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Ninety-seven tomato landraces collected from East Anatolian region of Turkey and North-West of Iran, along with three commercial cultivars were evaluated during two years. Experiment was carried out in an alpha lattice design at Agriculture and Natural Resources Research Center of West Azerbaijan, Iran. Analysis of variance revealed significant variation (P ≤ 0.01) among genotypes for all the experimental characters. Yield showed a positive and significant correlation with length and width of cotyledon leaf, length and width of true leaf, fruit weight, fruit length and diameter, pericarp thickness and fruit peduncle length. In principal component analysis, the first three components explained for 71.6% of total variations among genotypes. Since the first component determined 50% of total variations and yield had high significant coefficient with this component, thus it might be used as s selection criteria to identify genotypes with high yield in breeding programs. Cluster analysis using Ward method classified genotypes into five groups. Groups included: early maturing genotypes in group I, genotypes with high yield in group II, genotypes with large fruit in group III, late maturing and high total soluble solids (TSS) genotypes in group IV and genotypes with high acidity in group V.
Tomato (Solanum lycopersicum L.) is attacked by Pseudomonas syringae pv. tomato causing heavy damage to the crops. The present study focused on the application of aqueous fruit extracts of neem (Azadirachta indica L.) on a single node of aseptically raised tomato plants. Observations were done, and the changes in the activity and isoenzyme profile of polyphenol oxidase (PPO) and lysozyme, both at the site of treatment as well as away from it, were noted. The results demonstrate that neem extract could significantly induce the activities of both the enzymes as well as upregulate the de novo expression of additional PPO isoenzymes. Induction of systemic acquired resistance (SAR) by natural plant extracts is a potent eco-friendly crop protection method.
Salt stress is known as one of the most severe abiotic factors limiting the plant production all over the world. In this study, three additives: (i) supplemental Ca (5 mmol L–1) to nutrient solution, (ii) foliar application of micronutrients (Fe, Mn and Zn at 60, 160 and 110 mg L–1, respectively), and (iii) combination of both of them were evaluated aiming to reduce the negative impact of salt stress on tomato plants cultivated in a soilless culture and improve the internal quality of fruits. The obtained results show that salinity reduced vegetative growth and physiological parameters, fruit yield and its components, and even more lowered fruit market classification of tomatoes. Salinity treatment reduced most of essential macro- and micronutrients in tomato fruit, whilst Na content was increased. Tomato productivity and fruit quality were ameliorated under saline conditions by increasing Ca into nutrient solution and applying a foliar application of micronutrients. A combination of both additives ranked the first to alleviate the adverse effects of salinity on tomatoes, followed by solo supplemental Ca into saline nutrient solution. On the other hand, the internal fruit quality of antioxidant compounds, such as vitamin C, lycopene, α-carotene, β-carotene and lutein as well as acidity, total soluble solid and dry matter percent, were increased under saline conditions.
Over a period of few years, Pepino mosaic virus (PepMV) has become one of the most important viral pathogen in tomato production worldwide. So far, five PepMV genotypes (EU, LP, CH2, US2 and US1) have been detected. A real time reverse transcription polymerase chain reaction (RT-PCR) procedure, using the fluorescence dye SYBR Green was developed for a rapid and reliable detection of genetically diverse Pepino mosaic virus isolates. This procedure was used for the detection and identification of PepMV in both Solanum lycopersicum and Nicotiana benthamiana species. The melting temperature (T m) for members of a particular strain was very similar, with a host effect that did not hinder strain identification. Under optimal reaction conditions, sensitivity of the detection was as low as 100 fg of viral RNA from infected plants. This level of sensitivity indicated that the real time RT-PCR developed in the present study could be used for routine plant health assays.
