Brassica juncea leaf cuticle contains xylose and mannose (xylomannan) which inhibit ice recrystallization on the leaf surface.

MAIN CONCLUSION: Conjugated sugars showed antifreeze activity in the cuticle by ice recrystallization inhibition rather than thermal hysteresis, enhancing freezing capacity at the surface of B. juncea leaves. Antifreeze biomolecules play a crucial role in mitigating the physical damage from frost by controlling extracellular ice crystal growth in plants. Antifreeze proteins (AFPs) are reported from the apoplast of different plants. Interestingly, there is no report about antifreeze properties of the cuticle. Here, we report the potential antifreeze activity in the Brassica juncea (BJ) leaf cuticle. Nano LC-MS/MS analysis of a cuticle protein enriched fraction (CPE) predicted over 30 putative AFPs using CryoProtect server and literature survey. Ice crystal morphology (ICM) and ice recrystallization inhibition (IRI) analysis of ABC supernatant showed heat and pronase-resistant, non-protein antifreeze activities as well as hexagonal ice crystals with TH of 0.17 °C and IRI 46%. The ZipTip processed ABC supernatant (without peptides) had no effect on TH activity, confirming a non-protein antifreeze molecule contributing to activity. To understand the origin and to confirm the source of antifreeze activity, cuticular membranes were isolated by pectinase and cellulase hydrolysis. FTIR analysis of the intact cuticle showed xylose, mannose, cellulose, and glucose. Xylanase and cellulase treatments of the ZipTip processed ABC supernatant led to an increase in sugar content and 50% loss in antifreeze activity. UV spectroscopy and NMR analysis supported the finding of FTIR and enzyme hydrolysis suggesting the contribution of xylose and mannose to antifreeze activity. By TLC analysis, conjugated sugars were found in the cuticle. This work has opened up a new research area where the antifreeze capacity needs to be established with regard to complete characterization and mechanism of action of the antifreeze carbohydrates (conjugated sugars) on the leaf surface.

Photosynthesis regulation, cell membrane stabilization and methylglyoxal detoxification seems major altered pathways under cold stress as revealed by integrated multi-omics meta-analysis.

Climate change has altered cold weather patterns, resulting in irregular cold weather conditions, and changing the global plant distribution pattern affecting plant development processes resulting in severe yield losses. Although molecular mechanisms and interconnections are quite well studied, a cumulative understanding of plant responses to cold stress (CS) is still lacking. Through meta-analysis, integration of data at the multi-omics level and its correlation with known physiological changes to map and understand the global changes in response to CS was made. Meta-analysis was conducted using the metafor R package program based on physiological parameters like relative electrolytic leakage, malondialdehyde, soluble sugar, proline and antioxidant enzymes activity. Proline and soluble sugars showed the highest (> 1.5 mean fold) change over control thus qualifying as global markers for studying CS. Surprisingly most up-regulated (> 15-fold) DEGs corresponded with the dehydrin family and glyoxalase superfamily proteins. Functional annotations of DEGs corresponded with photosynthesis and glycolysis pathway. Proteins responsible for cell signalling and increased soluble sugars were common in all the datasets studied thus correlating with the transcriptome and proteomic data. Proline and soluble sugars were positively regulated in all the metabolomics datasets. This study supported the earlier known players like proline and soluble sugars. Surprisingly, a new player glyoxalase seems to be contributing in CS. Supplementary Information: The online version contains supplementary material available at 10.1007/s12298-023-01367-9.

Nitric oxide (NO) modulates low temperature-stress signaling via S-nitrosation, a NO PTM, inducing ethylene biosynthesis inhibition leading to enhanced post-harvest shelf-life of agricultural produce.

