Genetic Diversity and Population Structure of Tomato (<i>Solanum lycopersicum</i>) Germplasm Developed by Texas A&M Breeding Programs

Genetic variation developed in plant breeding programs is fundamental to creating new combinations that result in cultivars with enhanced characteristics. Over the years, tomato (Solanum lycopersicum) breeding programs associated with the Texas A&M University system have developed morphologically diverse lines of tomatoes selected for heat tolerance, fruit quality, and disease resistance to adapt them to Texas growing conditions. Here we explored the intraspecific genetic variations of 322 cultivated tomato genotypes, including 300 breeding lines developed by three Texas A&M breeding programs, as an initial step toward implementing molecular breeding approaches. Genotyping by sequencing using low coverage whole-genome sequencing (SkimGBS) identified 10,236 high-quality single-nucleotide polymorphisms (SNPs) that were used to assess genetic diversity, population structure, and phylogenetic relationship between genotypes and breeding programs. Model-based population structure analysis, phylogenetic tree construction, and principal component analysis indicated that the genotypes were grouped into two main clusters. Genetic distance analysis revealed greater genetic diversity? among the products of the three breeding programs. The germplasm developed at Texas A&M programs at Weslaco, College Station, and by Dr. Paul Leeper exhibited genetic diversity ranges of 0.175 - 0.434, 0.099 - 0.392, and 0.183 - 0.347, respectively, suggesting that there is enough variation within and between the lines from the three programs to perform selection for cultivar development. The SNPs identified here could be used to develop molecular tools for selecting various traits of interest and to select parents for future tomato breeding.

Effects of Solanum lycopersicum Rootstock Grafting on Tomato Resistance and Quality

[Objectives] This experiment was carried out to explore the effects of Solanum lycopersicum rootstock grafting on tomato resistance and quality. [Methods] 6 different S. lycopersicum rootstocks were used to graft ＇Guihong 2＇ tomato. The grafting affinity was better and the resistance to bacterial wilt was higher. [Results] S. lycopersicum rootstock grafting may reduce the tomato, but it can improve the taste and endogenous quality of tomato. Besides, soluble solids, soluble sugars, Vc content, and sugar-acid ratio were all significantly higher than that of the control group. [Conclusions] S. lycopersicum rootstock y11, 53, and 177 grafting can increase Vc, soluble solids, and sugar-acid ratio of tomato fruit, so they are optimal rootstocks for tomato grafting.

Effect of Grafting on Growth and Shelf Life of Tomatoes (Solanum lycopersicum L.) Grafted on Two Local Solanum Species

The Rio Grande variety of tomato is widely grown because of its high productivity during the cold and dry seasons, and its resistance to Verticillium wilt (caused by Fusarium oxysporium) and to stem canker (Alternaria). Grafting tomato onto compatible rootstocks resistant to these diseases offers a better potential to overcome soil-borne diseases, abiotic stresses, improve growth, yield and fruit quality. However, in Cameroon, there is little or no information on grafting between Rio Grande tomato and selected eggplant rootstocks. The objectives of this study were: 1) To determine the compatibility between Rio tomato grafting and a popular local eggplant (Nkeya) rootstock;2) To verify the effect of grafting on flowering time;3) To evaluate the effect of eggplant rootstocks on growth, fruit shelf life and fruit quality of Rio tomatoes. The trial was conducted in a randomized complete block design with 3 replications. Rio Grande (To) was the ungrafted treatment used as a control. To/Ko, To/To and To/Nk were the grafted treatments eventually transplanted to the field. Growth data were subjected to analysis of variance using SPSS software. Descriptive analyses were performed for the other parameters. The results revealed that, 1) The cleft grafting method used was successful with success rate varying between 90 and 100%;2) Grafting influenced flowering date (DAT, p = 0.05) as well as tomato growth parameters including stem height (H, 1.49 × 10-10 p 0.00014) and collar diameter (SD, 4 × 10-14 p 0.009). The To/To treatment was significantly different from the ungrafted cultivar To, which had no significant difference in stem diameter. A significant difference in plant height was also observed between the ungrafted treatment To and the To/Ko and To/Nk treatments. In addition, only the collar diameter of To/Nk was different from To. Also, there was no significant difference between To/To and To, but a significant difference between To/Ko and To/Nk compared to To. Conversely, grafting improved the lifespan of To/Ko. Ultimately, the grafting method used was successful, but further studies are needed to overcome the problem of graft incompatibility in order to improve the agronomic performance of grafted plants.

