成熟和褐变荔枝果实呼吸作用和脂氧合酶活性

荔枝果实完全成熟和果皮变鮮红时,呼吸速率降低,仅相当于果皮带绿时的39.4％。此时果皮和果肉的脂氧合酶活性亦明显降低,分别相当于后者的60.2％和49.1％。成熟荔枝果实果皮呼吸作用对KCN抑制敏感。2mM KCN抑制果皮总呼吸的91.8％,而仅抑制果肉的56.9％。荔枝果皮呼吸的电了传递主要是通过细胞色素氧化酶途径,而果肉則可能一半是通过其它氧化酶途径。2mKCN和1.5mM SHAM抑制成熟果皮总呼吸97.9％,为SHAM抑制的交替途径呼吸占总呼吸5.28％。相同浓度KCN和SHAM抑制褐变果皮总呼吸79.7％,则SHAM抑制的交替途径呼吸占27.1％。果实褐变时,果成交替途径呼吸比例增高。这一变化可能促进H_2O_2积累、乙烯产生和果皮褐变深化。     

防止速冻荔枝果皮变褐的研究

荔枝(Litchi chinensis Sonn.)果实采收后容易变褐变质。三年来,我们研究了荔枝果皮的多酚氧化酶与变褐的关系以及防止速冻荔枝果皮变褐的各种枝术措施。证明:荔枝果皮中具有氧化邻苯二酚的多酚氧化酶,在果皮褐变过程中该酶起着重要的作用,采用热处理及化学药物处理能抑制多酚氧化酶活性,达到防止速冻荔枝果皮变褐的目的。     

荔枝果皮结构与果实贮藏性能关系的探讨

在荔枝淮枝品种果实贮藏中进行单果失重率的测定,并通过扫描电子显微镜对鲜果、褐变果、霉变果的果皮进行显微结构的观察,发现荔枝果实外果皮细胞形态结构特殊,向外突出成半球形并和栅状组织一样极易破损失水而加速果皮的褐变。褐变前、霉变前后果实失重率大。电镜下观察霉变果实表面布满着酵母和其它菌体,真菌菌丝侵入果皮内生长繁殖,破坏栅状组织等,是导致果实迅速霉烂的原因之一     

龙眼果实采后失水果皮褐变与活性氧及酚类代谢的关系

研究了(10±1)℃和50%相对湿度贮藏条件下"福眼"龙眼果实果皮褐变与活性氧和酚类代谢的关系.结果表明,采后失水导致龙眼果实果皮褐变,果皮活性氧清除酶SOD、CAT、APX、GR活性和内源抗氧化物质AsA、GSH含量下降,O-2产生速率和MDA含量增加,细胞膜透性迅速增大;PPO和POD活性增加,总酚和类黄酮含量明显下降.据此认为,果皮褐变可能是细胞的活性氧代谢失调,细胞膜结构破坏,使PPO、POD与酚类物质(含类黄酮)接触、酚类物质氧化的结果.     

O2和CO2配比对气调贮藏梨采后褐变及相关理化因子的影响

以采后'丰水'梨果实为材料,在乐扣气调试验箱中研究了O2和CO2配比对果实褐变率、多酚氧化酶(PPO)和过氧化物酶(POD)活性、丙二醛(MDA)和总酚含量的影响,以探讨适宜减轻梨气藏褐变的气体成份.结果表明:在整个贮藏过程(150 d)中,'丰水'梨果肉未发生褐变.从贮藏60 d开始,气调处理和冷藏对照果实的果皮均出现褐变,气调处理在贮藏120 d之前对果皮褐变的影响不显著,而在贮藏120～150 d内可显著减轻果皮的褐变、抑制果皮PPO和POD活性及降低总酚含量.与冷藏对照相比,气调处理可推迟果心褐变的时间,且(8%～10%)O2+3% CO2处理可完全抑制果心的褐变;气调处理亦可降低果心PPO活性、减少总酚及MDA含量;(8%～10%)O2+1% CO2处理能够显著提高果心的POD活性,而(8%～10%)O2+3% CO2处理对果实POD活性的影响不显著.可见,气调贮藏主要是通过降低'丰水'梨果皮PPO、POD活性及总酚含量来减轻组织的褐变,并以(8%～10%)O2+3% CO2处理对果实褐变因子的控制效果较理想.     