Low temperature (cold) stress is one of the major abiotic stress conditions affecting crop productivity worldwide. Nitric oxide (NO) is a dynamic signaling molecule that interacts with various stress regulators and provides abiotic stress tolerance. Stress enhanced NO contributes to S-nitrosothiol accumulation which causes oxidation of the -SH group in proteins leading to S-nitrosation, a post-translational modification. Cold stress induced in vivo S-nitrosation of > 240 proteins majorly belonging to stress/signaling/redox (myrosinase, SOD, GST, CS, DHAR), photosynthesis (RuBisCO, PRK), metabolism (FBA, GAPDH, TPI, SBPase), and cell wall modification (Beta-xylosidases, alpha-l-arabinogalactan) in different crop plants indicated role of NO in these important cellular and metabolic pathways. NO mediated regulation of a transcription factor CBF (C-repeat Binding Factor, a transcription factor) at transcriptional and post-translational level was shown in Solanum lycopersicum seedlings. NO donor priming enhances seed germination, breaks dormancy and provides tolerance to stress in crops. Its role in averting stress, promoting seed germination, and delaying senescence paved the way for use of NO and NO releasing compounds to prevent crop loss and increase the shelf-life of fruits and vegetables. An alternative to energy consuming and expensive cold storage led to development of a storage device called "shelf-life enhancer" that delays senescence and increases shelf-life at ambient temperature (25-27 °C) using NO donor. The present review summarizes NO research in plants and exploration of NO for its translational potential to improve agricultural yield and post-harvest crop loss. Supplementary Information: The online version contains supplementary material available at 10.1007/s12298-023-01371-z.

Dioscorea Alata Tuber Proteome Analysis Uncovers Differentially Regulated Growth-associated Pathways of Tuber Development.

During its life cycle, the Dioscorea tuber undergoes multiple morphological and biochemical changes. To gain a better understanding of the metabolic changes associated with tuber growth, a stage-specific gel-free proteome analysis of four distinct morphological stages namely germinating tuber (S1), degrading tuber (S2), new tuber formation (S3) and tuber maturation (S4) was done and validated by principal component analysis. A comprehensive data set identifying 78.2% of the total 3,681 proteins was generated. PANTHER and KEGG MAPPER revealed both expected (carbohydrate metabolism and redox regulation) and novel biological processes (transcription factors and hormonal regulation) characteristic for each developmental stage. Higher abundance of the enzymes of ascorbate-glutathione cycle and carbohydrate metabolism was detected during tuber germination (S1) and tuber formation stages (S3) in comparison with the mature tuber. The presence of ethylene biosynthesis components during tuber formation hints toward its probable role in postharvest shelf life. The data set comprehensively describes the proteome of Dioscorea tuber and provides growth-specific markers for tuber germination (ascorbate peroxidase, monodehydroascorbate reductase, invertase) and tuber formation (sucrose synthase), which were validated by enzyme activity assays and Western blotting. The study provides information that may influence the direction of research for improving the productivity of this under-utilized and largely neglected crop.

Plant RABs: Role in Development and in Abiotic and Biotic Stress Responses.

Endosomal trafficking plays an integral role in various eukaryotic cellular activities and is vital for higher-order functions in multicellular organisms. RAB GTPases are important proteins that influence various aspects of membrane traffic, which consequently influence many cellular functions and responses. Compared to yeast and mammals, plants have evolved a unique set of plant-specific RABs that play a significant role in their development. RABs form the largest family of small guanosine triphosphate (GTP)-binding proteins, and are divided into eight sub-families named RAB1, RAB2, RAB5, RAB6, RAB7, RAB8, RAB11 and RAB18. Recent studies on different species suggest that RAB proteins play crucial roles in intracellular trafficking and cytokinesis, in autophagy, plant microbe interactions and in biotic and abiotic stress responses. This review recaptures and summarizes the roles of RABs in plant cell functions and in enhancing plant survival under stress conditions.

Ecophysiolomic analysis of stress tolerant Himalayan shrub Hipppophae rhamnoides shows multifactorial acclimation strategies induced by diverse environmental conditions.

