Effects of hot water treatments and storage temperatures on the ripening and the use of electrical impedance as an index for assessing post-harvest changes in mango fruits

The effects of hot water treatment and storage temperature (4°C, 13°C or 22°C) on the quality and impedance of outer and inner mesocarp of mango were assessed in two experiments during storage, impedance being a potential non‐destructive measure of tissue damage following heat treatment. Fruits were subjected to equivalent heat units at 36.5°C for 60 min plus 46.5°C for 43 min or 46.5°C for 90 min by hot water treatments (hwt) on the assumption of cumulative heat effects and a base temperature of 12–13°C. Fruit reflectance decreased whereas chroma and hue angle increased over storage time and also with increase in storage temperature. The yellow colour increased with a rise in storage temperature in hot water treated mangoes. Soluble solids content of mangoes held at 22°C was highest at 5 days of storage but decreased subsequently over storage time. Impedance of all fruits decreased with increase in frequency, storage temperature and time in store. The impedance of hwt mangoes was lower than that of non‐hwt fruits 8 h after immersion, but recovered almost to control levels on day 5 at 4°C or 13°C, but decreased gradually after 5 days at 13°C. Impedance of all mangoes stored at 22°C decreased continuously during storage. Impedance was higher in the inner mesocarp than outer pulp. Impedance of hwt fruits was poorly correlated with soluble solid content and chroma but well correlated with reflectance of fruit pulp at 22°C. Changes in impedance of mangoes are discussed in relation to physiological and biochemical changes that occur during heat treatment and storage.     

杧果采后生理研究

适期采收的果．采收时呼吸速率为２３．２ｍｇＣＯ２·ｋｇ（－１）ｈ（－１）果皮深绿色．果肉硬度＞３０Ｐ／ｃｍ２．置室温下（３０℃）８ｄ出现呼吸高峰,速率１３２．９ｍｇＣＯ２·ｋｇ（－１）ｈ（－１）,果皮的颜色黄绿各半．果肉硬度８—９Ｐ／ｃｍ２。采后１２—１４ｄ果实达到完熟,果皮金黄色,硬度＜３Ｐ／ｃｍ２,呼吸速率下降到３９—４５ｍｇＣＯ２·ｋｇ（－１）ｈ（－１）。试验结果还表明．可溶性糖、还原糖、非还原糖、固形物等含量．均在采后第５天明显增高,果皮从深绿转为淡绿色。可溶性糖在采后第１４天增至最高．达９．９２％,此时可滴定酸度下降至０．１４％．ＰＨ值升至６．１５,此时为果实的最佳供食状态．生产上可据此为制定果贮藏措施提供依据．     

芒果生长素反应因子类蛋白的cDNA克隆和表达

通过SSH法获得了一个与不定根形成相关的差异表达的cDNA片段,其推导的氨基酸序列与拟南芥的生长素反应因子(ARF)类蛋白具有较大的同源性,因此将它命名为MiARF。用所设计的基因特异引物进行3′RACE扩增获得包含完整读码框架(ORF)的MiARF1（GenBank登录号为AY255705）和MiARF2（GenBank登录号为AY300808）。MiARF1全长为3272bp,其中,ORF含2523bp,5′非翻译区（5′UTR）含285bp, 3′非翻译区(3′UTR)含464bp。由该序列所推导的氨基酸序列与拟南芥ARF2（BAB10162）的ID值为64%, E值为0,在DNA结合区域（DBD）、III和IV区域的同源性更高,ID值均大于80%。MiARF2cDNA全长为1474bp,其中ORF含981bp,5′非翻译区含285bp, 3′非翻译区含208bp,由该序列所推导的氨基酸序列与拟南芥ARF2（BAB10162）的ID值为84%,E值为e-151。 MiARF2仅具有DBD保守区并与MiARF1的基本相同,但缺乏III和IV区域。Virtural Northern 杂交表明：MiARF2在生根的组织中表达水平高, 而在非生根的组织中未见表达;MiARF1在生根及非生根的组织中均有表达。     

