Fruit Malformation of Satsuma Mandarin (Citrus unshiu Marc.) Infected by Citrus Yellow Vein Clearing Virus

In 2013–2014, malformed young Satsuma mandarin (Citrus unshiu Marc.) fruits were found in Xunwu County, Jiangxi Province, China. Common disease symptoms include slightly curled and backward‐twisted spring leaves, cracked and deformed leaf edges, thickly grown spring twigs with twisted and slightly bent shoots, and malformed young fruits where groovelike depression forms from the upper portion and resembles a pumpkin. On the basis of the morphological characteristics, sequencing results and phylogenetic analysis of the infected plant, we identified the disease as citrus yellow vein clearing, which is caused by Citrus yellow vein clearing virus (CYVCV). To our knowledge, this study is the first to report CYVCV infecting Satsuma mandarin.     

温州蜜柑果实发育进程中光合产物运输分配及糖积累特性

测定了温州蜜柑果实发育进程中糖的积累动态,并用14C示踪方法研究了果实发育不同阶段源叶的光合产物在果实中的运输分配特性.结果表明(1)果实组织中的糖含量随果实发育持续上升,果皮以积累己糖为主而其它组织则以积累蔗糖为主或略多.(2)在果实完熟之前,汁囊分配到的光合产物均占果实的50%以上,为果实中的光合产物分配中心;而到完熟阶段分配到汁囊的14C光合产物与其它组织接近,不再有明显的分配中心.(3)汁囊中的14C放射性比活度随着果实发育呈下降趋势,尤其在后期下降极为明显.(4)维管束/囊瓣表皮和囊瓣表皮/汁囊的14C放射性比活度的比率都随果实发育进程而增大,但后者的比率要大大高于前者,表明韧皮部后运输是光合产物进入汁囊的限速阶段.(5)输入到汁囊的14C光合产物主要以蔗糖形式存在,说明光合产物是以蔗糖为主体输入汁囊参与糖积累和代谢的.     

Ethylene-induced changes of chloroplast structure in Satsuma mandarin (Citrus unshiu Marc.)

Ethylene-induced changes of chloroplast structure in Satsumamandarin (Citrus unshiu Marc.) were examined using light andelectron microscopy. In ethylene-treated fruits, the numberof chloroplasts decreased; this was especially remarkable incells distant from the epidermis. Rapid reduction in chloroplastsize was a characteristic feature. The inner membrane system of the chloroplasts of ethylene-treatedfruits disintegrated prior to the disintegration of other cellstructures. The disintegration of the membranes within the chloroplastswas expressed by the word "melt". The double-layered structureof lamellar and granal membranes was degraded and the membranelayers became separated. Another interesting feature was the appearance of finger-likeprotuberances and peripheral reticula in the chloroplasts ofthe ethylene-treated fruits. (Received June 13, 1977; )     

温州蜜柑叶片气体交换和叶绿素荧光对低温的响应

研究了低温对温州蜜柑叶片气体交换和叶绿素荧光的影响 ,结果表明 :(1) 8℃低温处理 18h对气体交换和叶绿素荧光影响不大。 (2 ) 2℃低温处理 15h后 ,净光合速率 (Pn)、气孔导度 (Gs)、羧化效率 (CE)下降 ,胞间CO2 浓度 (Ci)升高 ,表观量子效率 (AQY)和叶绿素荧光参数F0 及Fv/Fm没有显著变化。 (3)室外自然低温处理 2和 7d ,Pn、Gs、CE、饱和CO2 光合速率、AQY及Fv/Fm显著下降 ,Ci及F0 显著升高 ;在 2 0℃室内 ,Fv/Fm、F0 和AQY比CE和Pn恢复快。 (4 )低温胁迫使Jf(依据叶绿素荧光参数计算所得的电子传递速率 )和Jc(依据CO2 同化测定所得的电子传递速率 )下降 ,Jf/Jc 值升高。 (5 )低温处理降低了Pn和光呼吸速率 (Pr) ,但Pr下降的速率小于Pn下降的速率     

