RNA interference (RNAi), a conserved RNA‐mediated gene regulatory mechanism in eukaryotes, plays an important role in plant growth and development, and as an antiviral defence system in plants. As a ...counter‐strategy, plant viruses encode RNAi suppressors to suppress the RNAi pathways and consequently down‐regulate plant defence. In geminiviruses, the proteins AC2, AC4 and AV2 are known to act as RNAi suppressors. In this study, we have designed a gene silencing vector using the features of trans‐acting small interfering RNA (tasiRNA), which is simple and can be used to target multiple genes at a time employing a single‐step cloning procedure. This vector was used to target two RNAi suppressor proteins (AC2 and AC4) of the geminivirus, Tomato leaf curl New Delhi virus (ToLCNDV). The vector containing fragments of ToLCNDV AC2 and AC4 genes, on agro‐infiltration, produced copious quantities of AC2 and AC4 specific siRNA in both tobacco and tomato plants. On challenge inoculation of the agro‐infiltrated plants with ToLCNDV, most plants showed an absence of symptoms and low accumulation of viral DNA. Transgenic tobacco plants were raised using the AC2 and AC4 tasiRNA‐generating constructs, and T₁ plants, obtained from the primary transgenic plants, were tested for resistance separately against ToLCNDV and Tomato leaf curl Gujarat virus. Most plants showed an absence of symptoms and low accumulation of the corresponding viruses, the resistance being generally proportional to the amounts of siRNA produced against AC2 and AC4 genes. This is the first report of the use of artificial tasiRNA to generate resistance against an important plant virus.
The tomato is one of the most important vegetable crops. The successful development of tomato cultures in Kazakhstan depends on the implementation of intensive agricultural methods, including ...breeding and selecting for new tomato varieties resistant to plant pathogens. Common tomato viruses, although not detected in our country to date, may potentially have a deleterious impact on agriculture if allowed to spread. The implementation of tomato breeding programs based on molecular markers of resistance is therefore an important preventive measure for protecting the agriculture and food safety of Kazakhstan. In the present work, we used nine molecular markers associated with resistance to three tomato viruses, i.e., tomato mosaic virus (ToMV), tomato spot wilt virus (TSWV), and tomato yellow leaf curl virus (TYLCV), to test the local breeding collection for the presence of genetic resistance factors. Two tomato varieties, ‘Zhiraf’ (Russia) and ‘Sunnik’ (Armenia), were revealed to possess the resistant allele marker PrRuG86-151 against ToMV; three hybrid forms had the same allele in the heterozygous state. One hybrid, based on the ‘Mirsini’ F1 variety from the Netherlands, had resistance to TSWV, which was confirmed by four markers: NCSw003, NCSw007, NCSw011, and NCSw012. Two cultivars, ‘Nicola’ and ‘Malinovyi Slon’ (Russia), and the local hybrid based on ‘Yarkiy Rumyanets’ had two to three resistant alleles of markers based on locus Tm-3 of resistance to TYLCV. The obtained results have demonstrated that the collection of tomato varieties involved in breeding programs in Kazakhstan lacks well-known genetic resistance factors to the considered tomato viruses. Thus, the prospective breeding programs require introduction of known resistant genetic resources to establish resistance to viruses using marker-assisted selection.
Tomato; Tomato mosaic virus; Tomato spot wilt virus; Tomato yellow curl leaf virus; SCAR; CAPS.
SUMMARY
Because of a high sensitivity to cold, both the yield and quality of tomato (Solanum lycopersicum L.) are severely restricted by cold stress. The NAC transcription factor (TF) family has been ...characterized as an important player in plant growth, development, and the stress response, but the role of NAC TFs in cold stress and their interaction with other post‐transcriptional regulators such as microRNAs in cold tolerance remains elusive. Here, we demonstrated that SlNAM3, the predicted target of Sl‐miR164a/b‐5p, improved cold tolerance as indicated by a higher maximum quantum efficiency of photosystem II (Fv/Fm), lower relative electrolyte leakage, and less wilting in SlNAM3‐overexpression plants compared to wild‐type. Further genetic and molecular confirmation revealed that Sl‐miR164a/b‐5p functioned upstream of SlNAM3 by inhibiting the expression of the latter, thus playing a negative role in cold tolerance. Interestingly, this role is partially mediated by an ethylene‐dependent pathway because either Sl‐miR164a/b‐5p silencing or SlNAM3 overexpression improved cold tolerance in the transgenic lines by promoting ethylene production. Moreover, silencing of the ethylene synthesis genes, SlACS1A, SlACS1B, SlACO1, and SlACO4, resulted in a significant decrease in cold tolerance. Further experiments demonstrated that NAM3 activates SlACS1A, SlACS1B, SlACO1, and SlACO4 transcription by directly binding to their promoters. Taken together, the present study identified the miR164a‐NAM3 module conferring cold tolerance in tomato plants via the direct regulation of SlACS1A, SlACS1B, SlACO1, and SlACO4 expression to induce ethylene synthesis.
