Potential roles of longan flower and seed extracts for anticancer

Polyphenol-rich plants are known to possess benefits to human health. Recent studies have revealed that many Traditional Chinese Medicines(TCMs) are rich sources of polyphenols and exhibit antioxidant and anti-inflammatory activities, and these TCMs have been shown experimentally to overcome some chronic diseases, including cancer. Longan flowers and seeds, two TCMs traditionally used for relieving pain and urinary diseases, have been revealed in our recent reports and other studies to possess rich amounts of polyphenolic species and exhibit strong anti-oxidant activity, and these could be applied for the treatment of diabetes and cancer. Herein, we review the recent findings regarding the benefits of these two TCMs in the treatment of humancancer and the possible cellular and molecular mechanisms of both substances.

Indicator Analysis of Off-season Longan Flower Reversal

[Objectives] This study was conducted to analyze the internal causes of flower reversal in Longan （ Dimocarpus longan Lour.） trees. [Methods] With flowering trees and flower reversal trees as experimental materials, the variations in sugar and starch in mature leaves, tender leaves, mature branches, twigs and terminal buds after flower forcing were analyzed. [Results] During flowering process, sugar content showed the greatest difference between flowering and flower reversal trees, and the difference was the greatest in mature leaves. Trees with mature leaves having a sugar content above 44.71 mg/g were found to be more prone to flowering, while those with leaf sugar content lower than 27.80 mg/g were susceptible to flower reversal. In addition, longan trees with a higher sugar content in tender leaves were not prone to flower reversal. [Conclusions] In future, whether off-season flower forcing can be performed on longan trees could be judged through the detection of tree leaves, which is of great significance to prevention of flower reversal in off-season longan production.

Analysis of Carbon Content in Off-season Flowering and Non-flowering Longan Trees

After flower induction, some longan trees can successfully blossom and bear fruit, while others with similar tree body status can only sprout leaf buds. In order to investigate the main reason for these differences, in this study, off-season flowering and non-flowering longan trees were used as experimental materials to analyze the changes of carbon content in mature leaves, tender leaves, mature shoots, tender shoots and terminal buds of longan trees after flower induction by potassium chlorate. The result showed that carbon content played an important role in flowering process. Off-season longan trees with carbon content in mature leaves reached 50.93 mg/g could successfully blossom, but those with carbon content in mature leaves lower than 37.40 mg/g were usually difficult to blossom. In addition, the maturity of tender leaves posed great influence on flowering. Specifically, tender leaves with a higher maturity contained higher carbon content and could easily blossom, which could be used as a new indicator to evaluate flower induction in off-season longan trees.

Differences in Carbon Nutrition between On-season and Off-season Longan during the Flowering Process

Flower-bud differentiation is the most critical stage of fruit yield formation, as well as a complicated carbon transfer process. To understand the changes of carbon during the flower bud differentiation process of longan, it is very important to adopt suitable planting measures and control flowering time. This study fo- cused on the changes of sugar and starch content of on-season and off-season longan during the flowering process. The results showed that the accumulation and transformation of carben differed between on-season and off-season longan during flower-bud differentiation process ; to be specific, sugar and starch content in tissues differentiated from apical buds of on-season longan were reduced at the late flower-bud physiological differentiation stage except in leaf buds ; on the contrary, sugar and starch content in off-season longan increased at the late flower-bud physiological differentiation stage： specifically, total sugar content increased from 15.43 （ - 7 d） to 31.38 mg/g （7 d） ; starch content increased from 5.42 to 8.31 mg/g during this time, which may be relevant to the external environment or tree original metabolism damaged by potassium chlorate.

Effects of Two Signals on Flowering and FT Gene Expression in Off-season Longan

[Objective] This study aimed to investigate the effects of two signals, H2O2 and NO, on flowering and FT gene expression in off-season longan. [ Method] Nine-year-old off-season longan ＇ Shixia＇ was used as the experimental material and sprayed with signal promoting agent and blocking agent to analyze the dynamic changes of flowering and FT gene expression level. [ Result] The expression level of FT gene in off-season longan increased during the flowering process, and the expression level of FT gene in leaves reached the peak earlier than that in terminal buds. SNP and MV treatments improved FT gene expression in varying degrees. DMTU and L-NNA treatments effectively inhibited FT gene expression in terminal buds, but the inhibitory effects on FT gene expression in leaves were not significant at late stage of flower bud differentiation. [Condusion] According to the flowering performance of longan, H2O2 and NO play an important role in promoting and accelerating longan flowering.

