Assessment of genetic purity of tomato (Lycopersicon esculentum L.) hybrid using molecular markers

Three DNA molecular marker systems, RAPD, ISSR and SSR, were used to test seed genetic purity of two commercial hybrid tomato (Lycopersicon esculentum L.) cultivars ‘Hezuo 903’ and ‘Sufen No. 8’. Genomic DNA from the two F₁ hybrid cultivars and their corresponding parental lines was screened with 218 RAPD decamer primers, 54 ISSR primers and 49 SSR primers. Among the 321 primers, 4 primers for ‘Hezuo 903’ and 3 for ‘Sufen No. 8’, which could produce both female and male parent-specific markers, were selected for testing the genetic purity. A total of 210 hybrid individuals of each cultivar were analyzed using the identified primers. The combined results of the marker analysis showed that eight of the 210 F₁ plants in ‘Hezuo 903’ and 13 of 210 in ‘Sufen No. 8’ were false hybrids, and the overall genetic purity of the two F₁ hybrid seed lots was 96.2 and 93.8%, respectively. This study showed that RAPD and SSR markers could provide a practical and efficient tool in quality control of the tomato commercial hybrid seeds.     

Interactions between root-zone temperature and light levels on growth,development and photosynthesis of Lycopersicon esculentum Mill. cultivar ‘Vendor’

Six-week-old tomato plants were subjected to 5 root-zone temperatures, ranging from 12 to 36°C, and 4 light levels in a factorial design. Large increases in shoot dry weight, leaf area and fruit development resulted from soil warming to 24°C when plants were grown under high light conditions. Shoot growth and fruit weight were reduced at 24°C root temperature under low light conditions. Total plant photosynthesis, leaf area index, net assimilation rates and leaf chlorophyll content were related to plant growth and flower development for the various treatments. Our experiments have shown an interaction between root-zone temperature and light levels for greenhouse tomatoes. Soil warming caused large increases in shoot dry weight and fruit development when light was not limiting plant growth, but had deleterious effects on flowering and fruit set under shaded conditions.     

Effects of NaCl application to hydroponic nutrient solution on fruit characteristics of tomato (Lycopersicon esculentum Mill.)

NaCl was applied to nutrient solution (5 dS m⁻¹ versus 1.4 dS m⁻¹ in the control) of hydroponically-grown tomato and its effects on taste grading and chemical composition of fruit were investigated. Taste panels indicated NaCl treatment increased sweetness, acidity, umami (i.e. the taste of deliciousness) and overall preference. Hexose concentration of the fruit grown on NaCl treated plants significantly increased; and at the same time, chloric ion, organic and amino acids in general had higher concentrations in NaCl treated plants than the control. Our results showed that (1) consumer grading of the tomato fruit was influenced not only by sugar content but also by the organic and amino acids; (2) increased concentration of soluble solids in the fruit of NaCl treated plants was not the result of simple overall condensation due to the reduction of water transport. The relation of diversified consumer preference, fruit chemical composition, and appropriate evaluation of tomato fruit are also discussed.     

番茄砧木及品种对南方根结线虫的抗性鉴定

 为了测定3种番茄砧木及7个番茄品种对南方根结线虫的抗病程度, 采用室内盆栽番茄人工接种南方根结线虫法调查番茄植株对根结线虫的抗性指标, 结果表明: 国外引进的5 个番茄抗性品种(Trofeo、Beatrice、1411、Romana、Garry) 及两个番茄砧木( Energy、He-Man) 均为抗性品种; 荷兰的Cairo和国内的耐线虫番茄品种中华一号为感病品种, 番茄砧木Beaufort为中感品种。     

Alteration of tomato fruit quality by root inoculation with plant growth-promoting rhizobacteria (PGPR): Bacillus subtilis BEB-13bs

In this study the effect of inoculation of tomato (Lycopersicon esculentum Mill.) roots with plant growth-promoting rhizobacteria (PGPR) on yield and fruit quality was evaluated. The control treatment was non-inoculated (CTL) and the PGPR treatment was inoculated with Bacillus subtilis BEB-lSbs (BS13). Yield per plant and marketable yield, as well as fruit weight and length were increased by the BS13 treatment when compared to the CTL treatment. Texture of red fruits was also enhanced by the BS13 treatment compared to that in the CTL treatment. These results demonstrated that PGPR have positive effects on tomato fruit quality attributes, particularly on size and texture.     

