Performance of New Muchamiel Tomato Lines with Virus Resistance Genes Grafted onto Two Commercial Rootstocks

Tomato landraces are regaining interest in Spain because their great fruit quality and value in popular gastronomy. Muchamiel is a traditional tomato variety grown in SE Spain that has been recently improved by the CIAGRO-UMH Tomato Breeding Group, resulting in several lines and hybrids with genetic resistances to virus and most of the original Muchamiel genome. In the current study, two hybrids and one pure line from CIAGRO-UMH and a commercial Muchamiel were grown under conventional conditions to evaluate three different grafting treatments: non-grafting and grafting onto the commercial Beaufort and Maxifort rootstocks. The yield parameters and fruit quality were assessed, and a sensory analysis was performed to evaluate the behavior of every scion/rootstock combination. Overall, significantly worse yield and fruit number in Maxifort-grafted plants were reported; as well as a slight reductions in SSC, fructose, and sucrose; and significant effects on few sensory traits. Instead, Beaufort-grafted plants showed no reduced yield, whereas no differences were reported between grafting treatments in fruit weight, TA, and acid profile, as well as in most of flavor and texture sensory parameters. These results suggest that Muchamiel/Beaufort combination could be suitable under unfavorable conditions, while Maxifort do not seem to provide agronomic nor quality benefits.

Classification of CRISPR/Cas system and its application in tomato breeding

Remarkable diversity in the domain of genome loci architecture, structure of effector complex, array of protein composition, mechanisms of adaptation along with difference in pre-crRNA processing and interference have led to a vast scope of detailed classification in bacterial and archaeal CRISPR/Cas systems, their intrinsic weapon of adaptive immunity. Two classes: Class 1 and Class 2, several types and subtypes have been identified so far. While the evolution of the effector complexes of Class 2 is assigned solely to mobile genetic elements, the origin of Class 1 effector molecules is still in a haze. Majority of the types target DNA except type VI, which have been found to target RNA exclusively. Cas9, the single effector protein, has been the primary focus of CRISPR-mediated genome editing revolution and is an integral part of Class 2 (type II) system. The present review focuses on the different CRISPR types in depth and the application of CRISPR/Cas9 for epigenome modification, targeted base editing and improving traits such as abiotic and biotic stress tolerance, yield and nutritional aspects of tomato breeding.

Preliminary results on tomato breeding (Lycopersicon) in the Republic of Dagestan

The aim of the work is to separate from hybrid generations (F3-F4) the promising material of high-temperature stress resistance. Scientific novelty. Testing the growth of the germ root at 35, 38 and especially 43 °C is an effective method of differentiating tomato genotypes and identifying their resistance to heat. As a result of our studies of inter-grade and remote hybridization, tomato lines have been obtained, combining heat-resistantness with high productivity and valuable biochemical indicators of fruit quality. Methods. The material for research served 11 promising varieties and lines of tomato. Dedicated genetic sources of heat resistance were included in inter-grade crossings. The selection of genotypes for heat-resistantness in the field was carried out taking into account the complex of morphological and agrochemical features (type and strength of plant growth, bush foliage, phenology, shape and size of the fruit, general productivity of commodity fruits, the mass of the fetus). Results. It has been established that in varieties and lines of tomato, created as a result of inter-grade and interspecies interbreeding, heat-resistant sporophyte varied to large limits depending on the genotype and temperature level. The fruit's product ranged depending on the genotype and the year of cultivation (71.8–98.3 %). All forms turned out to be large-fruited – the weight of the fruit was from 87.8–124.6 g. L132, L204, L112 lines stood out as early forms. The dry matter content of all the genotypes studied is high, as it is above 5.0 %, except for the lines L122, L211 dry matter content of which was 4.74 and 4.58 %, respectively. Vitamin C was highest in L143 (63.32), L141 (62.65), L112 (63.38).

Physico-Chemical, Nutritional, and Sensory Evaluation of Two New Commercial Tomato Hybrids and Their Parental Lines

Tomato (Solanum lycopersicum) is the globally most consumed vegetable. The objective of this research was to analyze physico-chemical, nutritional and sensorial components (taste and flavor) in two new commercial hybrids (AS 300 F1 and AS 400 F1) and their four F7 parental lines. Two widely grown F1 hybrids (Precos F1 and Addalyn F1) were used as controls. The results obtained for carbohydrates (HPLC-RID) indicated that the highest values (27.82 mg/g) were recorded in the paternal line AS 10 of the new hybrid AS 400 F1. The highest values of total organic acids (HPLC-VWD) were recorded in Addalyn F1 (5.06 m/g), while the highest value of phenolic compounds (HPLC-DAD-ESI⁺) were identified in the maternal line AS 09 of the hybrid AS 400 F1 (96.3 µg/g). Intrinsic sensory values were analyzed by male and female tasters of different ages using a hedonic scale. The tasters’ perception revealed obvious taste differences between tomato genotypes. The study allowed determining genetic parameters of interest (heterosis and heterobeltosis) for the new hybrids, as well as a detailed characterization of the chemical composition and organoleptic quality of the parental breeding lines and their hybrids, which is useful in tomato breeding.