Transcriptional search to identify and assess reference genes for expression analysis in Solanum lycopersicum under stress and hormone treatment conditions

Tomato(Solanum lycopersicum)is a model plant for research on fruit development and stress response,in which gene expression analysis is frequently conducted.Quantitative PCR(qPCR)is a widely used technique for gene expression analysis,and the selection of reference genes may affect the accuracy of results and even conclusions.Although there have been some frequently used reference genes in tomato,it has been shown that the expressions of some of these genes are not constant in different tissues and environmental conditions.Moreover,little information on genomic identification of reference genes is available in tomato.Here,we mined the publicly available transcriptional sequencing data and screened out fifteen candidate reference genes,and the expression stability of these candidate genes and seven traditionally used ones were evaluated under stress and hormone treatment.The results showed that over half of the selected candidate references were housekeeping genes in tomato cells.Among the candidate reference genes and the traditionally used ones,the most stably expressed genes varied under different treatments,and most of these genes were recommended as preferred reference genes at least once except Solyc04g009030 and Solyc07g066610,two traditionally used reference genes.This study provides some novel reference genes in tomato,and the preferred reference genes under different environmental stimuli,which may be useful for future research.Our study suggests that excavating stably expressed genes from transcriptome sequencing data is a reliable approach to screening reference genes for qPCR analysis.

SlTPP4 participates in ABA-mediated salt tolerance by enhancing root architecture in tomato

Salinity tolerance is an important physiological index for crop breeding.Roots are typically the first plant tissue to withstand salt stress.In this study,we found that the tomato(Solanum lycopersicum)trehalose-6-phosphate phosphatase(SlTPP4)gene is induced by abscisic acid(ABA)and salt,and is mainly expressed in roots.Overexpression of SlTPP4 in tomato enhanced tolerance to salt stress,resulting in better growth performance.Under saline conditions,SlTPP4 overexpression plants demonstrated enhanced sucrose metabolism,as well as increased expression of genes related to salt tolerance.At the same time,expression of genes related to ABA biosynthesis and signal transduction was enhanced or altered,respectively.In-depth exploration demonstrated that SlTPP4 enhances Casparian band development in roots to restrict the intake of Na^(+).Our study thus clarifies the mechanism of SlTPP4-mediated salt tolerance,which will be of great importance for the breeding of salt-tolerant tomato crops.

不同生育期番茄植株根际土壤微生物群落结构特征

为构建番茄生态优质高产栽培技术体系及挖掘有益的微生物资源,比较了不同生育期番茄植株根际土壤肥力以及微生物群落结构与功能特征。基于传统与现代高通量测序技术分析番茄幼苗期、花芽分化期、结果期根际土壤肥力与微生物(细菌、真菌)群落结构与功能特征。结果显示,番茄结果期根际土壤中具有更为丰富的碳、氮、磷源;另一方面,不同生育期番茄根际土壤微生物群落结构和功能发生显著变化。其中,norank_f_norank_o_norank_c_KD4-96,norank_f_A4b和Bryobacter属细菌是幼苗期番茄植株根际土壤中特有的优势细菌属;TM7a和Saccharomonospora属细菌是花芽分化期番茄植株根际土壤中特有的优势细菌属;Gem⁃matimonas属细菌是结果期番茄植株根际土壤中特有的优势细菌属;此外,鲍尔壶菌属(Powellomyces)真菌是幼苗期番茄植株根际土壤中特有的优势真菌属;Apiotrichum和unclassified_f_Chytridiaceae真菌是花芽分化期番茄植株根际土壤中特有的优势真菌属;链格孢属(Alternaria)真菌是结果期番茄植株根际土壤中特有的优势真菌属。结果表明:不同生育期番茄植株根际土壤中形成了特异的根际土壤微生物群落,幼苗期根际土壤中主要富集了可以产生生长激素的微生物类群;花芽分化期根际土壤中主要富集了具有抗逆功能的微生物类群;结果期根际土壤中主要富集了具有促进养分循环功能的微生物类群。

