Polyphenoloxidase Silencing Affects Latex Coagulation in Taraxacum Species

Latex is the milky sap that is found in many different plants. It is produced by specialized cells known as laticifers and can comprise a mixture of proteins, carbohydrates, oils, secondary metabolites, and rubber that may help to prevent herbivory and protect wound sites against infection. The wound-induced browning of latex suggests that it contains one or more phenol-oxidizing enzymes. Here, we present a comprehensive analysis of the major latex proteins from two dandelion species, Taraxacum officinale and Taraxacum kok-saghyz, and enzymatic studies showing that polyphenoloxidase (PPO) is responsible for latex browning. Electrophoretic analysis and amino-terminal sequencing of the most abundant proteins in the aqueous latex fraction revealed the presence of three PPO-related proteins generated by the proteolytic cleavage of a single precursor (pre-PPO). The laticifer-specific pre-PPO protein contains a transit peptide that can target reporter proteins into chloroplasts when constitutively expressed in dandelion protoplasts, perhaps indicating the presence of structures similar to plastids in laticifers, which lack genuine chloroplasts. Silencing the PPO gene by constitutive RNA interference in transgenic plants reduced PPO activity compared with wild-type controls, allowing T. kok-saghyz RNA interference lines to expel four to five times more latex than controls. Latex fluidity analysis in silenced plants showed a strong correlation between residual PPO activity and the coagulation rate, indicating that laticifer-specific PPO plays a major role in latex coagulation and wound sealing in dandelions. In contrast, very little PPO activity is found in the latex of the rubber tree Hevea brasiliensis, suggesting functional divergence of latex proteins during plant evolution.Latex is a milky sap produced by more than 12,500 plant species spanning 20 families (Metcalfe, 1966). It is often white or colorless but can range from yellow to scarlet (e.g. in some members of the poppy family [Papaveraceae]). Latex coagulates when exposed to air and consists of an emulsion of polymers and metabolites that are often bitter or toxic. Therefore, it is proposed that natural latex has a protective function, sealing wounds, acting as a barrier to microorganisms, and discouraging herbivory (El Moussaoui et al., 2001). In addition to a wide range of low-molecular-weight polypeptides (Nessler and Burnett, 1992; Azarkan et al., 2004), several other proteins and enzymes have been identified in the latices of laticiferous plants. These include the wound-induced proteins trypsin inhibitor, class II chitinase, and glutaminyl cyclase in the latex of papaya (Carica papaya; Azarkan et al., 2004) as well as chitinases and β-1,3-glucanase in the latex of the rubber tree Hevea brasiliensis (Martin, 1991; Subroto et al., 1996). The latex from some plants is a good source of natural rubber, and H. brasiliensis is widely cultivated for this purpose.Latex is produced in specialized cells known as laticifers, which arise in two distinct ways depending on the species (Evert, 2006). Articulated laticifers (found in the Papaveraceae, Asteraceae, and in H. brasiliensis) are organized in longitudinal chains originally laid down in the meristem, and the cell walls become perforated or completely degraded during development to form continuous channels called latex vessels. In contrast, nonarticulated laticifers (found in milkweeds [Asclepias spp.]) are organized in a branching system originating from a single precursor cell in the embryo that divides rapidly and spreads invasively during development. These are multinucleate cells that tend not to fuse into vessels (Serpe et al., 2002).Taraxacum officinale (common dandelion) and Taraxacum kok-saghyz (Russian dandelion) are members of the Asteraceae and therefore possess articulated laticifers (Esau, 1965; Evert, 2006) that secrete a latex rich in polyphenols (Schütz et al., 2005; C. Schulze Gronover, unpublished data). T. kok-saghyz latex is a good source of high-molecular-weight rubber (Mooibroek and Cornish, 2000; Bushman et al., 2006) and was investigated as an alternative to H. brasiliensis during World War II, when rubber supplies to Europe and the United States were interrupted. Unfortunately, the extraction of rubber from Russian dandelion latex is laborious and expensive because of rapid coagulation, and further development was abandoned when Hevea rubber became available. Coagulation of H. brasiliensis latex is caused by the major latex proteins (MLPs), which include hevein, the hevein receptor, and chitinase (Gidrol et al., 1994; Chrestin et al., 1997). A similar role has been proposed for the polyphenoloxidases (PPOs) present in the latex of certain Hevea spp. (Hanower and Brzozowska, 1977), although our data indicate that this is not the case.PPOs are found throughout the plant kingdom (Mayer and Harel, 1979; Vaughn and Duke, 1984; Mayer, 1987; Vaughn et al., 1988; Sherman et al., 1991), and they probably play a role in defense against pathogens and herbivores (Vörös et al., 1957; Felton et al., 1989; Duffey and Felton, 1991; Constabel and Ryan, 1998; Stout et al., 1999; Gatehouse, 2002). They are plastid-localized copper metalloenzymes that catalyze the oxidation of o-diphenols to o-diquinones (diphenolase activity; EC 1.10.3.2) and, in some species, also the o-hydroxylation of monophenols (monophenolase activity; EC 1.14.18.1; Vaughn et al., 1988; Mayer, 2006). Quinones are highly reactive electrophiles responsible for much of the oxidative browning in fruits and vegetables after wounding (Yoruk and Marshall, 2003). The wound-inducible expression of PPOs has been reported in apple (Malus domestica; Boss et al., 1995), tomato (Solanum lycopersicum; Constabel et al., 1995; Thipyapong and Steffens 1997), potato (Solanum tuberosum; Thipyapong et al., 1995), and hybrid poplar (Populus spp.; Constabel et al., 2000). In addition, the down-regulation of PPO activity by antisense RNA in tomato confers hypersusceptibility to pathogens (Thipyapong et al., 2004), whereas PPO overexpression confers enhanced resistance to bacterial diseases (Li and Steffens, 2002). It has also been suggested that PPOs evolved to protect plants against photochemical oxidation, since most PPOs characterized thus far appear to be localized in the plastids of photosynthetic cells (Sherman et al., 1995).The rapid wound-induced browning of dandelion latex suggests the presence of significant PPO activity in the laticifers. Here, we show that the PPO is the major component of the latex proteome in Taraxacum spp. and that the down-regulation of PPO activity by RNA interference (RNAi) in transgenic T. officinale and T. kok-saghyz plants inhibits browning and coagulation. This suggests that PPO may be a key factor controlling the coagulation of dandelion latex and thus its protective role. This contrasts to the situation in H. brasiliensis, where we show that PPO appears to have a negligible effect on latex coagulation.     