Significance Statement
The present study identified the miR164a‐NAM3 module conferring cold tolerance in tomato plants via the direct regulation of SlACS1A, SlACS1B, SlACO1, and SlACO4 expression to induce ethylene synthesis.
Tomatoes are among the most consumed vegetables worldwide and represent a source of health-beneficial substances. Our study represents the first investigating the peel-associated epiphytic bacteria ...of red and purple (anthocyanin-rich) tomatoes subjected to organic and conventional farming systems. Proteobacteria was the dominant phylum (relative abundances 79–91%) in all experimental conditions. Enterobacteriaceae represented a large fraction (39.3–47.5%) of the communities, with Buttiauxella and Atlantibacter as the most represented genera. The core microbiota was composed of 59 operational taxonomic units (OTUs), including the majority of the most abundant ones. The occurrence of the most abundant OTUs differed among the experimental conditions. OTU 1 (Buttiauxella), OTU 2 (Enterobacteriales), and OTU 6 (Bacillales) were higher in red and purple tomatoes grown under organic farming. OTU 5 (Acinetobacter) had the highest abundance in red tomatoes subjected to organic farming. OTU 3 (Atlantibacter) was among the major OTUs in red tomatoes under both farming conditions. OTU 7 (Clavibacter) and OTU 8 (Enterobacteriaceae) had abundances ≥1% only in red tomatoes grown under conventional farming. PCA and clustering analysis highlighted a high similarity between the bacterial communities of red and purple tomatoes grown under organic farming. Furthermore, the bacterial communities of purple tomatoes grown under organic farming showed the lowest diversity and evenness. This work paves the way to understand the role of nutritional superior tomato genotypes, combined with organic farming, to modulate the presence of beneficial/harmful bacteria and supply healthier foods within a sustainable agriculture.
Mosaic diseases caused by tobamoviruses have posed significant threats to tomato production. In this review, we overview studies of tomato mosaic diseases published over the past century, which have ...led to several important discoveries in plant virology, such as the application of attenuated strains. A resistance breeding program established in the 1970s successfully controlled tomato mosaic virus for over 40 years; however, newly emerging tobamoviruses are posing serious challenges in current tomato production. We introduce recent biotechnological attempts to engineer tobamovirus-resistant tomato plants, which offer promising technologies for eradicating the current outbreak.
Tomato chlorosis virus (genus
Crinivirus
, family
Closteroviridae
) (ToCV) is rapidly emerging, causing increased damage to tomato production worldwide. The virus is transmitted in a semipersistent ...manner by several whitefly (Hemiptera: Aleyrodidae) species and is expanding its geographical and host ranges associated with the emergence of whiteflies of the
Bemisia tabaci
complex. Control is based essentially on intensive insecticide applications against the insect vector but is largely ineffective. No virus-resistant or tolerant commercial tomato cultivars are available. Recently, a
B. tabaci
-resistant tomato line based on the introgression of type IV leaf glandular trichomes and secretion of acylsucroses from the wild tomato
Solanum pimpinellifolium
was shown to effectively control the spread of tomato yellow leaf curl virus, a begomovirus (genus
Begomovirus
, family
Geminiviridae
) persistently transmitted by
B. tabaci
. As short acquisition and transmission periods are associated to the semipersistent transmission of ToCV, its possible control by means of the
B. tabaci
-resistant tomato could be compromised. Moreover, if the antixenosis effect of the resistance trait present in those tomato plants results in increased
B. tabaci
mobility, an increased ToCV spread might even occur. We demonstrated, however, that the use of acylsugar-producing
B. tabaci
-resistant tomatoes effectively controls ToCV spread compared to a near-isogenic line without type IV trichomes and acylsugar secretion. No increase in the primary ToCV spread is observed, and secondary spread could be reduced significantly decreasing the incidence of this virus. The possible use of host plant resistance to whiteflies to limit spread of ToCV opens up new alternatives for a more effective control of this virus to reduce the damage caused in tomato crops.
