寄主植物对荔枝蒂蛀虫产卵的引诱作用

试验观察荔枝蒂蛀虫Conopomorpha sinensisBradley对寄主植物品种、器官及器官部位的产卵选择性规律。结果表明,与老梢相比,荔枝蒂蛀虫明显倾向于选择嫩梢产卵;4个荔枝品种果枝中以妃子笑上落卵数最多,在淮枝、糯米糍荔枝果实上较少,桂味荔枝上最少;不同的荔枝品种果实气味引诱雌虫产卵的能力不同,其中妃子笑引诱力最强,淮枝、糯米糍引诱力较低,桂味最低;在同一荔枝果实不同部位的落卵量,以果皮上、下两部分较大,全果明显低于果皮上部,而荔枝肉和荔枝核上没有落卵。     

荔枝果实发育过程中果皮色素的变化

以妃子笑、糯米糍荔枝为材料,研究了二者果实发育过程中色素形成规律。结果表明：妃子笑、糯米糍果实发育生长曲线均呈单“Ｓ”型;妃子笑果实发育第Ｉ期比糯米糍短７－１０ｄ;二者果实花青苷在发育期第Ｉ、ＩＩ期均有一个合成高峰;妃子笑的花青苷总体水平明显低于糯米糍;妃子笑、糯米糍花青苷合成与叶绿素含量虽不呈显著的相关性,但在果实发育后期花色苷合成迅速上升时,伴随着叶绿素含量的急剧下降;妃子笑、糯米糍的花色苷合成与苯丙氨酸解氨酶（ＰＡＬ）活性变化不存在显著相关性。     

霜疫霉菌侵染对荔枝氧化作用的影响

淮枝、桂味和糯米糍 3种荔枝经接种霜疫霉菌后 ,果皮超氧化物歧化酶 (SOD)和过氧化氢酶 (CAT)活性下降 ;而过氧化氢 (H2 O2 )含量升高 ,超氧阴离子自由基 (O2 .)产生速率增加 ,丙二醛 (MDA)积累增多 ,与果实感病指数增加相一致 ,表明霜疫霉菌侵染加速荔枝氧化作用的进程。实验还表明不同荔枝品种对霜疫霉菌抵抗力与其自由基清除能力有关     

不同品种荔枝对荔枝蒂蛀虫引诱活性成分的研究

首次采用顶空单滴液相微萃取(HS-SDME)结合气质联用(GC-MS)法,对比分析对荔枝蒂蛀虫具有不同引诱力的4个品种荔枝(妃子笑＞黑叶＞糯米糍＞桂味)成熟果实的果皮、幼果的挥发性物质.结果表明:挥发物组成和含量在不同荔枝品种间、同一品种荔枝不同组织间差异显著.2-乙基-1-己醇、α-姜黄烯、姜烯、β-甜没药烯、β-倍半水芹烯及β-杜松烯等6个物质主要存在于易感虫荔枝品种中,(E)-β-金合欢烯与(Z)-β-金合欢烯只存在于妃子笑成熟果实的果皮中,故初步推测这8个化合物按照一定比例复配组合后的混合物,可能是荔枝吸引荔枝蒂蛀虫的活性物质.     

荔枝花蜜分泌规律及可溶性糖组分和含量的分析

为了解荔枝(Litchi chinensis)花蜜的分泌规律和主要组分,对‘糯米糍’、‘桂味’和‘怀枝’3个主栽品种雄花和雌花的花蜜分泌模式进行研究,并测定花蜜中可溶性糖的组分和含量。结果表明,采样期间果园阴天和晴天气温差异不明显,但阴天的相对空气湿度显著高于晴天。总体上阴天的荔枝花蜜分泌量高于晴天,雌花的花蜜分泌量高于雄花,‘桂味’和‘糯米糍’的花蜜分泌量均高于‘怀枝’。晴天花蜜中的可溶性固形物含量高于阴天的,且在雌花中表现尤为明显。‘怀枝’花蜜中的可溶性固形物含量最高,可达37.7%,‘桂味’其次,‘糯米糍’最少(17.7%)。利用高效液相色谱检测,荔枝花蜜中主要可溶性糖组分为葡萄糖、果糖和蔗糖,以葡萄糖含量最高。晴天时‘怀枝’雌花花蜜中可溶性糖含量达450.36μg m L–1,显著高于另外两个品种。这为荔枝栽培和花蜜生产提供科学依据。     

