Characterization of embryogenic mango cultures selected for resistance to Colletotrichum gloeosporioides culture filtrate and phytotoxin

 Embryogenic nucellar cultures of two polyembryonic mango cultivars, ‘Hindi’ and ‘Carabao’, were selected for resistance to the culture filtrate and phytotoxin of a virulent strain of Colletotrichum gloeosporioides Penz. that was isolated from mango leaves. The cultures were recurrently selected either with progressively increasing concentrations of culture filtrate or by continuous challenge with the same concentration of either culture filtrate phytotoxin. Mycelium growth was inhibited when the pathogen was cocultured with the selected, resistant embryogenic cultures. Conditioned plant growth medium containing macerated resistant embryogenic cultures did not inhibit mycelium growth, confirming that extracellular antifungal compounds were involved in the defense response. Enhanced secretion of chitinase and glucanase was observed in the plant growth medium in which resistant embryogenic cultures and regenerated somatic embryos were grown in comparison with the controls. Received: 6 February 1997 / Accepted: 4 November 1997     

Isolation and characterization of new microsatellite markers in mango (Mangifera indica)

Six microsatellite loci that were isolated from a microsatellite‐enriched genomic library of mango (Mangifera indica) along with their specific primer sets were each characterized by using 36 cultivars collected mainly in Thailand. The observed and expected heterozygosities ranged from 0 to 0.83 and from 0.29 to 0.73, respectively. The number of putative alleles are two to six. Three of the six alleles have frequencies of over 75%. The high frequency may be attributed to the bias in the origin of cultivars. Among 36 mango cultivars tested, 29 cultivars showed a unique pattern by six primer sets, whereas seven cultivars cannot be identified because of genotype similarities. This suggests the potentials for identification of mango cultivars by microsatellite markers.     

Comparison of the volatile components of some mango cultivars

Three cultivars of mango from Sri Lanka (Jaffna, Willard and Parrot) were analysed for their volatile aroma components. The total concentrations of volatiles obtained were ca 251, 422 and 628 μg per kg of fresh fruit, respectively. Terpenes were the main volatiles of all three cultivars, with monoterpene hydrocarbons contributing 50–63 % w/w of the total volatiles and sesquiterpene hydrocarbons 14–19 %. Whilst the major volatile of Jaffna mango was cis-β-ocimene (38 %), α-terpinolene was the major volatile of the other two cultivars (32 % and 35 %). Esters were produced by all cultivars (2–16 %), Jaffna yielding most, the majority being unsaturated (12 %). Willard mango gave particularly high levels of non-terpene hydrocarbons (19 %), including a range of six long-chain alkanes (8 %), not detected in the other cultivars.     

芒果畸形病病原菌Fusarium mangiferae的快速分子检测

芒果畸形病是芒果上的重要病害之一,由镰孢菌侵染引起,其中以Fusarium mangiferae为主要致病菌.该病害诊断困难,且难于有效控制,因此,一旦发生则对芒果生产造成严重威胁.研究基于ISSR分子标记技术,从50条已知引物中筛选得到一条目的引物UBC 888,该引物可稳定扩增出大小为479bp的F. mangiferae特异性条带(GenBank Accession No. KJ526382).根据获得的特异性片段序列设计引物,成功地将ISSR标记转化为SCAR标记,并获得一对SCAR特异性引物(W342,W1772)和一段大小为1 376bp的特异性扩增片段(GenBank Accession No. KJ526383).通过优化特异性引物扩增条件,获得最适退火温度,构建芒果畸形病病原菌F. mangiferae的快速分子检测技术.此技术操作简单,特异性强,可检测真菌DNA的含量最低为10pg,适用于F. mangiferae和田间带菌芒果组织高灵敏度快速检测,为芒果畸形病的早期诊断和及时预防提供可靠理论依据和技术方法.     