Tomato (Solanum lycopersicum L.) is one of the most consumed vegetable crops worldwide. Tomato fruits are rich in vitamins, minerals, and pigments, including lycopene. The high demand and the need to ...enhance tomato production call for new improved cultivars and F 1 hybrids. Biotechnological methods reduce the time for source material development and the labor intensity of breeding efforts. Obtaining doubled haploid plants makes it possible to fix and analyze new gene combinations faster than with conventional breeding techniques, and produce homozygous genotypes. Tomato is highly unsusceptible to haploid induction, which has been continuously studied for more than 40 years and is still of special interest. The main methods for producing haploids are based on androgenesis and gynogenesis. Androgenesis is the production of haploids from the cells of the male gametophyte, and gynogenesis from the cells of the female gametophyte. The objective was to review the research on the induction of tomato haploids based on androgenesis and gynogenesis. No standardized, efficient or reproducible protocols are currently available to produce doubled haploids of tomato. It is necessary to determine the incubation conditions, physicochemical environments, dependence of the genotype in vitro , physiological state of the donor plant, and development of the anther, which affect the reproducibility of protocols to achieve haploid induction. Anther culture for obtaining haploid tomato plants has not yielded successful results, and the studies on microspore culture were too few, so it is difficult to understand the effectiveness of this technique. The method of gynogenesis is poorly investigated, but the culture of unfertilized ovules can become a successful way to obtain tomato haploids, with more research on this subject.
ERF proteins are plant-specific transcription factors that play significant roles in plant defense against various stresses. However, only little information regarding stress-related ERF genes is ...available in tomato (Solanum lycopersicum, Sl). In this study, a tomato ERF gene, SlERF84, was cloned and functionally characterized. The nucleus localization of SlERF84-sGFP was confirmed through a transient expression assay. Transactivation assays in yeast demonstrated that SlERF84 functions as a transcriptional activator. Real-time PCR analysis revealed that SlERF84 could be markedly induced by drought, salt and by several phytohormones (ABA, MeJA and ACC). Overexpression of SlERF84 in Arabidopsis endows transgenic plants with ABA hypersensitivity and enhanced tolerance to drought and salt stress. Histochemical staining assay showed that SlERF84 renders transgenic plants better ROS-scavenging capability. Pathogen inoculation assay revealed that SlERF84 might negatively modulate plant defense response to Pseudomonas syringae pv. tomato DC3000. Moreover, the transcript levels of pathogenesis-related genes AtPR1 and AtPR3 were compromised in transgenic Arabidopsis, as compared to that in Col-0 plants when inoculated with Pseudomonas syringae pv. tomato DC3000. These results suggest that SlERF84 functions as a stress-responsive transcription factor in differentially modulation of abiotic and biotic stress tolerance, and may have applications in the engineering of economically important crops.
•SlERF84 could be induced by various abiotic stresses and plant hormones.•SlERF84 functions as a transcriptional activator.•Overexpression of SlERF84 in Arabidopsis enhanced tolerance to drought and salt stress.•SlERF84 negatively modulate plant defense response to pathogen Pst DC3000.
Given the potential environmental and economic sustainability consequences of cover crop adoption, N fertilizer application, and residue management, this study focuses on the yield and financial ...effects of these on processing tomato production in Ontario, Canada. The study employs financial modeling using field data from a long-term cover crop experiment (oat, cereal rye, radish, and a radish-rye mixture) from 2010 to 2020. Averaged over six experimental years, compared to no cover (87 Mg ha−1) radish (99.6 Mg ha−1) and radish-rye mix (95.2 Mg ha−1) cover crops produce statistically significantly higher tomato yields as isolated practices, increasing farm net returns by $1120 ha−1 and $604 ha−1, respectively. When combined with N application, rye application additionally results in tomato yields statistically significantly higher than the base practice of no cover crop, zero N application and retained residue. Oat cover does not appear to have a statistically significant effect on tomato yields in this dataset. The application of N fertilizer results in statistically significantly higher tomato yield, increasing net returns by $882 ha−1, while residue management does not.
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