Yeasts in <Emphasis Type="Italic">Hevea brasiliensis</Emphasis> latex

Yeast abundance and species diversity in the latex of rubber tree Hevea brasiliensis (Willd. ex Juss.) Müll. Arg., on its green leaves, and in soil below the plant were studied. The yeasts present in the fresh latex in numbers of up to 5.5 log(CFU/g) were almost exclusively represented by the species Candida heveicola. This species was previously isolated from Hevea latex in China. In the course of natural modification of the latex (turned from liquid to solid form), yeast diversity increased, while yeast abundance decreased. The yeasts in thickened and solidified latex were represented by typical epiphytic and ubiquitous species: Kodamea ohmeri, Debaryomyces hansenii, Rhodotorula mucilaginosa, and synanthropic species Candida parapsilosis and Cutaneotrichosporon arboriformis. The role of yeasts in latex modification at the initial stages of succession and their probable role in development of antifungal activity in the latex are discussed.     

Cloning and Aggregation Characterization of Rubber Elongation Factor and Small Rubber Particle Protein from <Emphasis Type="Italic">Ficus carica</Emphasis>

Rubber elongation factor (REF) and small rubber particle protein (SRPP) are major latex proteins harvested from Hevea brasiliensis (the rubber tree; HbREF and HbSRPP, respectively). Their amino acid sequences exhibit high homology with each other. In the present study, we cloned two cDNAs encoding REF/SRPP-family proteins (FcREF/SRPP-1 and -2) from the laticifers of Ficus carica (fig tree). The amino acid sequences of these proteins showed high homology not only with each other but also with HbREF and HbSRPP. Recombinant FcREF/SRPP-1 and -2 were expressed in E. coli, and their aggregation properties were examined using a Congo red binding assay, agarose gel electrophoresis, and transmission electron microscopy. FcREF/SRPP-1 formed fibrils when incubated in PBS, and grew to micrometer-sized amorphous aggregates that precipitated rapidly. These aggregation properties of FcREF/SRPP-1 are quite similar to those of HbREF, although the growth rate and size of FcREF/SRPP-1 aggregates were inferior to those of HbREF. FcREF/SRPP-2 also formed aggregates during the incubation, but they did not precipitate, as has been reported for HbSRPP. Our results suggest that FcREF/SRPP-1 and -2 correspond to HbREF and HbSRPP, respectively. These aggregation properties could provide useful benchmarks for classifying REF/SRPP-family proteins as REF or SRPP.     