Effect of mango weevil (Coleoptera: Curculionidae) damage on mango seed viability in Tanzania

Studies were conducted at the horticulture unit of Sokoine University of Agriculture, Morogoro, Tanzania, to assess the incidence and effect of mango weevil, Cryptorhynchus mangiferae (F.) (Coleoptera: Curculionidae), infestation on mango, Mangifera indica L., seed viability. Three polyembryo mango cultivars ('Sindano nyeusi', 'Sindano nyeupe', and 'Dodo') as well as three monoembryo mango cultivars ('Ex-horticulture', 'Tango', and 'Bongwa') were collected and examined for the presence of C. mangiferae. The effect of seed damage on viability was assessed for both naturally and artificially damaged seeds. However, for artificially damaged seeds, the viability was assessed by cutting away 0, 25, 50, or 75% of the cotyledon before planting. In this experiment, only monoembryo mango cultivars were used. All the examined cultivars were infested by C. mangiferae, although at varying levels. Polyembryo mango cultivars were relatively more infested than monoembryo cultivars. Bongwa and Tango were least infested, whereas Sindano nyeusi recorded the highest C. mangiferae incidence. Germination rates of damaged seeds of polyembryonic cultivars differed significantly from the uninfested control, except for Sindano nyeusi. There were no significant differences in germination percentage among the three monoembryo cultivars, and all the cultivars differed significantly from the uninfested control. The germination rates of seeds with 25% of their cotyledons removed did not differ significantly from the undamaged seeds, indicating that monoembryo cultivar seeds can withstand up to 25% damage and germinate successfully.     

ISSR鉴定亲缘关系非常近的芒果栽培品种

用ISSR技术鉴定7个吕宋芒品种(系)和柳州吕宋芒。从30个引物中筛选出6个多态性好的ISSR引物建立DNA指纹图谱用于区分吕宋芒品种(系)。分析DNA指纹图谱,发现这6个引物中每个引物都能区分吕宋系列品种(系),表明ISSR-PCR技术对芒果品种(系)的鉴定非常有效,能区分亲缘关系很近的品种(系)。基于69条多态性条带的聚类分析结果,发现吕宋芒和其它供试的7个品种(系)同源性低,而这7个品种(系):高州吕宋芒、湛江吕宋芒、田阳香芒、金钱芒、柳州吕宋芒、粤西一号、攀西红吕宋同源性较高,可归为一类。     

Correlation of volatile profiles of twenty mango cultivars with their susceptibilities to mango gall fly infestation

Mango gall fly (Procontarinia matteiana) is an orchard pest that parasitises flush leaves of mango and serious outbreaks may result in reduced fruit yield. The trigger for infestation is unknown, but terpenes emitted by the leaves appear to play a role in attraction. Metabolic profiles of three mango cultivars of varying susceptibility to mango gall fly attack were obtained by headspace profiling using GC-FID and GC-MS analysis. Chemometric models constructed from the data revealed that three terpenes, α- and β-pinene and camphene could be useful as biomarkers for susceptibility. Headspace profiles of twenty other cultivars, naturally exposed to gall fly, were obtained in the same way. Susceptibility or resistance of these cultivars was predicted using the developed orthogonal partial least squares model. Predictive outcomes were thereafter verified by visual examination of the leaves to detect gall formation, an indication of gall fly infestation. The model was found to predict the susceptibility or resistance of 90% of the cultivars accurately. This finding indicates the contributory role of the three terpene biomarkers in mango gall fly interaction and may direct future studies to determine their inter-relationship.     

AFLP在芒果品种鉴定中的应用

利用 AFLP分子标记技术对 1 6个芒果 (Mangif era indica L.)品种以及 7个芒果砧木材料进行了初步研究 ,6对 AFLP选择性引物共产生 2 0 4条清晰谱带。同时利用品种间共有谱带率 (Band-sharing)对某些品种间的遗传关系进行了分析。 1 6个栽培品种间的平均共有谱带率为 83 % ,变异幅度为 70 %～ 94% ,7个砧木间的平均共有谱带率则为 80 % ,变异幅度为 5 3 %～ 96%。     

Change in termite communities along a chronosequence of mango tree orchards in the north of Côte d’Ivoire

