Cytokinins from terminal buds of Euphoria longana during different growth stages

The presence of endogenous cytokinins were detected in the terminal buds of longan ( Euphoria longana Lam.) after purification by ion exchange and Sephadex LH-20 chromatography, and bioassay, enzymic degradation, high-performance liquid chromatography and gas chromatography-mass spectrometry. Permethylated derivatives of two highly active cytokinin glucoside compounds from dormant buds were: 6-(4-O-β-D-glucosyl-3-methyl-but-2-enylamino) purine (zeatin-O-glucoside) and 9-β-D-ribofuranosyl-6-(4-hydroxy-3-methyl-but-2-enylamino) purine (zeatin riboside-O-glucoside). Simultaneously, four active cytokinins from buds at the stages of leaf flush and flower bud initiation were identified as 6-(4-hydroxy-3-methyl-but- trans -2-enylamino) purine (zeatin), zeatin-9-β-D-ribofuranosylpurine (zeatin riboside), 6-(3-methyl-2-butenyl) aminopurine (isopentenyladenosine, 2iPA) and N-(3-methyl-2-butenyl) adenine (isopentenyladenine, 2iP). The total cytokinin levels were low at leaf flush, with the zeatin and zeatin riboside in the buds about 70% of the total. In the transition of the terminal bud from leaf flush to dormancy, the principal cytokinins were zeatin-O-glucoside and zeatin riboside-O-glucoside. However, significant decreases in the levels of zeatin-O-glucoside and zeatin riboside-O-glucoside and increases in those of zeatin, zeatin riboside, 2iPA and 2iP were observed at flower bud initiation. It is suggested that in longan, the cytokinins that are translocated to the shoots are accumulated in the buds at the dormant stage, and that later there is a considerable increase in free cytokinins during flower bud initiation, leading to the promotion of flower bud development.     

龙眼DlPPO1基因的克隆及其表达调控分析

该研究根据同源克隆技术,利用RT-PCR和RACE技术,以‘四季蜜’龙眼叶片cDNA为模板,获得龙眼多酚氧化酶基因(polyphenol oxidase,PPO)的3个转录本DlPPO1-a、DlPPO1-b和DlPPO1-c的cDNA全长序列(KM387405、KM516087和KM516088)和1条DNA序列DlPPO1(KU837229)。DlPPO1-a、DlPPO1-b和DlPPO1-c的全长分别为1 969、1 960和1 920bp,包含相同的完整开放阅读框1 800bp并编码599个氨基酸;该基因与荔枝、橄榄和枣等物种的PPO基因同源性较高。生物信息学分析表明,DlPPO1保守结构域具有多酚氧化酶的典型结构域特征。利用实时荧光定量PCR技术检测DlPPO1表达结果表明,在龙眼体胚发生过程中,DlPPO1从心形胚时期开始上调表达至子叶胚时期达到最高,推测其在龙眼体胚发生中后期可能发挥重要作用;DlPPO1在龙眼叶片中表达量最高,其次是花芽,而在其他组织部位表达量较低。激素和非生物胁迫处理下的表达分析表明,水杨酸(SA)、低浓度茉莉酸甲酯(MeJA)、NaCl、甘露醇及PEG可诱导DlPPO1基因上调表达,这些表达模式暗示其可能参与多种非生物胁迫应答过程。     

喙副黛缘蝽初步研究

副黛缘蝽Paradasynus longirostris Hsiao隶半翅目缘蝽科,是莆田龙眼一种重要害虫。该虫50-60年代经调查已见发生危害．但迄未对其进行研究。本是首欢报道。喙副黛缘蝽成虫、若虫刺吸危害龙眼果穗、幼果及叶片。一年发生2代．以成虫越冬;翌年4月下旬出蛰,产卵于叶片上;每雌产卵约60粒,1-2卵块;卵期6-10天。若虫5龄．若虫期20-40天。     

龙眼内生菌的分离与脂肪酸鉴定

对‘福眼’龙眼果实的内生菌进行分离纯化和脂肪酸鉴定,结果表明,在龙眼果实中检测到分属于肠杆菌属(Enterobacter)、果胶杆菌属(Pectobacterium)、克吕沃尔菌属(Kluyvera)和沙门氏杆菌属(Salmonella)的内生细菌,以及分属于枝孢霉属(Cladosporium)、柱顶孢霉属(Scytalidium)、外瓶霉属(Exophiala)的内生真菌。     

龙眼体胚发生过程中抗坏血酸过氧化物酶活性的变化

在龙眼体胚发生的阶段性同步化材料中,均检测到与体胚发生可能有密切关系的抗坏血酸过氧化物酶(APX)活性;龙眼体胚中至少存在有胞浆型APX和叶绿体型APX;APX的转录与其酶活性变化并不一致。     

龙眼叶片膜脂脂肪酸组分与龙眼耐寒性的关系

龙眼叶片膜脂不饱和脂肪酸含量和脂肪酸不饱和度与龙眼不同品种的耐寒性呈正相关;在年周期中,不饱和脂肪酸含量的变化与龙眼耐寒性的变化呈现平行关系;龙眼叶片膜脂脂肪酸组分含量反映着龙眼品种间耐寒性遗传上的差异,可作为耐寒性的鉴定指标。     