伴生栽培对主栽番茄植株根际土壤肥力及微生物多样性的影响

为探究伴生不同作物对主栽番茄根际土壤肥力与健康影响的作用机制,设置番茄伴生生菜、苋菜、菜心、薄荷和葱的栽培模式,基于高通量测序技术分析伴生不同作物栽培模式下主栽番茄根际土壤肥力及细菌、真菌多样性。结果显示:除菜心外,其他4种伴生作物均显著提高了主栽番茄植株根际土壤中涉及氮、磷循环的土壤酶活性以及微生物生物量碳、氮、磷;伴生栽培虽然没有丰富主栽番茄植株根际土壤中细菌、真菌多样性,但改变了主栽番茄植株根际土壤细菌、真菌优势门属间的丰度占比;门分类水平下,伴生管理均提高了变形菌门(Proteobacteria)、厚壁菌门(Firmicutes)、Patescibacteria细菌的丰度占比;属分类水平下,norank f Microscillace⁃ae、norank f norank o Vicinamibacterales、芽孢杆菌属(Bacillus)、norank f Gemmatimonadaceae、交替赤杆菌属(Altererythrobacter)细菌是番茄伴生不同作物中丰度占比前10的特有优势细菌属。此外,伴生栽培不同程度地改变了主栽番茄植株根际土壤真菌多样性和丰富度,富集了壶菌门、担子菌门和油壶菌门优势真菌门;同时富集了unclassified o Sordariales、油壶菌属(Olpidium)和锥盖伞属(Conocybe)、Phialemonium、unclassified o Pleosporales、unclassified o Boletales和Sodiomyces属等优势真菌属,亦提高了毛壳菌属(Chaetomium)的丰度占比。研究结果表明,番茄伴生栽培生菜、苋菜、薄荷和葱4种植物均同程度地有助于不提高番茄根际土壤肥力和维护根际微环境土壤健康的作用,其中,伴生栽培生菜和薄荷提升土壤肥力及维护土壤健康的效果优于伴生菜心、苋菜和葱。

番茄连作土壤中微生物群落的变化特征及其重塑研究进展

土壤微生物群落结构失衡是番茄连作障碍发生的重要因素之一。为探明番茄连作障碍发生机制,推动番茄产业的可持续发展,本文对番茄连作障碍土壤微生物群落的变化特征及其重塑技术研究进展进行了综述。番茄连作土壤中微生物多样性下降,土壤微生物群落结构由“细菌型”转变为“真菌型”,是番茄连作障碍发生的主要原因;轮作与间套作、嫁接、土壤消毒和施用有机肥均可重塑连作番茄土壤的微生物群落结构,有助于减轻连作障碍危害,尤其轮作与间套作豆科作物更有利于减轻番茄连作障碍危害。迄今,研究发现节杆菌属(Arthrobacter)、芽孢杆菌属(Bacillus)、假单胞菌属(Pseudomonas)、土壤红色杆形菌属(Solirubrobacter)细菌以及木霉菌属(Trichodermaspp.)真菌等微生物是有助于克服番茄连作障碍的功能微生物。开发与有机肥结合的生物有机肥,用于重塑农田土壤微生物群落的方法是一项极具开发前景的生物防控连作障碍发生的技术措施,但如何保障生物有机肥应用于不同环境中,功能微生物的定殖、存活与大量繁殖,是该项技术亟待解决的重要瓶颈问题。

Difference in volatile profile between pericarp tissue and locular gel in tomato fruit

Aroma, a complex mixture of volatile compounds, plays an important role in the perception and acceptability of tomato products by consumers. Numerous studies have reported volatile profiles in tomatoes based on measurement of the whole fruit or pericarp tissue, however, little is understood regarding the volatile compositions in the inner tissues. The objective of this study was to investigate the differences in volatile profile between pericarp tissue and Iocular gel in tomato fruit. Based on HS-SPME-GC-MS analysis, totally 42 volatile compounds were detected in FL 47 and Tasti-Lee tomato fruits. Regardless of cultivars, a substantial higher concentration of total volatile compounds was observed in pericarp than that in/ocular gel, associated with higher levels of aldehydes, hydrocarbons, and nitrogen compounds. Pericarp tissue possessed higher levels of cis-3-hexenal, hexanal, heptanal, octanal, nonanal, cymene, terpinolene, undecane, dodecane, 2-phenylethanol, 6-methyl-5-hepten-2-one, 2-methylbutyl acetate, 1-nitro-pentane, and 1-nitro-2-phenylethane, while the abundances of 2-methylpropanal, butanal, 2-methylbutanal, 2-methyl-2-butenal, 2-methylpropanol, 3-methylbutanol, 2-methylbutanol, and 2-butanone were higher in Iocular gel. Principal component analysis （PCA） and cluster analysis using GC-MS and electronic nose （E-nose） data discriminated the two tissues.

