Regulation of two germin-like protein genes during plum fruit development

Comparative analysis of infected cassava root transcriptomics reveals candidate genes for root rot disease resistance

Cassava root-rot incited by soil-borne pathogens is one of the major diseases that reduces root yield. Although the use of resistant cultivars is the most effective method of management, the genetic basis for root-rot resistance remains poorly understood. Therefore, our work analyzed the transcriptome of two contrasting genotypes (BRS Kiriris/resistant and BGM-1345/susceptible) using RNA-Seq to understand the molecular response and identify candidate genes for resistance. Cassava seedlings (resistant and susceptible to root-rot) were both planted in infested and sterilized soil and samples from Initial-time and Final-time periods, pooled. Two controls were used: (i) seedlings collected before planting in infested soil (absolute control) and, (ii) plants grown in sterilized soil (mock treatments). For the differentially expressed genes (DEGs) analysis 23.912 were expressed in the resistant genotype, where 10.307 were differentially expressed in the control treatment, 15 DEGs in the Initial Time-period and 366 DEGs in the Final Time-period. Eighteen candidate genes from the resistant genotype were related to plant defense, such as the MLP-like protein 31 and the peroxidase A2-like gene. This is the first model of resistance at the transcriptional level proposed for the cassava × root-rot pathosystem. Gene validation will contribute to screening for resistance of germplasm, segregating populations and/or use in gene editing in the pursuit to develop most promising cassava clones with resistance to root-rot.

OsGLP8-7 interacts with OsPRX111 to detoxify excess copper in rice

Lignin is a phenolic biopolymer generated from phenylpropanoid pathway in the secondary cell wall and is required for defense of plants against various stress. Although the fact of stress-induced lignin deposition has been clearly demonstrated, it remains largely elusive how the formation of lignin is promoted under Cu stress. The present study showed that OsGLP8-7, an extracellular glycoprotein of rice (Oryza sativa L.), plays an important function against Cu stress. The loss function of OsGLP8-7 results in Cu sensitivity whereas overexpression of OsGLP8-7 scavenges Cu-induced superoxide anion (O2•-). OsGLP8-7 interacts with apoplastic peroxidase111 (OsPRX111) and elevates OsPRX111 stability when exposed to excess Cu. In OsGLP8-7 overexpressing (OE) lines, the retention of Cu within cell wall limiting Cu uptake into cytoplasm is attributed to the enhanced lignification required for Cu tolerance. Exogenous application of a lignin inhibitor can impair the Cu tolerance of transgenic Arabidopsis lines overexpressing OsGLP8-7. In addition, co-expression of OsGLP8-7 and OsPRX111 genes in tobacco leaves leads to an improved lignin deposition compared to leaves expressing each gene individually or the empty vector. Taken together, our findings provided the convincing evidences that the interaction between OsGLP8-7 and OsPRX111 facilitates effectively lignin polymerization, thereby contributing to Cu tolerance in rice.

Genomic Exploration: Unraveling the Intricacies of Indica Rice Oryza sativa L. Germin-Like Protein Gene 12-3 (OsGLP12-3) Promoter via Cloning, Sequencing, and In Silico Analysis

Germin and Germin-like proteins (GLPs) are a class of plant proteins that are part of the Cupins superfamily, found in several plant organs including roots, seeds, leaves, and nectar glands. They play a crucial role in plant defense against pathogens and environmental stresses. Herein, this study focused on the promoter analysis of OsGLP12-3 in rice cultivar Swat-1 to elucidate its regulation and functions. The region (1863bp) of the OsGLP12-3 promoter from Swat-1 genomic DNA was amplified, purified, quantified, and cloned using Topo cloning technology, followed by sequencing. Further in silico comparative analysis was conducted between the OsGLP12-3 promoters from Nipponbare and Swat-1 using the Plant CARE database, identifying 24 cis-acting regulatory elements with diverse functions. These elements exhibited distinct distribution patterns in the 2 rice varieties. The OsGLP12-3 promoter revealed an abundance of regulatory elements associated with biotic and abiotic stress responses. Computational tools were employed to analyze the regulatory features of this region. In silico expression analysis of OsGLP12-3, considering various developmental stages, stress conditions, hormones, and expression timing, was performed using the TENOR tool. Pairwise alignment indicated 86% sequence similarity between Nipponbare and Swat-1. Phylogenetic analysis was conducted to explore the evolutionary relationship between the OsGLP12-3 and other plant GLPs. Additionally, 2 unique regulatory elements were modeled and docked, GARE and MBS to understand their hydrogen bonding interactions in gene regulation. The study highlights the importance of OsGLP12-3 in plant defense against biotic and abiotic stresses, supported by its expression patterns in response to various stressors and the presence of specific regulatory elements within its promoter region.

Analysis of Germin-like protein genes family in Vitis vinifera (VvGLPs) using various in silico approaches

Abstract Germin-like proteins (GLPs) play an important role against various stresses. Vitis vinifera L. genome contains 7 GLPs; many of them are functionally unexplored. However, the computational analysis may provide important new insight into their function. Currently, physicochemical properties, subcellular localization, domain architectures, 3D structures, N-glycosylation & phosphorylation sites, and phylogeney of the VvGLPs were investigated using the latest computational tools. Their functions were predicted using the Search tool for the retrieval of interacting genes/proteins (STRING) and Blast2Go servers. Most of the VvGLPs were extracellular (43%) in nature but also showed periplasmic (29%), plasma membrane (14%), and mitochondrial- or chloroplast-specific (14%) expression. The functional analysis predicted unique enzymatic activities for these proteins including terpene synthase, isoprenoid synthase, lipoxygenase, phosphate permease, receptor kinase, and hydrolases generally mediated by Mn+ cation. VvGLPs showed similarity in the overall structure, shape, and position of the cupin domain. Functionally, VvGLPs control and regulate the production of secondary metabolites to cope with various stresses. Phylogenetically VvGLP1, -3, -4, -5, and VvGLP7 showed greater similarity due to duplication while VvGLP2 and VvGLP6 revealed a distant relationship. Promoter analysis revealed the presence of diverse cis-regulatory elements among which CAAT box, MYB, MYC, unnamed-4 were common to all of them. The analysis will help to utilize VvGLPs and their promoters in future food programs by developing resistant cultivars against various biotic (Erysiphe necator and in Powdery Mildew etc.) and abiotic (Salt, drought, heat, dehydration, etc.) stresses.

PpARF6 acts as an integrator of auxin and ethylene signaling to promote fruit ripening in peach

Although auxin is known to induce ethylene biosynthesis in some Rosaceae fruit crops, the mechanisms underlying the auxin-ethylene interaction during fruit ripening remain largely unknown. Here, the regulatory role of an auxin response factor, PpARF6, in fruit ripening was investigated in peach. Peach fruits showed accelerated ripening after treatment with auxin and PpARF6 was found to be significantly induced. PpARF6 not only could induce ethylene synthesis by directly activating the transcription of ethylene biosynthetic genes, but also competed with EIN3-binding F-box proteins PpEBF1/2 for binding to ethylene-insensitive3-like proteins PpEIL2/3, thereby keeping PpEIL2/3 active. Moreover, PpARF6 showed an interaction with PpEIL2/3 to enhance the PpEIL2/3-activated transcription of ethylene biosynthetic genes. Additionally, ectopic overexpression of PpARF6 in tomato accelerated fruit ripening by promoting the expression of genes involved in ethylene synthesis and fruit texture. In summary, our results revealed a positive regulatory role of PpARF6 in peach fruit ripening via integrating auxin and ethylene signaling.