采后荔枝果实冷害过程中多胺含量的变化

以桂味荔枝果实为材料,研究冷害及外源亚精胺(Spd)处理对果实膜透性和内源多胺含量变化的影响。结果表明,在0℃下贮藏时果实发生冷害过程中,荔枝果皮中腐胺(Put)、Spd、精胺(Spm)含量在14d后明显增加,膜透性快速增大,21d时果皮出现明显的冷害褐变,Put进一步积累,而Spm含量下降,Spd保持较高水平。非冷害温度(3℃)下贮藏时,果皮多胺含量变化相对较小。0℃下果肉的多胺含量和变化幅度低于3℃果实,并延迟7d衰老。外源Spd处理明显提高果实内源多胺含量的同时,延缓了果皮相对膜透性增加,减轻了冷害。这表明果皮中Put的积累可能是荔枝果实冷害的结果,冷藏初期Spm含量的上升可能是果实对冷害的防卫反应。     

荔枝胚败育过程中内源激素与蛋白质含量的变化

连续3年(1999-2001年)对典型的荔枝焦核品种桂味、糯米糍和大核品种黑叶、怀枝花后10-40d的幼胚和胚乳内源激素、多酚含量及蛋白质动态变化进行研究。结果表明,焦核品种幼胚及胚乳中的IAA、GAs和ABA含量低于大核品种;多酚类物质含量在胚中低于大核品种,胚乳中则高于大核品种;胚和胚乳中的蛋白质含量均低于大核品种。蛋白质电泳结果显示,22．5、28．5和45kD这3类蛋白质在怀枝和黑叶的胚蛋白质代谢过程中表现出较高的稳定性,桂味和糯米糍胚蛋白质中的28．5kD蛋白质也有相似的特性。     

采后荔枝果实的类脂褐素和有机自由基水平的变化

两个荔枝品种(糯米糍和淮枝)果实的类脂褐素水平随贮放时间延长而增高。低温抑制类脂褐素的形成。品种间果皮的自由基水平呈不同类型的变化。     

糯米糍荔枝裂果的生理机理与防裂效果研究

以果实易裂品种糯米糍荔枝为材料,对果皮内与裂果有关的一些生理指标以及两种处理硝酸钙(Ca(NO3)2)和赤霉素(GA)的防裂效果进行了探索性研究。结果表明:在果实发育初期,果皮内的水溶性果胶和原果胶的含量均升高,且原果胶含量的增长幅度大于水溶性果胶。除果实成熟期外,果胶脂酶(PE)和多聚半乳糖醛酸酶(PG)的活性一直呈上升趋势,且水溶性果胶的含量与PG的活性有显著正相关关系。纤维素酶(CX)在整个果实发育期都表现出较高的活性且有两次明显的活性高峰。同时还发现除果实成熟期外,Ca(NO3)2处理能增强PE和PG活性,但对CX则有抑制作用。此外,Ca(NO3)2处理和GA处理均能明显地改善糯米糍荔枝果皮质地的组成,使果实的裂果率明显降低,且GA处理的效果要明显好于Ca(NO3)2处理。     

