potential yield and quality improvement. Results Two wheat cultivars, ZM366 and YM49–198 that differ in kernel hardness and starch characteristics, were used to examine the metabolic changes in amyloplasts at 10 and 15 days after anthesis (DAA) using label-free-based proteome analysis. We identified 523 differentially expressed proteins (DEPs) between 10 DAA and 15 DAA, and 229 DEPs between ZM366 and YM49–198. These DEPs mainly participate in eight biochemical processes: carbohydrate metabolism, nitrogen metabolism, stress/defense, transport, energetics-related, signal transduction, protein synthesis/assembly/degradation, and nucleic acid-related processes. Among these proteins, the DEPs showing higher expression levels at 10 DAA are mainly involved in carbohydrate metabolism, stress/defense, and nucleic acid related processes, whereas DEPs with higher expression levels at 15 DAA are mainly carbohydrate metabolism, energetics-related, and transport-related proteins. Among the DEPs between the two cultivars, ZM366 had more up-regulated proteins than YM49–198, and these are mainly involved in carbohydrate metabolism, nucleic acid-related processes, and transport. Conclusions The results of our study indicate that wheat grain amyloplast has the broad metabolic capability. The DEPs involved in carbohydrate metabolism, nucleic acids, stress/defense, and transport processes, with grain development and cultivar differences, are possibly responsible for different grain characteristics, especially with respect to yield and quality-related traits

Proteomics Reveals the Effects of Salicylic Acid on Growth and Tolerance to Subsequent Drought Stress in Wheat

Pretreatment with 0.5 mM salicylic acid (SA) for 3 days significantly enhanced the growth and tolerance to subsequent drought stress (PEG-6000, 15%) in wheat seedlings, manifesting as increased shoot and root dry weights, and decreased lipid peroxidation. Total proteins from wheat leaves exposed to (i) 0.5 mM SA pretreatment, (ii) drought stress, and (iii) 0.5 mM SA treatment plus drought-stress treatments were analyzed using a proteomics method. Eighty-two stress-responsive protein spots showed significant changes, of which 76 were successfully identified by MALDI-TOF-TOF. Analysis of protein expression patterns revealed that proteins associated with signal transduction, stress defense, photosynthesis, carbohydrate metabolism, protein metabolism, and energy production could by involved in SA-induced growth and drought tolerance in wheat seedlings. Furthermore, the SA-responsive protein interaction network revealed 35 key proteins, suggesting that these proteins are critical for SA-induced tolerance

Proteomics Reveals the Effects of Salicylic Acid on Growth and Tolerance to Subsequent Drought Stress in Wheat

Pretreatment with 0.5 mM salicylic acid (SA) for 3 days significantly enhanced the growth and tolerance to subsequent drought stress (PEG-6000, 15%) in wheat seedlings, manifesting as increased shoot and root dry weights, and decreased lipid peroxidation. Total proteins from wheat leaves exposed to (i) 0.5 mM SA pretreatment, (ii) drought stress, and (iii) 0.5 mM SA treatment plus drought-stress treatments were analyzed using a proteomics method. Eighty-two stress-responsive protein spots showed significant changes, of which 76 were successfully identified by MALDI-TOF-TOF. Analysis of protein expression patterns revealed that proteins associated with signal transduction, stress defense, photosynthesis, carbohydrate metabolism, protein metabolism, and energy production could by involved in SA-induced growth and drought tolerance in wheat seedlings. Furthermore, the SA-responsive protein interaction network revealed 35 key proteins, suggesting that these proteins are critical for SA-induced tolerance

Alleviation of Drought Stress by Hydrogen Sulfide Is Partially Related to the Abscisic Acid Signaling Pathway in Wheat

<div><p>Little information is available describing the effects of exogenous H₂S on the ABA pathway in the acquisition of drought tolerance in wheat. In this study, we investigated the physiological parameters, the transcription levels of several genes involved in the abscisic acid (ABA) metabolism pathway, and the ABA and H₂S contents in wheat leaves and roots under drought stress in response to exogenous NaHS treatment. The results showed that pretreatment with NaHS significantly increased plant height and the leaf relative water content of seedlings under drought stress. Compared with drought stress treatment alone, H₂S application increased antioxidant enzyme activities and reduced MDA and H₂O₂ contents in both leaves and roots. NaHS pretreatment increased the expression levels of ABA biosynthesis and ABA reactivation genes in leaves; whereas the expression levels of ABA biosynthesis and ABA catabolism genes were up-regulated in roots. These results indicated that ABA participates in drought tolerance induced by exogenous H₂S, and that the responses in leaves and roots are different. The transcription levels of genes encoding ABA receptors were up-regulated in response to NaHS pretreatment under drought conditions in both leaves and roots. Correspondingly, the H₂S contents in leaves and roots were increased by NaHS pretreatment, while the ABA contents of leaves and roots decreased. This implied that there is complex crosstalk between these two signal molecules, and that the alleviation of drought stress by H₂S, at least in part, involves the ABA signaling pathway.</p></div

Names and sequences of oligonucleotide primers used for gene amplification in this study.

<p>Names and sequences of oligonucleotide primers used for gene amplification in this study.</p

Effects of NaHS application on the relative expression levels of genes involved in the ABA metabolism pathway in wheat leaves in response to drought stress.

<p>Different lower case letters indicate significant differences (<i>p</i><0.05).</p

Effects of exogenous ABA application on the H₂S and ABA content of wheat leaves and roots in response to drought stress.

<p>Different lower case letters indicate significant differences (<i>p</i><0.05).</p

Effects of NaHS application on plant height, shoot weight, and leaf relative water content in wheat seedlings under drought stress.

<p>(A) Capital letters A, B and C stand for plant height, leaf relative water content, and shoot dry weight, respectively. (B) Different lower case letters indicate significant differences (<i>p</i><0.05).</p

Effects of NaHS pretreatment on H₂O₂ contents of wheat seedling leaves and roots (μmol/g Fw)^a^, ^b.

<p>Effects of NaHS pretreatment on H₂O₂ contents of wheat seedling leaves and roots (μmol/g Fw)<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0163082#t003fn001" target="_blank">^a</a>^, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0163082#t003fn002" target="_blank">^b</a>.</p