Molecular Characterization of Germin-like Protein Genes in Zea mays (ZmGLPs) Using Various In Silico Approaches

Germin (GER) and germin-like proteins (GLPs) play an important role in various plant processes. Zea mays contains 26 germin-like protein genes (ZmGLPs) located on chromosomes 2, 4, and 10; most of which are functionally unexplored. The present study aimed to characterize all ZmGLPs using the latest computational tools. All of them were studied at a physicochemical, subcellular, structural, and functional level, and their expression was predicted in plant development, against biotic and abiotic stresses using various in silico approaches. Overall, ZmGLPs showed greater similarity in their physicochemical properties, domain architecture, and structure, mostly localized in the cytoplasmic or extracellular regions. Phylogenetically, they have a narrow genetic background with a recent history of gene duplication events on chromosome 4. Functional analysis revealed novel enzymatic activities of phosphoglycolate phosphatase, adenosylhomocysteinase, phosphoglycolate phosphatase-like, osmotin/thaumatin-like, and acetohydroxy acid isomeroreductase largely mediated by disulfide bonding. Expression analysis revealed their crucial role in the root, root tips, crown root, elongation and maturation zones, radicle, and cortex with the highest expression being observed during germination and at the maturity levels. Further, ZmGLPs showed strong expression against biotic (Aspergillus flavus, Colletotrichum graminicola, Cercospora zeina, Fusarium verticillioides, and Fusarium virguliforme) while limited expression was noted against abiotic stresses. Concisely, our results provide a platform for additional functional exploration of the ZmGLP genes against various environmental stresses.

Divergent structures and functions of the Cupin proteins in plants

Cupin superfamily proteins have extensive functions. Their members are not only involved in the development of plants but also responded to various stresses. Whereas, the research on the Cupin members has not attracted enough attention. In this article, we summarized the research progress on these family genes in recent years and explored their evolution, structural characteristics, and biological functions. The significance of members of the Cupin family in the development of plant cell walls, roots, leaves, flowers, fruits, and seeds and their role in stress response are highlighted. Simultaneously, the prospective application of Cupin protein in crop enhancement was introduced. Some members can enhance plant growth, development, and resistance to adversity, thereby increasing crop yield. It will be as a foundation for future effective crop research and breeding.

Genome-wide analysis of the GLP gene family and overexpression of GLP1-5-1 to promote lignin accumulation during early somatic embryo development in Dimocarpus longan

Longan (Dimocarpus longan Lour.) is an economically important subtropical fruit tree. Its fruit quality and yield are affected by embryo development. As a plant seed germination marker gene, the germin-like protein (GLP) gene plays an important role in embryo development. However, the mechanism underlying the role of the GLP gene in somatic embryos is still unclear. Therefore, we conducted genome-wide identification of the longan GLP (DlGLP) gene and preliminarily verified the function of DlGLP1-5-1. Thirty-five genes were identified as longan GLP genes and divided into 8 subfamilies. Based on transcriptome data and qRT‒PCR results, DlGLP genes exhibited the highest expression levels in the root, and the expression of most DlGLPs was upregulated during the early somatic embryogenesis (SE) in longan and responded to high temperature stress and 2,4-D treatment; eight DlGLP genes were upregulated under MeJA treatment, and four of them were downregulated under ABA treatment. Subcellular localization showed that DlGLP5-8-2 and DlGLP1-5-1 were located in the cytoplasm and extracellular stroma/chloroplast, respectively. Overexpression of DIGLP1-5-1 in the globular embryos (GEs) of longan promoted the accumulation of lignin and decreased the H₂O₂ content by regulating the activities of ROS-related enzymes. The results provide a reference for the functional analysis of DlGLPs and related research on improving lignin accumulation in the agricultural industry through genetic engineering.

Tracing 100 million years of grass genome evolutionary plasticity

Grasses derive from a family of monocotyledonous plants that includes crops of major economic importance such as wheat, rice, sorghum and barley, sharing a common ancestor some 100 million years ago. The genomic attributes of plant adaptation remain obscure and the consequences of recurrent whole genome duplications (WGD) or polyploidization events, a major force in plant evolution, remain largely speculative. We conducted a comparative analysis of omics data from ten grass species to unveil structural (inversions, fusions, fissions, duplications, substitutions) and regulatory (expression and methylation) basis of genome plasticity, as possible attributes of plant long lasting evolution and adaptation. The present study demonstrates that diverged polyploid lineages sharing a common WGD event often present the same patterns of structural changes and evolutionary dynamics, but these patterns are difficult to generalize across independent WGD events as a result of non-WGD factors such as selection and domestication of crops. Polyploidy is unequivocally linked to the evolutionary success of grasses during the past 100 million years, although it remains difficult to attribute this success to particular genomic consequences of polyploidization, suggesting that polyploids harness the potential of genome duplication, at least partially, in lineage-specific ways. Overall, the present study clearly demonstrates that post-polyploidization reprogramming is more complex than traditionally reported in investigating single species and calls for a critical and comprehensive comparison across independently polyploidized lineages.

From fruit growth to ripening in plantain: a careful balance between carbohydrate synthesis and breakdown

In this study, we aimed to investigate for the first time different fruit development stages in plantain banana in order gain insights into the order of appearance and dominance of specific enzymes and fluxes. We examined fruit development in two plantain banana cultivars during the period between 2-12 weeks after bunch emergence using high-throughput proteomics, quantification of major metabolites, and analyses of metabolic fluxes. Starch synthesis and breakdown are processes that take place simultaneously. During the first 10 weeks fruits accumulated up to 48% of their dry weight as starch, and glucose 6-phosphate and fructose were important precursors. We found a unique amyloplast transporter and hypothesize that it facilitates the import of fructose. We identified an invertase originating from the Musa balbisiana genome that would enable carbon flow back to growth and starch synthesis and maintain a high starch content even during ripening. Enzymes associated with the initiation of ripening were involved in ethylene and auxin metabolism, starch breakdown, pulp softening, and ascorbate biosynthesis. The initiation of ripening was cultivar specific, with faster initiation being particularly linked to the 1-aminocyclopropane-1-carboxylate oxidase and 4-alpha glucanotransferase disproportionating enzymes. Information of this kind is fundamental to determining the optimal time for picking the fruit in order to reduce post-harvest losses, and has potential applications for breeding to improve fruit quality.

Genome-Wide Identification, Characterization, and Expression Analysis Related to Low-Temperature Stress of the CmGLP Gene Family in Cucumis melo L

Germin-like protein (GLP) participates in plant growth and development and plays an important role in plant stress. In the present study, 22 CmGLPs belonging to five classes were identified in the melon genome. Each member of the CmGLPs family contains a typical Cupin_1 domain. We conducted a genome-wide analysis of the melon GLP gene family characterization. CmGLPs were randomly distributed in the melon chromosomes, with the largest number on chromosome 8, having eight family members. Gene duplication events drive the evolution and expansion of the melon GLP gene family. Based on the phylogenetic tree analysis of GLP proteins in melon, rice, Arabidopsis, and cucumber, it was found that the GLP gene families of different species have diverged in evolution. Based on qRT-PCR results, all members of the CmGLP gene family could be expressed in different tissues of melon. Most CmGLP genes were up-regulated after low-temperature stress. The relative expression of CmGLP2-5 increased by 157.13 times at 48 h after low-temperature treatment. This finding suggests that the CmGLP2-5 might play an important role in low-temperature stress in melon. Furthermore, quantitative dual LUC assays indicated that CmMYB23 and CmWRKY33 can bind the promoter fragment of the CmGLP2-5. These results were helpful in understanding the functional succession and evolution of the melon GLP gene family and further revealed the response of CmGLPs to low-temperature stress in melon.