An Investigation on the Relationship between Oxidative Damage and Flowering of Longan (Dimocarpus longan Loureiro)

Eight-year-old ＂Shixia＂ longan （ Dimocarpus longan Loureiro ） trees were treated under low temperature stress, oxidative stress, and natural low temperature conditions ＋ experimental agents to investigate the relationship between oxidative damage and flowering of longan. The results indicated that oxidative stress was conducive to flowering of longan, which also led to accumulation of reactive oxygen species in various tissues of longan. The detection results of reactive oxygen species, ascorbic acid content and MDA content in apical buds and leaves showed that ascorbic acid could inhibit flowering of longan, while MDA could promote flowering of longan. Therefore, there was a positive correlation between reactive oxygen species and flowering of longan.

Effects of H_2O_2 and NO on Flower Development and AP1 Gene Expression of Off-season Longan

[Objective] This study aimed to investigate the effects of H2O2 and NO on flower development and 4P1 gene expression of off-season longan. [Meth-od ]Nine-year-old off-season Chuliang longan was sprayed with enhancers and blockers of H2O2 and NO to analyze dynamic changes of flower development and API expression. [ Result] The expression level of API gene in off-season longan was improved during flower development. SNP and MV treatments up-regulated the expression level of API gene in leaves and terminal buds to varying degrees during lateral primordium formation. Especially, SNP treatment exhibited the most remark-able effect. DMTU treatment significantly inhibited the expression of AP1 gene in leaves and terminal buds during lateral primordium formation. L-NNA treatment slightly inhibited the expression of API gene in leaves and exerted no significant effect on expression of AP1 gene in terminal buds. [ Conclusion] It can be specu-lated that the enhancement of NO and H2O2 signals is conducive to flower development of off-season longan, while blocking H2O2 signals may inhibit flower develop-ment of off-season longan.

不同疏花方式对龙眼开花坐果及果实品质的影响

通过对龙眼不同疏花方式处理组和对照组的观察和数据分析,探究了疏花方式不同对开花坐果及果实品质的影响。结果显示:完全疏花组的开花数量和果实数量显著减少,坐果率降低,但果实品质较好;部分疏花组保留了适量的花蕾,开花数量相对较多,坐果率相对较高,保持一定的产量和较好的果实品质;延迟疏花组保留了所有花蕾,开花数量最多,但坐果率受到影响,果实品质相对较差。研究结果可为龙眼种植者提供一定的参考和指导,为龙眼品种改良和栽培技术的发展提供理论基础和实践指导。

32份龙眼种质资源花氨基酸的分析评价

以国家果树种质福州龙眼圃32份龙眼种质资源为材料,测定分析了其干花中18 种氨基酸的含量和组成,并对其营养模式进行分析评价.结果表明,龙眼花中总氨基酸含量（TAA）为8091.06mg·hg-1,其中谷氨酸含量最高为1008.26mg·hg-1,而胱氨酸含量最低仅为17.19mg·hg^-1,谷氨酸、天门冬氨酸、赖氨酸、亮氨酸、精氨酸、缬氨酸、脯氨酸等7种氨基酸是龙眼花中主要的氨基酸,占TAA 含量的59.31%.不同龙眼种质资源中氨基酸积累差异明显,18种氨基酸的变异系数为11.00%～80.01%.营养评价分析表明,32份龙眼花中必需氨基酸（EAA）含量占TAA 含量的38.91% ～42.94%,2 份龙眼共有4 项优于氨基酸模式谱比例,（蛋氨酸＋胱氨酸）是龙眼花的第一限制氨基酸.龙眼种质资源花中还含有丰富的功能氨基酸和味觉氨基酸.通过聚类分析初步提出龙眼花氨基酸高、中、低分级标准,筛选出5份高氨基酸含量的龙眼特异资源.