Genetic and epigenetic uniformity of polyembryony derived multiple seedlings of <Emphasis Type="Italic">Hevea brasiliensis</Emphasis>

Hevea brasiliensis Muell. Arg (Para rubber tree) is a tropical tree species of Amazonian origin widely cultivated in several parts of the world for natural rubber, a highly priced commodity inevitable for the world rubber industry. Large, tree to tree variation in growth and latex yield among individual plants of high yielding Hevea clones is a common phenomenon observed in mature rubber plantations. The genetic heterogeneity of the seedlings which are used as rootstocks for propagation through budgrafting is considered as a major factor  responsible for this variation. In order to minimize this variation, attempts were made to develop highly uniform rootstock material via an in vitro technique by inducing zygotic polyembryony in Hevea. Immature open pollinated fruits of a high yielding clone RRII 105 were cultured by half ovulo embryo culture technique. Multiple embryos were induced from the 8–10-week-old zygote with a novel combination of gibberellic acid (GA₃), kinetin, and zeatin. Plantlets were successfully generated from the multiple embryos and raised in the field post hardening. Screening using genetic and epigenetic molecular markers revealed that the multiple seedlings developed are highly uniform and are of single zygotic origin. Development of plants having genetic and epigenetic uniformity suggests that this technique is ideal for raising uniform rootstock material in Hevea which may significantly reduce intraclonal variations. Moreover, these plants could serve as ideal material for physiological and molecular investigations towards the understanding of  stock–scion interaction process in rubber.     

Development of single nucleotide polymorphism markers in the large and complex rubber tree genome using next-generation sequence data

The development of single nucleotide polymorphism (SNP) markers provides the opportunity to improve many areas of plant breeding and population genetics. Unfortunately, for species such as the rubber tree (Hevea brasiliensis), the use of next-generation sequencing for genomic SNP discovery is very difficult because of the large genome size and the abundance of repeated sequences. Access to a set of validated SNP markers is a significant advantage for rubber researchers who wish to apply SNPs in scientific research. Here, we performed genomic sequencing of H. brasiliensis and generated 10,993,648 short reads, which were assembled into 10,071 contigs (N50 = 3078) by a de novo assembly strategy. A total of 2446 contigs presented no hits in the current H. brasiliensis genome assembly and may therefore be considered novel genomic sequences of rubber tree. A total of 143 putative polymorphic positions were selected, gene annotations were available for 58.7 % of the markers, and all of the sequences could be anchored to the released H. brasiliensis genome. These SNPs were validated in eight genotypes of H. brasiliensis and 15 F1 plants from a mapping population, resulting in 30 (20.9 %) positions correctly classified. The analysis revealed key candidate genes responsible for defence mechanisms and provided markers for further genetic improvement of Hevea in breeding programmes.     

Genome-wide identification,characterization, and expression analysis of <Emphasis Type="Italic">SnRK2</Emphasis> family in <Emphasis Type="Italic">Hevea brasiliensis</Emphasis>

The sucrose non-fermenting 1-related protein kinase 2 (SnRK2) gene family belongs to a group of plant-specific serine/threonine kinase family involved in abscisic acid (ABA) signaling and biotic and abiotic stress response. Although genome-wide analyses of the SnRK2 gene family have been conducted in some species, little is known about the SnRK2 gene family in rubber tree (Hevea brasiliensis). In this study, we identified 10 SnRK2s designated as HbSnRK2.1 to HbSnRK2.10 in the rubber tree genome. The subsequently constructed phylogenetic tree demonstrated that HbSnRK2s have three subfamilies that correlate well with those of Arabidopsis sp. and rice subfamilies. All SnRK2 genes contained nine exons and eight introns. Although the C-terminus was divergent, eight conserved motifs were found. Motifs 1–6 were common to all HbSnRK2s. Expression analysis results showed that 7 of the 10 HbSnRK2s were highly expressed in latex. HbSnRK2.7 was predominantly expressed and simultaneously regulated by abscisic acid, jasmonic acid, and ethylene treatment in laticifers. HbSnRK identification and characterization provided further understanding on the role of ABA signal in the rubber tree.     