Termites constitute the major component of the macrofauna of the soil, and influence the structure of the soil, in tropical regions. This study aimed to estimate their assemblages in a chronosequence of mango tree orchards in the north of Côte d’Ivoire and compare them with those in unmanaged savanna. Using a standardized method of rapid biodiversity estimation, termites were collected in seven age classes of mango tree orchards (class 1: <5 years; class 2: 5–9 years; class 3: 10–14 years; class 4: 15–19 years; class 5: 20–24 years; class 6: 25–29 years; class 7: 30 years and over) and compared with termites collected from the savanna. Results show that the species richness was lowest in the young orchards of class 1 (9 species), and increased with the age of the orchards to reach its maximum in the old orchards of class 7 (28 species); these latter were comparable in richness with the savanna (26 species). The Shannon index (H’) and the evenness (E) follow the same trend as the species richness. The orchards of classes 1 and 2 were more dissimilar to the savanna. In contrast, termites were well represented in the savanna and in the old orchard of classes 6 and 7. Rhinotermitinae and Cubitermitinae subfamilies, absent in the young orchards of classes 1 and 2, were very abundant in the old orchards (classes 6 and 7). Overall, the findings of this study show that only the old mango orchards sustain termite diversity that comes close to that of the savanna. In this region, the cessation of agricultural activities in mango orchards favors the reconstitution of termite communities and presumably the restoration of the ecosystem services provided by termites. Thus it would be possible to combine agriculture and the conservation soil biodiversity.     

Defence-related biochemical changes by elicitor of malformation pathogen,Fusarium mangiferae,in mango

Malformation of mango (Mangifera indica L.) induced by Fusarium moniliforme var. subglutinans is a plant disease of international importance. The paper reports the downstream defence responses at the initial stage in a susceptible host (cultivar Amrapali) after treatment with biotic (isolated from the pathogen cell wall) (BEL) and abiotic (salicylic acid, SA) elicitors, and inoculation of vegetative buds with the pathogen (IVB). The SA was further tested to induce resistance in field trials. The inoculation and application of elicitors increased β-1, 3 glucanase that causes lysis of fungal hyphae by many folds. Hydrogen peroxide (H₂O₂) (active oxygen species) that induces hypersensitive cell death was reduced to the minimum level after treatment with BEL. The reduction of H₂O₂ in the inoculated vegetative buds was also substantial; however, comparatively less with SA treatment. Consequently, there was no hypersensitive cell death in the malformed mango. Salicylic acid that enhances H₂O₂ content by suppressing H₂O₂-degradation by catalase, increased marginally with the SA treatment and in the IVB, but reduced with the BEL. The reduction of SA in BEL-treated buds concomitantly reduced its H₂O₂ content. The activity of catalase, suppressor of resistance mechanism, was reduced in all the treatments, but the reduction was not enough to arrest H₂O₂-degradation. Magiferin (1, 3, 6, 7-tetrahdroxyxanthone C₂-β-D glucoside), a defence metabolite of mango, increased substantially in all the treatments; maximum with the BEL. A pathogenesis-related (PR) protein of 20 KDa that resists symptom development appeared in all the treatments except the control. But light colour of the spots for the PR-protein indicated low protein accumulation. The maximum accumulation was with the IVB followed by SA and BEL treatments. The amount of total protein reduced considerably in all the treatments. The SA treatment on healthy plants failed to induce defence against malformation. Contrarily, the treatment on malformed seedlings restored normal growth within two months. Hence, SA acted better over the infected plants in presence of the pathogen. Thus, a signal transduction system involving SA and H₂O₂ remained nonfunctional and enough defence chemicals could not be synthesised. Defence genes that produce phenolic and β-1, 3 glucanase, however, became activated and saved the plants from death although could not prevent symptom manifestations.     