Effects of Nitrogen Forms on Carbon and Nitrogen Accumulation in Tomato Seedling

Utilization of organic nitrogen （N） is an important aspect of plant N assimilation and has potential application in sustainable agriculture. The aim of this study was to investigate the plant growth, C and N accumulation in leaves and roots of tomato seedlings in response to inorganic （NH4^＋-N, NO3^-N） and organic nitrogen （Gly-N）. Different forms of nitrogen （NH4^＋-N, NO3^--N, Gly-N） were supplied to two tomato cultivars （Shenfen 918 and Huying 932） using a hydroponics system. The plant dry biomass, chlorophyll content, root activity, total carbon and nitrogen content in roots and leaves, and total N absorption, etc. were assayed during the cultivation. Our results showed that no significant differences in plant height, dry biomass, and total N content were found within the first 16 d among three treatments; however, significant differences in treatments on 24 d and 32 d were observed, and the order was NO3^--N 〉 Gly-N 〉 NH4^＋-N. Significant differences were also observed between the two tomato cultivars. Chlorophyll contents in the two cultivars were significantly increased by the Gly-N treatment, and root activity showed a significant decrease in NHa^＋-N treatment. Tomato leaf total carbon content was slightly affected by different N forms; however, total carbon in root and total nitrogen in root and leaf were promoted significantly by inorganic and organic N. Among the applied N forms, the increasing effects of the NH4^＋-N treatment were larger than that of the Gly-N. In a word, different N resources resulted in different physiological effects in tomatoes. Organic nitrogen （e.g., Gly-N） can be a proper resource of plant N nutrition. Tomatoes of different genotypes had different responses under organic nitrogen （e.g., Gly-N） supplies.

Molecular Markers for Tm-2 Alleles of Tomato Mosaic Virus Resistance in Tomato

Tomato mosaic virus (ToMV) is one of the most infectious virus diseases in tomato (Solanum lycopersicum L). The practical and effective method of controlling this disease is through genetic control by using major resistance genes. So far, three genes Tm-1, Tm-2 and Tm-22 conferring resistance to ToMV have been reported and utilized in tomato culti-var development. Marker assisted selection (MAS) has become very important and useful tool in selection of ToMV re-sistant tomato lines or hybrids. The objective of this research was to identify allele-specific PCR-based, cleaved ampli-fied polymorphic sequence (CAPS), and allele-derived single nucleotide polymorphism (SNP) markers for Tm-2 loci. Four allele-specific PCR-based markers were identified: one for Tm-2, one for Tm-22, and two for the susceptible allele tm-2. Three allele-derived CAPS markers were identified, which can identify and distinguish three alleles, tm-2, Tm-2 and Tm-22 in tomato germplasm. Three SNP markers were developed specific for Tm-2 locus. These markers will pro-vide breeders with a tool in selection of Tm-2 and Tm-22 resistance genes in tomato breeding program.

Tomato SlPti5 plays a regulative role in the plant immune response against Botrytis cinerea through modulation of ROS system and hormone pathways

While SlPti5 has been shown to play a crucial role in the regulation of antagonistic genes in Solanum lycopersicum and Arabidopsis against pathogen infection,there have been no comprehensive studies on the effects of SlPti5 on the regulatory response mechanism of reactive oxygen species(ROS) system and hormone pathways during growth and disease resistance of tomato plants.Here,we investigated the function of SlPti5 in the defense response of tomato against Botrytis cinerea utilizing a virus-induced gene silencing(VIGS)-based system.Expression profile analysis showed that SlPti5 was significantly induced upon B.cinerea infection,with high expression levels in the leaves and fruit of tomato.VIGS-based silencing of SlPti5 inhibited early vegetative growth,increased the plant’s susceptibility to infection,promoted the development of ROS,affected the expression of genes involved in the ROS scavenging system,and attenuated the expression of genes associated with pathogenesis and the ethylene/jasmonic acid signaling pathways.In sum,our data demonstrated that SlPti5 stimulates the immune response of tomato plant to Botrytis cinerea infection by involving the ethylene(ET)-and jasmonic acid(JA)-mediated pathways and modulating the expression of some key pathogenesis-related(PR) genes.

