Deciphering molecular events behind Systemin-induced resistance against Botrytis cinerea in tomato plants.

Plant defense peptides are paramount endogenous danger signals secreted after a challenge intensifying the plant immune response. The peptidic hormone Systemin (Sys) was shown to participate in resistance in several plant-pathosystems, although the mechanisms behind Sys-IR when exogenously applied remain elusive. We performed proteomic, metabolomic and enzymatic studies to decipher the Sys-induced changes in tomato plants either in the absence or the presence of Botrytis cinerea infection. Sys-treatments triggered direct proteomic rearrangement mostly involved in carbon metabolism and photosynthesis. However, the final induction of defense proteins required concurrent challenge, triggering priming of pathogen-targeted proteins. Conversely, at the metabolomic level, Sys-treated plants showed an alternative behaviour following a general priming profile. Out of the primed metabolites, the flavonoids rutin and isorhamnetin and two alkaloids correlated with the proteins 4-coumarate-CoA-ligase and chalcone-flavanone-isomerase triggered by Sys treatment. In addition, the proteomic and enzymatic analyses revealed that Sys conditioned the primary metabolism towards the production of available sugars that could be fuelling the priming of callose deposition in Sys-treated plants, furthermore PR1 appeared as as key element in Sys-induced resistance. Collectively, the direct induction of proteins and priming of specific secondary metabolites in Sys-treated plants indicated that posttranslational protein regulation is an additional component of priming against necrotrophic fungi.

Transcriptional and epigenetic changes during tomato yellow leaf curl virus infection in tomato.

BACKGROUND: Geminiviruses are DNA plant viruses that cause highly damaging diseases affecting crops worldwide. During the infection, geminiviruses hijack cellular processes, suppress plant defenses, and cause a massive reprogramming of the infected cells leading to major changes in the whole plant homeostasis. The advances in sequencing technologies allow the simultaneous analysis of multiple aspects of viral infection at a large scale, generating new insights into the molecular mechanisms underlying plant-virus interactions. However, an integrative study of the changes in the host transcriptome, small RNA profile and methylome during a geminivirus infection has not been performed yet. Using a time-scale approach, we aim to decipher the gene regulation in tomato in response to the infection with the geminivirus, tomato yellow leaf curl virus (TYLCV). RESULTS: We showed that tomato undergoes substantial transcriptional and post-transcriptional changes upon TYLCV infection and identified the main altered regulatory pathways. Interestingly, although the principal plant defense-related processes, gene silencing and the immune response were induced, this cannot prevent the establishment of the infection. Moreover, we identified extra- and intracellular immune receptors as targets for the deregulated microRNAs (miRNAs) and established a network for those that also produced phased secondary small interfering RNAs (phasiRNAs). On the other hand, there were no significant genome-wide changes in tomato methylome at 14 days post infection, the time point at which the symptoms were general, and the amount of viral DNA had reached its maximum level, but we were able to identify differentially methylated regions that could be involved in the transcriptional regulation of some of the differentially expressed genes. CONCLUSION: We have conducted a comprehensive and reliable study on the changes at transcriptional, post-transcriptional and epigenetic levels in tomato throughout TYLCV infection. The generated genomic information is substantial for understanding the genetic, molecular and physiological changes caused by TYLCV infection in tomato.

Ultrasound-Guided Percutaneous Needle Electrolysis Combined With Therapeutic Exercise May Add Benefit in the Management of Soleus Injury in Female Soccer Players: A Pilot Study.

CONTEXT: The performance of sprints during male soccer matches usually is slow medium paced, where the soleus and gastrocnemius (ankle plantar flexors) play a very important role. As in male soccer, soleus injuries should be considered in female soccer; but the scientific evidence is very limited in this case. DESIGN: Pilot clinical trial study. OBJECTIVE: To determine whether adding an ultrasound-guided percutaneous needle electrolysis (US-guided PNE) technique to a specific exercise program improved perceived pain at stretching and at palpation, ankle dorsiflexion range of motion, muscle fatigue, and sport performance in women soccer players with soleus injury. METHODS: This pilot study recruited 20 female players with chronic soleus injury (type 1, characterized by hypoechoic image) who were assigned to one of 2 groups: an experimental group (exercise program + US-guided PNE; n = 10) or a control group (exercise program + sham stimulation; n = 10). Pain intensity, dorsiflexion range of motion, knee-flexion heel raise test, curve sprint test, and the global rating of change scale were analyzed at baseline and after treatment (4 wk) and there was no further follow-up. RESULTS: Pain intensity at palpation and at stretching, dorsiflexion range of motion, and heel raise test values showed significant improvements (P < .05) between pretreatment and posttreatment for both groups, however, no significant differences were observed between groups. Curve sprint tests did not show significant differences between pretreatment and posttreatment for either group or between groups. However, the percentage of changes always revealed better values in favor of the PNE group. Both groups showed good player satisfaction with the therapies. CONCLUSION: The application of the US-guided PNE combined with a specific exercise program may cause clinical benefits in the treatment of female soccer players with soleus injury.

Begomovirus Tomato Leaf Curl New Delhi Virus Is Seedborne but Not Seed Transmitted in Melon.