Development of Whole Genome SNP-CAPS Markers and Preliminary QTL Mapping of Fruit Pedicel Traits in Watermelon

Fruit pedicel (FP) is an important determinant of premium fruit quality that directly affects commercial market value. However, in-depth molecular and genetic basis of pedicel-related traits has not been identified in watermelon. Herein, a quantitative trait locus (QTL) mapping strategy was used to identify the potential genetic regions controlling FP traits based on newly derived whole-genome single nucleotide polymorphism based cleaved amplified polymorphism sequence (SNP-CAPS) markers. Next-generation sequencing based whole-genome re-sequencing of two watermelon parent lines revealed 98.30 and 98.40% of average coverage, 4,989,869 SNP variants, and 182,949 CAPS loci pairs across the reference genome, respectively. A total of 221 sets of codominant markers exhibited 46.42% polymorphism rate and were effectively genotyped within 100-F_2:3 derived mapping population. The developed linkage map covered a total of 2,630.49 cM genetic length with averaged 11.90 cM, and depicted a valid marker-trait association. In total, 6 QTLs (qFPL4.1, qFPW4.1, qFPD2.1, qFPD2.2, qFPD8.1, qFPD10.1) were mapped with five major effects and one minor effect between the whole genome adjacent markers positioned over distinct chromosomes (02, 04, 08, 10), based on the ICIM-ADD mapping approach. These significant QTLs were similarly mapped in delimited flanking regions of 675.10, 751.38, 859.24, 948.39, and 947.51 kb, which collectively explained 8.64-13.60% PVE, respectively. A highly significant and positive correlation was found among the observed variables. To our knowledge, we first time reported the mapped QTLs/genes affecting FP traits of watermelon, and our illustrated outcomes will deliver the potential insights for fine genetic mapping as well as functional gene analysis through MAS-based breeding approaches.

Bioinformatic approach for the discovery of cis-eQTL signals during fruit ripening of a woody species as grape (Vitis vinifera L.)

Expression quantitative trait loci (eQTLs) are associations between genetic variants, such as Single Nucleotide Polymorphisms (SNPs), and gene expression. eQTLs are an important tool to understand the genetic variance of gene expression of complex phenotypes. eQTLs analyses are common in biomedical models but are scarce in woody crop species such as fruit trees or grapes. In this study, a comprehensive bioinformatic analysis was conducted leveraging with expression data from two different growth stages, around ripening onset, of 10 genotypes of grape (Vitis vinifera L.). A total of 2170 cis-eQTL were identified in 212 gene modulated at ripening onset. The 48% of these DEGs have a known function. Among the annotated protein-coding genes, terpene synthase, auxin-regulatory factors, GRFS, ANK_REP_REGION domain-containing protein, Kinesin motor domain-containing protein and flavonol synthase were noted. This new inventory of cis-eQTLs influencing gene expression during fruit ripening will be an important resource to examine variation for this trait and will help to elucidate the complex genetic architecture underlying this process in grape.

The meristem-associated endosymbiont Methylorubrum extorquens DSM13060 reprograms development and stress responses of pine seedlings

Microbes living in plant tissues-endophytes-are mainly studied in crop plants where they typically colonize the root apoplast. Trees-a large carbon source with a high capacity for photosynthesis-provide a variety of niches for endophytic colonization. We have earlier identified a new type of plant-endophyte interaction in buds of adult Scots pine, where Methylorubrum species live inside the meristematic cells. The endosymbiont Methylorubrum extorquens DSM13060 significantly increases needle and root growth of pine seedlings without producing plant hormones, but by aggregating around host nuclei. Here, we studied gene expression and metabolites of the pine host induced by M. extorquens DSM13060 infection. Malic acid was produced by pine to potentially boost M. extorquens colonization and interaction. Based on gene expression, the endosymbiont activated the auxin- and ethylene (ET)-associated hormonal pathways through induction of CUL1 and HYL1, and suppressed salicylic and abscisic acid signaling of pine. Infection by the endosymbiont had an effect on pine meristem and leaf development through activation of GLP1-7 and ALE2, and suppressed flowering, root hair and lateral root formation by downregulation of AGL8, plantacyanin, GASA7, COW1 and RALFL34. Despite of systemic infection of pine seedlings by the endosymbiont, the pine genes CUL1, ETR2, ERF3, HYL, GLP1-7 and CYP71 were highly expressed in the shoot apical meristem, rarely in needles and not in stem or root tissues. Low expression of MERI5, CLH2, EULS3 and high quantities of ononitol suggest that endosymbiont promotes viability and protects pine seedlings against abiotic stress. Our results indicate that the endosymbiont positively affects host development and stress tolerance through mechanisms previously unknown for endophytic bacteria, manipulation of plant hormone signaling pathways, downregulation of senescence and cell death-associated genes and induction of ononitol biosynthesis.

Identification and functional analysis of a pollen fertility-associated gene GhGLP4 of Gossypium hirsutum L

KEY MESSAGE

Cotton male fertility-associated gene GhGLP4, encoding a germin-like protein, is essential for anthers development by keeping ROS homeostasis through reducing H2O2 level. Utilization of heterosis is an important way to increase cotton yield and improve fiber quality in hybrid cotton development programs. Male sterility is used in the development of cotton hybrids to reduce the cost of hybrid seed production by eliminating the process of emasculation. From the transcriptome analysis of genic male sterile mutant (ms1) and its background C312 of G. hirsutum, a gene encoding germin-like protein (GhGLP4) was found significantly down-regulated in different developmental stages of ms1 anthers. To explore the gene function in cotton fertility, GhGLP4 was further studied and interfered by virus-induced gene silencing. In the GhGLP4 interfered cotton lines, the expression level of GhGLP4 was significantly decreased in the stamens, and the down-regulation of GhGLP4 resulted in pollen sac closure, stigma exertion, filament shortening, decrease in the number of anthers and complete male sterility. The expression levels of respiratory burst oxidase homologs (Rboh, NADPH oxidase) were significantly altered. Further investigation showed that the SOD activity decreased while the H2O2 content increased in the atypical stamens. These results indicated that GhGLP4 gene affected the cotton anther development through maintenance of ROS homeostasis by H2O2 reduction.