Climatic fluctuations are a major global concern, affecting the agronomic productivity of plants. Hippophae rhamnoides a naturally growing stress tolerant Himalayan shrub was chosen to understand its stress hardiness mechanism. Comparative proteomic and biochemical analysis were done for pooled berry populations (HrB13 and HrB14) growing in two different environmental conditions. HrB13, growing under sub-optimal environmental conditions exhibited differential abundance of stress responsive proteins, which were the rate limiting enzymes associated with stress-responsive metabolic pathways, including Xanthine dehydrogenase (reactive oxygen species [ROS] signaling), Farnesyl diphosphate synthase (phenylpropanoid pathway), endosomal BRO-1 domain protein (ultraviolet [UV]-light stress), Phosphofructokinase (sugar metabolism) and Ubiquitin thioesterase (protein alterations). Biochemical investigations showed a positive correlation between proteomic plasticity (HrB13) and 1.6 to 15-fold accumulation of downstream adaptive metabolic signatures like enzymes and antioxidants involved in ROS scavenging pathways (Catalase, Ascorbate peroxidase, Glutathione reductase, ascorbate and glutathione content), secondary metabolites (phenolics, flavonoids, carotenoids) and polyunsaturated fatty acids (∝ - linolenic acid and linoleic acid). Interactome and KEGG pathway analysis also supported interactions of differentially accumulated proteins with stress-responsive signaling components involved in physiological pathways associated with stress tolerance. This is the first 'ecophysiolomics' study, showing the response of seabuckthorn to multiple stress conditions via activation of multifactorial acclimation strategies leading to morphological, metabolic and physiological modifications, resulting in dark orange berries in HrB13. Higher accumulation of omega-6 fatty acids, carotenoids and ascorbate during suboptimal growth conditions, provides exciting prospects for enhancing pharmaceutical properties of seabuckthorn berries, emphasizing need to analyze diversity of plant signaling mechanisms under changing climate conditions.

Comparative fatty acid profiling of Indian seabuckthorn showed altitudinal gradient dependent species-specific variations.

The present study provides the first comparative fatty acid profiling of the three Indian seabuckthorn species, collected from varying altitudes (2900-4300 masl) of Trans-Himalayas (Hippophae rhamnoides, H. tibetana) and Sikkim Himalayas (H. salicifolia) regions. Gas chromatography-mass spectrometry analysis showed variability in fatty acid composition of different seabuckthorn populations. Sikkim populations showed higher (1.28-1.6 folds) palmitic acid than Trans-Himalayan populations which possess higher linoleic (1.3-1.5 folds) and linolenic (1.6-1.8 folds) acids. Interestingly, a strong altitudinal gradient associated positive correlation was observed with the degree of unsaturation and PUFA content while negative correlation was observed with saturated fatty acids content of different seabuckthorn populations. H. salicifolia collected from Sikkim showed healthy ω-6:ω-3 ratio (closer to 1:1) of functional lipids exhibiting its better nutraceutical potential than other commonly used seed oils. Interestingly, H. tibetana from Losar showed higher (5.81) degree of unsaturation than Sikkim populations (3.5) suggesting its better stress tolerance trait. Chemo-taxonomic diversity analysis also formed two broad clusters of Trans-Himalayan and Sikkim populations which correlated with earlier taxonomic studies.

Single-step purification and characterization of antifreeze proteins from leaf and berry of a freeze-tolerant shrub seabuckthorn (Hippophae rhamnoides).

Seabuckthorn is a freeze-tolerant Himalayan shrub, capable of withstanding temperatures below -40°C. Antifreeze proteins prevent freezing associated damage by restricting ice crystals growth. In the present study, homogenous purification of two antifreeze proteins (41 and 39 kDa) from Hippophae rhamnoides leaf and one (41 kDa) from berry was performed using ice-affinity chromatography. MS identification and Basic Local Alignment Search Tool search showed homology of berry antifreeze proteins with disease resistance protein while leaf antifreeze proteins showed similarity with transmembrane protein (39 kDa) and low temperature induced protein (41 kDa) suggesting their role in cold stress signalling. Hexagon shaped ice crystals (Nanoliter osmometer) and ice recrystallization inhibition assay (Splat assay) confirmed higher ice recrystallization inhibition activity of purified leaf (2.5 fold decrease in mean ice crystal size) and berry (2.1 fold decrease) antifreeze proteins. String interactome analysis showed interaction of antifreeze proteins with cold stress modulated targets including pathogenesis related proteins. This probably is the first report of antifreeze proteins purification from naturally growing seabuckthorn. Further validation of these targets may open gates for commercial utilization of this plant growing abundantly in Himalayan regions of India, for crop improvement of freeze susceptible crops or biomedical applications like cryopreservation of tissues and cells.