Expression of the sucrose transporter 3 (<Emphasis Type="Italic">HbSUT3</Emphasis>) in rubber tree and its relation to latex yield

Sucrose is not only a precursor of rubber biosynthesis, but it also participates in other latex regeneration between repeated tapping. Sucrose transporter (HbSUT) genes play key roles in sinks and sources of the rubber biosynthesis pathway. HbSUT3 was dominant in expression in latex among the SUT member genes. Therefore, the expression level of HbSUT3 in latex is a potential indicator distinguishing between high- and low-yielding clones. The aim of this research was to assess the potential of this gene in selective breeding to improve latex yield, from the correlation of HbSUT3 expression with latex yield. Four high-yielding clones were sampled in this study and compared with the common RRIM 600 clone as the baseline, paired by the field. Among the putative full-length cDNAs of Hevea sucrose transporters available in the NCBI database, only HbSUT3 was detected. The HbSUT3 gene was overexpressed in the four rubber clones relative to the control, and the NK1 clone had the highest expression level. The expression level of HbSUT3 correlated positively with latex yield but negatively with the sucrose content of latex. Gene expression analysis of rubber seedlings indicated that the bark had higher expression of this gene than the leaves, and the levels correlated with latex yields of these clones. These data provided new candidate selection criteria for use in the early selection of high-yielding rubber clones, necessary for rapid cycle breeding programs.     

Variance,Inter-Trait Correlation,Heritability, and Marker-Trait Association of Rubber Yield-Related Characteristics in <Emphasis Type="Italic">Taraxacum kok-saghyz</Emphasis>

Rubber dandelion (Taraxacum kok-saghyz or TK) is a potential industrial crop species that can produce high-quality natural rubber in its roots. The present study estimated trait variance, inter-trait correlation, and entry-mean heritability for rubber yield-related traits and analyzed associations between these traits and 42 single-nucleotide polymorphism (SNP) markers. A trial was conducted at three environments to assess a biparental progeny of 66 F₁ full-sibs, in a randomized complete block design (RCBD) with two replicates. Significant correlations, broad ranges of variation, and significant genotypic variance components were identified for five measured phenotypic traits. Moderate broad-sense heritability on an entry-mean heritability estimates (0.51–0.61) were obtained for five rubber yield-related traits based on a 1-year trial. However, the broad-sense heritability in general sense ranged from 0.09 to 0.15 depending on the trait. Two linkage groups were identified. Association analysis identified seven significant marker-trait gene associations, and only one marker was related to two traits. The implications of trait correlations and heritability for selection and improvement are discussed.     

Virome analyses of <Emphasis Type="Italic">Hevea brasiliensis</Emphasis> using small RNA deep sequencing and PCR techniques reveal the presence of a potential new virus

Background

Hevea brasiliensis is an important commercial crop due to the high quality of the latex it produces; however, little is known about viral infections in this plant. The only virus described to infect H. brasiliensis until now is a Carlavirus, which was described more than 30?years ago. Virus-derived small interfering RNA (vsiRNAs) are the product of the plant’s antiviral defense triggered by dsRNA viral intermediates generated, during the replication cycle. These vsiRNAs are complementar to viral genomes and have been widely used to identify and characterize viruses in plants.

Methods

In the present study, we investigated the virome of leaf and sapwood samples from native H. brasiliensis trees collected in two geographic areas in the Brazilian Amazon. Small RNA (sRNA) deep sequencing and bioinformatic tools were used to assembly, identify and characterize viral contigs. Subsequently, PCR amplification techniques were performed to experimentally verify the presence of the viral sequences. Finally, the phylogenetic relationship of the putative new virus with related viral genomes was analyzed.

Results

Our strategy allowed the identification of 32 contigs with high similarity to viral reference genomes, from which 23 exhibited homology to viruses of the Tymoviridae family. The reads showed a predominant size distribution at 21?nt derived from both strands, which was consistent with the vsiRNAs profile. The presence and genome position of the viral contigs were experimentally confirmed using droplet digital PCR amplifications. A 1913 aa long fragment was obtained and used to infer the phylogenetic relationship of the putative new virus, which indicated that it is taxonomically related to the Grapevine fleck virus, genus Maculavirus. The putative new virus was named Hevea brasiliensis virus (HBrV) in reference to its host.

