桃果实PpFPPS和PpGGPPS基因的克隆及表达分析

本试验以桃果实为试验材料,利用RT-PCR结合RACE技术克隆获得法尼基焦磷酸合成酶(FPPS)和牻牛儿基牻牛儿基焦磷酸合成酶(GGPPS)基因的全长c DNA序列,分别命名为Pp FPPS和Pp GGPPS,并对它们进行生物学信息及表达分析。结果表明,Pp FPPS全长1 501 bp,开放阅读框1 029 bp,编码342个氨基酸;Pp GGPPS全长1 547 bp,开放阅读框1 113 bp,编码370个氨基酸。进化树分析表明,Pp FPPS与苹果和梨的亲缘性较高;Pp GGPPS与橡胶树的亲缘性较高。蛋白质序列分析表明,Pp FPPS和Pp GGPPS均含有5个保守域和2个天冬氨酸富集区(FARM和SARM),同属反式-异戊烯转移酶家族。实时荧光定量PCR分析表明,随着果实成熟度的提高,Pp FPPS和Pp GGPPS基因在桃果实果皮和果肉中的表达量总体上呈先增加后降低的趋势,并在膨大和硬熟期达到最大值。果实膨大期后,Pp FPPS和Pp GGPPS基因在果皮中的表达显著高于果肉,这可能是桃果实成熟后期果皮类胡萝卜素含量高于果肉的重要原因。本研究结果为进一步深入研究桃果实类胡萝卜素生物合成的分子机理奠定了理论基础。     

枇杷EjNAC82的克隆及其对类胡萝卜素合成基因EjPSY、EjBCH的转录激活分析

为了探讨NAC转录因子对枇杷果实类胡萝卜素代谢的调控机制,以大红袍(红肉枇杷)和白沙(白肉枇杷)为试验材料,利用RNA-Seq技术对大红袍和白沙进行转录组测序,通过分析两个品种间的转录组差异,初步筛选并克隆出了1个枇杷NAC转录因子,命名为EjNAC82。生物信息学技术分析结果发现,EjNAC82具有NAC转录因子特有的结构域、理化性质和蛋白质结构特点,是典型的NAC转录因子家族基因。亚细胞定位试验发现该转录因子定位于细胞核。实时荧光定量PCR结果表明,EjNAC82在枇杷老叶中的表达量高于根、芽、嫩叶、老叶、嫩枝、老枝、幼果和熟果。EjNAC82在果皮和果肉成熟过程中的表达模式相同,均呈先上升后下降再上升的趋势。随着果实的成熟,EjNAC82在大红袍果肉中的表达显著高于白沙(P<0.05)。EjNAC82在大红袍果皮S1、S2、S4时期的表达显著高于白沙。LUC/REN双荧光素酶试验结果表明,EjNAC82对EjPSY1、EjPSY2和EjBCH启动子具有激活作用。这些结果表明EjNAC82可能通过调控EjPSY1、EjPSY2和EjBCH基因的表达从而正向调控枇杷果实中类胡萝卜素的合成。本研究结果为揭示NAC转录因子对枇杷果实类胡萝卜素积累的转录调控功能提供了理论依据。     

桃果胶裂解酶编码基因PpPL1的鉴定及其在果实成熟软化过程中的表达

为了深入了解桃果胶裂解酶(PL)家族编码基因的功能,本研究利用生物信息学方法对桃基因组中的PL基因进行鉴定,并对这些基因在硬质型桃和溶质型桃果实成熟软化过程中的表达差异进行分析。结果表明,从桃基因组中共鉴定出20个PL基因,所有的PpPL蛋白都含有Pec-Lyase-C结构域,但其中只有4个PpPL(PpPL7、PpPL8、PpPL12、PpPL17)包含Pec-Lyase-N结构域。Pec-Lyase-N的保守性表明其可能是执行果胶裂解功能所必须的功能团。聚类分析表明,桃PL基因可以分为5类:这与模式植物拟南芥和番茄PL基因的聚类模式一致。基因表达分析表明,6个PL基因在桃果实成熟过程中高表达,其中PpPL1基因在有名硬质型桃成熟过程中表达量很低,而在黄金蜜3号溶质型桃成熟阶段高表达。序列比对和聚类分析发现,PpPL1基因与果实软化相关的番茄SLPL高度同源。以溶质型桃湖景蜜露和硬质型桃夏之梦为试材,检测采后软化过程中PpPL1的表达,结果表明PpPL1基因是与桃果实的成熟软化相关的主要基因。本研究结果为进一步探究PL基因家族在桃果实软化中作用的分子机理奠定了基础。     