化学调控四季花龙眼成花座果的初步研究

不同化学试剂组合对四季花龙眼枝梢生长和成花座果研究表明,不同时期成熟的枝梢对四季花龙眼成花座果无重大的影响;乙烯利、多效唑和赤霉素三者共同作用可促进成花座果;当枝梢充分成熟时,树冠喷施乙烯利250mg·L-1+多效唑450mg·L-1,谢花3/4时再喷施赤霉素50mg·L-1,可以有效抑制四季花龙眼植株新梢的萌发,促使植株100%成花,并且花穗和果穗性状的综合表现最好。

龙眼花芽形态分化期基枝叶片碳水化合物含量与成花逆转的关系

以成花逆转容易的乌龙岭和成花逆转不容易的立冬本龙眼为材料,测定了花芽形态分化期不同基枝叶片中碳水化合物含量.结果表明:不论是成花逆转容易的乌龙岭,还是成花逆转不容易的立冬本,基枝叶片中淀粉和可溶性糖含量均为:抽生纯花穗>抽生轻度成花逆转花穗>抽生重度成花逆转花穗.据此认为,基枝叶片淀粉和可溶性总糖含量高的基枝抽生的花穗不易发生成花逆转.

6-苄氨基嘌呤对水涨龙眼花芽分化的效应

6-BA25—100ppm11月下旬处理水涨龙眼,对小年树的花芽分化有一定的效应,植株的花穗抽生率,随着处理浓度的增加而提高,高浓度(10 ppm)处理有明显的促花效应(P≤0.05)。大年树处理后花穗抽生率与对照相比无明显差异。所有处理对大年和小年的花穗、夏梢和秋梢结果母校的生长发育均未见不良影响。

龙眼成花逆转花芽α-tubulin基因的克隆与原核表达

运用蛋白质组学方法比较龙眼(Dimocarpus longanLour.)正常成花和成花逆转花芽的差异蛋白质组,并应用RACE方法克隆其中上调表达的α-微管蛋白基因α-tubulin,获得一段长度为1641 bp的cDNA,其中包括1个1350 bp的开放阅读框[GenBank登录号:FJ479617(GI:218202929)]。将α-tubulin全长cDNA在大肠杆菌中表达,获得1个约49.6 kD的外源蛋白,经Western blotting验证为α-微管蛋白。RT-PCR和Western blotting分别检测了α-tubulin在转录和翻译水平上的表达,结果表明,α-微管蛋白在成花逆转的龙眼花芽中上调表达,可能是逆转花芽形态差异表现的原因之一。

大乌圆龙眼开花特性观察

从单穗、单株和植株群体3个方面调查分析大乌圆龙眼雌雄花开花特性。结果表明，大乌圆龙眼雌雄花交替开放的顺序是雄-雌-雄，植株群体雌雄花开放相遇时间比单穗和单株长；雌花在开花后5-14d为落花高峰期。雄花在开花后8-18d、19-26d分别出现两个落花高峰。因此，生产上大乌圆龙眼园种植株数要在10株以上，以增加雌雄花花期相遇天数。促进授粉受精,实现丰产。

龙眼成花逆转与花芽形态分化期秋梢叶片矿质营养的关系

调查了8个龙眼品种发生成花逆转的情况,发现松风本和立冬本不易发生成花逆转;普明庵次之,油潭本、九月乌、水南1号、乌龙岭和东壁容易发生成花逆转.研究了成花逆转容易的乌龙岭和成花逆转不容易的立冬本龙眼品种花芽形态分化期秋梢叶片矿质营养的变化.叶片K含量高、N含量和N/K低的秋梢抽生的花穗不易发生成花逆转;Ca可能有利于成花,减少成花逆转.