Comparison of three pea cultivars (Pisum sativum) regarding their responses to direct and bicarbonate-induced iron deficiency

The aim of this work was to explore leaf characteristics underlining the difference in the sensitivity of pea cultivars (cv. Kelvedon, Douce and Lincoln) to Fe deficiency. Plants were grown in a greenhouse under controlled conditions in continuously aerated solution. Three treatments were used: 30 μM Fe (+Fe), 0 μM Fe (−Fe); direct deficiency and 30 μM Fe + 10 mM NaHCO₃ (+Fe+Bic); indirect deficiency for 12 days. Growth parameters, iron status, potassium content, chlorophyll fluorescence and photosynthetic capacity were studied. Our results showed that Fe deficiency led to a significant decrease of chlorophyll index (SPAD readings) and bivalent iron content in all Pisum sativum cultivars. The lower reduction was observed in Fe-deficient plants of Kelvedon and Douce. In addition, shoot length and whole plant dry weight were not affected by Fe deficiency in the latter cultivars. Both tolerant cultivars showed higher accumulation of potassium content in their leaves compared with the sensitive one. Moreover, both chlorophyll fluorescence ratios (F_v/F_m and F_v/F₀) were significantly decreased in all cultivars under both Fe deficiency treatments. The photosynthetic electron transport activity was reduced in the sensitive cultivar, especially in the absence of iron. The adverse effect of bicarbonate-induced Fe deficiency on the above mentioned parameters were more pronounced than that of the direct one. The capacity of both tolerant cultivars to preserve adequate chlorophyll synthesis, photosynthetic capacity and plant growth under iron-limiting conditions is related to the suitable nutrition of their leaves in ferrous iron, due to (at least partially) their higher potassium content.     

Regeneration and characterization of plants derived from leaf in vitro culture of two sweet orange (Citrus sinensis (L.) Osbeck) cultivars

In the current work attempts were made to investigate culture of leaf explants derived from in vitro seedlings of two sweet orange (Citrus sinensis (L.) Osbeck) cultivars, Bingtangcheng and Valencia. Effects of several factors, including culture medium, lighting condition, explant age and genotype on regeneration response were examined based on three parameters, percentage of explants producing shoots, mean number of shoots per explant and shoot forming capacity. Culture of the explants on shoot-inducing media (SIM) composed of MT salts supplemented with different growth regulators gave rise to disparate shoot regeneration, in which SIM₁ (MT + 0.5 mg L⁻¹ BA + 0.5 mg L⁻¹ Kinetin + 0.1 mg L⁻¹ NAA + 3% sucrose + 0.8% agar, pH 5.8) was shown to be the most effective medium for direct induction of shoots from leaf explants. Highly significant difference in the response of shoot bud regeneration was noted between the two cultivars, with Bingtangcheng being more responsive than Valencia. Culture of explants from fully developed leaves led to better shoot regeneration capacity in comparison to undeveloped ones. However, the two lighting conditions used herein did not cause significant difference in shoot regeneration. Phenotypic observation and randomly amplified polymorphic DNA (RAPD) analysis confirmed that all the regenerated plants from both genotypes were genetically identical to their donor plants, suggesting absence of detectable genetic variation in the regenerated plants. The data presented here demonstrated that direct initiation of plants from leaf explants has been successfully accomplished. To our knowledge, this is the first report on direct regeneration of shoots from leaf explants in Citrus, which will provide an alternative source for citrus genetic manipulation in the future.     