荔枝受荔枝蝽危害后对平腹小蜂趋性的影响

采用Y-型嗅觉仪测定了荔枝蝽Tessaratoma papillosa成虫危害后,糯米糍、桂味和三月红3个荔枝品种对平腹小蜂Anastatus japonicus行为的影响。结果发现：只有当超过3头荔枝蝽成虫危害时,糯米糍植株才对平腹小蜂具有较强的引诱效果;三月红健康植株本身对平腹小蜂的引诱效果就较强,对其进行机械损伤或者害虫取食后这种作用有一定程度的增强;而桂味健康植株与机械损伤植株、虫害植株对平腹小蜂行为的影响大致相同。随着荔枝蝽危害时间的延长,以上3个品种都在被害后第2天对平腹小蜂的引诱作用达到最强,此后这种效果逐渐降低。3个品种中三月红植株在虫害后做出反应的速度最快。平腹小蜂对桂味植株的趋性一直处于相对较低的水平。     

裂果易发性不同的荔枝品种果皮中细胞壁代谢酶活性的比较

“糯米糍”荔枝裂果率极显著高于“淮枝”,前者果皮中的果胶酶、纤维素酶和果胶甲酯酶的活性高于后者,其中以果胶酶活性差异最明显,其次是纤维素酶,果胶甲酯酶差异最小;“糯米糍”细胞壁结合型的过氧化物酶(POD)和多酚氧化酶(PP0)活性明显高于“淮枝”,而水溶性POD和PP0的活性则两个品种间无明显差异。据此认为,果皮细胞壁水解酶活性以及细胞壁结合型的POD和PPO的活性高的荔枝品种,其裂果率也高。文章对细胞壁代谢相关酶类在果皮抗裂性形成中的作用进行了讨论。     

Cloning and Expression Analysis of Litchi (Litchi Chinensis Sonn.) Polyphenol Oxidase Gene and Relationship with Postharvest Pericarp Browning

Polyphenol oxidase (PPO) plays a key role in the postharvest pericarp browning of litchi fruit, but its underlying mechanism remains unclear. In this study, we cloned the litchi PPO gene (LcPPO, {"type":"entrez-nucleotide","attrs":{"text":"JF926153","term_id":"350601663","term_text":"JF926153"}}JF926153), and described its expression patterns. The LcPPO cDNA sequence was 2120 bps in length with an open reading frame (ORF) of 1800 bps. The ORF encoded a polypeptide with 599 amino acid residues, sharing high similarities with other plant PPO. The DNA sequence of the ORF contained a 215-bp intron. After carrying out quantitative RT-PCR, we proved that the LcPPO expression was tissue-specific, exhibiting the highest level in the flower and leaf. In the pericarp of newly-harvested litchi fruits, the LcPPO expression level was relatively high compared with developing fruits. Regardless of the litchi cultivar and treatment conditions, the LcPPO expression level and the PPO activity in pericarp of postharvest fruits exhibited the similar variations. When the fruits were stored at room temperature without packaging, all the pericarp browning index, PPO activity and the LcPPO expression level of litchi pericarps were reaching the highest in Nandaowuhe (the most rapid browning cultivar), but the lowest in Ziniangxi (the slowest browning cultivar) within 2 d postharvest. Preserving the fruits of Feizixiao in 0.2-μm plastic bag at room temperature would decrease the rate of pericarp water loss, delay the pericarp browning, and also cause the reduction of the pericarp PPO activity and LcPPO expression level within 3 d postharvest. In addition, postharvest storage of Feizixiao fruit stored at 4°C delayed the pericarp browning while decreasing the pericarp PPO activity and LcPPO expression level within 2 d after harvest. Thus, we concluded that the up-regulation of LcPPO expression in pericarp at early stage of postharvest storage likely enhanced the PPO activity and further accelerated the postharvest pericarp browning of litchi fruit.     