Scanning Electron Microscopic Studies on the Organ Development of

The pattern of development of the floral parts of Longan flower was followed using scanning electron microscope. Floral initiation begins with the formation of calyx protrusions around the floral apex. After the calyx protrusions have appeared, the petal primordia at the base of the floral apex start to appear and then followed by the androecium primordia which appear at the periphery of the floral apex. Gynoecium formation begins much later (at about 30 days after floral initiation). In the male flower, androecium develops normally forming anthers and filaments. Anthers also develop in the female flowers but they are smaller and the filaments much shorter. Gynoecium in the female flower is well developed and when mature it produces a long style, a two-prong-stigma and two ovaries. In the male flower the gynoecium is poorly developed the style is short and the stigma seldom splits. Ovaries are also poorly developed in the male flower. In addition to male and female flowers, Longan also forms a number of abnormal flowers with poorly developed androecium and gyn6ecium. Male and female flowers only become apparent at about 40 days after the initiation of flower differentiation. Prior to this it is difficult to know whether a particular developing flower is going ultimately to become a male or female flower. The formation of abnormal flowers also become obvious' at about 40 days after the initiation of flower differentation.     

不同龙眼资源遗传多样性的SCoT和ISSR 比较分析

应用SCoT和ISSR标记对36份龙眼资源和1份近缘种龙荔的遗传多样性进行分析。结果表明:12对SCoT引物共扩增出127条带,平均每条引物扩增10.58条带;15条ISSR引物共扩增出117个条带,平均扩增7.8条带。UPGMA聚类结果表明:SCoT标记和ISSR标记分别在相似系数0.672和0.685水平上,均可将37份材料分成6大类群,SCoT和ISSR标记均适用于龙眼材料的遗传多样性分析,如果将两种标记的数据进行综合分析,可以缩小单一标记的误差。研究结果为龙眼种质资源的保存和利用提供了重要的依据。     

不同生态类型龙眼种质亲缘关系的ISSR分析

利用ISSR分子标记技术对不同生态类型的39份龙眼种质进行亲缘关系分析。研究结果表明,从100条ISSR引物中筛选出12条重复性好、条带清晰的引物,对39份龙眼种质基因组DNA进行扩增,得到152个位点,其中多态性位点117个,多态性比例为76.97%。供试龙眼种质间遗传相似系数变幅为0.57～0.92,说明ISSR标记能够揭示材料间较高的遗传多样性。UPGMA聚类结果表明,在0.65相似水平可以将39份龙眼种质分为3个类群,类群Ⅰ均为来自中国的南亚热带生态型龙眼;类群Ⅱ包括石硖和大乌圆2个南亚热带生态型龙眼品种,以及热带生态型龙眼四季蜜类型的品种和单株;类群Ⅲ包括来自越南和泰国的龙眼种质。不同生态类型对龙眼的亲缘关系影响不大,热带生态型和南亚热带生态型龙眼相互聚在一起,说明两种不同生态类型龙眼具有较多相同的遗传背景。本试验结果将有助于进一步开展龙眼的分类、遗传与进化研究。     

龙眼体胚发生过程中DlAGO4基因的克隆及表达分析

该研究基于龙眼基因组数据库,采用RT-PCR技术,以‘红核子’品种龙眼松散型胚性愈伤组织cDNA为模板,进行龙眼胚性愈伤组织DlAGO4基因的克隆和生物信息学分析,并采用实时荧光定量技术分析其在龙眼体细胞胚胎发生不同阶段、不同组织部位、激素和非生物胁迫处理以及5-氮胞苷(5-azac)处理的表达模式。结果表明:(1)DlAGO4基因cDNA全长为3 425 bp,包含开放阅读框长度为2 781 bp,编码926个氨基酸。(2)生物信息学分析表明,DlAGO4蛋白为碱性亲水非分泌蛋白,含有AGO经典的保守结构域PAZ和Piwi,与克莱门柚CcAGO4的同源性最近,含有85个磷酸化位点和2个糖基化位点;亚细胞定位预测其最可能定位于细胞核;MicroRNA预测显示,DlAGO4基因受到4个miRNA靶向调控。(3)qRT-PCR结果表明,DlAGO4在龙眼球形胚阶段和种子中相对表达量最高;激动素、水杨酸、NaCl、甘露醇、PEG-4000和ABA处理均能促进DlAGO4基因的表达,而2,4-D和MeJA处理抑制其表达;不同浓度的5-azac处理1 d和3 d抑制DlAGO4的表达,但从处理第6天开始该基因呈上调表达,并于处理第12天相对表达量最高。研究认为,DlAGO4基因可能参与龙眼球形胚和种子的转录调控,且可能参与KT、SA的激素信号转导途径和NaCl、甘露醇、PEG-4000、ABA的逆境胁迫响应途径以及DNA甲基化调控机制。