Hippophae rhamnoides N-glycoproteome analysis: a small step towards sea buckthorn proteome mining.

Hippophae rhamnoides is a hardy shrub capable of growing under extreme environmental conditions namely, high salt, drought and cold. Its ability to grow under extreme conditions and its wide application in pharmaceutical and nutraceutical industry calls for its in-depth analysis. N-glycoproteome mining by con A affinity chromatography from seedling was attempted. The glycoproteome was resolved on first and second dimension gel electrophoresis. A total of 48 spots were detected and 10 non-redundant proteins were identified by MALDI-TOF/TOF. Arabidopsis thaliana protein disulfide isomerase-like 1-4 (ATPDIL1-4) electron transporter, protein disulphide isomerase, calreticulin 1 (CRT1), glycosyl hydrolase family 38 (GH 38) protein, phantastica, maturase k, Arabidopsis trithorax related protein 6 (ATXR 6), cysteine protease inhibitor were identified out of which ATXR 6, phantastica and putative ATPDIL1-4 electron transporter are novel glycoproteins. Calcium binding protein CRT1 was validated for its calcium binding by stains all staining. GO analysis showed involvement of GH 38 and ATXR 6 in glycan and lysine degradation pathways. This is to our knowledge the first report of glycoproteome analysis for any Elaeagnaceae member.

First systematic plant proteomics workshop in Botany Department, University of Delhi: transferring proteomics knowledge to next-generation researchers and students.

International Plant Proteomics Organization (INPPO) outlined ten initiatives to promote plant proteomics in each and every country. With greater emphasis in developing countries, one of those was to "organize workshops at national and international levels to train manpower and exchange information". This third INPPO highlights covers the workshop organized for the very first time in a developing country, India, at the Department of Botany in University of Delhi on December 26-30, 2013 titled - "1(st) Plant Proteomics Workshop / Training Program" under the umbrella of INPPO India-Nepal chapter. Selected 20 participants received on-hand training mainly on gel-based proteomics approach along with manual booklet and parallel lectures on this and associated topics. In house, as well as invited experts drawn from other Universities and Institutes (national and international), delivered talks on different aspects of gel-based and gel-free proteomics. Importance of gel-free proteomics approach, translational proteomics, and INPPO roles were presented and interactively discussed by a group of three invited speakers Drs. Ganesh Kumar Agrawal (Nepal), Randeep Rakwal (Japan), and Antonio Masi (Italy). Given the output of this systematic workshop, it was proposed and thereafter decided to be organized every alternate year; the next workshop will be held in 2015. Furthermore, possibilities on providing advanced training to those students / researchers / teachers with basic knowledge in proteomics theory and experiments at national and international levels were discussed. INPPO is committed to generating next-generation trained manpower in proteomics, and it would only happen by the firm determination of scientists to come forward and do it.

S-nitrosylation analysis in Brassica juncea apoplast highlights the importance of nitric oxide in cold-stress signaling.

Reactive nitrogen species (RNS) including nitric oxide (NO) are important components of stress signaling. However, RNS-mediated signaling in the apoplast remains largely unknown. NO production measured in the shoot apoplast of Brassica juncea seedlings showed nonenzymatic nitrite reduction to NO. Thiol pool quantification showed cold-induced increase in the protein (including S-nitrosothiols) as well as non protein thiols. Proteins from the apoplast were resolved as 109 spots on the 2-D gel, while S-nitrosoglutathione-treated (a NO donor), neutravidin-agarose affinity chromatography-purified S-nitrosylated proteins were resolved as 52 spots. Functional categorization after MALDI-TOF/TOF identification showed 41 and 38% targets to be metabolic/cell-wall-modifying and stress-related, respectively, suggesting the potential role(s) of S-nitrosylation in regulating these responses. Additionally, identification of cold-stress-modulated putative S-nitrosylated proteins by nLC-MS/MS showed that only 38.4% targets with increased S-nitrosylation were secreted by classical pathway, while the majority (61.6%) of these were secreted by unknown/nonclassical pathways. Cold-stress-increased dehydroascorbate reductase and glutathione S-transferase activity via S-nitrosylation and promoted ROS detoxification by ascorbate regeneration and hydrogen peroxide detoxification. Taken together, cold-mediated NO production, thiol pool enrichment, and identification of the 48 putative S-nitrosylated proteins, including 25 novel targets, provided the preview of RNS-mediated cold-stress signaling in the apoplast.