Seed transmission can be of considerable relevance to the dissemination of plant viruses in nature and for their prevalence and perpetuation. Long-distance spread of isolates of the begomovirus species Tomato leaf curl New Delhi virus (genus Begomovirus, family Geminiviridae) has recently occurred from Asia to the Middle East and the Mediterranean Basin. Here, we investigated the possible transmission by melon (Cucumis melo L.) seeds of a tomato leaf curl New Delhi virus (ToLCNDV) isolate of the "Spain" strain widely distributed in the Mediterranean area as an alternative mechanism for long-distance spread. PCR amplification detection of ToLCNDV in floral parts and mature seeds of melon plants reveals that this virus is seedborne. "Seedborne" is defined as the ability of a virus to be carried through seeds, which does not necessarily lead to transmission to the next generation. Treatment with a chemical disinfectant significantly reduced the detectable virus associated with melon seeds, suggesting ToLCNDV contamination of the external portion of the seed coat. Also, when the internal fraction of the mature seed (seed cotyledons + embryo) was analyzed by quantitative PCR amplification, ToLCNDV was detectable at low levels, suggesting the potential for viral contamination or infection of the internal portions of seed. However, grow-out studies conducted with melon progeny plants germinated from mature seeds collected from ToLCNDV-infected plants and evaluated at early (1-leaf) or at late (20-leaf) growth stages did not support the transmission of ToLCNDV from seeds to offspring.

Characterization of Curtovirus V2 Protein, a Functional Homolog of Begomovirus V2.

Geminiviruses are single-stranded DNA plant viruses with circular genomes packaged within geminate particles. Among the Geminiviridae family, Begomovirus and Curtovirus comprise the two best characterized genera. Curtovirus and Old World begomovirus possess similar genome structures with six to seven open-reading frames (ORF). Among them, begomovirus and curtovirus V2 ORFs share the same location in the viral genome, encode proteins of similar size, but show extremely poor sequence homology between the genera. V2 from Beet curly top virus (BCTV), the model species for the Curtovirus genus, as it begomoviral counterpart, suppresses post-transcriptional gene silencing (PTGS) by impairing the RDR6/SGS3 pathway and localizes in the nucleus spanning from the perinuclear region to the cell periphery. By aminoacid sequence comparison we have identified that curtoviral and begomoviral V2 proteins shared two hydrophobic domains and a putative phosphorylation motif. These three domains are essential for BCTV V2 silencing suppression activity, for the proper nuclear localization of the protein and for systemic infection. The lack of suppression activity in the mutated versions of V2 is complemented by the impaired function of RDR6 in Nicotiana benthamiana but the ability of the viral mutants to produce a systemic infection is not recovered in gene silencing mutant backgrounds. We have also demonstrated that, as its begomoviral homolog, V2 from BCTV is able to induce systemic symptoms and necrosis associated with a hypersensitive response-like (HR-like) when expressed from Potato virus X vector in N. benthamiana, and that this pathogenicity activity does not dependent of its ability to supress PTGS.

Cutting-edge technology to generate plant immunity against geminiviruses.

Geminiviruses (viruses with circular, single-stranded DNA genomes) are one of the major groups of plant viruses causing severe economic problems for agriculture worldwide. The control of these pathogens has become a priority to maintain the production of important crops, including cotton, maize, cassava, and other vegetables. Obtaining resistant plants is the most powerful strategy and a key factor to stablish an effective integrated pest management for a robust control. In the last few decades, numerous studies have successfully approached that goal using diverse strategies based on plant variability or on the engineered expression of proteins/RNAs. The increasing knowledge of the mechanisms involved in the geminivirus-plant-vector interactions, in combination with the development of gene editing technology and nanoparticles, draw new and promising strategies for a durable control of these emerging pathogens.

Revisiting Seed Transmission of the Type Strain of Tomato yellow leaf curl virus in Tomato Plants.

Isolates of the Tomato yellow leaf curl virus (TYLCV) species (genus Begomovirus, family Geminiviridae) infect tomato crops worldwide, causing severe economic damage. Members of the whitefly Bemisia tabaci sibling species group are the vector of begomoviruses, including TYLCV. However, transmission of isolates of the type strain (Israel [IL]) of TYLCV (TYLCV-IL) by tomato seed has recently been reported based on infections occurring in Korea. Because of the consequences of this finding on the epidemiology and control of the disease caused by TYLCV and on the seed market, it was considered essential to revisit and expand those results to other tomato-growing areas. TYLCV DNA content was detected in tomato and Nicotiana benthamiana seed collected from plants naturally or experimentally infected with TYLCV-IL, supporting its seedborne nature. The TYLCV-IL replication detected in tomato and N. benthamiana flower reproductive organs demonstrated close association of this virus with the seed during maturation. However, the significant reduction of TYLCV DNA load after surface disinfections of tomato seed suggests that most of the virus is located externally, as contaminant of the seed coat. Transmission assays, carried out with seven tomato genotypes and more than 3,000 tomato plants, revealed no evidence of seed transmission from "surface-disinfected" or untreated seed for two Mediterranean isolates of TYLCV-IL. Similar results were also obtained for seed collected from TYLCV-IL-infected N. benthamiana plants. The results support the conclusion that TYLCV-IL is seedborne but is not seed transmitted in tomato or N. benthamiana, suggesting that transmission through seed is not a general property of TYLCV.