Photosynthetic and growth responses of juvenile Chinese kale (Brassica oleracea var. alboglabra) and Caisin (Brassica rapa subsp. parachinensis) to waterlogging and water deficit

Chinese kale (Brassica oleracea var. alboglabra) and Caisin (Brassica rapa subsp. parachinensis) are leafy vegetable crops grown in south-east Asian countries where rainfall varies dramatically from excess to deficit within and between seasons. We investigated the physiological and growth responses of these plants to waterlogging and water deficit in a controlled experiment in a glasshouse. Juvenile plants were subjected to waterlogging or water deficit for 19 days in case of Chinese kale and 14 days in case of Caisin and compared with well-watered controls. Caisin tolerated waterlogging better than Chinese kale because it produced hypocotyl roots and gas spaces developed at the stem base. In Chinese kale, waterlogging reduced plant fresh weight (90%), leaf area (86%), dry weight (80%) and leaf number (38%). In contrast, waterlogging had no impact on leaf number in Caisin and reduced plant fresh and dry weights and leaf area by 60–70%. Water deficit reduced leaf area, fresh weight and dry weight of both species by more than half. Leaf number in Chinese kale was reduced by 38% but no effect occurred in Caisin. Water deficit increased the concentration of nitrogen in the leaf dry matter by more than 60% in both species and the leaf colour of water deficient plants was dark green compared with the leaf colour of well-watered plants. Soil water deficit delayed flowering of Caisin while waterlogging accelerated it. Thickening and whitening of the cuticle on the leaves of Chinese kale probably increased its ability to retain water under drought while Caisin adjusted osmotically and Chinese kale did not. Waterlogging and water deficit had strong effects on leaf gas exchange of both Brassica species. Water deficit closed the stomata in both species and this was associated with a leaf water content of 9 g g⁻¹ DW. In contrast, waterlogging reduced conductance from 1.0 to 0.1 mol H₂O m⁻² s⁻¹ in direct proportion to changes in leaf water content, which fell from 11 to 5 g g⁻¹ DW. This separation of the effects of water deficit and waterlogging on conductance was reflected in transpiration, internal CO₂ concentration and net photosynthesis. In conclusion, Chinese kale and Caisin showed rather different adaptations in response to waterlogging and water deficit. Caisin was more tolerant of waterlogging than Chinese kale and also showed evidence of tolerance of drought. There is genetic variation to waterlogging within the Brassica genus among the leafy vegetables that could be used for cultivar improvement.     

Phytochemical composition and antioxidant activity of high-lycopene tomato (Solanum lycopersicum L.) cultivars grown in Southern Italy

In this study, the antioxidant components and of six high-lycopene (Lyco 1, Lyco 2, HLY 02, HLY 13, HLY 18 and Kalvert) and one ordinary (Donald) tomato cultivars (cvs) grown simultaneously in an open-field of the Southern Italy were investigated. Lycopene, β-carotene, lutein, total phenols, flavonoids, ascorbic acid (AsA), dehydroascorbic acid (DHA) and total vitamin C (AsA + DHA) contents, as well as hydrophilic and lipophilic antioxidant activities (HAA and LAA) were determined. Significant differences were detected among tomato cvs in all studied antioxidant components, as well as in the antioxidant activity of their hydrophilic and lipophilic fractions. High-lycopene tomato cvs showed higher lycopene, β-carotene, HAA and LAA when compared to cv Donald. Cv HLY 18 showed the highest lycopene and β-carotene content with 232.9 mg/kg fresh weight (fw) and 19.4 mg/kg fw, respectively. Except for Kalvert, high-lycopene tomato cvs also obtained higher total vitamin C levels, with cv HLY 13 top ranking with an average of 352.8 mg/kg fw. LAA ranged from 133.5 μM Trolox/100 g fw in cv Donald to 540.1 μM Trolox/100 g fw in cv Lyco 2 and was significantly correlated to lycopene (r = 0.53; p < 0.01) and β-carotene (r = 0.56; p < 0.01) contents. A variation between 2.7- and 4.0-fold was found in LAA of high-lycopene tomato cvs compared to Donald. HAA was significantly correlated to the amount of DHA (r = 0.61; p < 0.01) and total vitamin C (r = 0.60; p < 0.01). Although these data require confirmation over a longer period of time, this investigation suggests a promising use of the high-lycopene tomato cvs for the production of tomatoes with higher nutritional quality.     