荔枝果皮过氧化酶的纯化与性质研究(英)

荔枝果皮采后褐变是影响这一重要热带水果经济价值的主要问题,酚类物质的酶促氧化一直被认为是造成植物组织褐变的关键因素,其中多酚氧化酶被研究得最多.过氧化物酶在植物体中分布很广,能够氧化多种底物,在荔枝果皮中的含量也很高.非结合性过氧化物酶已经被证明在果实的采后成熟与老化过程中参与多种过程.在这项研究中,用磷酸缓冲液提取荔枝果皮的非结合性过氧化物酶,并通过硫酸铵沉淀,DEAE Sephadex A-50离子交换柱层析以及Sephadex G-100凝胶过滤进行纯化.对得到的酶溶液进行了酶学性质的研究,发现荔枝果皮过氧化物酶具有较高的热稳定性和高的最适反应pH值（6.8）,能够氧化许多底物尤其是单酚和各种多酚类物质,反应抑制剂专一性与其他植物来源的过氧化物酶略有不同.显示了过氧化物酶参与荔枝果皮褐变过程的可能性,并为提高荔枝采后贮藏性提供了新的思路.     

荔枝果皮过氧化酶的纯化与性质研究

荔枝果皮采后褐变是影响这一重要热带水果经济价值的主要问题,酚类物质的酶促氧化一直被认为是造成植物组织褐变的关键因素,其中多酚氧化酶被研究得最多.过氧化物酶在植物体中分布很广,能够氧化多种底物,在荔枝果皮中的含量也很高.非结合性过氧化物酶已经被证明在果实的采后成熟与老化过程中参与多种过程.在这项研究中,用磷酸缓冲液提取荔枝果皮的非结合性过氧化物酶,并通过硫酸铵沉淀,DEAFSephadex A-50离子交换柱层析以及Sephadex G-100凝胶过滤进行纯化.对得到的酶溶液进行了酶学性质的研究,发现荔枝果皮过氧化物酶具有较高的热稳定性和高的最适反应pH值(6.8),能够氧化许多底物尤其是单酚和各种多酚类物质,反应抑制剂专一性与其他植物来源的过氧化物酶略有不同显示了过氧化物酶参与荔枝果皮褐变过程的可能性,并为提高荔枝采后贮藏性提供了新的思路.     

易褐变材料荔枝果皮透射电镜制样固定方法的改进

荔枝果皮组织在切块固定过程中 ,快速褐变引起细胞超微结构变化。用戊二醛固定剂固定也无法终止褐变反应。如在戊二醛液中添加 0 .5 %抗坏血酸 ,即可有效地克服褐变反应 ,因而固定的样品能更好地保持原有的结构。     

拟茎点霉侵染对采后龙眼果皮LOX活性和膜脂脂肪酸组分的影响

用拟茎点霉(Phomopsis longanae Chi)侵染福眼龙眼(Dimocarpus longan Lour. ‘Fuyan’)果实,研究龙眼果皮脂氧合酶(LOX)活性、膜脂脂肪酸组分和细胞膜透性的变化及其与果皮褐变的关系。结果表明：拟茎点霉侵染导致龙眼果皮褐变指数、LOX活性和细胞膜透性增加,不饱和脂肪酸组分[亚油酸(C18∶2)、亚麻酸(C18∶3)和花生一烯酸(C20∶1)]下降而饱和脂肪酸组分[棕榈酸(C16∶0)和硬脂酸(C18∶0)]增加,脂肪酸不饱和指数(IUFA)和脂肪酸不饱和度下降。拟茎点霉侵染提高龙眼果皮LOX活性和加速膜脂不饱和脂肪酸的降解,从而破坏细胞膜系统的完整性,导致膜系统区室化功能丧失,使多酚氧化酶与酚类物质接触,引起酚类物质的酶促氧化和黑褐色高聚物形成,导致龙眼果皮褐变。     