Molecular mechanisms for magnesium-deficiency-induced leaf vein lignification, enlargement and cracking in Citrus sinensis revealed by RNA-Seq

Citrus sinensis (L.) Osbeck seedlings were fertigated with nutrient solution containing 2 [magnesium (Mg)-sufficiency] or 0 mM (Mg-deficiency) Mg(NO3)2 for 16 weeks. Thereafter, RNA-Seq was used to investigate Mg-deficiency-responsive genes in the veins of upper and lower leaves in order to understand the molecular mechanisms for Mg-deficiency-induced vein lignification, enlargement and cracking, which appeared only in the lower leaves. In this study, 3065 upregulated and 1220 downregulated, and 1390 upregulated and 375 downregulated genes were identified in Mg-deficiency veins of lower leaves (MDVLL) vs Mg-sufficiency veins of lower leaves (MSVLL) and Mg-deficiency veins of upper leaves (MDVUL) vs Mg-sufficiency veins of upper leaves (MSVUL), respectively. There were 1473 common differentially expressed genes (DEGs) between MDVLL vs MSVLL and MDVUL vs MSVUL, 1463 of which displayed the same expression trend. Magnesium-deficiency-induced lignification, enlargement and cracking in veins of lower leaves might be related to the following factors: (i) numerous transciption factors and genes involved in lignin biosynthesis pathways, regulation of cell cycle and cell wall metabolism were upregulated; and (ii) reactive oxygen species, phytohormone and cell wall integrity signalings were activated. Conjoint analysis of proteome and transcriptome indicated that there were 287 and 56 common elements between DEGs and differentially abundant proteins (DAPs) identified in MDVLL vs MSVLL and MDVUL vs MSVUL, respectively, and that among these common elements, the abundances of 198 and 55 DAPs matched well with the transcript levels of the corresponding DEGs in MDVLL vs MSVLL and MDVUL vs MSVUL, respectively, indicating the existence of concordances between protein and transcript levels.

The major-effect quantitative trait locus Fnl7.1 encodes a late embryogenesis abundant protein associated with fruit neck length in cucumber

Fruit neck length (FNL) is an important quality trait in cucumber because it directly affects its market value. However, its genetic basis remains largely unknown. We identified a candidate gene for FNL in cucumber using a next-generation sequencing-based bulked segregant analysis in F₂ populations, derived from a cross between Jin5-508 (long necked) and YN (short necked). A quantitative trait locus (QTL) on chromosome 7, Fnl7.1, was identified through a genome-wide comparison of single nucleotide polymorphisms between long and short FNL F₂ pools, and it was confirmed by traditional QTL mapping in multiple environments. Fine genetic mapping, sequences alignment and gene expression analysis revealed that CsFnl7.1 was the most likely candidate Fnl7.1 locus, which encodes a late embryogenesis abundant protein. The increased expression of CsFnl7.1 in long-necked Jin5-508 may be attributed to mutations in the promoter region upstream of the gene body. The function of CsFnl7.1 in FNL control was confirmed by its overexpression in transgenic cucumbers. CsFnl7.1 regulates fruit neck development by modulating cell expansion. Probably, this is achieved through the direct protein-protein interactions between CsFnl7.1 and a dynamin-related protein CsDRP6 and a germin-like protein CsGLP1. Geographical distribution differences of the FNL phenotype were found among the different cucumber types. The East Asian and Eurasian cucumber accessions were highly enriched with the long-necked and short-necked phenotypes, respectively. A further phylogenetic analysis revealed that the Fnl7.1 locus might have originated from India. Thus, these data support that the CsFnl7.1 has an important role in increasing cucumber FNL.

Analysis of Germin-like Protein Genes (OsGLPs) Family in Rice Using Various In silico Approaches

Background:

Germin-like Proteins (GLPs) play an important role in various stresses. Rice contains 43 GLPs, among which many remain functionally unexplored. The computational analysis will provide significant insight into their function.

Objective:

To find various structural properties, functional importance, phylogeny and expression pattern of all OsGLPs using various bioinformatics tools.

Methods:

Physiochemical properties, sub-cellular localization, domain composition, Nglycosylation and Phosphorylation sites, and 3D structural models of the OsGLPs were predicted using various bioinformatics tools. Functional analysis was carried out with the Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) and Blast2GO servers. The expression profile of the OsGLPs was predicted by retrieving the data for expression values from tissuespecific and hormonal stressed array libraries of RiceXPro. Their phylogenetic relationship was computed using Molecular and Evolutionary Genetic Analysis (MEGA6) tool.

Results:

Most of the OsGLPs are stable in the cellular environment with a prominent expression in the extracellular region (57%) and plasma membrane (33%). Besides, 3 basic cupin domains, 7 more were reported, among which NTTNKVGSNVTLINV, FLLAALLALASWQAI, and MASSSF were common to 99% of the sequences, related to bacterial pathogenicity, peroxidase activity, and peptide signal activity, respectively. Structurally, OsGLPs are similar but functionally they are diverse with novel enzymatic activities of oxalate decarboxylase, lyase, peroxidase, and oxidoreductase. Expression analysis revealed prominent activities in the root, endosperm, and leaves. OsGLPs were strongly expressed by abscisic acid, auxin, gibberellin, cytokinin, and brassinosteroid. Phylogenetically they showed polyphyletic origin with a narrow genetic background of 0.05%. OsGLPs of chromosome 3, 8, and 12 are functionally more important due to their defensive role against various stresses through co-expression strategy.

Conclusion:

The analysis will help to utilize OsGLPs in future food programs.

GhABP19, a Novel Germin-Like Protein From Gossypium hirsutum, Plays an Important Role in the Regulation of Resistance to Verticillium and Fusarium Wilt Pathogens

Germin-like proteins (GLPs) are water-soluble plant glycoproteins belonging to the cupin superfamily. The important role of GLPs in plant responses against various abiotic and biotic stresses, especially pathogens, is well validated. However, little is known about cotton GLPs in relation to fungal pathogens. Here, a novel GLP gene was isolated from Gossypium hirsutum and designated as GhABP19. The expression of GhABP19 was upregulated in cotton plants inoculated with Verticillium dahliae and Fusarium oxysporum and in response to treatment with jasmonic acid (JA) but was suppressed in response to salicylic acid treatment. A relatively small transient increase in GhABP19 was seen in H2O2 treated samples. The three-dimensional structure prediction of the GhABP19 protein indicated that the protein has three histidine and one glutamate residues responsible for metal ion binding and superoxide dismutase (SOD) activity. Purified recombinant GhABP19 exhibits SOD activity and could inhibit growth of V. dahliae, F. oxysporum, Rhizoctonia solani, Botrytis cinerea, and Valsa mali in vitro. To further verify the role of GhABP19 in fungal resistance, GhABP19-overexpressing Arabidopsis plants and GhABP19-silenced cotton plants were developed. GhABP19-transgenic Arabidopsis lines showed much stronger resistance to V. dahliae and F. oxysporum infection than control (empty vector) plants did. On the contrary, silencing of GhABP19 in cotton conferred enhanced susceptibility to fungal pathogens, which resulted in necrosis and wilt on leaves and vascular discoloration in GhABP19-silenced cotton plants. The H2O2 content and endogenous SOD activity were affected by GhABP19 expression levels in Arabidopsis and cotton plants after inoculation with V. dahliae and F. oxysporum, respectively. Furthermore, GhABP19 overexpression or silencing resulted in activation or suppression of JA-mediated signaling, respectively. Thus, GhABP19 plays important roles in the regulation of resistance to verticillium and fusarium wilt in plants. These modulatory roles were exerted by its SOD activity and ability to activate the JA pathway. All results suggest that GhABP19 was involved in plant disease resistance.