环割对葡萄VvNCED基因的表达和果实成熟的影响

9-顺式-环氧类胡萝卜素双加氧酶(NCED)为脱落酸(ABA)合成途径的关键基因,参与果实生长发育。为明确NCED基因家族对葡萄果实成熟的调控功能,以鄞红葡萄为材料,在开花后50 d进行环割处理,以不环割为对照,分析其果实成熟期、内源脱落酸含量和NCED家族中6个成员表达的变化;通过克隆这6条基因编码区目的片段,构建了pCambia1302过表达植物载体,在花蕾期用农杆菌侵染液浸泡花序,以空载和野生型为对照,分析农杆菌侵染后的果肉中ABA含量和基因表达变化。结果表明,环割后鄞红葡萄果实较对照提前成熟13 d左右;实时荧光定量PCR分析结果显示,环割处理7 d后的果肉中VvNCED1、VvNCED3、VvNCED4和VvNCED7表达量显著上调,与葡萄果肉中内源ABA变化相关;农杆菌侵染花穗后阳性转基因果肉中VvNCED1、VvNCED3、VvNCED4和VvNCED7基因表达量和ABA含量显著高于野生型。综上可知,VvNCED1、VvNCED3、VvNCED4和VvNCED7的表达具有调控葡萄果实成熟的作用。本研究结果为葡萄成熟期的分子调控提供了理论基础。     

草莓果实中BG基因的克隆及功能分析

脱落酸(abscisic acid,ABA)能促进草莓(Fragaria×ananassa)果实的发育成熟,葡萄糖苷酶(β-glucosidase,BG)能通过水解ABA葡萄糖酯(ABA glucose ester,ABA-GE),把非活性的ABA转换成有活性的ABA,因此,BG参与果实发育进程.但是目前还没有遗传学证据来揭示BG对果实发育的作用机理.为了研究BG在果实发育中的作用,本实验以草莓品种甜查理为试材,通过PCR分子克隆的方法分离到3个编码BG的基因FaBG1、FaBG2和FaBG3;首先对3个基因进行生物信息学、时空表达分析,以及测定果实内源ABA含量的变化;其次通过分子调控FaBG3基因的表达量影响果实内源BG的活性,分析草莓果实的生理指标以及与ABA信号路径、色素代谢和细胞壁代谢相关基因的表达水平.实验结果表明,BG蛋白含有一个BglB区域,是能水解其他的复合物的特异区域.随着草莓果实的发育成熟,ABA的含量逐渐升高,FaBG1基因的表达量一直很低,FaBG2的表达量呈总体的下降趋势,只有FaBG3的表达量与ABA含量变化相一致.利用RNA干扰技术调低草莓果实中FaBG3基因的表达量也下调了FaBG1和FaBG2的表达量,同时降低了果实中BG的活性,导致果实中ABA含量、果实色素和可溶性固形物含量降低,提高了果实的硬度等生理指标,与生理指标相关的如色素代谢基因查尔酮合酶(chalcone synthase, CHS)、查尔酮异构酶(chalcone isomerase,CHI)、类黄酮-3-羟化酶(flavonoid-3-hydroxy-lase,F3H)、类黄酮-3-O-葡萄糖基转移酶(UDP Glc-flavonoid 3-O-glucosyl transferase,UFGT)和二氢黄酮醇-4-还原酶(dihydroflavo-nol-4-reductase,DFR),果实软化基因果胶甲酯酶(pectin methylesterase,PE)、伸展蛋白(expansin,EXP)、多聚半乳糖醛酸酶(polygalacturonase,PG)和果胶酸裂解酶(pectate lyases,PL),果实香味代谢基因醌氧化还原酶(quinone oxidoreductase,QR)、酰基转移酶(alcohol acyltransferase,AT)和ABA信号路径中的基因抗副球菌素蛋白(pyrabatin resistance,PYR)、ABA不敏感体1(ABA insensitive 1,AB11)、ABI3、ABI4和ABI5的表达量等分子指标也出现了不同程度的变化,最后导致了果实延迟成熟.与此相反,FaBG3基因超表达的草莓果实出现了提前着色成熟的现象.果实生理及分子指标的变化可揭示BG调控草莓果实发育进程的机理.     