Conclusion

The methodological strategy applied here proved to be efficient in detecting and confirming the presence of new viral sequences on a ‘very difficult to manage’ sample. This is the second time that viral sequences, that could be ascribed as a putative novel virus, associated to the rubber tree has been identified.

     

Reproductive Behavior of the Bug <Emphasis Type="Italic">Molipteryx fuliginosa</Emphasis> Uhler (Heteroptera,Coreidae) in the South of the Russian Far East

Reproductive behavior of Molipteryx fuliginosa (Uhler) was investigated in Primorskii Territory of Russia. From 4 to 18 repeated copulations of one female lasting from 2 to 48 hours were recorded in cages. The behavior of ovipositing females and the stages of oviposition are described for the first time. The number of eggs laid between copulations varied from 1 to 13, the number of oviposition acts, from 4 to 11, and the total female fecundity, from 21 to 38 eggs. Caged females laid eggs on plants and also on dead substrates unsuitable for nymphal feeding, such as cloth, dry branches, and a wooden pole. Copulation of M. fuliginosa was also observed under natural conditions. The preferred mating places of M. fuliginosa in anthropogenically modified habitats and in small-leaved riparian forests were plants of Rubus idaeus L., R. caesius L., and Rubus sp. After mating, females migrated in search of places for oviposition. Single eggs were found on the following plants not known previously as hosts of this bug: Solanum lycopersicum L., Carex sp., Elytrigia repens (L.) Nevski, and Taraxacum officinale Wigg. The females seemed to lack selectivity in the choice of place for oviposition, which was not always associated with host plants, despite their abundance and availability.     

Characterization and expression analysis of cytokinin biosynthesis genes in <Emphasis Type="Italic">Fragaria vesca</Emphasis>

Strawberry is one of the most economically important fruit crops in the world. Cytokinins (CKs) play a critical role in plant growth and development, as well as the stress response, and the level of CKs in plants is regulated by synthesis and degradation pathways. The key synthetic enzymes of CKs are isopentenyl transferases (IPTs) and LONELY GUYS (LOGs). We surveyed the strawberry genome and identified seven FvIPT genes and nine FvLOG genes. We analyzed gene structures, conserved domains, and their phylogenetic relationships with rice and Arabidopsis. The isoelectric points and glycosylation sites of the proteins were predicted. We also analyzed tissue- or organ-specific expression patterns of the FvIPT and FvLOG genes. The FvIPT and FvLOG genes showed different expression profiles in different organs. Most FvIPT and FvLOG genes were down-regulated in response to osmotic stress, high-temperature treatment, and exogenous abscisic acid (ABA) application, suggesting possible roles of these genes in the plants’ resistance to abiotic stresses. In addition, we found that the results of bioinformatics analyses to identify cis-regulatory elements may not be consistent with experimental expression data; thus, computer-predicted putative cis-elements need to be confirmed by experiments. Our systematic analyses of the FvIPT and FvLOG families provide a foundation for characterizing the function of these genes in the regulation of growth, development, and stress tolerance in Fragaria vesca, as well as a reference for improving stress tolerance by manipulating CK content.     

Genome-wide survey and expression analysis of the stress-associated protein gene family in desert poplar, <Emphasis Type="Italic">Populus euphratica</Emphasis>

Stress-associated proteins (SAPs) are a novel class of zinc finger proteins that extensively participate in abiotic stress responses. To date, no overall analysis and expression profiling of SAP genes in woody plants have been reported. Populus euphratica is distributed in desert regions and is extraordinarily adaptable to abiotic stresses. Thus, it is regarded as a promising candidate for studying abiotic stress resistance mechanisms of woody plants. In this study, 18 non-redundant SAP genes were identified from the genome of P. euphratica using basic local alignment search tool algorithms and functional domain verification. Among these 18 PeuSAP genes, 15 were intronless. To investigate the evolutionary relationships of SAP genes in P. euphratica and other Salicaceae plants, phylogenetic analyses were performed. Subsequently, the expression profiles of the 18 PeuSAP genes were analyzed in different tissues and under various stresses (drought, salt, heat, cold, and abscisic acid (ABA) treatment) using quantitative real-time PCR. Tissue expression analysis indicated that PeuSAPs showed no tissue specificity. PeuSAPs were induced by multiple abiotic stresses, especially drought, salt, and heat stresses, perhaps because of abundant cis-acting heat shock elements and drought-inducible elements in the promoter regions of the PeuSAPs. Moreover, single nucleotide polymorphisms (SNPs) variant analysis revealed many synonymous and non-synonymous SNPs in PeuSAP genes, but the zinc finger structure was conserved during evolution. These results provide an overview of the SAP gene family in P. euphratica and a reference for further functional research on PeuSAP genes.     