Species composition and population dynamics of thrips (Thysanoptera) in mango orchards of northern peninsular Malaysia

Thrips are key pests of mango, Mangifera indica (L.), in Malaysia, including the Northern Peninsular. As Penang has year-round equatorial climate and high of rainfall, the populations of thrips may be subject to variations in composition and size. With a goal of developing an appropriate control strategy, a survey was conducted in Penang to determine species composition and abundance in relation to some environmental factors. Sprayed and unsprayed orchards were sampled on weekly basis through two flowering seasons of 2009 using CO(2) collection technique. Larval population falling into the ground to pupate and adults emerging from the soil were investigated in both orchards. Thrips hawaiiensis (Morgan) and Scirtothrips dorsalis (Hood) were the most prevalent species in the sprayed and the unsprayed orchards, respectively. The abundance of thrips was high during the flowering period of the dry season and decreased during the flowering period of the rainy season. This latter period coincided with decreased temperature and increased relative humidity. Percentage of adult emergence from the soil was lower in the rainy season than recorded in the dry season in both orchards. Taken together, these observations suggest that T. hawaiiensis and S. dorsalis are the main thrips species pests of mango panicles in Penang. Direct control with insecticides focusing on these two species may help to reduce cosmetic injuries and other damages on mango fruits.     

Attraction of the West Indian fruit fly to mango fruit volatiles

In this study, we investigated the attraction of West Indian fruit fly, Anastrepha obliqua (Macquart) (Diptera: Tephritidae), to volatiles of three mango [Mangifera indica L. (Anacardiaceae)] cultivars in field cage tests. The number of flies captured with Multilure traps baited with Amate mature green mangoes was significantly higher than that captured in traps baited with Coche and Ataulfo fruits. There was no significant difference between the number of flies captured in traps baited with Coche or Ataulfo mangoes. Gas chromatography‐mass spectrometry analysis of mango fruit volatiles identified 24, 22, and 19 compounds for Amate, Ataulfo, and Coche mango cultivars, respectively. A principal component analysis of the volatiles revealed that the Amate mango was more distant from the Ataulfo mango, and the latter cultivar was closer to the Coche mango. The compounds myrcene, α‐pinene, β‐selinene, and trans‐β‐ocimene were the most abundant in Amate mangoes, whereas 3‐carene, β‐selinene, terpinolene, and α‐pinene were the predominant compounds of Ataulfo cultivars. In the Coche mango, the predominant compounds were 3‐carene, β‐selinene, terpinolene, and limonene. Traps baited with a blend of myrcene, α‐pinene, and trans‐β‐ocimene captured more A. obliqua females and males than control traps. Flies were more attracted to the Super Q volatile extracts of Amate mango than to the three‐component blend formulated in a ratio of 1:1:1. However, there was no significant difference between the number of flies caught by traps baited with Amate mango extracts and that caught by traps baited with the three‐blend component when this was formulated according to the relative proportions in the mango extracts. Traps baited with myrcene, the major component, caught fewer flies than traps baited with Amate mango extracts.     

flg22诱导的拟南芥转录组分析及芥子油苷代谢途径的变化

flg22是细菌鞭毛蛋白N端的一段保守性极高的区域,能够诱导植物天然的免疫反应,为全面了解植物在受到细菌性病原菌侵害后的系统响应,利用Illumina Hiseq2000对flg22处理和未处理的拟南芥幼苗进行转录组测序。对两组数据进行差异表达分析,共获得1 200个差异表达基因,包括290个下调基因和910个上调基因。对差异表达基因进行GO富集分析和KEGG pathway富集分析,结果显示,flg22处理后,拟南芥在能量代谢、氨基酸代谢及次生代谢产物的生物合成等方面产生了巨大变化。芥子油苷是一类在植物防御病原菌的天然免疫反应中起重要作用的次生代谢产物,因此对芥子油苷代谢途径的变化进行了深入分析。根据测序结果,Flg22处理后吲哚族芥子油苷合成途径的基因表达水平显著提高,而脂肪族芥子油苷代谢途径几乎没有变化,进一步对吲哚族芥子油苷合成途径的关键酶基因进行Real Time RT-PCR的分析,验证了测序结果的正确性,证明了吲哚族芥子油苷在植物抗病防御反应中的重要作用。这为深入理解病原菌诱导的植物防御性反应及吲哚族芥子油苷的抗病机制提供了大量参考数据。     

Role of hydrogen peroxide and ascorbate-glutathione pathway in host resistance to bacterial wilt of eggplant

