Project description:Salt stress causes the quality change and significant yield loss of tomato. However, the resources of salt-resistant tomato were still deficient and the mechanisms of tomato resistance to salt stress were still unclear. In this study, the proteomic profiles of two salt-tolerant and salt-sensitive tomato cultivars were investigated to deciphered the salt-resistance mechanism of tomato and provide novel resources for tomato breeding. We found that there is an over-abundant proteins relevant to Nitrate and amino acids metabolisms in the Salt-tolerant cultivars. The significant increase in expression of proteins involved in Brassinolides and GABA biosynthesis were verified in salt-tolerant cultivars, strengthening the salt resistance of tomato. Meanwhile, salt-tolerant cultivars with higher abundance and activity of antioxidant-related proteins have more advantages in dealing with reactive oxygen species caused by salt stress. And the salt-tolerant cultivars had higher photosynthetic activity based on overexpression of proteins functioned in chloroplast, guaranteeing the sufficient nutrient for plant growth under salt stress. Furthermore, three key proteins were identified as important salt-resistant resources for breeding salt-tolerant cultivars, including Sterol side chain reductase, gamma aminobutyrate transaminase and Starch synthase. Our results provided series valuable strategies for salt-tolerant cultivars which can be used in future
Project description:C4 grasses, such as maize (Zea mays), have high photosynthetic efficiency through combined biochemical and structural adaptations.C4 photosynthesis is established along the developmental axis of the leafblade, leading from an undifferentiated leaf base just above the ligule into highly specialized mesophyll cells (MCs) and bundle sheath cells (BSCs) at the tip. To resolve the kinetics of maize leaf development and C4 differentiation and to obtain a systems-level understanding of maize leaf formation, the accumulation profiles of proteomes of the leaf and the isolated BSCs with their vascular bundle along the developmental gradient were determined using large-scale mass spectrometry. This was complemented by extensive qualitative and quantitative microscopy analysis of structural features (e.g., Kranz anatomy, plasmodesmata, cell wall, and organelles). More than 4300 proteins were identified and functionally annotated. Developmental protein accumulation profiles and hierarchical cluster analysis then determined the kinetics of organelle biogenesis, formation of cellular structures, metabolism, and coexpression patterns. Two main expression clusters were observed, each divided in subclusters, suggesting that a limited number of developmental regulatory networks organize concerted protein accumulation along the leaf gradient. The coexpression with BSC and MC markers provided strong candidates for further analysis of C4 specialization, in particular transporters and biogenesis factors. Based on the integrated information, we describe five developmental transitions that provide a conceptual and practical template for further analysis. An online protein expression viewer is provided through the PlantProteomeDatabase.
Project description:During Zea mays (maize) C4 differentiation, mesophyll (M) and bundle sheath (BS) cells accumulate distinct sets of photosynthetic enzymes, with very low photosystem II (PSII) content in BS chloroplasts. Consequently, there is little linear electron transport in the BS and ATP is generated by cyclic electron flow. In contrast, M thylakoids are very similar to those of C3 plants and produce the ATP and NADPH that drive metabolic activities. Regulation of this differentiation process is poorly understood but involves expression and coordination of nuclear and plastid genomes. Here, we identify a recessive allele of the maize Hcf136 homologue that in Arabidopsis thaliana functions as a PSII stability or assembly factor located in the thylakoid lumen. Proteome analysis of the thylakoids and electron microscopy reveal that Zm hcf136 lacks PSII complexes and grana thylakoids in M chloroplasts, consistent with the previously defined Arabidopsis function. Interestingly, hcf136 is also defective in processing the full-length psbB-psbT-psbH-petB-petD polycistron specifically in M chloroplasts. To determine whether the loss of PSII in M cells affects C4 differentiation, we performed cell-type specific transcript analysis of hcf136 and wild-type seedlings. The results indicate that M and BS cells respond uniquely to the loss of PSII, with little overlap in gene expression changes between data sets. These results are discussed in the context of signals that may drive differential gene expression in C4 photosynthesis. To explore the disruption of PSII activity on gene expression, transcript profiles from separated M and BS cells were examined using two-label microarray analysis. Total RNA was isolated from the second leaves of mutant and wild-type silbings. Six biological replicates were used to compare wild-type and mutant transcript profiles in separate M and BS experiments. To maximize biological replication, different seedling pools were used for each of the 12 hybridizations. Microarray experiments and analyses were performed using the Genisphere MPX900 kit and the Maize Array Consortium oligonucleotide platform (GPL5439; GPL5440). Feature intensity values were log-transformed and corrected for local background signal, and a LOWESS procedure (Dudoit et al., 2002) was used to normalize between channels. Features with either low or saturating signal intensity were discarded from further analysis. High expression filtering was less stringent to avoid elimination of previously characterized, high abundance, C4 cell-specific transcripts. After filtering, features that were not assigned an MZ number by the Maize Array Consortium were discarded from further analysis. The moderated t-test (Smyth, 2004) using the R package limma was applied to identify differentially expressed genes. The p-values for each test (gene) were converted to q-values for false discovery rate analysis as described by Storey et al. (2004). To avoid confounding treatment effects associated with direct comparisons of M and BS transcriptomes (Sawers et al., 2007), comparisons were only made using the same cell type across the hcf136 and wild-type sibling genotypes. Bundle sheath (BS) Samples: GSM245063-GSM245164 Mesophyll (M) Samples: GSM245165 - GSM245206
Project description:Two maize genotypes exhibiting differential tolerance towards LT including the temperate grown Gurez local and its tropical counterpart GM6 were dissected for analysing and characterizing the functions of differentially regulated proteins (DRPs) in response to LT stress.