Arabidopsis thaliana responds to colonisation of Piriformospora indica by secretion of symbiosis-specific proteins

Plants interact with a wide variety of fungi in a mutualistic, parasitic or neutral way. The associations formed depend on the exchange of nutrients and signalling molecules between the partners. This includes a diverse set of protein classes involved in defence, nutrient uptake or establishing a symbiotic relationship. Here, we have analysed the secretomes of the mutualistic, root-endophytic fungus Piriformospora indica and Arabidopsis thaliana when cultivated alone or in a co-culture. More than one hundred proteins were identified as differentially secreted, including proteins associated with growth, development, abiotic and biotic stress response and mucilage. While some of the proteins have been associated before to be involved in plant-microbial interaction, other proteins are newly described in this context. One plant protein found in the co-culture is PLAT1 (Polycystin, Lipoxygenase, Alpha-toxin and Triacylglycerol lipase). PLAT1 has not been associated with plant-fungal-interaction and is known to play a role in abiotic stress responses. In colonised roots PLAT1 shows an altered gene expression in a stage specific manner and plat1 knock-out plants are colonised stronger. It co-localises with Brassicaceae-specific endoplasmic reticulum bodies (ER-bodies) which are involved in the formation of the defence compound scopolin. We observed degraded ER-bodies in infected Arabidopsis roots and a change in the scopolin level in response to the presence of the fungus.

Characterization of regulatory elements in OsRGLP2 gene promoter from different rice accessions through sequencing and in silico evaluation

Germins and germin-like proteins from cupin superfamily contribute resistance to heat denaturation, chemical degradation and against plant pathogens, further functions in plant growth and development. In this study, from three different Oryza sativa accessions KS-282 and Pak 7178 and Pak 7865, OsRGLP2 gene promoter region was amplified, sequenced and analyzed. Sequencing data was evaluated via different computational tools. The regulatory elements were predicted by Consite tool and mapping was done. Many transcription factors binding sites were discovered in OsRGLP2 gene promoter; among these factors, HFH-1 having a significant role in germination was picked for further investigation. To study the interaction between HFH-1 and corresponding regulatory factors, HADDOCK Webserver was used. Graphical models for the interactions of HFH-1 and related regulatory elements were studied by graphic molecular system PyMOL. Mapping of cis-acting regulatory elements in OsRGLP2 gene promoter from three rice accessions showed differences in their position and copy number. Important regulatory elements found in OsRGLP2 promoter region were TATA, CAAT Box, ARR1, GATA, AGAAA, CAAT and DNA-binding One Zinc Finger (Dof) factors, few of them contribute to the regulation of plant defensive system, light responses, developmental and growth activities. Furthermore, during DNA interaction studies, it was found that HFH-1 transcription factor participates in hydrogen bonds formation with thymine and adenine bases.

The peach HECATE3-like gene FLESHY plays a double role during fruit development

Tight control of cell/tissue identity is essential for a correct and functional organ patterning, an important component of overall fruit development and eventual maturation and ripening. Despite many investigations regarding the molecular determinants of cell identity in fruits of different species, a useful model able to depict the regulatory networks governing this relevant part of fruit development is still missing. Here we described the peach fruit as a system to link the phenotype of a slow ripening (SR) selection to an altered transcriptional regulation of genes involved in determination of mesocarp cell identity providing insight toward molecular regulation of fruit tissue formation. Morpho-anatomical observations and metabolomics analyses performed during fruit development on the reference cultivar Fantasia, compared to SR, revealed that the mesocarp of SR maintained typical immaturity traits (e.g. small cell size, high amino acid contents and reduced sucrose) throughout development, along with a strong alteration of phenylpropanoid contents, resulting in accumulation of phenylalanine and lignin. These findings suggest that the SR mesocarp is phenotypically similar to a lignifying endocarp. To test this hypothesis, the expression of genes putatively involved in determination of drupe tissues identity was assessed. Among these, the peach HEC3-like gene FLESHY showed a strongly altered expression profile consistent with pit hardening and fruit ripening, generated at a post-transcriptional level. A double function for FLESHY in channelling the phenylpropanoid pathway to either lignin or flavour/aroma is suggested, along with its possible role in triggering auxin-ethylene cross talk at the start of ripening.

Overexpression of plum auxin receptor PslTIR1 in tomato alters plant growth, fruit development and fruit shelf-life characteristics

BACKGROUND

TIR1-like proteins are F-box auxin receptors. Auxin binding to the F-box receptor proteins promotes the formation of SCF(TIR1) ubiquitin ligase complex that targets the auxin repressors, Aux/IAAs, for degradation via the ubiquitin/26S proteasome pathway. The release of auxin response factors (ARFs) from their Aux/IAA partners allows ARFs to mediate auxin-responsive changes in downstream gene transcription. In an attempt to understand the potential role of auxin during fruit development, a plum auxin receptor, PslTIR1, has previously been characterized at the cellular, biochemical and molecular levels, but the biological significance of this protein is still lacking. In the present study, tomato (Solanum lycopersicum) was used as a model to investigate the phenotypic and molecular changes associated with the overexpression of PslTIR1.

RESULTS

The findings of the present study highlighted the critical role of PslTIR1 as positive regulator of auxin-signalling in coordinating the development of leaves and fruits. This was manifested by the entire leaf morphology of transgenic tomato plants compared to the wild-type compound leaf patterning. Moreover, transgenic plants produced parthenocarpic fruits, a characteristic property of auxin hypersensitivity. The autocatalytic ethylene production associated with the ripening of climacteric fruits was not significantly altered in transgenic tomato fruits. Nevertheless, the fruit shelf-life characteristics were affected by transgene presence, mainly through enhancing fruit softening rate. The short shelf-life of transgenic tomatoes was associated with dramatic upregulation of several genes encoding proteins involved in cell-wall degradation, which determine fruit softening and subsequent fruit shelf-life.

CONCLUSIONS

The present study sheds light into the involvement of PslTIR1 in regulating leaf morphology, fruit development and fruit softening-associated ripening, but not autocatalytic ethylene production. The results demonstrate that auxin accelerates fruit softening independently of ethylene action and this is probably mediated through the upregulation of many cell-wall metabolism genes.

Cell wall metabolism of peaches and nectarines treated with UV-B radiation: a biochemical and molecular approach

BACKGROUND

Ultra-violet B (UV-B) radiation has been shown to improve, at least in selected genotypes, both the health-promoting potential and the aesthetic properties of tomato and peach fruits during their post-harvest period. The effects of post-harvest UV-B treatment on the cell-wall metabolism of peaches and nectarines (Prunus persica L. Batsch) were assessed in this study. Three cultivars, Suncrest (melting flesh, MF) and Babygold 7 (non-melting flesh, NMF) peaches and Big Top (slow melting, SM) nectarine, differing in the characteristics of textural changes and softening during ripening, were analysed.

RESULTS

The effects of UV-B differ in relation to the cultivar considered. In MF 'Suncrest' fruit, UV-B treatment significantly reduced the loss of flesh firmness despite the slight increase in the presence and activity of endo-polygalacturonase. The activity of exo-polygalacturonase increased as well, while endo-1,4-β-D-glucanase/β-D-glucosidase, β-galactosidase and pectin methylesterase were substantially unaffected by the treatment. The UV-B-induced reduction of flesh softening was paralleled by the inhibition of PpExp gene transcription and expansin protein accumulation. The UV-B treatment did not induce differences in flesh firmness between control and UV-B-treated NMF 'Babygold 7' and SM 'Big Top' fruit.

CONCLUSION

Based on these results, post-harvest UV-B treatment may be considered a promising tool to improve shelf-life and quality of peach fruit.