Microclimate modification using eco-friendly nets and floating row covers improves tomato (<i>Lycopersicon esculentum</i>) yield and quality for small holder farmers in East Africa

Tomato (Lycopersicon esculentum) is one of the important vegetables in supplying vitamins, minerals and fiber to human diets worldwide. Its successful production in the tropics is, however, constrained by environmental variations especially under open field conditions. Two trials were conducted at the Horticulture Research and Teaching Field, Egerton University, Kenya to evaluate the effects of agricultural nets (agronets) herein called eco-friendly nets (EFNs) and floating row covers (FRCs) on microclimate modification, yield, and quality of tomato. A randomized complete block design with five replications was used. Tomato plants were grown under fine mesh EFN (0.4-mm pore diameter) cover, large mesh EFN (0.9-mm pore diameter) cover or FRC. The EFN and FRC were maintained either permanently closed or opened thrice a week from 9 am to 3 pm. Two open control treatments were used: unsprayed (untreated control) or sprayed with chemicals (treated control). The use of EFN or FRC modified the microclimate with higher temperatures, lower diurnal temperature ranges, and higher volumetric water content recorded compared with the controls. On the other hand, light quantity and photosynthetic active radiation were reduced by the use of EFN and FRC compared with the controls. The use of FRC and EFN resulted in more fruit and higher percent in marketable yield compared with open field production. Fruit quality at harvest was also significantly improved by the use of EFN and FRC. Fruits with higher total soluble solids (TSS), lower titratable acidity (TA), and higher sugar acid ratio were obtained in EFN and FRC treatments compared with the controls. Fruits harvested from EFN and FRC were also firmer compared with control fruits. These findings demonstrate the potential of EFN and FRC in modifying microclimate conditions and improving yields and quality of tomato under tropical field conditions.

Influence of Seedling Age on the Susceptibility of Tomato Plants to <i>Ralstonia solanacearum</i>during Protray Screening and at Transplanting

The study was undertaken to assess whether seedling age played any role in governing the vulnerability of tomato to the bacterial wilt pathogen, Ralstonia solanacearum, based on the preliminary observations that the extent of mortality during seedling-stage screening was relatively less in older seedlings. Employing the virulent strain ‘NH-Av01’ isolated from tomato, 2-, 3-, 4- or 5-week-old seedlings of susceptible ‘Arka Vikas’ raised in organic cocopeat in 98 cavity protrays were inoculated with the pathogen through root-injury inoculation approach. Disease symptoms appeared earlier and with more severity in 2-week-old seedlings followed by 3-, 4- and 5-week-old saplings recording 74%, 68%, 63% and 49% mortality, respectively, after four weeks of inoculation suggesting that older the seedlings, less the susceptibility to the pathogen. The growth characteristics of seedlings (shoot height, shoot and root weights) showed a significant increase with seedling age (0.21, 0.54, 1.14 and 2.09 g gross weight/seedling at 2, 3, 4 and 5 weeks, respectively) indicating healthier saplings with delay in inoculation time. In subsequent trials, seedlings of 3, 4, 5 or 6 weeks were transplanted to field-sick soil in protrays or in pots with monitoring for 1 - 4 months which indicated a significant reduction in disease incidence and severity with increase in seedling age. The observations suggested that seedling age should be considered as a major factor influencing the susceptibility of tomato seedlings to R. solanacearum with the chances of variations in the extent of disease incidence or inconsistent results during seedling-stage screening and the possibility of escapes with older seedlings. Two-week seedlings formed the best when the aim is to induce maximum disease incidence, while transplanting at 5 - 6 weeks stage appeared the best when the objective is minimal disease incidence or formulating disease management strategies.