Ralstonia solanacearum, a soil-borne bacterium causes bacterial wilt, is a lethal disease of eggplant (Solanum melongena L.). However, the first line of defense mechanism of R. solanacearum infection remains unclear. The present study focused on the role of induced H₂O₂, defense-related enzymes of ascorbate-glutathione pathway variations in resistant and susceptible cultivars of eggplant under biotic stress. Fifteen cultivars of eggplant were screened for bacterial wilt resistance, and the concentration of antioxidant enzymes were estimated upon infection with R. solanacearum. A quantitative real-time PCR was also carried out to study the expression of defense genes. The concentration of H₂O₂ in the pathogen inoculated seedlings was two folds higher at 12 h after pathogen inoculation compared to control. Antioxidant enzymes of ascorbate-glutathione pathway were rapidly increased in resistant cultivars followed by susceptible and highly susceptible cultivars upon pathogen inoculation. The enzyme activity of ascorbate-glutathione pathway correlates by amplification of their defense genes along with pathogenesis-related protein-1a (PR-1a). The expressions of defense genes increased 2.5?3.5 folds in resistant eggplant cultivars after pathogen inoculation. The biochemical and molecular markers provided an insight to understand the first line of defense responses in eggplant cultivars upon inoculation with the pathogen.     

Three types of defense-responsive genes are involved in resistance to bacterial blight and fungal blast diseases in rice

Bacterial blight and fungal blast diseases of rice, caused by Xanthomonas oryzae pv. oryzae and Pyricularia grisea Sacc., respectively, are two of the most devastating diseases in rice worldwide. To study the defense responses to infection with each of these pathogens, expression profiling of 12 defense-responsive genes was performed using near-isogenic rice lines that are resistant or susceptible to bacterial blight and fungal blast, respectively, and rice cultivars that are resistant or susceptible to both pathogens. All 12 genes showed constitutive expression, but expression levels increased in response to infection. Based on their expression patterns in 12 host-pathogen combinations, these genes could be classified into three types, pathogen non-specific (6), pathogen specific but race non-specific (4) and race specific (2). Most of the 12 genes were only responsive during incompatible interactions. These results suggest that bacterial blight and fungal blast resistances share common pathway(s), but are also regulated by different defense pathways in rice. Activation of the corresponding R gene is the key step that initiates the action of these genes in defense responses. The chromosomal locations and pathogen specificities of seven of the 12 genes were consistent with those of previously identified quantitative trait loci for rice disease resistance, which indicates that some of the 12 genes studied may have a phenotypic impact on disease resistance in rice.     

Seasonal abundance and spatial distribution of larval and adult thrips (Thysanoptera) on weed host plants in mango orchards in Penang,Malaysia

The spatial distribution of larval and adult thrips (Thysanoptera) was studied on mango panicles, Mangifera indica L., on Penang Island, Malaysia, during two consecutive mango flowering seasons from December 2008 to March 2009 and from August to September 2009. Larval and adult thrips were sampled from mango panicles using the carbon dioxide (CO₂) collection technique weekly in treated and untreated orchards. Seasonal abundance and dispersion pattern of thrips were investigated on weed host plants in the treated orchard between June 2008 and March 2009. Spatiotemporal dynamics of larvae and adults was analyzed using Taylor’s Power Law (TPL), Lloyd’s Index (LI), and Green’s Index (GI). Thrips hawaiiensis (Morgan) was the dominant thrips species recovered from mango panicles and weeds in the treated orchard, whereas Scirtothrips dorsalis (Hood) was the most abundant species captured in the untreated orchard. Thrips adults and larvae analyzed via dispersion indices were found to be aggregated in mango panicles in both orchards. The value of the aggregation index (b) of TPL for the total number of adult thrips was significantly higher in the treated orchard than in the untreated orchard, whereas slopes of TPL for the total number of larval thrips did not differ significantly between treated and untreated orchards. All adult thrips species were distributed regularly on the weed plants; however, their larvae were aggregated. It is concluded that pesticide treatment caused adult thrips to become more aggregated on mango panicles, hiding in flower parts that were less exposed to the chemicals.     