Sub-proteome S-nitrosylation analysis in Brassica juncea hints at the regulation of Brassicaceae specific as well as other vital metabolic pathway(s) by nitric oxide and suggests post-translational modifications cross-talk.

Abiotic stress affects the normal physiology of the plants and results in crop loss. Brassica juncea is an oil yielding crop affected by abiotic stress. In future, over 30% yield loss by abiotic stress is predicted in India. Understanding the mechanism of plant response to stress would help in developing stress tolerant crops. Nitric oxide (NO) is now viewed as a remarkably important signaling molecule, involved in regulating stress responses. S-Nitrosylation is a NO based post-translational modification (PTM), linked with the regulation of many physiologically relevant targets. In the last decade, over 700 functionally varied S-nitrosylated proteins were identified, which suggested broad-spectrum regulation. To understand the physiological significance of S-nitrosylation, it was analyzed in cold stress. Functional categorization and validation of some of the B. juncea S-nitrosylated targets, suggested that NO produced during stress regulates cellular detoxification by modulating enzymes of ascorbate glutathione cycle, superoxide dismutase, glutathione S-transferase and glyoxalase I by S-nitrosylation in crude, ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) depleted and apoplastic fractions. Interestingly, S-nitrosylation of enzymes associated with glucosinolate hydrolysis pathway, suggests a novel regulation of this Brassicaceae specific pathway by NO. Moreover, identification of enzymes of Glycolysis and Calvin cycle in crude and RuBisCO depleted fractions showed the regulation of metabolic as well as photosynthetic pathways by S-nitrosylation. S-Nitrosylation of cell wall modifying and proteolytic enzymes in the apoplast suggested differential and spatial regulation by S-nitrosylation. To have an overview of physiological role(s) of NO, collective information on NO based signaling (mainly by S-nitrosylation) is presented in this review.

Identification of nitric oxide regulated low abundant myrosinases from seeds and seedlings of Brassica juncea.

Myrosinases constitute an important component of the glucosinolate-myrosinase system responsible for interaction of plants with microorganisms, insects, pest, and herbivores. It is a distinctive feature of Brassicales. Multiple isozymes of myrosinases are present in the vacuoles. Active myrosinases are also present in the apoplast and the nucleus however, the similarity or difference in the biochemical properties with the vacuolar myrosinases are not known. Here, we have attempted to isolate, characterize, and identify myrosinases from seeds, seedlings, apoplast, and nucleus to understand these forms. 2D-CN/SDS-PAGE coupled with western blotting and MS have shown low abundant myrosinases (65/70/72/75 kDa) in seeds and seedlings and apoplast & nucleus of seedlings to exist as dimers, oligomers, and as protein complex. Nuclear membrane associated form of myrosinase was also identified. The present study for the first time has shown enzymatically active myrosinase-alpha-mannosidase complex in seedlings. Both 65 and 70 kDa myrosinase in seedlings were S-nitrosated. Nitric oxide donor treatment (GSNO) led to 25% reduction in myrosinase activity which was reversed by DTT suggesting redox regulation of myrosinase. These S-nitrosated myrosinases might be a component of NO signalling in B. juncea.

Differential S-nitrosylation and characterization of purified S-nitrosoglutathione reductase (GSNOR) from Brassica juncea shows multiple forms of the enzyme.