Relationship between inbreeding coefficients and plant height of 1-year-old seedlings in crosses among Japanese pear (Pyrus pyrifolia Nakai) cultivars/selections

Plant height, a vigor trait, in 1-year-old seedlings made from Japanese pear (Pyrus pyrifolia) cultivars/selections was measured using 994 individuals from 29 families. The family mean of plant height was negatively correlated (r = −0.72**) to the inbreeding coefficients (F). The regression of the family mean (Fm) on the F value (Fm = 130 − 104F) showed that inbreeding depressions were 8%, 20%, and 40% for F = 0.1, 0.25, and 0.5, respectively. According to the regression, the family mean at F = 0 was estimated at 130 cm. These results showed that the vigor was greatly influenced by inbreeding in Japanese pear. Within-family variances, the genetic segregation of offspring in a family, differed according to family. The proportions of offspring with plant height above 130 cm (estimated Fm for F = 0) were extremely low, i.e., 0–17% for 0.5 ≤ F < 0.60 and 0–8% for F = 0.75.     

成都番茄青枯菌生理分化和品种抗性鉴定

初步鉴定出成都地区番茄青枯菌（Ｐｓｅｕｄｏｍｏｎａｓｓｏｌａｎａｃｅａｒｕｍ）属小种１，并根据其对不同寄主的致病力不同进一步划分成４个致病类型；还用３个不同菌株接种鉴定了成都的６个主要番茄栽培品种的青枯病抗性，结果表明６个品种均不抗青枯病，属高感品种     

Photosynthesis of field-grown Arracacha (Arracacia xanthorriza Bancroft) cultivars in relation to root-yield

There has been limited research on measuring potential differences in leaf gas exchange of Arracacha (Peruvian parsnip, Arracacia xanthorriza Bancroft) cultivars, as affected by different environments, as well as its relation to storage root-yield. The present paper reports field measurements of leaf CO₂ assimilation rates (A) for five contrasting cultivars grown at two different high-altitude locations. Using a design of plots chosen at random with three repetitions, commercial root production was determined in the two locations at different altitude (1580 and 1930 m). Daily leaf gas exchange was repeatedly monitored with a portable open-mode infrared gas analyzer at different times in both locations during the growth cycle. Root-yield, leaf area and dry weight were measured. Significant differences in leaf photosynthetic rate and in specific leaf area (SLA) were observed among cultivars. Cultivars with high SLA, had high CO₂ assimilation. Mean (A_n) and total (A_tot) of CO₂ assimilation and SLA were significantly correlated with storage root-yield across cultivars and locations. The three cultivars with the greatest commercial root production also had the highest maximum values for A and the highest specific leaf area, indicating that these two parameters can be used to select for highly productive cultivars of A. xanthorriza.     

The inheritance of systemic resistance to the bacterial blight pathogen (Xanthomonas axonopodis pv. dieffenbachiae) in Anthurium andraeanum (Hort.)

The inheritance of resistance to systemic infection by bacterial blight disease (blight) caused by Xanthomonas axonopodis pv. dieffenbachiae in anthurium (Anthurium andraeanum Hort.) was investigated in 83 biparental crosses involving 39 anthurium cultivars, using a green fluorescent protein-based screening method. Genetic analysis was based on North Carolina mating design II analysis, combining ability analysis and parent–offspring regression analysis. The results showed a role for both additive and non-additive effects in the inheritance of systemic resistance to blight, although the former was predominant and between four- to five-fold larger than the latter. General combining ability (GCA) of the parents was able to fairly accurately predict the performance of progeny in 15 of the 17 M × N (‘M’ male cultivars crossed with ‘N’ female cultivars) mating designs. The highly resistant cultivars were the best general combiners, while the susceptible cultivars generally produced negative GCA values. Dominance was in the direction of susceptibility. Narrow sense heritability (h²) based on North Carolina mating design II analysis, was 42.5%, with broad sense heritability (H²) of 96.5%. The estimate of h² based on mid-parent–offspring regression analysis was slightly higher (58–62%). In conclusion, the results indicated that resistance to systemic blight is governed by both additive and non-additive genetic effects with the former playing a larger role. Clonal breeding for systemic resistance to blight using a family selection approach is suggested.     