利用RAPD标记研究荔枝品种的新缘关系

采用改进的ＣＴＡＢ方法提取３４个荔枝品种的基因组ＤＮＡ为模板,从５０个１０碱基的随机引物中获得了３７个多态性ＲＡＰＤ标记,聚类分析结果表明这３４个荔枝品种可以分成４组,第一组有“状元红”、“元红”、“桂林”、“宋家香”、“台湾荔”、“下番枝”、“东刘一号”、“妃子笑”、“白糖罂”、“香丸”、“绿沙”;第二组有“无栗子”、“水东”、“乌叶”、“蔡家肉丸”、“青壳糯米糍”、“糯米糍”;第三组有“桂味”     

荔龙宝叶面肥对荔枝果实产量及品质的影响

1998年和1999年连续两年的田间试验表明,喷施荔龙宝可显著提高妃子笑和糯米糍荔枝的产量,显著增加两品种的单果重和可溶性固形物含量。按1999年数据计算,在妃子笑和糯米糍上应用荔龙宝的投入产出比分别是1:35和1:57。     

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.     

Differential expression of anthocyanin biosynthetic genes in relation to anthocyanin accumulation in the pericarp of Litchi chinensis Sonn

Litchi has diverse fruit color phenotypes, yet no research reflects the biochemical background of this diversity. In this study, we evaluated 12 litchi cultivars for chromatic parameters and pigments, and investigated the effects of abscisic acid, forchlorofenron (CPPU), bagging and debagging treatments on fruit coloration in cv. Feizixiao, an unevenly red cultivar. Six genes encoding chalcone synthase (CHS), chalcone isomerase (CHI), flavanone 3-hydroxylase (F3H), dihydroflavonol 4-reductase (DFR), anthocyanidin synthase (ANS) and UDP-glucose: flavonoid 3-O-glucosyltransferase (UFGT) were isolated from the pericarp of the fully red litchi cv. Nuomici, and their expression was analyzed in different cultivars and under the above mentioned treatments. Pericarp anthocyanin concentration varied from none to 734 mg m⁻² among the 12 litchi cultivars, which were divided into three coloration types, i.e. non-red (‘Kuixingqingpitian’, ‘Xingqiumili’, ‘Yamulong’and ‘Yongxing No. 2′), unevenly red (‘Feizixiao’ and ‘Sanyuehong’) and fully red (‘Meiguili’, ‘Baila’, Baitangying’ ’Guiwei’, ‘Nuomici’ and ‘Guinuo’). The fully red type cultivars had different levels of anthocyanin but with the same composition. The expression of the six genes, especially LcF3H, LcDFR, LcANS and LcUFGT, in the pericarp of non-red cultivars was much weaker as compared to those red cultivars. Their expression, LcDFR and LcUFGT in particular, was positively correlated with anthocyanin concentrations in the pericarp. These results suggest the late genes in the anthocyanin biosynthetic pathway were coordinately expressed during red coloration of litchi fruits. Low expression of these genes resulted in absence or extremely low anthocyanin accumulation in non-red cultivars. Zero-red pericarp from either immature or CPPU treated fruits appeared to be lacking in anthocyanins due to the absence of UFGT expression. Among these six genes, only the expression of UFGT was found significantly correlated with the pericarp anthocyanin concentration (r = 0.84). These results suggest that UFGT played a predominant role in the anthocyanin accumulation in litchi as well as pericarp coloration of a given cultivar.     

炭疽病菌侵染对荔枝果实生理生化变化的影响

本研究测定了荔枝果实人工接种炭疽病菌后呼吸速率、乙烯释放量的变化和果皮氧化、过氧化作用以及与酚类代谢有关的几种酶活性的变化。结果表明,接种炭疽病菌的荔枝果实呼吸速率和乙烯释放量显著增高,果皮活性氧(O₂^·)产生速率和丙二醛(MDA)含量显著增加,超氧化物歧化酶(SOD)活性显著降低,过氧化物酶(POD)、多酚氧化酶(PPO)和苯丙氨酸解氨酶(PAL)活性显著增高。说明炭疽病菌的侵染可导致荔枝果实呼吸速率和乙烯释放量的增高,加速荔枝果皮氧化和过氧化进程,并诱导荔枝果皮PPO、POD、PAL活性增高,是加速采收后荔枝果实衰老、褐变、腐烂的一个重要原因。