Epiphytic and Endophytic Fungal Communities of Tomato Plants

Plants harbor diverse fungal communities both on their surfaces(epiphytic)and inside of plant tissues(endophytic),and these fungi play important roles in plant health and vigor.However,comparisons of epiphytes and endophytes have rarely been performed.In this study,the soil,epiphytic and endophytic fungal assemblages of greenhouse-grown tomato plants were extensively examined and compared by Illumina sequencing of 18S rRNA amplicons.The fungal communities differed in both size and composition.The soil communities were the richest and most abundant,while the endophytes showed the lowest richness and diversity.The diversity of endophytes also differed in different tissues,with the highest diversity occurring in the roots.In both the epiphytic and endophytic samples,the majority of fungi corresponded to ascomycetes,amongwhich Sordariomycetes,Dothideomycetes and Eurotiomyceteswere the most frequent classes.Themajor non-ascomycete fungi were associated only with the class Exobasidiomycetes(Basidiomycota).At the order level,the epiphytes showed similar distribution patterns in the stems and leaves,but among the endophytes,distinct fungal orders were enriched in different tissues.Capnodialeswas recorded as amajor fungal group in the stems,leaves and seeds,and Saccharomycetales was specifically enriched in the pericarp and jelly around seeds.The present data suggested that different drivers shaped epiphytic and endophytic fungi communities and deepened our knowledge of the complex plant-fungus interaction in tomato.

Relative Response of Four Tomato Species to <i>Rotylenchulus reniformis</i>Infestation

The reniform nematode (Rotylenchulus reniformis) is among the most economically damaging plant pathogens in the United States. This nematode is mostly known for its damage to cotton but tomato is also well-within its vast host range that includes 314 plant species across 77 plant families. Nematode-resistant genotypes offer an effective, environmentally safe alternative to agro-chemicals for reniform nematode management. Resistance genes can be introgressed into cultivars through plant improvement efforts. Tomato is a diploid species which is more amenable to identification of resistance genes in contrast to cotton where cultivars are either tetraploid or hexaploid.This greenhouse study examined cultivated and wild Solanum species represented by 40 tomato accessions, to identify resistance and susceptibility responses to R. reniformis. Accessions were evaluated by using single plants in six replicates. Seeds were germinated in sterile soil and inoculated with mixed vermiform R. reniformis. After seven weeks, eggs and vermiform stages were extracted from the root system and counted. A susceptible control S. lycopersicum “Rutgers” (LA1090) was included. Seven putatively resistant tomato genotypes were identified. These genotypes in increasing order of resistance are S. chilense (LA1029), S. lycopersicum (LA1792), S. chilense (LA1932), S. peruvianum var. humifusum (LA0385) S. pimpinellifolium (LA2934), S. peruvianum f. glandulosum (LA1283) and S. pimpinellifolium (LA1579).

The Transfer of Cu, Zn, Mn and Fe between Soils and <i>Allium</i>Plants (Garlic and Onion), and Tomato in the Southwest of the Buenos Aires Province, Argentina

Chemical extraction methods are generally used to evaluate trace element concentrations in soils. The adequacy of these soil tests is commonly assessed by comparing the extraction results with the metal contents in the plants. In this study, soil and leaf samples were collected in the southwest area of the Buenos Aires Province, Argentina. Garlic (Allium sativum L.), onion (Allium cepa L.) and tomato (Solanum lycopersicum L.) are species of great regional economic importance. These crops need good mineral nutrition for optimum growth and sustainable production. Cu, Zn, Mn and Fe micronutrient uptake by plants was analyzed together with the trace element contents in the soil in which those plants were grown. A single EDTA-extraction procedure was performed to determine soil micronutrients. The amount of extractable-trace elements increased as the concentration of the chelating agent EDTA increased. The range of total element content in soil was: 15.68-31.5 mg·kg-1 for Cu, 75.0-386.3 mg·kg-1 for Zn, 542.5 -1686 mg·kg-1 for Mn and 28,325-32,675 mg·kg-1 for Fe. Micronutrient contents in mature leaf tissue were determined by the acid digestion method. Total and available micronutrient content in soil as well as total content in leaves were measured by flame atomic absorption spectrometry (FAAS). Total micronutrient content and the available extractable-fraction in soils were below the critical values for plant growth. This was in agreement with the amount of micronutrients present in the leaf tissue. A strong relationship between the extraction data and the soil-plant transfer coefficients suggested an appropriate exchange of trace elements from soils to garlic, onion and tomato plants.