评价番茄砧木组培苗对南方根结线虫的抗性

对引自意大利的番茄抗性砧木进行组织培养并鉴定其组培苗对南方根结线虫的抗性。结果表明:砧木组培苗与砧木实生苗相比对南方根结线虫的抗性显著下降,但与对照合作908相比抗性仍较高,差异达显著水平;砧木组培苗嫁接合作908后的抗性与没有嫁接的组培苗抗性变化一致。抗性砧木及组培苗接种南方根结线虫后与没有接种的植株生长势差异不显著,而合作908在接种南方根结线虫后生长势受到明显抑制。     

Production and evaluation of transgenic sweet orange (Citrus sinensis Osbeck) containing bivalent antibacterial peptide genes (Shiva A and Cecropin B) via a novel Agrobacterium-mediated transformation of mature axillary buds

Transgenic plants of Jincheng orange (Citrus sinensis Osbeck) and Newhall navel orange (C. sinensis Osbeck) containing antibacterial peptide genes Shiva A and Cecropin B were successfully obtained by a novel Agrobacterium tumefaciens-mediated transformation of the mature axillary buds. PCR and Southern blot analysis of the transgenic plants verified that the Shiva A and Cecropin B genes were integrated into the citrus genome. The transgenic plants began to blossom and bear fruit in the 2nd year after grafting on trifoliate orange (Poncirus trifoliata Raf) rootstock in greenhouse. Water-soluble extracts from transgenic citrus leaves exhibit in vitro suppressive effects on Xanthomonas axonopodis pv. citri, suggesting that the expressed products of Shiva A and Cecropin B in citrus retain their native antibacterial activities. Artificial inoculation in greenhouse and open field further indicates significantly increased resistance of transgenic plants to X. axonopodis pv. citri when compared with non-transgenic lines. No significant difference was found in the content of total soluble solids, total acidity, reduced sugar content and other fruit characteristics between transgenic and non-transgenic plants. In this present study, 11 transgenic lines were obtained from 40 transgenic lines, showing enhanced resistance to citrus canker disease.     

Parameters of inner quality of the apple scab resistant and susceptible apple cultivars (Malus domestica Borkh.)

Individual organic acids and sugars were analysed in the fruits of scab resistant and susceptible apple cultivars. The total sugars ranged between 128.2 and 191.6 g/kg, and the total organic acid between 5.1 and 13.4 g/kg. In the flesh and peels of different apple varieties single phenolics (gallic, protocatehuic, chlorogenic, caffeic, ferulic and p-coumaric acid, phloridzin, epicatechin, catechin, quercitrin and rutin) were analysed together with their total phenolic content (TPC). ‘Golden Delicious’ was the cultivar with the lowest TPC whereas ‘Rubinola’, ‘Jonagold’ and ‘Goldrush’ had the highest level of TPC in the pulp. Peels showed a 2–9 times higher phenolic content than the pulp. ‘Goldrush’ had the highest content of TPC in its peel. The total antioxidant capacity of peels was about 2–5 times higher than respective pulps. Scab resistant apple cultivars had significantly higher content of some single and total phenolic contents in comparison with the scab susceptible, especially the pulp.     

Genetic diversity of Dianthus accessions as assessed using two molecular marker systems (SRAPs and ISSRs) and morphological traits

Dianthus chinensis, Dianthus barbatus and Dianthus superbus are members of the Caryophyllaceae and are grown widely as ornamental plants. Information about relative genetic relationships can facilitate breeding programs. Here, we have compared two polymerase chain reaction (PCR)-based systems (sequence-related amplified polymorphisms (SRAPs) and inter-simple sequence repeats (ISSRs)) and morpological trait measurements for their relative effectiveness in estimating the genetic diversity found between 22 Chinese pink (D. chinensis) inbred-lines, one accession of D. barbatus and one accession of D. superbus. Interspecific differences were readily detected but the markers were less reliable in distinguishing the accessions according to their region of origin or in separating the wild species from the cultivars. Morphological traits were found to be the least effective genetic markers. The relative effectiveness of the three systems as markers for genetic diversity was concluded to be SRAP > ISSR > morphological traits, but the combined data from ISSR + SRAP analyses was superior to all three. The information generated by the SRAP marker system correlated more closely with morphological variability than did the ISSR marker system. The morphological markers of plant height/crown size ratio, lower leaf length, ovary shape index and calyx length showed strong correlations with the genetic diversity index (GD_ij, PPB(II) and PSB) as generated by the percentage of polymorphic bands and percentage of special bands of the PCR-based markers.     

