Zinc-phosphorus interactions in two cultivars of tomato (Lycopersicon esculentum L.) grown in chelator-buffered nutrient solutions

Zinc-phosphorus interactions have been frequently studied using a diverse number of crop species, but attainment of reproducible Zn deficiencies, especially severe ones, has been hampered by the use of conventional hydroponic solutions wherein contaminating levels of Zn are often near-adequate for normal growth. We utilized novel, chelator-buffered nutrient solutions for precise imposition of Zn deficiencies. Tomato (Lycopersicon esculentum L. cv. Jackpot or Celebrity) seedlings were grown for 15 to 18 d in nutrient solutions containing 200, 600, or 1200 M P, and 0 to 91 M total Zn. Computed free Zn²⁺ activities were buffered at 10^-10.3 M by inclusion of a 100-M excess (above the sum of the micronutrient metal concentrations) of the chelator DTPA. At total added Zn=0, acute Zn deficiency resulted in zero growth after seedling transfer, and plant death prior to termination. Free Zn²⁺ activities 10^-10.6 M resulted in Zn deficiencies ranging from mild to severe, but activities 10^-11.2 were required to cause hyperaccumulation of shoot P to potentially toxic levels. Despite severe Zn deficiency (i.e. ca. 20% of control growth), tissue Zn levels were usually much higher than the widely reported critical value of 20 mg kg^-1, which may be an artifact of the selection of DTPA for buffering free Zn²⁺. Across Zn treatments, increasing solution P depressed growth slightly, especially in Celebrity, but corresponding increases in tissue P (indicative of enhanced P toxicity) or decreases in tissue Zn (P-induced Zn deficiency) were not observed. The depressive effect of P was also not explained by reductions in the water-soluble Zn fraction. Within 40 h, restoration of Zn supply did not ameliorate high leakage rates (as measured by K⁺ efflux) of Zn-deficient roots. Similarly, transfer of Zn-sufficient plants to deficient solutions did not induce leakiness within 40 h. Foliar sprays of ZnSO₄ almost completely corrected both Zn deficiency and membrane leakiness of plants grown in low-Zn solutions. Hence, maintenance of root membrane integrity appears to depend on the overall Zn nutritional status of the plant, and not on the presence of certain free Zn²⁺ levels in the root apoplasm.     

A comparison of tomato (Lycopersicon esculentum) lectin with its deglycosylated derivative

A regime is proposed for the design of coupled enzyme assays in which auxiliary enzymes are added at concentrations proportional to their Km values. Under these conditions it is possible to calculate the complete time course of the assay including the time required for the system to approach its steady state. The consequence of increasing the number of coupling enzymes is shown to be a considerable decrease in time required to reach the steady state provided that the overall transient time remains the same. The method is extended to the general consideration of pathways and shows that pathways of the same length exhibit identical temporal responses provided that the units of concentration and time used are based on the steady-state concentration of intermediates and the transient time respectively. An unexpected finding is that increasing the number of intermediates in a pathway can decrease the time required to enter a steady state.     

Comparison of the response to aluminum toxicity in gametophyte and sporophyte of four tomato (Lycopersicon esculentum Mill.) cultivars

Summary We tested pollen from four tomato cultivars differing in sensitivity to aluminum in the sporophyte to determine if Al sensitivity was also expressed in pollen. Pollen sensitivity to Al was measured by the ability to germinate and grow in a control solution after a short period in a high concentration of Al. The response was ranked and compared to the Al sensitivity ranking of the four cultivars based on top growth in Al toxic soil. In addition, seedlings from the most and least sensitive cultivars, based on pollen germination, were compared for Al sensitivity in nutrient solutions. Treatment with Al significantly reduced pollen germination in the two more sensitive cultivars, but not in the two more resistant cultivars. However, the ranking was not the same as that based on the shoot growth of the sporophyte. Root growth as a criterion of sporophytic Al sensitivity produced results similar to pollen germination. The study suggests that although the correspondence is better for some phenotypic responses of the sporophyte than others, Al tolerance appears to be another character expressed in both pollen and sporophyte.     

Genetic mapping of tandemly repeated telomeric DNA sequences in tomato (Lycopersicon esculentum).