Fungal entomopathogens can naturally regulate populations of various insects. The entomopathogen Beauveria bassiana (Bals.- Criv.) Vuill. is also able to endophytically colonize different plants. Endophytic colonization by entomopathogens may provide a source of indirect interactions between fungi and insects and has been associated with the ability of the fungus to control insect pests. The tomato leaf miner, Tuta absoluta (Meyrick) is considered one of the most devastating pests of tomato (Solanum lycopersicum L.) and its difficult control is due to its miner habit, short life cycle, and high reproductive capacity. The aims of this study were: (i) to use three different techniques, i.e. leaf spraying, seed immersion and root dipping, for the endophytic inoculation of B. bassiana in tomato plants; and (ii) to assess the effect of B. bassiana on tomato leaf consumption and mortality of T. absoluta after inoculation. The percentage of colonization by B. bassiana was assessed 7, 14 and 28 days after inoculation. All inoculation techniques employed allowed the recovery of B. bassiana, although our results showed significant differences between techniques. Leaf spraying was the most effective, with the highest percentage of colonization recorded 7 days after inoculation. We also evaluated (i) the effect on the mortality of T. absoluta by direct contact with conidia of B. bassiana, and (ii) the effect on tomato leaf consumption and mortality by indirect contact through ingestion of inoculated plant tissues with B. bassiana. Mortality bioassays showed that B. bassiana infected T. absoluta, either by direct contact or indirectly, via ingestion of inoculated tomato leaves. Direct contact showed a higher percentage of mortality and a lower median survival time (MST) than indirect contact. Significant differences in the mortality percentages of T. absoluta after exposure with B. bassiana were found among the treatments and the control. Our results suggest that the endophytic inoculation of B. bassiana in tomato crops provides the basis for further investigation, which should focus on the virulence of the endophytic B. bassiana against T. absoluta.
Flooding of the soil induces stomata to close within a few hours decreasing a potential damage of leaves which would otherwise occur because of a decrease of root hydraulic conductivity. The signals triggering these shoot responses have not been fully identified but could include changes in hormone transport from roots to shoots as their synthesis and xylem loading are altered. The present research determined if changes in the delivery of indole acetic acid (IAA) could be a root-born signal comparable with decreases in abscisic acid (ABA) reported previously. Tomato plants at the 7-8-leaf stage were flooded up to 48 h by submerging their pots individually in tap water. Xylem sap was collected from freshly detopped and pneumatically pressurised roots at flow rates equivalent to those of whole-plant transpiration. Concentrations of ABA and IAA in the sap were quantified by the GC-MS and their delivery rates from roots to shoots (fluxes) was calculated an the basis of transpiration rates of the whole plant calculating the amounts delivered per unit area of leaf. Leaf conductance (a measure of stomatal closure) and leaf water potential (LWP) were also measured. Stomata were closed almost completely in 8 h of flooding. This decreased transpiration significantly. Stomatal closure and transpiration remained much below than those of well-drained plants for at least 48 h. Between 4-8 h of flooding, a marked transient decrease in LWP took place which was quickly succeeded by its increase even to values above those of well-drained plants. The concentration and the delivery of ABA from flooded roots to shoots in xylem sap decreased 5- and 7-fold, respectively, within 2 h of flooding and remained lower for at least 48 h, as compared to the control. In contrast, IAA concentrations in xylem sap of flooded plants were above those of well-drained plants. However, slower rates of transpiration generated IAA deliveries that were decreased by 36, 35, 18 and 28% after 2, 4, 6 and 8 h of flooding respectively. The rapid and transient decrease in LWP of leaves and decrease in the delivery of ABA and IAA from roots to shoots during the first hours of flooding were always observed before the stomata started to close. Each is a potentially active signal. While the decrease in ABA is diffucult to explain the stomatal closure, the involvement of the rapidly depressed delivery rates of IAA from roots to shoots during the early flooding merits further investigation.
Salinity inhibition of plant growth is the result of osmotic and ionic effect and different plant species have developed different mechanisms to cope with those effects. With the discovery of molecular markers and marker assisted selection technology, it is possible to develop markers that identify salt tolerance. The genetic diversity of tomato genotypes were analyzed using SSRs polymorphic markers and Unweighted Pair Group Method with Arithmetic Mean. Leaves of the twenty tomato genotypes (landraces/accessions in Nigeria) were used to isolate their DNA using Bioland Plant Genomic DNA protocols. Primers were designed from 15 different salt responsive candidate genes, using Vector NTI and the sequence of the genes were obtained from ncbi genomic web site. All 15 primers sets generated shows clear distinct polymorphic profiles as evident from the 6% agarose gel profile. Dendrogram generated shows three groups, none of the panel intermixed in a subgroup. The genetic distance information reported in this study might be used by breeders when planning future crosses among tomato genotypes. From the result obtained UC82B recorded the highest vegetative and yield parameters, therefore, adoption of this genotype could be help to increase the tomato production in Sokoto agro-climatic area.
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