S-nitrosoglutathione reductase (GSNOR). a master regulator of NO homeostasis, is a single-copy gene in most plants. In Lotus japonicus, two GSNOR isoforms were identified exhibiting similar kinetic properties but differential tissue-specific expressions. Previously, a genome-wide identification in Brassica juncea revealed four copies of GSNOR, each encoding proteins that vary in subunit molecular weights and pI. Here, we report multiple forms of GSNOR using 2D immunoblot which showed 4 immunopositive spots of 41.5 kDa (pl 5.79 and 6.78) and 43 kDa (pl 6.16 and 6.23). To confirm, purification of GSNOR using anion-exchange chromatography yielded 2 distinct pools (GSNOR-A & GSNOR-B) with GSNOR activities. Subsequently, affinity-based purification resulted in 1 polypeptide from GSNOR-A and 2 polypeptides from GSNOR-B. Size exclusion-HPLC confirmed 3 GSNORs with molecular weight of 87.48 ± 2.74 KDa (GSNOR-A); 87.36 ± 3.25 and 82.74 ± 2.75 kDa (GSNOR-B). Kinetic analysis showed Km of 118 ± 11 µM and Vmax of 287 ± 22 nkat/mg for GSNOR-A, whereas Km of 96.4 ± 8 µM and Vmax of 349 ± 15 nkat/mg for GSNOR-B. S-nitrosylation and inhibition by NO showed redox regulation of all BjGSNORs. Both purified GSNORs exhibited variable denitrosylation efficiency as depicted by Biotin Switch assay. To the best of our knowledge, this is the first report confirming multiple isoforms of GSNOR in B. juncea.

Expanding roles of cross-talk between hydrogen sulfide and nitric oxide under abiotic stress in plants.

Abiotic stress such as salt, heavy metals, drought, temperature, and others can affect plants from seed germination to seedling growth to reproductive maturity. Abiotic stress increases reactive oxygen species and lowers antioxidant enzymes in plants resulted the plant tolerance ability against stress conditions decrease. Hydrogen sulfide (H2S) and nitric oxide (NO) are important gasotransmitters involved in seed germination, photosynthesis, growth and development, metabolism, different physiological processes and functions in plants. In plants, various enzymes are responsible for the biosynthesis of both H2S and NO via both enzymatic and non-enzymatic pathways. They also mediate post-translation modification, such as persulfidation, and nitrosylation, which are protective mechanisms against oxidative damage. They also regulate some cellular signalling pathways in response to various abiotic stress. H2S and NO also stimulate biochemical reactions in plants, including cytosolic osmoprotectant accumulation, reactive oxygen species regulation, antioxidant system activation, K+ uptake, and Na+ cell extrusion or vacuolar compartmentation. In this review, we summarize how H2S and NO interact with each other, the function of both H2S and NO, the mechanism of biosynthesis, and post-translational modification under different abiotic stress. Our main emphasis was to find the cross-talk between NO and H2S and how they regulate genes in plants under abiotic stress.

Nitric oxide-cold stress signalling cross-talk, evolution of a novel regulatory mechanism.

Plants enhance their cold stress tolerance by cold acclimation, a process which results in vast reprogramming of transcriptome, proteome and metabolome. Evidence suggests nitric oxide (NO) production during cold stress which regulates genes (especially the C-repeat binding factor (CBF) cold stress signalling pathway), diverse proteins including transcription factors (TFs) and phosphosphingolipids. About 59% (redox), 50% (defence/stress) and 30% (signalling) cold responsive proteins are modulated by NO-based post translational modifications (PTMs) namely S-nitrosylation, tyrosine nitration and S-glutathionylation, suggesting a cross-talk between NO and cold. Analysis of cold stress responsive deep proteome in apoplast, mitochondria, chloroplast and nucleus suggested continuation of this cross-talk in sub-cellular systems. Modulation of cold responsive proteins by these PTMs right from cytoskeletal elements in plasma membrane to TFs in nucleus suggests a novel regulation of cold stress signalling. NO-mediated altered protein transport in nucleus seems an important stress regulatory mechanism. This review addresses the NO and cold stress signalling cross-talk to present the overview of this novel regulatory mechanism.