A telomere-associated tandemly repeated DNA sequence of tomato, TGR I, has been used to map telomeres on the tomato RFLP linkage map. Mapping was performed by monitoring the segregation of entire arrays of TGR I from a segregating F2 population using pulsed-field gel electrophoresis (PFGE). With this strategy, four telomeres have been mapped to the ends of the short arm of chromosomes 9 and 12 and the long arms of chromosomes 5 and 11, using a saturated RFLP map of tomato containing approximately 1000 RFLP markers. In all four cases, the TGR I locus maps to the end of the chromosome, and the distance between the most distal single-copy RFLP marker and the telomeric TGR I locus was between 1.6 and 9.6 cM. This indicates that the region close to the telomeres does not show an excessive rate of recombination compared to other regions of the genome and that the RFLP map of tomato is essentially complete and covers the entire genome for all practical purposes. Additionally, the mapping technique presented here should be generally applicable to the mapping of other tandemly repeated DNA sequences.     

Influence of the antibiotic timentin on plant regeneration of tomato (Lycopersicon esculentum Mill.) cultivars

 Cotyledon explants of tomato (Lycopersicon esculentum Mill. cvs 'Santa Clara', 'Firme' mutant, 'IPA-5' and 'IPA-6') were excised from 8- to 10-day-old in vitro-grown seedlings. Four different shoot induction media supplemented with timentin (300 mg l^–1) were screened. When cotyledon explants were cultured on MS-based medium with 1.0 mg l^–1 zeatin plus 0.1 mg l^–1 IAA and supplemented with timentin, higher regeneration frequencies and a greater number of elongated shoots were obtained. It was observed that timentin caused an increase in the morphogenesis of in vitro cotyledon explants of tomato cultivars. In two of three cultivars tested, rooting of shoots was positively influenced, both in the presence and absence of timentin in the rooting medium, among shoots regenerated from explants derived from timentin-supplemented medium. The results confirm those of a previous investigation on the beneficial effects of this class of antibiotics on tomato regeneration and, consequently, its reliability for use in the transformation of this species. Received: 1 December 1998 / Revision received: 19 May 1999 · Accepted: 3 May 1999     

不同番茄品种对缺钙敏感性的差异

分别在苗期和果实成熟期对不同品种番茄对缺钙反应的敏感性进行了研究。钙效率的高低是衡量番茄对缺钙敏感性的重要指标。苗期聚类分析表明,33个品种可以被分为3个大类,分别是钙高效品种(7个)、钙低效品种(5个)和钙中效品种(21个),钙效率系数平均值分别为87％、49．5％和70．2％。缺钙条件下钙效率越高的品种其根部、地上部吸收和积累钙的能力越强,吸钙量越高;在正常供钙条件下,钙系数与植株的根、地上部及整株的吸钙量成显著负相关关系,表明充足供钙使钙低效品种吸钙能力增加,且增加的程度远大于钙高效品种,同时也表明钙低效品种具有在供钙充足时需钙量较大的特性。苗期钙效率与果实钙含量和果实钙效率及BER发生并不完全一致,苗期钙效率较低、果实钙含量也较低的品种BER发生率较高(No．4);而苗期钙效率较高的品种当果实钙含量较低时也可完全减少BER的发生(No．3);低钙培养对No．5品种果实钙含量无显著影响,表明该品种较耐低钙胁迫。因此,在进一步的机理研究中可以选择No．5和No．4作为耐低钙和不耐低钙的试验材料。     

An immunochemical testing of pathophysiological reactions of several PSTVinfected tomato (Lycopersicon esculentum L.) cultivars

Several tomato cultivars were infected with a severe strain of PSTV and a pathophysiological reaction was characterized by means of enzyme-linked immunosorbent assay with serum containing IgGs to disease-associated host-specific leaf proteins. A strong expression of disease-associated symptoms (stunting, epinasty, leaf blade malformation and rugosity) and strong immunochemical reaction was found for cultivars Bizon, Linia, Revermun and Rutgers. The immunochemical assay revealed appearence of a major antigenic protein having a molecular mass of about 70 kD in these cultivars. The immunochemical reaction with disease-associated proteins reached a maximum four weeks after inoculation of PSTV. A weak immunochemical reaction was observed, if proteins from cvs. Sonato, Harzfeuer and Karlik were analyzed. Cvs. Sonato and Harzfeuer did not show characteristic symptoms such as stunting, leaf blade malformation and rugosity. Except for stunting, the same was true for cv. Karlik. On the other hand, no significant difference in PSTV accumulation was observed among the cultivars analyzed. Reciprocal hybrids obtained by crossing cvs. Revermun and Karlik showed strong symptoms of the disease (Revermun-type) and increased activity of nuclease due to PSTV infection. On the contrary, an immunochemical analysis revealed a low level of the disease-associated antigens in these hybrid tomatoes, suggesting rather recessive genetic background determining their expression during PSTV-caused pathogenesis.     