桃果实向光素基因PpPHOT1和隐花色素基因PpCRY2的克隆与表达分析

蓝光是调节植物生长发育最重要的环境因素之一。为了研究蓝光对桃果实类胡萝卜素合成的影响,本试验利用RT-PCR结合RACE的方法,从桃果实中克隆了向光素基因PpPHOT1以及隐花色素基因PpCRY2的c DNA全长序列。序列和生物信息学分析结果表明,PpPHOT1含有向光素所共有的蛋白保守功能域,即N端的LOV结构域和C端的丝/苏氨酸激酶结构域;而PpCRY2则含有隐花色素所共有的蛋白保守功能域,即N端的光裂解酶类似结构域(PHR)和C端的DAS功能域。蓝光处理显著增强了桃果实PpPHOT1和PpCRY2基因的表达,这表明PpPHOT1和PpCRY2可能是桃果实采后响应外源蓝光信号的重要因子。此外,PpPHOT1和PpCRY2在金丽果实中的表达量显著高于湖景蜜露果实,表明蓝光处理诱导金丽类胡萝卜素积累效应更显著,这可能与果实的品种有关。本研究结果为揭示蓝光诱导桃果实类胡萝卜素合成的分子机理提供了一定的理论依据。     

铜胺氧化酶基因PpCuAO4在桃成熟中的功能鉴定

为明确铜胺氧化酶(CuAO)在桃果实成熟过程中的作用,分别采用1.0、5.0和10.0 mmol·L^-1的CuAO抑制剂氨基胍(AG)对黄水蜜桃果实进行喷施处理,并于桃果实成熟后测定果实硬度。结果表明,5 mmol·L^-1 AG处理组桃果实的硬度保持效果最好。进一步采用5.0 mmol·L^-1 AG处理黄水蜜桃果实,并测定果实成熟相关生理指标。结果表明,AG处理下桃果实在采后7 d内果实硬度均显著高于对照水平,乙烯释放量和呼吸强度均显著低于对照水平,表明抑制CuAO介导的多胺分解可显著延缓桃果实成熟。AG处理显著抑制乙烯合成、生长素转运和细胞壁降解相关基因PpACO1、PpACS、PpPIN1、PpGH3.3、PpPG和PpPME1的表达水平。为进一步明确CuAO在桃成熟中的功能,利用病毒诱导的基因沉默(VIGS)技术沉默腐胺(Put)分解关键基因PpCuAO4。结果显示,转基因桃果实PpCuAO4表达水平仅为对照的18%,Put含量和果实硬度显著高于对照水平,而乙烯释放量和呼吸强度均显著低于对照水平。上述结果表明,PpCuAO4介导的Put分解可以促进桃果实成熟。本研究为进一步深入解析多胺(polyamine)调控桃果实成熟的机制提供了重要的理论依据。     