Antagonistic Activity of <Emphasis Type="Italic">Nocardia brasiliensis</Emphasis> PTCC 1422 Against Isolated Enterobacteriaceae from Urinary Tract Infections

The main drawback of current antibiotic therapies is the emergence and rapid increase in antibiotic resistance. Nocardiae are aerobic, Gram-positive, catalase-positive, non-motile actinomycetes. Nocardia brasiliensis was reported as antibiotic producer. The purpose of the study was to determine antibacterial activity of N. brasiliensis PTCC 1422 against isolated Enterobacteriaceae from urinary tract infections (UTIs). The common bacteria from UTIs were isolated from hospital samples. Antimicrobial susceptibility test was performed for the isolated pathogens using Kirby–Bauer disk diffusion method according to clinical and Laboratory Standards Institute guideline. Antagonistic activity of N. brasiliensis PTCC 1422 was examined with well diffusion methods. Supernatant of N. brasiliensis PTCC 1422 by submerged culture was analyzed with gas chromatography–mass spectrometry. Isolated strains included Escherichia coli, Klebsiella pneumoniae, Serratia marcescens and Proteus mirabilis. The most common pathogen isolated was E. coli (72.5 %). Bacterial isolates revealed the presence of high levels of antimicrobial resistances to ceftriaxone and low levels of resistance to cephalexin. Supernatant of N. brasiliensis PTCC 1422 showed antibacterial activity against all of the isolated microorganisms in well diffusion method. The antibiotic resistance among the uropathogens is an evolving process, so a routine surveillance to monitor the etiologic agents of UTI and the resistance pattern should be carried out timely to choose the most effective empirical treatment by the physicians. Our present investigation indicates that the substances present in the N. brasiliensis PTCC 1422 could be used to inhibit the growth of human pathogen. Antibacterial resistance among bacterial uropathogen is an evolving process. Therefore, in the field on the need of re-evaluation of empirical treatment of UTIs, our present. The study has demonstrated that N. brasiliensis PTCC 1422 has a high potential for the treatment of UTIs.     

Comparative proteomic analysis of leaf tissue from tomato plants colonized with <Emphasis Type="Italic">Rhizophagus irregularis</Emphasis>

A comparative proteomic approach was performed to analyze the differential accumulation of leaf proteins in response to the symbiosis between Solanum lycopersicum and the arbuscular mycorrhizal fungus (AMF) Rhizophagus irregularis. Protein profiling was examined in leaves from tomato plants colonized with AMF (M), as well as non-colonized plants fertilized with low phosphate (20 μM P; NM-LP) and non-colonized plants fertilized with regular phosphate Hoagland’s solution (200 μM P; NM-RP). Comparisons were made between these groups, and 2D-SDS-PAGE revealed that 27 spots were differentially accumulated in M vs. NM-LP. Twenty-three out of the 27 spots were successfully identified by mass spectrometry. Two of these proteins, 2-methylene-furan-3-one reductase and auxin-binding protein ABP19a, were up-accumulated in M plants. The down-accumulated proteins in M plants were associated mainly with photosynthesis, redox, and other molecular functions. Superoxide dismutase, harpin binding protein, and thioredoxin peroxidase were down-accumulated in leaves of M tomato plants when compared to NM-LP and NM-RP, indicating that these proteins are responsive to AMF colonization independently of the phosphate regime under which they were grown. 14-3-3 protein was up-accumulated in NM-RP vs. NM-LP plants, whereas it was down-accumulated in M vs. NM-LP and M vs. NM-RP, regardless of their phosphate nutrition. This suggests a possible regulation by P nutrition and AMF colonization. Our results demonstrate AMF-induced systemic changes in the expression of tomato leaf proteins, including the down-accumulation of proteins related to photosynthesis and redox function.