Transcriptome analysis in Coffea eugenioides, an Arabica coffee ancestor, reveals differentially expressed genes in leaves and fruits

Studies in diploid parental species of polyploid plants are important to understand their contributions to the formation of plant and species evolution. Coffea eugenioides is a diploid species that is considered to be an ancestor of allopolyploid Coffea arabica together with Coffea canephora. Despite its importance in the evolutionary history of the main economic species of coffee, no study has focused on C. eugenioides molecular genetics. RNA-seq creates the possibility to generate reference transcriptomes and identify coding genes and potential candidates related to important agronomic traits. Therefore, the main objectives were to obtain a global overview of transcriptionally active genes in this species using next-generation sequencing and to analyze specific genes that were highly expressed in leaves and fruits with potential exploratory characteristics for breeding and understanding the evolutionary biology of coffee. A de novo assembly generated 36,935 contigs that were annotated using eight databases. We observed a total of ~5000 differentially expressed genes between leaves and fruits. Several genes exclusively expressed in fruits did not exhibit similarities with sequences in any database. We selected ten differentially expressed unigenes in leaves and fruits to evaluate transcriptional profiles using qPCR. Our study provides the first gene catalog for C. eugenioides and enhances the knowledge concerning the mechanisms involved in the C. arabica homeologous. Furthermore, this work will open new avenues for studies into specific genes and pathways in this species, especially related to fruit, and our data have potential value in assisted breeding applications.

Discovery of non-climacteric and suppressed climacteric bud sport mutations originating from a climacteric Japanese plum cultivar (Prunus salicina Lindl.)

Japanese plums are classified as climacteric; however, some economically important cultivars selected in California produce very little ethylene and require long ripening both "on" and "off" the tree to reach eating-ripe firmness. To unravel the ripening behavior of different Japanese plum cultivars, ripening was examined in the absence (air) or in the presence of ethylene or propylene (an ethylene analog) following a treatment or not with 1-methylcyclopropene (1-MCP, an ethylene action inhibitor). Detailed physiological studies revealed for the first time three distinct ripening types in plum fruit: climacteric, suppressed-climacteric, and non-climacteric. Responding to exogenous ethylene or propylene, the slow-softening supressed-climacteric cultivars produced detectable amounts of ethylene, in contrast to the novel non-climacteric cultivar that produced no ethylene and softened extremely slowly. Genetic analysis using microsatellite markers produced identical DNA profiles for the climacteric cultivars "Santa Rosa" and "July Santa Rosa," the suppressed-climacteric cultivars "Late Santa Rosa," "Casselman," and "Roysum" and the novel non-climacteric "Sweet Miriam," as expected since historic records present most of these cultivars as bud-sport mutations derived initially from "Santa Rosa." This present study provides a novel fruit system to address the molecular basis of ripening and to develop markers that assist breeders in providing high-quality stone fruit cultivars that can remain "on-tree," increasing fruit flavor, saving harvesting costs, and potentially reducing the need for low-temperature storage during postharvest handling.

Correlation analysis of proteins responsive to Zn, Mn, or Fe deficiency in Arabidopsis roots based on iTRAQ analysis

For discovering the functional correlation between the identified and quantified proteins by iTRAQ analysis, here we propose a correlation analysis method with cosine correlation coefficients as a powerful tool. iTRAQ analysis is a quantitative proteomics approach that enables identification and quantification of a large number of proteins. In order to obtain proteins responsive to Zn, Mn, or Fe mineral deficiency, we conducted iTRAQ analysis using a microsomal fraction of protein extractions from Arabidopsis root tissues. We identified and quantified 730 common proteins in three biological replicates with less than 1 % false discovery rate. To determine the role of these proteins in tolerating mineral deficiencies and their relation to each other, we calculated cosine correlation coefficients and represented the outcomes on a correlation map for visual understanding of functional relations among the identified proteins. Functionally similar proteins were gathered into the same clusters. Interestingly, a cluster of proteins (FRO2, IRT1, AHA2, PDR9/ABCG37, and GLP5) highly responsive to Fe deficiency was identified, which included both known and unknown novel proteins involved in tolerating Fe deficiency. We propose that the correlation analysis with the cosine correlation coefficients is a powerful method for finding important proteins of interest to several biological processes through comprehensive data sets.

TIR1-like auxin-receptors are involved in the regulation of plum fruit development

Ethylene has long been considered the key regulator of ripening in climacteric fruit. Recent evidence showed that auxin also plays an important role during fruit ripening, but the nature of the interaction between the two hormones has remained unclear. To understand the differences in ethylene- and auxin-related behaviours that might reveal how the two hormones interact, we compared two plum (Prunus salicina L.) cultivars with widely varying fruit development and ripening ontogeny. The early-ripening cultivar, Early Golden (EG), exhibited high endogenous auxin levels and auxin hypersensitivity during fruit development, while the late-ripening cultivar, V98041 (V9), displayed reduced auxin content and sensitivity. We show that exogenous auxin is capable of dramatically accelerating fruit development and ripening in plum, indicating that this hormone is actively involved in the ripening process. Further, we demonstrate that the variations in auxin sensitivity between plum cultivars could be partially due to PslAFB5, which encodes a TIR1-like auxin receptor. Two different PslAFB5 alleles were identified, one (Pslafb5) inactive due to substitution of the conserved F-box amino acid residue Pro61 to Ser. The early-ripening cultivar, EG, exhibited homozygosity for the inactive allele; however, the late cultivar, V9, displayed a PslAFB5/afb5 heterozygous genotype. Our results highlight the impact of auxin in stimulating fruit development, especially the ripening process and the potential for differential auxin sensitivity to alter important fruit developmental processes.

Developmental stimuli and stress factors affect expression of ClGLP1, an emerging allergen-related gene in Citrus limon

Germins and germin-like proteins (GLPs) constitute an ubiquitous family of plant proteins that seem to be involved in many developmental and stress related processes. A novel GLP cDNA was isolated from Citrus limon and structural features and genomic organization were investigated by in silico and Southern blots analysis. In lemon, the ClGLP1 encodes a 24.38 kDa which possesses a conserved motif of plant GLPs proteins. A phylogetic analysis mapped ClGLP1 as belonging to the GER3 subfamily into the GLP1 group of large GLP family. ClGLP1 was differentially expressed in the various organs and was highest in mature fruit. Moreover, expression in the fruit was tissue- and stage-related as well as dependent on agricultural practice (organic vs conventional). ClGLP1 transcripts increased during the transition from the green (180 days after blooming) to the yellow (240 days after blooming) mature fruit and were strongly enhanced in yellow mature fruit from organic compared with conventional culture. A sudden and systemic increase in ClGLP1 expression level was observed in leaves injured by wounding, together with an increase of endogenous H2O2 amount. Notably, an enhancement of H202 was observed in fruit peel during transition from green to yellow fruit stage. All together our data showed that ClGLP1 expression can be modulated in relation to both developmental stimuli and culture practices; evidence is also provided that through an oxidase activity this gene could play a role in fruit maturation as well as in stress responses.