Development of high yield and tomato yellow leaf curl virus(TYLCV)resistance using conventional and molecular approaches:A review

Tomato(Solanum lycopersicum L.)belonging to the family Solanaceae is the second most consumed and cultivated vegetable globally.Since the ancient time of its domestication,thousands of cultivated tomato varieties have been developed targeting an array of aspects.Among which breeding for yield and yield-related traits are mostly focused.Cultivated tomato is extremely genetically poor and hence it is a victim for several biotic and abiotic stresses.Among the biotic stresses,the impact of viral diseases is critical all over tomato cultivating areas.Improvement of tomato still largely rely on conventional methods worldwide while molecular approaches,particularly Marker Assisted Selection(MAS)has become popular across the globe as a fast,low cost and precise tool which is essential in present day plant breeding.In this review paper,breeding tomato for high yield and viral disease resistance,particularly to tomato yellow leaf curl virus disease(TYLCVD)using conventional and molecular approaches will be discussed.Lining up of this set of information will be useful to those who are interested in tomato variety development with high yielding and TYLCVD resistance.

肉桂醛对NaCl胁迫下番茄幼苗生长特性的影响

为探明肉桂醛对番茄幼苗耐盐性的影响,该研究以番茄‘合作903’为试验材料,探究肉桂醛(100μg·L^(-1))对处于100 mmol·L^(-1)NaCl胁迫下番茄种子萌发与幼苗生长特性的影响。在试验中设置4组处理:对照(CK,蒸馏水)、NaCl(100 mmol·L^(-1))、NaCl+CA(100 mmol·L^(-1)NaCl+100μg·L^(-1)CA)、CA(100μg·L^(-1))。结果表明:(1)在100 mmol·L^(-1)NaCl胁迫下,添加100μg·L^(-1)的肉桂醛,番茄种子的发芽势和发芽率均有所提升,番茄幼苗的根长和鲜重均显著提高,说明添加肉桂醛对NaCl胁迫下番茄种子的萌发与幼苗生长均有一定缓解作用。(2)肉桂醛能够有效降低NaCl胁迫导致的番茄幼苗根尖总活性氧(reactive oxygen species,ROS)的过量累积,缓解膜脂过氧化程度从而降低细胞死亡率。综上表明,肉桂醛处理能够通过缓解幼苗的氧化损伤程度,提高番茄萌发与幼苗时期的耐盐性,肉桂醛作为一种新型制剂具有在田间生产应用的潜力。

发酵花生壳和牛粪替代草炭基质的番茄育苗效果分析

为明确发酵花生壳和牛粪替代草炭基质用于番茄育苗的可行性,筛选出其最佳配比,以发酵花生壳和牛粪为主要原料,按花生壳∶牛粪∶珍珠岩(体积比)为0∶6∶3(T1)、2∶4∶3(T2)、4∶2∶3(T3)和6∶0∶3(T4)复配形成基质,以草炭∶珍珠岩为6∶3的基质作为对照(CK),测定不同基质的理化特性、植株形态指标和营养元素含量,分析影响番茄植株性状的关键基质理化特性,并对育苗效果进行综合评价。结果表明,与CK相比,T1~T4基质中总磷、总钾、有效磷、镁和过氧化氢酶活性均显著增加,而总氮、碱解氮和钙含量均显著下降。在不同的发酵花生壳和牛粪复配基质中,随花生壳比例增大,脲酶和磷酸酶活性增大,而电导率、容重和速效钾含量下降。植株各形态指标均在T3处理下具有最高值,且显著高于CK。各处理基质中植株钾含量均显著高于CK,但氮、钙和镁含量均显著低于CK。植株中磷含量在T4处理下最高,而在T2处理下最低。番茄植株综合性状与基质中pH、总钾、有效磷、镁、过氧化氢酶和脲酶呈显著正相关,而与电导率、有机质、总氮、碱解氮和速效钾呈负相关。通过综合评价可知,T3处理下番茄植株综合性状表现最优。因此,在番茄育苗中发酵花生壳和牛粪复配基质可替代草炭基质,且以花生壳∶牛粪∶珍珠岩为4∶2∶3效果最好。以上结果为农业废弃物基质化利用提供了理论依据和指导。