Direct somatic embryogenesis induced from cotyledons of mango immature zygotic embryos

Summary For the first time, regenerated plantlets were obtained from immature zygotic embryos of mango (Mangifera indica L.) through direct somatic embryogenesis. Pro-embryogenic mass (PEM)-like structures, which are differentiated as clusters of globular structures, were easily induced directly from the abaxial side of cotyledons from immature fruits, 2.0–3.5 cm diameter by a 2-wk culture period on a modified Murashige and Skoog medium with 5 mgl⁻¹ (25μM) indole-3-butyric acid (IBA). Conversion of somatic embryos into plantlets was achieved after 4 wk of culture on the conversion medium containing 5mgl⁻¹ (23 μM) kinetin. Secondary somatic embryogenesis could also be obtained directly from the hypocotyls of mature primary somatic embryos cultured on the conversion medium. In our experimental system, only minor problems were noted with browning of cultures.     

Assessing allometric models to predict vegetative growth of mango (Mangifera indica; Anacardiaceae) at the current-year branch scale

? Premise of the study: Accurate and reliable predictive models are necessary to estimate nondestructively key variables for plant growth studies such as leaf area and leaf, stem, and total biomass. Predictive models are lacking at the current-year branch scale despite the importance of this scale in plant science. ? Methods: We calibrated allometric models to estimate leaf area and stem and branch (leaves + stem) mass of current-year branches, i.e., branches several months old studied at the end of the vegetative growth season, of four mango cultivars on the basis of their basal cross-sectional area. The effects of year, site, and cultivar were tested. Models were validated with independent data and prediction accuracy was evaluated with the appropriate statistics. ? Key results: Models revealed a positive allometry between dependent and independent variables, whose y-intercept but not the slope, was affected by the cultivar. The effects of year and site were negligible. For each branch characteristic, cultivar-specific models were more accurate than common models built with pooled data from the four cultivars. Prediction quality was satisfactory but with data dispersion around the models, particularly for large values. ? Conclusions: Leaf area and stem and branch mass of mango current-year branches could be satisfactorily estimated on the basis of branch basal cross-sectional area with cultivar-specific allometric models. The results suggested that, in addition to the heteroscedastic behavior of the variables studied, model accuracy was probably related to the functional plasticity of branches in relation to the light environment and/or to the number of growth units composing the branches.     

芒果叶化学成分研究 II

为探讨芒果(Mangifera indica L.)的化学成分,从芒果叶的70%乙醇提取物中分离鉴定了13个化合物,经波谱分析,分别鉴定为:(–)-secoisolariciresinol-9′-O-D-glucopyranoside(1)、7S,8R-erythro-4,7,9-trihydroxy-3,3′-dimethoxy-8-O-4′-neolignan-9′-O-β-D-glucopyranoside(2)、7R,8R-threo-4,7,9-trihydroxy-3,3′-dimethoxy-8-O-4′-neolignan-9′-O-β-D-glucopyranoside(3)、(7R/S,8R)-7,8-dihydro-9′-hydroxyl-3′-methoxyl-8-hydroxymethyl-7-(4-hydroxy-3-methoxyphenyl)-1′-benzofuranpropanol 9′-O-β-D-glucopyranoside(4)、citrusin D(5)、丁香苷(6)、2,6-二甲氧基-4-羟基苯基-1-O-β-D-葡萄糖苷(7)、原儿茶酸(8)、没食子酸(9)、没食子酸甲酯(10)、没食子酸乙酯(11)、4,5-二羟基-3-甲氧基苯甲酸(12)、β-胡萝卜苷(13)。其中化合物1～7和12为首次从芒果属植物中分离得到。     

RAPD analysis of Fusarium Isolates Causing “Mango Malformation” Disease in Pakistan