Proteomic analysis of tomato (Lycopersicon esculentum) pollen

In flowering plants, pollen grains are produced in the anther and released to the external environment with the primary function of delivering sperm cells to the female gametophyte. This study was conducted to identify proteins in tomato pollen and to analyse their roles in relation to pollen function. Tomato is an important crop which is grown worldwide and is an excellent experimental system. Proteins were extracted from pollen, separated by two-dimensional gel electrophoresis (2-DE), and identified by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) and peptide mass fingerprinting. Of the 960 spots observed on Colloidal Coomassie Blue (CCB)-stained 2-DE gels, 190 were selected for analysis. Of these, 158 spots, representing 133 distinct proteins, were identified by searching the NCBInr and Expressed Sequence Tag databases. The identified proteins were classified based on designated functions and the majority included those involved in defence mechanisms, energy conversions, protein synthesis and processing, cytoskeleton formation, Ca(2+) signalling, and as allergens. A number of proteins in tomato pollen were similar to those reported in the pollen of other species; however, several additional proteins with roles in defence mechanisms, metabolic processes, and hormone signalling were identified. The potential roles of the identified proteins in the survival strategy of the small, independent, two-celled pollen grain of tomato, and subsequently in pollen germination and tube growth are discussed.     

Induced androgenesis in tomato (Lycopersicon esculentum Mill). II. Factors affecting induction of androgenesis

The influence on androgenesis of donor plant growth conditions, anther size and developmental stage of the microspore, medium composition and different anther treatments prior to culture was investigated in L. esculentum Mill. cv Roma and its hybrids. Growth conditions of donor plants affected the induction of tomato androgenesis. Anthers isolated from plants grown in the greenhouse during winter at high humidity and in short days possessed higher androgenetic ability than those grown in the field. The physiological state and age of the donor plants also influenced the processes investigated. Regarding the developmental stage of microspores, the period from prophase to telophase II is optimal for tomato anther implantation. More then 20 culture media were tested. Two, based on Murashige and Skoog medium were selected as most favourable for callus induction, organogenesis and regeneration. The effect on callus induction of 2ip in combination with indole-3-acetic acid (IAA) was greater than that of zeatin and IAA. Zeatin promoted entire plant regeneration. A highly significant interaction between genotype and medium was observed. Temperature and gamma ray treatments of anthers enhanced callus production, shoot formation and plant regeneration. Treatments at 4 °C (48 h) and 10 °C (9 days) stimulated these processes. Combined treatment of anthers with 4 Gy and 10 °C for 9 days was the most efficient. Received: 5 September 1997 / Revision recieved: 5 June 1998 / Accepted: 15 June 1998     

Physiological response and yield of paclobutrazol treated tomato plants (Lycopersicon esculentum Mill.)

Experiments were conducted to study the physiologicaleffect of the plant growth retardant paclobutrazol(PBZ) and its impact on the yield of tomato plants(cv. Precador). Seedlings were treated at the time of prickingout with soil and foliar applications of PBZ atconcentrations of 1.0 and 25.0 mg l^-1respectively. The results established that:-- The reduced height and the increased thickness ofthe young plant stem, as well as the accelerated rootformation are a significant advantage of the PBZtreatment, contributing to the improvement of seedlingquality at planting.-- Soil treatment (1 mg l^-1) and foliar treatment(25 mg l^-1) with PBZ improves the photosyntheticactivity and water balance of tomato cv. Precador.-- PBZ accelerates fruit formation and increases earlyfruit yield.-- The concentrations of the retardant used and themode of its application ensure the production offruits without any residual retardant and harmless tohuman health from a phytosanitary point of view.     

Highly efficlent plant regeneration from mesophyll protoplasts of Indian field cultivars of tomato (Lycopersicon esculentum)

Three Indian cultivars ofL. esculentum were assessed for shoot regeneration from protoplast-derived calli. Consistent yields of viable protoplasts (>9.0×10⁶ g f.wt.^-1) were obtained from leaflets of 14 days old cultured shoots. Protoplast viability (88–94%) and planting efficiency (55–70%) were recorded for the three cultivars. Up to 71% of the protoplast-derived tissues regenerated shoots.Abbreviations BAP 6-benzylaminopurine - 2,4-d 2,4-dichlorophenoxyacetic acid - g f.wt. gram fresh weight - IAA indoleacetic acid - MS Murashige & Skoog (1962) - NAA -naphthaleneacetic acid - Zea zeatin     