Breeding for Resistance to Fusarium Wilt of Tomato: A Review

For over a century, breeders have worked to develop tomato (Solanum lycopersicum) cultivars with resistance to Fusarium wilt (Fol) caused by the soilborne fungus Fusarium oxysporum f. sp. lycopersici. Host resistance is the most effective strategy for the management of this disease. For each of the three Fol races, resistance has been introgressed from wild tomato species, predominately in the form of R genes. The I, I-2, I-3, and I-7 R genes have each been identified, as well as the corresponding Avr effectors in the fungus with the exception of Avr7. The mechanisms by which the R gene protein products recognize these effectors, however, has not been elucidated. Extensive genetic mapping, gene cloning, and genome sequencing efforts support the development of tightly-linked molecular markers, which greatly expedite tomato breeding and the development of elite, Fol resistant cultivars. These resources also provide important tools for pyramiding resistance genes and should support the durability of host resistance.

Does Tomato Breeding for Improved Performance Under LED Supplemental Lighting Make Sense?

Differences in growth have been reported for tomato under LED compared to HPS light, however, it is not clear if breeding specific for LED supplemental light is worthwhile. Therefore, we derived four recombinant inbred line (RIL) tomato populations from parents with contrasting growth responses to different light spectra. These RIL populations were grown for four weeks under supplemental HPS or 95% red and 5% blue LED light in the greenhouse. For one population we also studied fruit production. Plant height and size of the side shoots of the young plants were strongly reduced under LED supplemental lighting compared to HPS in all populations. The adult plants showed shorter internode lengths, less trusses, less fruits, and lower yield of ripe fruits per plant under LED. However, when the unripe fruits at the last harvest day were included, the difference in yield between HPS and LED disappeared, indicating that the plants under LED light were compacter and slower in development, but in the end produced similar yield. We found numerous QTL, but hardly any of these QTL appeared to be significantly LED-specific. Also, we found very significant genetic effects of maternally inherited plastids and mitochondria, showing the importance of using a parental genotype as mother or as father. However, these effects were very similar between the two light conditions. We conclude that our study does not justify tomato breeding programs that are specifically targeted at 95% red and 5% blue LED supplemental lighting.

All-Flesh Tomato Regulated by Reduced Expression Dosage of AFF Through a Promoter SV Mutation

The formation of locule gel is an important process in tomato and a typical characteristic of berry fruit. In this study, we collected a tomato natural mutant that produces all-flesh fruits (AFF) in which the locule tissue remains in a solid state during fruit development. We built genetic populations to fine-map the causal gene of the AFF trait and identified the gene AFF (SlMBP3) as the locus conferring the locule gel formation. We determined the causal mutation as a 416-bp deletion that occurred in the promoter region of AFF and reduced its expression dosage. The 416-bp sequence is highly conserved among Solanaceae species, as well as within the tomato germplasm. Furthermore, with the BC6 NIL materials, we revealed that the reduced expression dosage of AFF did not impact the normal development of seeds but produced unique non-liquefied locule tissue, which was distinct from that of normal tomatoes in terms of metabolic components. We further revealed the importance of AFF gene in locule tissue liquefaction through combined analysis using mRNA-seq and metabolomics. Our findings provide clues to investigate fruit type differentiation in Solanaceae crops and also contribute to the application of the AFF gene in tomato breeding programs.

DNA technologies (molecular marking) in tomato breeding for resistance to Tobacco Mosaic Virus

Relevance. The purpose of this work is to create new discrete competitive tomato genotypes based on modern biotechnological approaches with increased resistance to the tobacco mosaic virus, economically valuable traits and adapted to the soil and climatic conditions of cultivation in the southern regions of the Russian Federation.Methods. At the first stage of the study, SSR markers taken from literature sources were tested [1;2] and PCR conditions were optimized for the identification of target Tm genes (Tm2a, Tm22, providing resistance to tobacco mosaic virus at the tissue level) in the breeding material available in the department of vegetable and potato growing.Results. Two informative molecular markers Tms 37 and UMD 2060 were selected, which reveal the allelic difference between resistant and susceptible samples. Hybridization of FMS tomato lines with samples having the desired genes of interest in the genotype for obtaining tomato lines resistant to TMV was carried out. Seeds of paternal forms - donors of target genes were obtained for their further use in breeding work. The scientific novelty lies in the study of the discrete genetic material of Solanumlycopersicum, used in the breeding process, and preserving its functions in a new genetic environment.

Factors Affecting Tolerance to Low Night Temperature Differ by Fruit Types in Tomato

Tolerance to low night temperature (LNT) can be a practical and economical target in tomato breeding programs for energy saving in greenhouses. This study was conducted to investigate the physiological and biochemical responses to LNT using four tomato accessions with cherry or large fruit types having LNT tolerance or sensitivity. The accessions were grown in two polyethylene film greenhouses with night temperature set-points of 10 and 15 °C for heating. LNT significantly reduced the plant height, and photosynthetic parameters were also lower in 10 than 15 °C among all accessions. Photosynthetic rate in 10 °C during the early growth period was reduced more in LNT-tolerant than -sensitive accessions. The numbers of flowers in 10 °C were significantly reduced in cherry but not in large fruit types. Fruit set in 10 °C significantly decreased in LNT-sensitive accessions of both fruit types, which was due to abnormal flower morphology. Proline accumulation patterns between 10 and 15 °C significantly differed between cherry and large fruit types as well as between LNT-tolerant and -sensitive accessions. Chlorophyll content at later growth stages in 10 °C was significantly higher in LNT-tolerant than -sensitive accessions in both fruit types. These results suggest that different tomato fruit types may have different mechanisms for LNT tolerance, possibly due to different proline accumulation patterns between cherry and large fruit types.