2,4-二硝基苯酚对采后龙眼果皮脂氧合酶活性和膜脂脂肪酸组分的影响

以'福眼'龙眼(Dimocarpus longan Lour.'Fuyan')果实为材料,研究呼吸解偶联剂2,4-二硝基苯酚(DNP)对采后果皮脂氧合酶(LOX)活性、膜脂脂肪酸组分和细胞膜透性的影响及其与果皮褐变的关系.结果表明:DNP处理导致龙眼果皮细胞膜透性、LOX活性和褐变指数增加,膜脂脂肪酸组分中的棕榈酸(C16:0)、硬脂酸(C18:0)等饱和 脂肪酸的组分增加,亚油酸(C18:2)、亚麻酸(C18:3)和花生一烯酸(C20:1)等不饱和脂肪酸的组分下降,脂肪酸不饱和指数和脂肪酸不饱和度下降.因此认为,DNP促进了龙眼果实果皮褐变可能是由于提高了LOX活性,促进了膜脂不饱和脂肪酸的降解而引起膜系统完整性受损,最终导致细胞膜结构的破坏,使酚酶与酚类物质接触而引起酚类物质氧化的结果.     

Inadequate pollination services limit watermelon yields in northern Tanzania

Insect pollination plays a vital role for the yield of many crops, such as apples, strawberries and coffee, which are economically significant commodities on the global market. Yet, knowledge about the role of insect pollination is lacking for many cash crops that support the livelihoods of small-scale farmers in developing countries.To assess if yields of watermelon are pollen limited, we conducted a supplemental hand-pollinated experiment (using a pollen mixture of cross and self-pollen) in 13 small-scale farms in an agricultural landscape in the Kilimanjaro and Arusha regions in northern Tanzania. We assessed fruit set, fruit abortion and weight of the mature fruits stemming from hand pollinated and control flowers. To check if differences in yield responses between hand-pollinated and control treatments depended on resource availability, we also accounted for local soil conditions.We found that hand pollination (i) increased the probability of fruit initiation by 30%, (ii) reduced the probability of fruit abortion by 13%, (iii) increased the probability of flowers developing into mature fruits by 42% and (iv) increased average fruit weight by 1.3 kg (±0.15 SE). Our results indicate that our system is pollen limited, due to insufficient visitor frequency and/or inefficient pollinator species.Fruit initiation and fruit weight were positively related to soil carbon, irrespective of treatment. The influence of soil moisture was not consistent across the measured responses, and differed between hand-pollinated and the control treatments.We suggest that farmers in our focal area should focus on improving the quality of the landscape to sustain and enhance healthy pollinator communities ultimately improving yields. We also suggest that farmers should continue current practices with respect to fertilization. The role of soil moisture on fruit initiation and maturation should be investigated to ensure that the positive effects of pollen is not hindered by soil moisture conditions.     

Facultative ripening in Hamelia patens (Rubiaceae): effects of fruit removal and rotting

Summary In Costa Rica individual Hamelia patens trees produce fruit throughout the year and experience dramatic changes in rates of fruit removal and rotting. During some moths, most fruits rot because they are not removed. Rotting fruits increase the probability that other fruits on the same infructescence will rot. When removal rates are high, fruits are taken as soon as their seeds become viable but before the fruit is completely ripe. Experimental removal of fruits produced significantly higher ripening rates than on control infructescences. This response allows Hamelia to ripen more fruit and increase the number of fruits taken when dispersers are abundant (e.g., during migration). The proximate mechanism of this response probably includes reallocation of energy conserved when partially ripe fruits are removed. Responding to fluctuating disperser populations likely increases dispersal success and may function as the ultimate cause.     

Expression of the <Emphasis Type="Italic">ipt</Emphasis> Gene with the AGPase S1 Promoter in Tomato Results in Unbranched Roots and Delayed Leaf Senescence

Transgenic tomato plants were produced with the isopentenyl transferase gene (ipt) ligated to a promoter that is active exclusively in sink tissue. Initially, transgenic plants had smaller, round-scale leaves, swollen stems, and exhibited early development of lateral shoots compared to wild type. Expression of the ipt gene resulted in the formation of unbranched roots on cuttings and delayed senescence in excised leaves. Callus and root formation occurred on excised leaves and leaf discs during dark incubation. The retention percentage of chlorophyll, as well as cytokinin in excised leaves or discs was significantly greater than wild type. Transgenic tomato fruit had elevated levels of cytokinins in the first days after fruit set and these levels were maintained longer during fruit development.     