Characterization of gibberellin-signalling elements during plum fruit ontogeny defines the essentiality of gibberellin in fruit development

Fruit growth is a coordinated, complex interaction of cell division, differentiation and expansion. Gibberellin (GA) involvement in the reproductive events is an important aspect of GA effects. Perennial fruit-trees such as plum (Prunus salicina L.) have distinct features that are economically important and provide opportunities to dissect specific GA mechanisms. Currently, very little is known on the molecular mechanism(s) mediating GA effects on fruit development. Determination of bioactive GA content during plum fruit ontogeny revealed that GA1 and GA4 are critical for fruit growth and development. Further, characterization of several genes involved in GA-signalling showed that their transcriptional regulation are generally GA-dependent, confirming their involvement in GA-signalling. Based on these results, a model is presented elucidating how the potential association between GA and other hormones may contribute to fruit development. PslGID1 proteins structure, Y2H and BiFC assays indicated that plum GA-receptors can form a complex with AtDELLA-repressors in a GA-dependent manner. Moreover, phenotypical-, molecular- and GA-analyses of various Arabidopsis backgrounds ectopically expressing PslGID1 sequences provide evidence on their role as active GA-signalling components that mediate GA-responsiveness. Our findings support the critical contribution of GA alone or in association with other hormones in mediating plum fruit growth and development.

A proteomic study on molecular mechanism of poor grain-filling of rice (Oryza sativa L.) inferior spikelets

Cultivars of rice (Oryza sativa L.), especially of the type with large spikelets, often fail to reach the yield potential as expected due to the poor grain-filling on the later flowering inferior spikelets (in contrast to the earlier-flowering superior spikelets). The present study showed that the size and grain weight of superior spikelets (SS) was greater than those of inferior spikelets (IS), and the carbohydrate supply should not be the major problem for the poor grain-filling because there was adequate amount of sucrose in IS at the initial grain-filling stage. High resolution two-dimensional gel electrophoresis (2-DE) in combination with Coomassie-brilliant blue (CBB) and Pro-Q Diamond phosphoprotein fluorescence stain revealed that 123 proteins in abundance and 43 phosphoproteins generated from phosphorylation were significantly different between SS and IS. These proteins and phosphoproteins were involved in different cellular and metabolic processes with a prominently functional skew toward metabolism and protein synthesis/destination. Expression analyses of the proteins and phosphoproteins associated with different functional categories/subcategories indicated that the starch synthesis, central carbon metabolism, N metabolism and cell growth/division were closely related to the poor grain-filling of IS. Functional and expression pattern studies also suggested that 14-3-3 proteins played important roles in IS poor grain-filling by regulating the activity of starch synthesis enzymes. The proteome and phosphoproteome obtained from this study provided a better understanding of the molecular mechanism of the IS poor grain-filling. They were also expected to be highly useful for improving the grain filling of rice.

Calmodulin-mediated signal transduction pathways in Arabidopsis are fine-tuned by methylation

Calmodulin N-methyltransferase (CaM KMT) is an evolutionarily conserved enzyme in eukaryotes that transfers three methyl groups to a highly conserved lysyl residue at position 115 in calmodulin (CaM). We sought to elucidate whether the methylation status of CaM plays a role in CaM-mediated signaling pathways by gene expression analyses of CaM KMT and phenotypic characterization of Arabidopsis thaliana lines wherein CaM KMT was overexpressed (OX), partially silenced, or knocked out. CaM KMT was expressed in discreet spatial and tissue-specific patterns, most notably in root tips, floral buds, stamens, apical meristems, and germinating seeds. Analysis of transgenic plants with genetic dysfunction in CaM KMT revealed a link between the methylation status of CaM and root length. Plants with suppressed CaM methylation had longer roots and CaM KMT OX lines had shorter roots than wild type (Columbia-0). CaM KMT was also found to influence the root radial developmental program. Protein microarray analyses revealed a number of proteins with specificity for methylated forms of CaM, providing candidate functional intermediates between the observed phenotypes and the target pathways. This work demonstrates that the functionality of the large CaM family in plants is fine-tuned by an overarching methylation mechanism.

Characterization of peanut germin-like proteins, AhGLPs in plant development and defense

Background

Germin-like superfamily members are ubiquitously expressed in various plant species and play important roles in plant development and defense. Although several GLPs have been identified in peanut (Arachis hypogaea L.), their roles in development and defense remain unknown. In this research, we study the spatiotemporal expression of AhGLPs in peanut and their functions in plant defense.

Results

We have identified three new AhGLP members (AhGLP3b, AhGLP5b and AhGLP7b) that have distinct but very closely related DNA sequences. The spatial and temporal expression profiles revealed that each peanut GLP gene has its distinct expression pattern in various tissues and developmental stages. This suggests that these genes all have their distinct roles in peanut development. Subcellular location analysis demonstrated that AhGLP2 and 5 undergo a protein transport process after synthesis. The expression of all AhGLPs increased in responding to Aspergillus flavus infection, suggesting AhGLPs' ubiquitous roles in defense to A. flavus. Each AhGLP gene had its unique response to various abiotic stresses (including salt, H₂O₂ stress and wound), biotic stresses (including leaf spot, mosaic and rust) and plant hormone stimulations (including SA and ABA treatments). These results indicate that AhGLPs have their distinct roles in plant defense. Moreover, in vivo study of AhGLP transgenic Arabidopsis showed that both AhGLP2 and 3 had salt tolerance, which made transgenic Arabidopsis grow well under 100 mM NaCl stress.

Conclusions

For the first time, our study analyzes the AhGLP gene expression profiles in peanut and reveals their roles under various stresses. These results provide an insight into the developmental and defensive roles of GLP gene family in peanut.

Increased levels of IAA are required for system 2 ethylene synthesis causing fruit softening in peach (Prunus persica L. Batsch)

The fruit of melting-flesh peach (Prunus persica L. Batsch) cultivars produce high levels of ethylene caused by high expression of PpACS1 (an isogene of 1-aminocyclopropane-1-carboxylic acid synthase), resulting in rapid fruit softening at the late-ripening stage. In contrast, the fruit of stony hard peach cultivars do not soften and produce little ethylene due to low expression of PpACS1. To elucidate the mechanism for suppressing PpACS1 expression in stony hard peaches, a microarray analysis was performed. Several genes that displayed similar expression patterns as PpACS1 were identified and shown to be indole-3-acetic acid (IAA)-inducible genes (Aux/IAA, SAUR). That is, expression of IAA-inducible genes increased at the late-ripening stage in melting flesh peaches; however, these transcripts were low in mature fruit of stony hard peaches. The IAA concentration increased suddenly just before harvest time in melting flesh peaches exactly coinciding with system 2 ethylene production. In contrast, the IAA concentration did not increase in stony hard peaches. Application of 1-naphthalene acetic acid, a synthetic auxin, to stony hard peaches induced a high level of PpACS1 expression, a large amount of ethylene production and softening. Application of an anti-auxin, α-(phenylethyl-2-one)-IAA, to melting flesh peaches reduced levels of PpACS1 expression and ethylene production. These observations indicate that suppression of PpACS1 expression at the late-ripening stage of stony hard peach may result from a low level of IAA and that a high concentration of IAA is required to generate a large amount of system 2 ethylene in peaches.

Molecular cloning and characterization of novel Morus alba germin-like protein gene which encodes for a silkworm gut digestion-resistant antimicrobial protein

Background

Silkworm fecal matter is considered one of the richest sources of antimicrobial and antiviral protein (substances) and such economically feasible and eco-friendly proteins acting as secondary metabolites from the insect system can be explored for their practical utility in conferring broad spectrum disease resistance against pathogenic microbial specimens.