两种不同耐贮性桃果实采后乙烯合成和果实软化相关基因表达的差异

以商业成熟期的桃(Prunus persica)栽培品种秦王(极耐贮)和沙红(不耐贮)为试材,采用气相色谱测定乙烯释放量;利用实时荧光定量PCR(quantitative Real-time PCR,q RT-PCR)技术分析乙烯合成关键酶和果实软化相关基因在两个品种中的表达差异。研究结果表明,秦王果实在贮藏期间ACC合成酶基因(1-aminocyclopropane-1-carboxylic acid synthase gene,Pp ACS1)相对表达量极低,乙烯释放速率也极低,一直保持较高的硬度;而沙红果实在贮藏过程中Pp ACS1的相对表达量随软化进程迅速增加,释放大量乙烯,果实硬度下降快。秦王果实中ACC氧化酶基因(1-aminocyclopropane-1-carboxylic acid oxidase gene,Pp ACO1)虽有一定的表达量,但没有随贮藏时间而增加;而Pp ACO1在沙红桃中随果实的软化表达量呈显著上升的趋势。秦王果实中细胞壁降解酶果胶甲酯酶基因(pectin methylesterase gene,Pp PME)和多聚半乳糖醛酸酶基因(polygalacturonase gene,Pp PG)的表达量都极低;而在沙红果实中其表达量均呈持续增加趋势。此外,秦王果实中扩张蛋白基因(expansin gene,Pp EXP)的表达量也较低;而在沙红中表达量较高。N-聚糖加工酶α-甘露糖苷酶基因(α-mannosidase gene,Ppα-Man)和β-氨基己糖苷酶基因(β-hexosaminidase gene,Pp Hex1,Pp Hex2)在沙红和秦王贮藏期间均有较高表达量,且秦王中的表达量显著高于沙红(P<0.05)。这表明秦王果实采后不软化是由于Pp ACS1的转录受阻,不能产生乙烯,从而致使细胞壁水解酶Pp PME和Pp PG几乎不表达,果胶代谢受阻,因而果实一直保持较高硬度;而沙红果实在采后贮藏中释放大量乙烯,促进了Pp EXP、Pp PME和Pp PG的表达,引起细胞壁果胶的大量降解,导致果实迅速软化。而Ppα-Man、Pp Hex1和Pp Hex2可能不是秦王软化过程的关键基因。本研究为阐明桃果实成熟软化机理及其高效培育耐贮品种提供基础资料。     

番茄果实特异表达启动子ESp1的克隆及表达

E8启动子是番茄果实成熟乙烯响应性基因E8的启动子区。这个区域中存在着一些响应乙烯以及在果实发育和成熟过程中起调节作用的顺式作用元件，调节E8基因在果实成熟过程中表达（Deikmaa et al．，1998）。本研究根据GenBank中E8基因的启动子区序列设计引物，从番茄基因组中克隆了该启动子，构建了番茄果实特异表达载体，并通过RT-PCR和gus基因检测了该表达载体的果实特异表达活性。     

光诱导转录因子MdMYB1对苹果果皮花青苷合成调控的表达分析

MdMYB1是调控苹果(Malus domestica)果皮着色的重要转录因子。黄绿色苹果脱袋后果面现红色,为了研究其花青苷合成表达调控机制,本研究采用Real-time PCR方法分析了光照对4种不同颜色苹果黄绿色品种金冠和陆奥、红色品种富士、深红色品种红星果皮转录因子MdMYB1表达的影响。研究表明,不同颜色苹果品种着色速度、面积和MdMYB1转录表达速度及累积量有关。通过金冠、红星苹果果实套袋处理,研究了果皮着色过程中结构基因苯丙氨酸解氨酶(MdPAL)、花青素合成酶(MdANS)、查尔酮异构酶(MdCHI)和类黄酮糖基转移酶(MdUFGT)的相对表达变化,结果表明,红星处理和对照转录因子MdMYB1及结构基因在着色过程中是持续表达的,而黄绿色品种金冠则没有出现持续表达的态势。金冠苹果转录因子MdMYB1与结构基因MdCHI表达模式相同,与MdPAL相似,经分析MdMYB1和结构基因MdCHI和MdPAL启动子序列,金冠苹果携带等位基因MdMYB1-2,其启动子区域有多个G-box光结合位点,据此推测,光照调控的光敏色素通过结合其启动子区域的G-box位点来调控转录因子MdMYB1-2;MdCHI在启动子区域含有顺式作用元件MBS,MdPAL含有顺式作用元件MBS和MBSⅡ,说明转录因子MdMYB1-2调控结构基因MdCHI表达,并有可能调控基因MdPAL或有密切相关性。结果表明,红星果皮全面着色可能与着色期转录因子及结构基因的持续表达和基因间协调表达有关;而金冠果皮在着红色过程中光诱导的转录因子MdMYB1调控的结构基因起决定性作用。     

Differences in the carotenoid content of ordinary citrus and lycopene-accumulating mutants