塔里木沙拐枣果实刺毛对果实扩散及萌发的影响

塔里木沙拐枣（Calligonum roborowskii A.Los.）是仅分布于我国西北地区荒漠环境的特有种,其果实为不开裂而周围有椭圆形刺毛的瘦果,以果实为单元进行扩散和萌发。本文采用野外观察与室内控制实验相结合的方法,对塔里木沙拐枣刺毛在果实扩散、吸水、脱水及萌发中的作用进行研究。结果显示：不同贮藏时间的果实颜色、大小、重量及刺毛长度存在显著差异。完整果实在水面漂浮时间及水媒扩散能力比去除刺毛的果实更强。完整果实在1 m/s和4 m/s风速下的扩散距离比无刺毛果实的扩散距离长。10 mmol/L赤霉素（AG₃）及不同干藏时间处理的完整果实与无刺毛果实在20℃/30℃光照和黑暗条件下的萌发率间存在显著差异,其中无刺毛果实的萌发率要高于完整果实的萌发率。室外盆栽实验显示,无刺毛果实的萌发率比完整果实高,说明果实刺毛对果实萌发有抑制作用。研究结果表明果实刺毛对塔里木沙拐枣在塔克拉玛干沙漠边缘荒漠环境中的扩散、萌发及种群更新具有重要的辅助作用。     

Proteomics in the fruit tree science arena: New insights into fruit defense,development, and ripening

Fruit tree crops are agricultural commodities of high economic importance, while fruits also represent one of the most vital components of the human diet. Therefore, a great effort has been made to understand the molecular mechanisms covering fundamental biological processes in fruit tree physiology and fruit biology. Thanks to the development of cutting‐edge “omics” technologies such as proteomic analysis, scientists now have powerful tools to support traditional fruit tree research. Such proteomic analyses are establishing high‐density 2DE reference maps and peptide mass fingerprint databases that can lead fruit science into a new postgenomic research era. Here, an overview of the application of proteomics in key aspects of fruit tree physiology as well as in fruit biology, including defense responses to abiotic and biotic stress factors, is presented. Α panoramic view of ripening‐related proteins is also discussed, as an example of proteomic application in fruit science.     

云南元江干热河谷木本植物的物候

在中国西南干热河谷的典型地段——元江干热河谷,连续3年观测了32种木本植物的枝条生长、叶片动态、花期、果期和果实类型。这些植物的枝条生长方式可以分为连续生长、枝条枯死、陡长和间歇生长4个类型。其中连续生长型占优势,包括13种植物,它们的枝条在雨季连续不断伸长。9种植物雨季的枝条伸长与连续生长型的相似,但它们顶部的枝条在旱季末期出现枯死现象。6种植物属于陡长型,在2周内完成抽枝,且一年只抽一次枝。4种植物属于间歇生长型,枝条在雨季来临后伸长一段时间,然后生长停滞,过一段时间后再接着伸长。从叶片物候类型看,元江干热河谷植被以落叶植物占优势。落叶植物中冷凉旱季（11月～2月）落叶植物占优势（19种）,而干热旱季（3—4月）落叶植物很少（4种）。除红花柴（Indigofera pulchella）和狭叶山黄麻（Trema angustifolia）从雨季中期开始脱落叶片外,其它30种植物从雨季末期开始脱落叶片,落叶期至少延续3个月以上。常绿植物脱落近1／3～1／2的当年生叶片。共有6种植物能在旱季末期长出新叶。常绿植物的叶面积、单个枝条上的总叶面积和枝条承载（总叶面积／枝条长度）比落叶植物小。虽然一年四季都有不同植物开花和结果,但多数植物（29种,占观测树种的91％）的花期集中在旱季和雨季初期,而果实（种子）成熟期从雨季末期延续到旱季末期和下个雨季初期。果实多为核果。     

Does individual variation in fruit profitability override color differences in avian choice of red or white <Emphasis Type="Italic">Ilex serrata</Emphasis> fruits?