Mango Malformation (MM) disease is a major constraint to mango production. A total of 20 Fusarium isolates from MM-affected mango plants were collected from 14 locations in Pakistan and assessed for genetic diversity using the random amplified polymorphic DNA (RAPD) technique. A total of 393 fragments were amplified after screening with 50 random primers. The amplifications with 45 primers identified scoreable polymorphisms among the isolates. A genetic similarity matrix based on Nei and Li’s index determined coefficients ranging from 46.46% to 92.51%. These coefficients were used to construct a dendrogram using the UPGMA algorithm. The isolates grouped into two main clusters, comprising 13 and 7 isolates respectively, at a genetic relatedness of 52%. Within the clusters, Fusarium isolates were not necessarily related either by geographic origin or by the mango cultivar from which they were isolated. RAPD proved a reproducible and tractable means of differentiating Fusarium isolates. These findings also suggest that some infections originate not from adjacent plants within an orchard but from geographically distant areas; indicating that most probably infection occurs in nurseries prior to plants being transported around the country for subsequent cultivation, and that improved plant hygiene could significantly curb MM infection and spread.     

Effects of a natural extract from Mangifera indica L,and its active compound,mangiferin, on energy state and lipid peroxidation of red blood cells

Following oxidative stress, modifications of several biologically important macromolecules have been demonstrated. In this study we investigated the effect of a natural extract from Mangifera indica L (Vimang), its main ingredient mangiferin and epigallocatechin gallate (EGCG) on energy metabolism, energy state and malondialdehyde (MDA) production in a red blood cell system. Analysis of MDA, high energy phosphates and ascorbate was carried out by high performance liquid chromatography (HPLC). Under the experimental conditions, concentrations of MDA and ATP catabolites were affected in a dose-dependent way by H₂O₂. Incubation with Vimang (0.1, 1, 10, 50 and 100 μg/mL), mangiferin (1, 10, 100 μg/mL) and EGCG (0.01, 0.1, 1, 10 μM) significantly enhances erythrocyte resistance to H₂O₂-induced reactive oxygen species production. In particular, we demonstrate the protective activity of these compounds on ATP, GTP and total nucleotides (NT) depletion after H₂O₂-induced damage and a reduction of NAD and ADP, which both increase because of the energy consumption following H₂O₂ addition. Energy charge potential, decreased in H₂O₂-treated erythrocytes, was also restored in a dose-dependent way by these substances. Their protective effects might be related to the strong free radical scavenging ability described for polyphenols.     

Analysis of diversity and relationships among mango cultivars using Start Codon Targeted (SCoT) markers

Genetic variation and relationships among 47 mango germplasm and 3 relative species from Guangxi province in China, were analyzed using Start Codon Targeted (SCoT) markers. Using 33 selected SCoT primers 273 bands were generated with an average of 8.27 bands per primer among the 50 accessions, of which 208 (76.19%) were polymorphic. Genetic relationships estimated using the SM similarity coefficient generated values between different pairs of accessions that varied from 0.531 to 0.923 with an average of 0.782. These coefficients were utilized to construct a dendrogram using the UPGMA. All 50 accessions were basically classified into six clusters and correspond well with their recorded pedigrees. The results will provide much more useful information for the management of germplasm and will also be useful to improve the current breeding strategies. The results also demonstrate that the SCoT marker system is useful for identification and genetic diversity analysis of mango cultivars.     

渗透胁迫对杧果叶片活性氧伤害的影响

杧果叶片经渗透胁迫处理后,叶水势Ψ_L下降,O₂^·产生速率和MDA含量增加,SOD、POD和CAT的活性水平与O₂^·和MDA的变化相一致。结果表明,杧果叶片的渗透胁迫损伤,是由O₂^·引发的膜脂过氧化,致使MDA含量增加,破坏细胞膜系统所致。渗透胁迫处理过程中,GSH和AsA含量下降。