2D-DIGE analysis of mango (Mangifera indica L.) fruit reveals major proteomic changes associated with ripening

A comparative proteomic investigation between the pre-climacteric and climacteric mango fruits (cv. Keitt) was performed to identify protein species with variable abundance during ripening. Proteins were phenol-extracted from fruits, cyanine-dye-labeled, and separated on 2D gels at pH 4-7. Total spot count of about 373 proteins spots was detected in each gel and forty-seven were consistently different between pre-climacteric and climacteric fruits and were subjected to LC-MS/MS analysis. Functional classification revealed that protein species involved in carbon fixation and hormone biosynthesis decreased during ripening, whereas those related to catabolism and the stress-response, including oxidative stress and abiotic and pathogen defense factors, accumulated. In relation to fruit quality, protein species putatively involved in color development and pulp softening were also identified. This study on mango proteomics provides an overview of the biological processes that occur during ripening.     

Carbon and water footprints of Brazilian mango produced in the semiarid region

Purpose

Awareness regarding carbon and water footprint has gained visibility, encouraging actions towards compliance with the main available standards by fruit producers. This study presents the carbon and water footprint of packed mango produced in Vale do São Francisco, the main irrigated valley in Brazil. It provides an approach to identify the critical processes and opportunities for improvements in the conventional crop system that may support producers in the task of developing future site-specific assessments.

Methods

This assessment followed ISO 14046 and ISO 14067 for water and carbon footprints, respectively, as well as specific requirements of product category rule (PCR) 013 for fruits and nuts and Publicly Available Specification (PAS) 2051-1 for horticulture products. Primary data was collected for nursery (seedling), land use change, crop production, and packaging, considering five exported mango varieties: Palmer, Keitt, Kent, Haden, and Tommy Atkins. The carbon footprint assessment was based on the impact category climate change, while water footprint encompassed the following categories: water scarcity, marine and freshwater eutrophication, human toxicity (carcinogenic and non-carcinogenic), and freshwater ecotoxicity. The footprint analysis was performed for 1 kg of packed mango.

Results and discussion

The three main processes responsible for both footprints were related to crop production: fertilizer and electricity production as well as mango cropping. Moving from Caatinga vegetation to mango orchards increased carbon storage but was not enough to offset the impact on climate change. For water footprint, it was observed that the total volume of applied irrigation water was already below technical requirements and cannot be reduced, the same occurring for nitrogen fertilization. Scenario analysis showed that the use of alternative electricity sources and the reuse of wastewater brought no major improvement in results. Furthermore, the choice of local or country level characterization factors for water scarcity changed results significantly. Discussions are made regarding (i) the relevance of mango footprints when compared to other irrigated fruits, (ii) possibilities for improving mango footprint performance, (iii) the need for updating product category rules for fruits, and (iv) the quality of provided inventories and results.

Conclusions

The comparison of mango footprints with previous studies of irrigated fruits showed that mango performance is similar or better than many irrigated fruits, cultivated all over the world. Moreover, footprints may be further reduced if mango orchards are established in previously deforested land or areas occupied with annual crops and if improvements are made in the irrigation and fertilization practices at each mango production stage.

     

A model for estimating infection levels of anthracnose disease of mango

Anthracnose disease of mango caused by Colletotrichum gloeosporioides var. minor, spreads by water-borne conidia from vegetative parts of the tree to attack inflorescences and prevent fruit set. An analysis of data from laboratory studies demonstrated that infection by conidia during wet periods was related both to the temperature and to the duration of the wet period. A model was used to estimate infection levels of anthracnose disease in two mango orchards over three seasons. The number of infection periods recorded and the estimated percentage of conidia forming appressoria in these periods matched disease development during flush growth and flowering. In 1980, only two infection periods were detected during flowering in one of these orchards and blossom blight did not prevent fruit set. In 1981 and 1982 however, higher estimated levels of infection were recorded more frequently during the same time and severe blossom blight developed. A second orchard, situated in an area less favourable to disease, was also monitored during 1982. Nine infection periods were recorded during flowering in this orchard compared to 14 in the first. A moderate level of blossom blight developed in this orchard.