High-performance liquid chromatography, coupled with photodiode array detection, was used to analyze the carotenoid composition of peel and juice vesicle tissues of ordinary and lycopene-accumulating mutants (referred to as red mutants in this article) of orange, pummelo, and grapefruit. Thirty-six major carotenoids, including some cis-trans isomers, were separated on a C30 reversed phase column, and 23 of them were identified on the basis of retention times and spectral characteristics with authentic standards. Carotenoid profiles varied with tissue types, citrus species, and mutations. beta-Citraurin occurred in the peel of oranges but not in juice vesicles, whereas the reverse was found for violaxanthin, 9-cis-violaxanthin, and luteoxanthin. The diversity of carotenoids in peel and juice vesicle tissues and the fact that there was over 250 times higher content of total carotenoids in peels of Yuhuan pummelo than juice vesicles suggested that the biosynthesis of carotenoids in these two tissues was independent and exchange of carotenoids between the tissues was not likely. Lutein was observed in peels of pummelos and grapefruits and juice vesicles of ordinary pummelo but not in orange tissues. Accumulation of lycopene and beta-carotene was observed in red mutant citrus, except for the peel of Cara Cara red orange. Additionally, phytoene accumulated in all tissues except for the peel of Chuzhou Early Red pummelo. No obvious change in the total content of xanthophylls was observed in the Cara Cara red orange. Ordinary grapefruit (Marsh) tissues and pummelo (Yuhuan) juice vesicles were almost devoid of carotenoids, and in red mutants, the content of total carotenoids increased dramatically up to 790-fold. The different changes in carotenoid content and profiles in mutant(s) of different citrus species suggest that the underlying mechanisms for the mutations might be different.     

Chlorophyll and carotenoid patterns in olive fruits, Olea europaea Cv. arbequina

In olive fruits of the cultivar Arbequina, the chlorophyll pigments decrease significantly throughout ripening, while the carotenoids decrease more gradually and discontinuously. There is no degradation of the carotenoid fraction in stages before complete ripeness. The presence of esterified xanthophylls exclusively in this variety suggests that the chloroplast pigment metabolism is different from that in other olive varieties studied previously. There are increases of specific carotenoids, violaxanthin, neoxanthin, antheraxanthin, lutein epoxide, and esterified xanthophylls between the light green and yellowish green ripening stages. Such increases are related to the detection of precursor carotenoids (phytofluene and xi-carotene) in the yellowish green stage. Chlorophyllides (a and b) and alpha-carotene have also been detected exclusively in this variety. Quantitatively, the drastic change in color between light green and yellowish green ripening stages characteristic of this variety can be explained by the considerable reduction found in the chlorophylls/carotenoids ratio. The study of the pigments present in skin and pulp has shown that the pattern of carotenoid distribution differs depending on the fruit part concerned.     

Carotenoid accumulation in Japanese apricot (Prunus mume Siebold & Zucc.): molecular analysis of carotenogenic gene expression and ethylene regulation

To elucidate the regulatory mechanisms of carotenogenesis in Japanese apricot (Prunus mume Siebold & Zucc.), the relationships between carotenoid accumulation and the expression of the carotenogenic genes, phytoene synthase (PmPSY-1), phytoene desaturase (PmPDS), zeta-carotene desaturase (PmZDS), lycopene beta-cyclase (PmLCYb), lycopene epsilon-cyclase (PmLCYe), beta-carotene hydroxylase (PmHYb), and zeaxanthin epoxidase (PmZEP), were analyzed in two cultivars with different ripening traits, 'Orihime' and 'Nanko.' In 'Orihime' fruits, large amounts of carotenoids accumulated on the tree, concomitant with the induction of PmPSY-1 and the downstream carotenogenic genes PmLCYb, PmHYb, and PmZEP. In 'Nanko' fruits, carotenoids accumulated mainly after harvest, correlating with an appreciable induction of PmPSY-1 expression, but the downstream genes were not notably induced, which may explain the lower total carotenoid content in 'Nanko' than in 'Orihime.' In both cultivars, a decrease in PmLCYe expression and increased or constant PmLCYb expression could cause the metabolic shift from beta,epsilon-carotenoid synthesis to beta,beta-carotenoid synthesis that occurs as ripening approaches. Next, the effects of ethylene on the expression of PmPSY-1 and carotenoid accumulation were investigated in 'Nanko' fruits treated with propylene or 1-methylcyclopropene (1-MCP). Propylene treatment induced both ethylene production and carotenoid accumulation. PmPSY-1 was constitutively expressed, but propylene treatment accelerated its induction. 1-MCP treatment caused a slight inhibition of carotenoid accumulation along with the repression, although not complete, of PmPSY-1. Collectively, although PmPSY-1 expression was not exclusively regulated by ethylene, both the notable induction of PmPSY-1 accelerated by ethylene and the subsequent induction of the downstream carotenogenic genes, especially PmLCYb, could be necessary for the massive carotenoid accumulation that occurs during ripening. Furthermore, the switch from PmLCYe expression to PmLCYb expression could cause beta,beta-carotenoid accumulation in both Japanese apricot cultivars.     