Plant proteomics in India and Nepal: current status and challenges ahead.

Plant proteomics has made tremendous contributions in understanding the complex processes of plant biology. Here, its current status in India and Nepal is discussed. Gel-based proteomics is predominantly utilized on crops and non-crops to analyze majorly abiotic (49 %) and biotic (18 %) stress, development (11 %) and post-translational modifications (7 %). Rice is the most explored system (36 %) with major focus on abiotic mainly dehydration (36 %) stress. In spite of expensive proteomics setup and scarcity of trained workforce, output in form of publications is encouraging. To boost plant proteomics in India and Nepal, researchers have discussed ground level issues among themselves and with the International Plant Proteomics Organization (INPPO) to act in priority on concerns like food security. Active collaboration may help in translating this knowledge to fruitful applications.

N-Linked Glycoproteome Analysis of Diosorea alata Tuber Shows Atypical Glycosylation and Indicates Central Role of Glycosylated Proteins in Tuber Maturation.

Glycosylation is an important post translational modification in plants. First analysis of N-linked glycosylated proteins of Dioscorea alata using Concanavalin A lectin affinity chromatography enrichment coupled with label free quantification is presented. In total, 114 enriched glycoproteins were detected. Signal P and sub-cellular localization showed 42.2% of proteins to be secretory. These included peroxidases, endochitinases, calreticulin, calnexin, thaumatins and lipid transfer proteins. Gene Ontology and MapMan analysis predicted the enriched glycoproteins to be involved in processes essential for tuber maturation namely: signal transduction, lignification, protein trafficking, endoplasmic reticulum quality control and cell wall remodeling. This was supported by biochemical validation of the essential glycoproteins. Interestingly, out of the two dioscorin isoforms, Dio B was the only N-glycosylated form. In silico analysis showed O-glycosylation sites in the other form, Dio A suggesting its similarity with sporamin, the storage protein of sweet potato. Absence of signal peptide in Dio B and the presence of non-canonical motif hints towards its atypical glycosylation. The analysis revealed that N-glycosylation of Dio B isoform maintains the activities associated with Dioscorin at maturity and provides an overview of protein N-glycosylation, enriching the glycoproteome database of plants especially tubers.

Boosting the globalization of plant proteomics through INPPO: current developments and future prospects.

The International Plant Proteomics Organization (INPPO) is a non-profit-organization consisting of people who are involved or interested in plant proteomics. INPPO is constantly growing in volume and activity, which is mostly due to the realization among plant proteomics researchers worldwide for the need of such a global platform. Their active participation resulted in the rapid growth within the first year of INPPO's official launch in 2011 via its website (www.inppo.com) and publication of the 'Viewpoint paper' in a special issue of PROTEOMICS (May 2011). Here, we will be highlighting the progress achieved in the year 2011 and the future targets for the year 2012 and onwards. INPPO has achieved a successful administrative structure, the Core Committee (CC; composed of President, Vice-President, and General Secretaries), Executive Council (EC), and General Body (GB) to achieve INPPO objectives. Various committees and subcommittees are in the process of being functionalized via discussion amongst scientists around the globe. INPPO's primary aim to popularize the plant proteomics research in biological sciences has also been recognized by PROTEOMICS where a section dedicated to plant proteomics has been introduced starting January 2012, following the very first issue of this journal devoted to plant proteomics in May 2011. To disseminate organizational activities to the scientific community, INPPO has launched a biannual (in January and July) newsletter entitled 'INPPO Express: News & Views' with the first issue published in January 2012. INPPO is also planning to have several activities in 2012, including programs within the Education Outreach committee in different countries, and the development of research ideas and proposals with priority on crop and horticultural plants, while keeping tight interactions with proteomics programs on model plants such as Arabidopsis thaliana, rice, and Medicago truncatula. Altogether, the INPPO progress and upcoming activities are because of immense support, dedication, and hard work of all members of the INPPO community, and also due to the wide encouragement and support from the communities (scientific and non-scientific).