四季蜜龙眼夏季开花坐果特性及传粉昆虫种类调查

为了解四季蜜龙眼夏季开花坐果特性和传粉昆虫种类,于夏季开花期间选定花穗记录雌雄花和果实数量,并以随机网捕方式采集传粉昆虫进行鉴定。结果表明:四季蜜龙眼夏季花期平均每穗开花天数为12.9天,雌雄花比例为1:6.57,授粉受精期的温度处于25～36℃之间,在较高的温度条件下雌花坐果率达到27.6%;雌花脱落占雌花数的11.1%,小果脱落占雌花数的61.3%。传粉昆虫有5目13科21种,以花金龟科的种类最多,占总数的33.3%;其次为蜂类和蝇类昆虫,分别占总数的30.1%和24.1%。

龙眼成花与氧化损伤的关系探讨

以储良龙眼为试材,通过分析低温诱导、氧化胁迫、自然低温+药剂处理龙眼成化过程中氧化损伤各指标变化,研究龙眼成花和氧化胁迫之间的相关性。结果表明,氧化胁迫有利于龙眼成花。对顶芽和叶片活性氧、抗坏血酸和丙二醛(MDA)含量的检测结果也表明,氧化胁迫诱导龙眼成花的同时,也导致了龙眼树各组织活性氧的累积,且抗坏血酸抑制龙眼成花,MDA促进龙眼成花。因此认为活性氧与龙眼成花呈正相关。

龙眼控梢催花和保花保果的技术

进行了龙眼控梢催花和保花保果技术开发研究,研制出“龙眼四季催花灵”药剂及龙眼控梢催花剂2号。“龙眼四季催花灵”的最佳处理量为树冠每米直径施用140g,土施该药剂10d后叶面喷施本所配制的龙眼控梢催花剂2号,在不同季节、不同气候类型区、不同土壤类型区对不同品种、不同树龄的龙眼进行催花,并配合常规的保花保果等管理技术措施。试验结果表明:小区的开花株率达100%,大田示范区的开花株率达95%以上,平均枝条开花率达74.5%;盛产期果园平均每公顷11.25t以上,每公顷比常规催花技术增产8805kg以上,每公顷新增利润135000多元;且反季节催花的经济效益比正常季节高,每公顷利润增加67.27%。施用广东农科院果树所生产的龙眼控梢促花剂及华南农业大学配制的龙眼控梢催花素1号均无催花作用,与对照一样均不开花。

龙眼成花与抗氧化防御体系关系研究

以石硖龙眼为材料,通过低温诱导、氧化胁迫、自然低温+药剂处理试验,探讨龙眼成花和抗氧化防御之间的相关性。结果表明,氧化胁迫处理或低温+NO/H2O2促进剂处理均有利于龙眼早花。NO促进剂可抑制成花后期龙眼顶芽POD活性,H2O2清除剂可促使POD和SOD活性大幅上升,表明氧化胁迫信号正调控龙眼成花,而氧化防御体系负调控龙眼成花。

基于生长期和累积生长度日的龙眼果树催花法

龙眼树开花少和座果效益低是全球范围内热带水果生产最突出的共性问题之一。龙眼(Dimocarpus longan)是主要的热带名特优水果,危及龙眼产业生存的主要原因在于冬季早春气候变暖,不能满足花芽分化所需要的低温,龙眼树无法扬花。本研究目的是利用龙眼树的生长期和累积生长度日(cumulative growing degreedays,CGDD)进行适时花器官生长诱导以及检验催花肥氯酸钾(KCl O3)的催花效率。试验起始于2012年夏季,地处热带海南岛北部,试验地土壤为酸性沙质红壤(p H5.43±0.49),龙眼树品种是国内主栽品种‘石硖’。修剪矮化后,在新梢生长起始时开始计算CGDD值,依据龙眼生长期季节性累积CGDD值进行催花处理。结果表明:CGDD为1 650℃时可使用多效唑(PP333)诱导中止梢枝营养生长,CGDD为1 850℃时可使用复合型细胞分裂素GA3使龙眼营养生长集中向花器官生长转化;CGDD值为2 150℃时龙眼花开始萌芽,CGDD为2 850℃时开花;依据生长期CGDD进行的催花处理(每株根施0.60 kg KCl O3,加少量叶营养肥KH2PO4)显著地促进了龙眼树生理光合作用和花芽分化(p<0.05)。本研究开发了基于生长期CGDD的综合使用催花肥-植物生长调节剂-叶营养素的催花配套技术,为在冬季气候变暖环境条件下有效地诱导龙眼树开花和座果提供定量信息,有助于龙眼生产的可持续性发展。