Determination of carotenoids, total phenolic content, and antioxidant activity of Arazá (Eugenia stipitata McVaugh), an Amazonian fruit

The fruit of Arazá (Eugenia stipitata McVaugh) native to the Colombian Amazon is considered a potentially economically valuable fruit for the Andean economy due to its novel and unique taste. The fruit has an intense yellow color, but its chemical composition and properties have not been well studied. Here we report the identification and quantitation of carotenoids in the ripe fruit using high performance liquid chromatography (HPLC) with photodiode array detector (PDA) and atmospheric pressure chemical ionization (APcI) mass spectrometry (MS/MS). The qualitative carotenoid profile of the fruit according to maturity stage was also observed. Furthermore, antioxidant activity of the peel and pulp were assessed using the ferric reducing ability of plasma (FRAP), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and 1,1-diphenyl-2-picrylhydrazyl (DPPH) methods, in addition to chemical indexes and total phenolic content. Multiple carotenoids were identified in the peel and pulp including four xanthophylls (free and esterified as their mono and diesters) and two carotenes. One of the xanthophylls was tentatively identified as zeinoxanthin, while the others were identified as lutein, zeaxanthin, and β-cryptoxanthin. Carotenes included α-carotene and β-carotene. The total carotenoid content was significantly higher in the peel (2484 ± 421 μg/100 g FW) than in the pulp (806 ± 348 μg/100 g FW) with lutein, β-cryptoxanthin, and zeinoxanthin as the major carotenoid components. The unique carotenoid composition of this fruit can differentiate it from other carotenoid-rich fruits and perhaps be useful in authentication procedures. Overall, results from this study suggest that Colombian Arazá may be a good edible source of carotenoids important in retinal health as well as carotenoids with provitamin A activity. Therefore, Arazá fruit can be used as a nutraceutical ingredient and in production of functional foods in the Colombian diet.     

Effect of blue and red LED light irradiation on β-cryptoxanthin accumulation in the flavedo of citrus fruits

β-Cryptoxanthin (β-cry), an antioxidant abundant in citrus fruits, plays an important role in the prevention and treatment of certain diseases, especially cancers. In the present study, to increase the content of β-cry in citrus flavedo, the effects of blue (470 nm) and red (660 nm) light-emitting diode (LED) lights on the accumulation of carotenoids and expression of genes related to carotenoid biosynthesis were investigated in the flavedo of Satsuma mandarin. The results showed that accumulation of β-cry was induced by red light, while it was not affected by blue light. The accumulation of β-cry under red light was attributed to simultaneous increases in the expression of CitPSY, CitPDS, CitZDS, CitLCYb1, CitLCYb2, CitHYb, and CitZEP. The results presented herein might provide new strategies to enhance the commercial and nutritional value of citrus fruits.     