Growth of tomato (Lycopersicon esculentum) in response to salicylic acid under water stress

Abstract

Plants of Lycopersicon esculentum L. cv. K-25 were subjected to water stress by withholding water for 10 days at 20 (WS I) and 30 (WS II) days after sowing (DAS). Seedlings were sprayed with double distilled water (DDW) or 10^?5M salicylic acid (SA) at 45 DAS. The water stress at earlier stage of growth (20 day stage) was more inhibitory as compared to the later stage (30 day stage). The plants exposed to water stress exhibited a significant (p<0.05) decline in photosynthetic parameters, membrane stability index (MSI), leaf water potential, activity of nitrate reductase (NR), carbonic anhydrase (CA), chlorophyll and relative water content (RWC). A follow-up treatment with SA protected against the stress generated by water and significantly improved the above parameters. However, proline content and antioxidant enzymes increased under drought as well as under SA treatments.     

Factors influencing transformation frequency of tomato (Lycopersicon esculentum)

We developed an efficient procedure for transformation and regeneration of L. esculentum cv. Moneymaker from cotyledon explants. The effect of two parameters on the transformation frequency was investigated in detail. The use of feeder layers during cocultivation proved to be critical. In addition, it was found that Agrobacterium strains harbouring a L,L-succinamopine type helper plasmid yielded significantly higher transformation frequencies than those with octopine or nopaline type helper plasmids. The optimized protocol was used to obtain transformation frequencies averaging 9%. Of the plants produced approximately 80% proved to be diploid, of which 67% contained the transgene(s) on a single locus.Abbreviations 2,4D 2,4-dichlorophenoxy-acetic acid - gus ß-glucoronidase - IAA indoleacetic acid - LB Luria-Bertani - NPTII neomycin phosphotransferase II - ZR zeatin riboside     

The growth of tomato (Lycopersicon esculentum Mill.) hypocotyls in the light and in darkness differentially involves auxin.

Light and auxin antagonistically regulate hypocotyl elongation. We have investigated the physiological interactions of light and auxin in the control of tomato (Lycopersicon esculentum Mill.) hypocotyl elongation by studying the auxin-insensitive mutant diageotropica (dgt). The length of the hypocotyls of the dgt mutant is significantly reduced when compared to the wild type line Ailsa Craig (AC) in the dark and under red light, but not under the other light conditions tested, indicating that auxin sensitivity is involved in the elongation of hypocotyls only in these conditions. Similarly, the auxin transport inhibitor naphthylphthalamic [correction of naphtylphtalamic] acid (NPA) differentially affects elongation of dark- or light-grown hypocotyls of the MoneyMaker (MM) tomato wild type. Using different photomorphogenic mutants, we demonstrate that at least phytochrome A, phytochrome B1 and, to a much lesser extent [correction of extend], cryptochrome 1, are necessary for a switch from an auxin transport-dependent elongation of hypocotyls in the dark to an auxin transport-independent elongation in the light. Interestingly, the dgt mutant and NPA-treated seedlings exhibit a looped phenotype only under red light, indicating that the negative gravitropism of hypocotyls also differentially involves auxin in the various light conditions.     

Development and differentiation of haploid Lycopersicon esculentum (tomato)

Summary Haploid callus cultures of selected races of Lycopersicon (tomato) species can be obtained from anther culture. This is a further demonstration of a proposed general method of haploid culture developed with Arabidopsis thaliana. Differentiation of haploid callus of Lycopersicon esculentum can be controlled both in the dark and the light by hormones added to defined minimal media. Development to plantlets is achieved only in the light. Callus cells can be induced to develop into seedless pseudo-fruits. Chromosome counts on callus cells or root-tip cells establishes haploidy (n=12).Haploidy can be maintained in culture on defined minimal media for at least one year.     

Isolation of signaling mutants of tomato (Lycopersicon esculentum)

As a first step towards developing a genetic system for investigating signaling processes in plants, we have developed a screen for signaling mutants deficient in a wound response. We have isolated two mutants of tomato that lack detectable production of proteinase inhibitors induced systemically in leaves by wounding. The mutants are deficient in the induction of both proteinase Inhibitor I and proteinase Inhibitor II but can be induced to respond at near wild-type levels by methyl jasmonate, a known elicitor of inhibitor production in tomato. While completely deficient in systemic production of proteinase inhibitors, both mutants produce some proteinase inhibitor in wounded leaves. This evidence suggests the existence of two signaling pathways, one local and one systemic, that regulate the induction of proteinase inhibitor snythesis in response to wounding.