Methodology/Principal Findings

Silkworm fecal matter extracts prepared in 0.02 M phosphate buffer saline (pH 7.4), at a temperature of 60°C was subjected to 40% saturated ammonium sulphate precipitation and purified by gel-filtration chromatography (GFC). SDS-PAGE under denaturing conditions showed a single band at about 21.5 kDa. The peak fraction, thus obtained by GFC wastested for homogeneityusing C18reverse-phase high performance liquid chromatography (HPLC). The activity of the purified protein was tested against selected Gram +/− bacteria and phytopathogenic Fusarium species with concentration-dependent inhibitionrelationship. The purified bioactive protein was subjected to matrix-assisted laser desorption and ionization-time of flight mass spectrometry (MALDI-TOF-MS) and N-terminal sequencing by Edman degradation towards its identification. The N-terminal first 18 amino acid sequence following the predicted signal peptide showed homology to plant germin-like proteins (Glp). In order to characterize the full-length gene sequence in detail, the partial cDNA was cloned and sequenced using degenerate primers, followed by 5′- and 3′-rapid amplification of cDNA ends (RACE-PCR). The full-length cDNA sequence composed of 630 bp encoding 209 amino acids and corresponded to germin-like proteins (Glps) involved in plant development and defense.

Conclusions/Significance

The study reports, characterization of novel Glpbelonging to subfamily 3 from M. alba by the purification of mature active protein from silkworm fecal matter. The N-terminal amino acid sequence of the purified protein was found similar to the deduced amino acid sequence (without the transit peptide sequence) of the full length cDNA from M. alba.

Expression of PiABP19, Picdc2 and PiSERK3 during induction of somatic embryogenesis in leaflets of Prunus incisa (Thunb.)

Somatic embryogenesis is a useful tool of plant breeding. In this context, a procedure for inducing somatic embryogenesis in Prunus incisa leaf explants had been previously developed. The original in vitro protocol relies on picloram treatments and exposure to darkness as inductive conditions, the best frequency of embryogenesis being obtained on the second leaf (F(2)) exposed to 4 μM picloram during 30 days. The morphological and biochemical changes observed during somatic embryogenesis occur in response to alterations in gene expression regulation patterns. A molecular study was conducted in order to provide deeper insight into the fundamental biological factors involved in the induction of this process using a gene candidate strategy and semi-quantitative reverse transcription polymerase chain reaction analysis. So far, no sequence data related to somatic embryogenesis has been available in cherry. In the present study, we cloned and sequenced cDNA fragments of putative genes encoding auxin-binding protein, cell cycle regulator and somatic embryogenesis receptor kinase. Time-course differential transcript accumulations were observed for all investigated genes in leaves or derived callus tissues during the observation period (first month of culture). Their possible involvement in the sequential steps of the embryogenic pathway (dedifferentiation, cell proliferation, differentiation through somatic embryogenesis) is presented and discussed.

Expression of auxin-binding protein1 during plum fruit ontogeny supports the potential role of auxin in initiating and enhancing climacteric ripening

Auxin-binding protein1 (ABP1) is an active element involved in auxin signaling and plays critical roles in auxin-mediated plant development. Here, we report the isolation and characterization of a putative sequence from Prunus salicina L., designated PslABP1. The expected protein exhibits a similar molecular structure to that of well-characterized maize-ABP1; however, PslABP1 displays more sequence polarity in the active-binding site due to substitution of some crucial amino-acid residues predicted to be involved in auxin-binding. Further, PslABP1 expression was assessed throughout fruit ontogeny to determine its role in fruit development. Comparing the expression data with the physiological aspects that characterize fruit-development stages indicates that PslABP1 up-regulation is usually associated with the signature events that are triggered in an auxin-dependent manner such as floral induction, fruit initiation, embryogenesis, and cell division and elongation. However, the diversity in PslABP1 expression profile during the ripening process of early and late plum cultivars seems to be due to the variability of endogenous auxin levels among the two cultivars, which consequently can change the levels of autocatalytic ethylene available for the fruit to co-ordinate ripening. The effect of auxin on stimulating ethylene production and in regulating PslABP1 was investigated. Our data suggest that auxin is involved in the transition of the mature green fruit into the ripening phase and in enhancing the ripening process in both auxin- and ethylene-dependent manners thereafter.

Identification and genetic characterization of a gibberellin 2-oxidase gene that controls tree stature and reproductive growth in plum

Several dwarf plum genotypes (Prunus salicina L.), due to deficiency of unknown gibberellin (GA) signalling, were identified. A cDNA encoding GA 2-oxidase (PslGA2ox), the major gibberellin catabolic enzyme in plants, was cloned and used to screen the GA-deficient hybrids. This resulted in the identification of a dwarf plum hybrid, designated as DGO24, that exhibits a markedly elevated PslGA2ox signal. Grafting 'Early Golden' (EG), a commercial plum cultivar, on DGO24 (EG/D) enhanced PslGA2ox accumulation in the scion part and generated trees of compact stature. Assessment of active GAs in such trees revealed that DGO24 and EG/D accumulated relatively much lower quantities of main bioactive GAs (GA(1) and GA(4)) than control trees (EG/M). Moreover, the physiological function of PslGA2ox was studied by determining the molecular and developmental consequences due to ectopic expression in Arabidopsis. Among several lines, two groups of homozygous transgenics that exhibited contrasting phenotypes were identified. Group-1 displayed a dwarf growth pattern typical of mutants with a GA deficiency including smaller leaves, shorter stems, and delay in the development of reproductive events. In contrast, Group-2 exhibited a 'GA overdose' phenotype as all the plants showed elongated growth, a typical response to GA application, even under limited GA conditions, potentially due to co-suppression of closely related Arabidopsis homologous. The studies reveal the possibility of utilizing PslGA2ox as a marker for developing size-controlling rootstocks in Prunus.

The fading distinctions between classical patterns of ripening in climacteric and non-climacteric fruit and the ubiquity of ethylene-An overview

The process of fruit ripening is normally viewed distinctly in climacteric and non-climacteric fruits. But, many fruits such as guava, melon, Japanese plum, Asian pear and pepper show climacteric as well as non-climacteric behaviour depending on the cultivar or genotype. Investigations on in planta levels of CO2 and ethylene at various stages of fruits during ripening supported the role and involvement of changes in the rate of respiration and ethylene production in non-climacteric fruits such as strawberry, grapes and citrus. Non-climacteric fruits are also reported to respond to the exogenous application of ethylene. Comparative analysis of plant-attached and plant-detached fruits did not show similarity in their ripening behaviour. This disparity is being explained in view of 1. Hypothetical ripening inhibitor, 2. Differences in the production, release and endogenous levels of ethylene, 3. Sensitivity of fruits towards ethylene and 4. Variations in the gaseous microenvironment among fruits and their varieties. Detailed studies on genetic and inheritance patterns along with the application of '-omics' research indicated that ethylene-dependent and ethylene-independent pathways coexist in both climacteric and non-climacteric fruits. Auxin levels also interact with ethylene in regulating ripening. These findings therefore reveal that the classification of fruits based on climacteric rise and/or ethylene production status is not very distinct or perfect. However, presence of a characteristic rise in CO2 levels and a burst in ethylene production in some non-climacteric fruits as well as the presence of system 2 of ethylene production point to a ubiquitous role for ethylene in fruit ripening.