Although avian color preferences have been studied and documented in controlled experiments, they have not been demonstrated under natural conditions in most cases. We hypothesized that avian fruit choice reflects intraspecific variation in fruit characteristics other than color, rather than fruit color differences. By planting one Ilex serrata Thunb. (red form) and one I. serrata forma leucocarpa Beissner (white form), which produce red and white fruits, respectively, at each of five points, we examined the proportion of fruits removed per tree and fruit choice by three avian species based on fruit color and other fruit characteristics. The proportion of fruits removed increased with pulpy sugar concentration and fruit diameter, but it did not differ between fruit colors. The main foragers, resident brown-eared bulbuls Hypsypetes amaurotis, consumed fruits regardless of color, but correspondingly to fruit removal, and appeared to base their fruit choice on pulpy sugar concentration and fruit diameter rather than on color. In contrast, the minor foragers, migrant Daurian redstarts Phoenicurus auroreus (Pallas) and Siberian bluechats Tarsiger cyanurus (Pallas), tended to choose red fruits and were possibly attracted by them. In conclusion, fruit removal per tree reflected individual variation in fruit profitability more strongly than differences in fruit color, even though the individual variation was not remarkable. The importance of color in fruit choice differed based on species, residency status, and major/minor foragers.     

中华猕猴桃和毛花猕猴桃果实碳水化合物及维生素Ｃ的动态变化研究

分别对中华猕猴桃（Actinidia chinensis）黄肉品种‘金桃’和毛花猕猴桃（Actinidia eriantha）品系‘6113’果实生长发育过程中碳水化合物及维生素C的动态变化进行了系统研究。结果表明,中华猕猴桃‘金桃’和毛花猕猴桃‘6113’果实的可溶性固形物（SSC）含量均于谢花后146d内保持相对平稳,而后开始上升;此时,两物种果实的淀粉含量均上升到最大值,之后两者均开始下降。两者糖含量的变化与SSC相似,且中华猕猴桃‘金桃’果实糖含量进入快速增长期的时间比毛花猕猴桃‘6113’早1个月。两者果实Vc含量的变化趋势相似,均于7月上中旬达到一个高峰,以后随着果实的生长发育,含量下降,‘金桃’于8月14日降至最低值,‘6113’于9月13日降至最低值;两者的Vc含量降到最低值后均缓慢上升,到果实完全成熟期（树上自然软熟期）回升到第二个峰值。‘6113’果实的Vc含量在完全成熟期的峰值远远高于7月上旬的高峰值。对‘金桃’和‘6113’果实碳水化合物及Vc含量方差分析表明,两者的可溶性固形物、淀粉和总糖没有明显差异,而毛花猕猴桃‘6113’的Vc含量显著高于中华猕猴桃‘金桃’。     

Parthenocarpic fruit set in triploid watermelon induced by CPPUand 2,4-D applications

The localized application of the synthetic cytokinin CPPU ((2-chloro-4-pyridyl)-N-phenyl urea) to ovaries at flower opening was as effective as free pollination in setting parthenocarpic fruit in the triploid watermelon cultivar ‘Reina de Corazones’, and increased yield per unit land area by at least 50%, simply due to the lack of requirement for diploid pollen producing plants within the orchard. The application of the synthetic auxin 2,4-D (2,4-dichlorophenoxy acetic acid) as a full coverage spray, was also effective in setting fruit; total yield was however 10% smaller than in the CPPU-treated plots, but the cost of application was much less expensive. These applications had no adverse effect on fruit quality, and their effectiveness in commercial watermelon production was evaluated over 4 years. Localized applications of 2,4-D to ovaries were less effective in setting fruit, and increased hollow fruit.     

温州蜜柑裂果因子调查初报

通过对1990年温州蜜柑裂果的调查,初步探明了不同品系,不同的基砧、中间砧及砧木高度,树体在园中所处的位置,树体的不同部位、树势,结果枝上的裂果顺序,灌溉条件,气象要素的变化,果实某些指标的差异等因子与裂果的关系。据此,提出防止裂果措施。