Project description:Lotus (Nelumbo nucifera Gaertn) belongs to the family Nymphaeaceae, and is a popular aquatic vegetable that is rich in nutrients. It is widely cultivated in China, and many varieties of lotus are used for different purposes, suited to different climates, and consumed in different ways. Lotus is commonly produced by asexual propagation, so mutation through hybridization and variation fixed by asexual propagation are the main ways to create new varieties. Therefore, the formation of adventitious roots (ARs) in lotus, which does not have a well-developed principal root, is an important part of growth and development. It would be very useful to control ARs formation for lotus production and breeding.
Project description:We conducted a RNA-Seq analysis of MeJA-treated Chinese cabbage leaf transcriptome. Total 14,619,469 sequence reads were generated to produce 27,461 detected genes, among which 1,451 genes were up-regulated and 991 genes were down-regulated as differentially expressed genes (DEGs) (log2 ratio â¥1, false discovery rate â¤0.001). More than 90% of the DEGs (2,278) were between 1.0- and 3.0-fold (log2 ratio). The most highly represented pathways by 1,674 annotated DEGs were related to âmetabolic pathwaysâ (333 members), âribosomeâ (314 members), âbiosynthesis of secondary metabolitesâ (218 members), âplant-pathogen interactionâ (146 members), and âplant hormone signal transductionâ (99 members). Fourteen genes involved in JA biosynthesis pathway were up-regulated. As many as 182 genes for the biosynthesis of several secondary metabolites were induced, and the level of indole glucosinolate was highly increased by MeJA treatment. The genes encoding sugar catabolism and some amino acids synthesis were up-regulated, which could supply structural intermediates and energy for the biosynthesis of secondary metabolites. The results demonstrated a high degree of transcriptional complexity with dynamic coordinated changes in global gene expression of Chinese cabbage in response to MeJA treatment. It expands our understanding of the complex molecular events on JA-induced plant resistance and accumulation of secondary metabolites. It also provides a foundation for further studies on the molecular mechanisms of different pathways in other Brassica crops under MeJA treatment. Transcriptomic analysis of MeJA-treated Chinese cabbage leaf
Project description:Plastids contain multiple copies of the plastid chromosome, folded together with proteins and RNA into nucleoids. The degree to which components of the plastid gene expression and protein biogenesis machineries are nucleoid associated, and the factors involved in plastid DNA organization, repair, and replication, are poorly understood. To provide a conceptual framework for nucleoid function, we characterized the proteomes of highly enriched nucleoid fractions of proplastids and mature chloroplasts isolated from the maize (Zea mays) leaf base and tip, respectively, using mass spectrometry. Quantitative comparisons with proteomes of unfractionated proplastids and chloroplasts facilitated the determination of nucleoid-enriched proteins. This nucleoid-enriched proteome included proteins involved in DNA replication, organization, and repair as well as transcription, mRNA processing, splicing, and editing. Many proteins of unknown function, including pentatricopeptide repeat (PPR), tetratricopeptide repeat (TPR), DnaJ, and mitochondrial transcription factor (mTERF) domain proteins, were identified. Strikingly, 70S ribosome and ribosome assembly factors were strongly overrepresented in nucleoid fractions, but protein chaperones were not. Our analysis strongly suggests that mRNA processing, splicing, and editing, as well as ribosome assembly, take place in association with the nucleoid, suggesting that these processes occur cotranscriptionally. The plastid developmental state did not dramatically change the nucleoid-enriched proteome but did quantitatively shift the predominating function from RNA metabolism in undeveloped plastids to translation and homeostasis in chloroplasts. This study extends the known maize plastid proteome by hundreds of proteins, including more than 40 PPR and mTERF domain proteins, and provides a resource for targeted studies on plastid gene expression. Details of protein identification and annotation are provided in the Plant Proteome Database.
Project description:We use the gowth zone of the maize leaf as a model system to study the growth reduction in response to drought stress. The spatial gradient and the relatively large size of the maize leaf allowed us to sample at a subzonal rezolution and to examine different developmental stages at the same time. We compared the response to different levels of drought stress (mild and severe) of proliferating (meristem), expanding (elongation zone) and differentiated (mature zone) tissue. Three separate loop designs were used for the three zones of the maize leaf (meristem, elongation zone, and mature zone). In each loop three treatments were contrasted (control, mild stress, and severe stress). Four biological replicates were used for each zone/condition (4 replicates x 3 zones x 3 conditions = 36 samples).