Benzylglucosinolate, benzylisothiocyanate, and myrosinase activity in papaya fruit during development and ripening

Papaya is a climacteric fruit that has high amounts of benzylglucosinolates (BG) and benzylisothiocyanates (BITC), but information regarding levels of BG or BITC during fruit development and ripening is limited. Because BG and BITC are compounds of importance from both a nutritional and a crop yield standpoint, the aim of this work was to access data on the distribution and changes of BG and BITC levels during fruit development and ripening. BG and BITC levels were quantified in peel, pulp, and seeds of papaya fruit. Volatile BITC was also verified in the internal cavity of the fruit during ripening. The influence of the ethylene in BG and BITC levels and mirosinase activity was tested by exposing mature green fruits to ethylene and 1-methylcyclopropene (1-MCP). The highest BG levels were detected in seeds, followed by the peel and pulp being decreased in all tissues during fruit development. Similarly, the levels of BITC were much higher in the seeds than the peel and pulp. The levels of BG for control and ethylene-treated fruit were very similar, increasing in the pulp and peel during late ripening but not changing significantly in seeds. On the other hand, fruit exposed to 1-MCP showed a decrease in BG amount in the pulp and accumulation in seed. The treatments did not result in clear differences regarding the amount of BITC in the pulp and peel of the fruit. According to the results, ethylene does not have a clear effect on BITC accumulation in ripening papaya fruit. The fact that BG levels in the pulp did not decrease during ripening, regardless of the treatment employed, and that papaya is consumed mainly as fresh fruit, speaks in favor of this fruit as a good dietary source for glucosinolate and isothiocyanates.     

Changes in chloroplast pigments of olive varieties during fruit ripening

Changes in chlorophyll and carotenoid pigments of five olive (Olea europaea L.) varieties destined for milling were investigated at six consecutive ripening stages. There was a manifest dependence between olive variety, moment of picking, and chloroplast pigment composition of the fruits. Although the content of chlorophylls and carotenoids differed with fruit variety, ripening always involved their gradual loss, which becames more pronounced with increased presence of anthocyanin compounds. The relative rates of disappearance of chlorophylls and carotenoids were markedly different between varieties, implying that the catabolism of these pigments takes place at a relative rate inherent to each variety. The varieties less rich in pigments showed the most extreme behavior. The highest relative rate of disappearance was observed in fruits of the Blanqueta variety, and the lowest was observed in those of Arbequina. The chlorophyll a/chlorophyll b ratio remained practically constant during ripening, with a value very similar for Hojiblanca, Picual, Cornicabra, and Blanqueta, but much higher for Arbequina, implying that the structure of the photosynthetic apparatus is different in the latter variety. In the five varieties studied, lutein was the slowest carotenoid to be degraded, so that its percentage in the fruits increased with ripening, whereas beta-carotene was the fastest to disappear. In ripe fruits covered with anthocyanins, chloroplast pigments were retained in both skin and pulp, with the rate of disappearance being much higher in the latter.     

Carotenoids in white- and red-fleshed loquat fruits

Fruits of 23 loquat ( Eriobotrya japonica Lindl.) cultivars, of which 11 were white-fleshed and 12 red-fleshed, were analyzed for color, carotenoid content, and vitamin A values. Color differences between two loquat groups were observed in the peel as well as in the flesh. beta-Carotene and lutein were the major carotenoids in the peel, which accounted for about 60% of the total colored carotenoids in both red- and white-fleshed cultivars. beta-Cryptoxanthin and, in some red-fleshed cultivars, beta-carotene were the most abundant carotenoids in the flesh, and in total, they accounted for over half of the colored carotenoids. Neoxanthin, violaxanthin, luteoxanthin, 9- cis-violaxanthin, phytoene, phytofluene, and zeta-carotene were also identified, while zeaxanthin, alpha-carotene, and lycopene were undetectable. Xanthophylls were highly esterified. On average, 1.3- and 10.8-fold higher levels of colored carotenoids were observed in the peel and flesh tissue of red-fleshed cultivars, respectively. The percentage of beta-carotene among colored carotenoids was higher in both the peel and the flesh of red-fleshed cultivars. Correlations between the levels of total colored carotenoids and the color indices were analyzed. The a* and the ratio of a*/ b* were positively correlated with the total content of colored carotenoids, while L*, b*, and H degrees correlated negatively. Vitamin A values, as retinol equivalents (RE), of loquat flesh were 0.49 and 8.77 microg/g DW (8.46 and 136.41 microg/100 g FW) on average for white- and red-fleshed cultivars, respectively. The RE values for the red-fleshed fruits were higher than fruits such as mango, red watermelon, papaya, and orange as reported in the literature, suggesting that loquat is an excellent source of provitamin A.