Elimination of a new ampelovirus (GLRaV-Pr) and Grapevine rupestris stem pitting associated virus (GRSPaV) from two Vitis vinifera cultivars combining in vitro thermotherapy with shoot tip culture

A new virus species designated as Grapevine leafroll associated virus-Pr (GLRaV-Pr), which is classified in a distinct phylogenetic group of the genus Ampelovirus (Closteroviridae), was recently characterized from Greek grapevine cultivars. Elimination studies of GLRaV-Pr were carried out in two grapevine cultivars, ‘Mantilaria’ and ‘Prevezaniko’, co-infected with Grapevine rupestris stem pitting associated virus (GRSPaV, Flexiviridae). Both viruses were detected by nested RT-PCR assays. Virus elimination was achieved by combining in vitro thermotherapy with meristem (≤0.2 mm) or shoot tip culture (≤0.5 cm). The survival and regeneration rate of meristems was very low. On the other hand, high survival rates were observed in the cultured shoot tips accompanied with high elimination rates for both viruses. Data obtained in this study indicate that virus elimination depends on the genotype of grapevine. The results confirmed that sanitation is easier for species of the Closteroviridae family than for GRSPaV, whereas it seems that eradication of GLRaV-Pr and GRSPaV is feasible even with larger plant tissue parts if combined with an appropriate thermotherapy profile in vitro.     

SSR fingerprinting Chinese peach cultivars and landraces (Prunus persica) and analysis of their genetic relationships

Thirty-two Chinese peach landraces/cultivars, a major subset of the core Chinese peach collection, were fingerprinted using seven pairs of SSR primers to assess their genetic diversity and relatedness. The seven primer pairs detected eight loci and revealed an allele richness of 3.125 (average alleles per locus), an expected heterozygosity (He) of 0.450, and a Shannon index of 0.728 among the landraces/cultivars. This level of genetic diversity is lower compared to other fruit trees and Prunus congenus species (cherry and apricot), but it is comparable to previous reports in peaches. A greater level of genetic diversity was observed in landraces than in cultivars, indicating that peach landraces are valuable for germplasm collection. All cultivars and landraces, except two, were unambiguously identified based on multi-locus genotypes. Eight unique alleles were detected among this group of Chinese peaches. UPGMA clustering analysis separated the 32 cultivars/landraces into two distinct groups, which is generally in accordance with the known pedigree information. The results provide accurate genetic information for defined acquisition policy in the repositories, improving the integrity and efficiency of germplasm management and giving evidences for protection of breeder's intellectual rights.     

Response of gladiolus (Gladiolus spp) plants after exposure corms to chitosan and hot water treatments

The state of Morelos, Mexico has gradually become an important producer of gladiolus. Some preconditioning treatments of corms are empirically done causing uneven emergence and low quality of flowers. In this investigation, before planting, gladiolus corms var. ‘Blanca Borrego’ were dipped in chitosan (chitosan reagent and commercial chitosan Biorend^®), in hot water at various temperatures and in treatments combined with Biorend^® at 1.5% and hot water. Results indicated that the most influenced variables were corm germination, number of flowers per spike, number of cormlets and vase life. Overall, the commercial product Biorend^® at 1.5% accelerated corm emergence in approximately 4 days, the number of flowers increased by 2–7 and the vase life extended for 3 days. The number of cormlets was also duplicated. Corms dipped in the commercial chitosan Biorend^® at 1.5% at different intervals of time were not greatly affected except for the emergence and number of cormlets. However, for this experiment there were significant effects on the number of leaves and flowers because of the interactions between chitosan and the immersion time. The temperature of 55 °C affected plant development because emergence was delayed by 6 days; and there were less number of leaves, flowers and cormlets. On the other hand, the incidence of Fusarium oxysporum in naturally infected corms was 0% at temperatures of 55 °C and 50 °C. Immersion times (0, 10, 15 and 20 min) in hot water at 50 °C did not show significant effects on plant development and vase life. Corms dipped in Biorend^® at 1.5% and hot water at 50 °C accelerated their emergence for about 1–7 days, the number of flowers increased by two, extended the storage life for 1–3 days and increased the number of cormlets. The integration of these two treatments -Biorend^® and hot water- might be a good option for increasing the gladiolus plant quality and vase life.