柑橘果实遮光处理对发育中的果实光合产物分配、糖代谢与积累的影响

研究了柑橘果实膨大初期遮光处理对果皮色素、果实含糖量、光合产物在果实内的分配及果实中蔗糖代谢相关酶活力变化的影响.结果表明遮光处理使果皮中的叶绿素含量迅速降低而类胡萝卜素积累缓慢,蔗糖的相对含量则明显上升.遮光处理还促进了光合产物向果皮运输,相应地降低了汁囊中光合产物分配比率,使果实汁囊中蔗糖含量下降.果皮中SS、SPS和转化酶活力在遮光处理后均有较大的提高,而汁囊中则差异不大.上述结果表明,在果实自身光合作用被抑制的条件下,果皮是通过提高酶活力来增强库强度,从而使其在与汁囊竞争中获得更多的光合产物,造成汁囊含糖量下降.     

Ethylene Production and Respiration of Postharvest Acid Citrus Fruits and Wase Satsuma Mandarin Fruit

Ethylene production and respiratory rate were examined in acid citrus fruits such as yuzu, seedless yuzu and daidai, and wase satsuma mandarin. A large amount of ethylene was produced from four varieties of citrus fruits harvested from May to July but not after September. A rise in ethylene production did not always coincide with a rise in respiratory rate. Excised tissues of fruits contained the ability of ethylene production throughout the developmental stages. The endogenous ethylene level at the ripening stage, reached the maximum when the color changed from green to yellow.     

Wound-induced Ethylene Formation in Albedo Tissue of Citrus Fruit

Excised albedo tissue of citrus fruit (Citrus unshiu and Citrus hassaku) produced ethylene at an increasing rate in response to wounding and aging. The application of 1-aminocyclopropane-1-carboxylic acid (ACC) enhanced ethylene production in both the fresh and aged tissues, but this increase was greater in the aged tissue than in the fresh tissue. ACC content was very low in fresh tissue but increased greatly in aging tissue, paralleling the rise in ethylene production. Aminoethoxyvinylglycine (AVG) strongly inhibited ethylene production in the aged tissue. In the presence of ACC, however, ethylene production was not inhibited by AVG. These results suggest that ACC is an intermediate in the pathway of ethylene biosynthesis in the albedo tissue and that both steps of ACC formation and ACC conversion to ethylene are enhanced by wounding and aging. Inhibitors of protein synthesis, cycloheximide and 2-(4-methyl-2,6-dinitroanilino)-N-methyl propionamide, strongly inhibited ethylene production in the albedo tissue, implying that protein synthesis is required to maintain the continuous evolution of ethylene. The stimulation of ethylene production by ACC was reduced by the addition of l-methionine, whereas d-methionine had very little inhibitory effect. Ethylene production in the albedo tissue was also inhibited by the addition of n-propyl gallate and 3,5-dibromo-4-hydroxybenzoic acid.     

Low concentrations of NaHSO3 increase photosynthesis, biomass, and attenuate photoinhibition in Satsuma mandarin (Citrus unshiu Marc.) plants

Spraying low concentrated (0.5–5.0 mM) solutions of NaHSO₃ on Satsuma mandarin (Citrus unshiu Marc.) leaves resulted in enhancement (maximal about 15 % at 1 mM NaHSO₃) of net photosynthetic rate (P _N) for 6 d. The potential photochemical efficiency of photosystem 2 (PS2, F_v/F_m) and the quantum yield of PS2 electron transport (Φ_PS2) were increased under strong photon flux density (PFD). The slow phase of millisecond delayed light emission (ms-DLE) was increased, showing that the transmembrane proton motive force related to photophosphorylation was enhanced. We also observed that low concentrations of NaHSO₃ promoted the production of ATP in irradiated leaves. We suggest that the increase in P _N in Satsuma mandarin leaves caused by low concentrations of NaHSO₃ solution may have been due to the stimulation of photophosphorylation and, hence, the increase in photochemical efficiency through speeding-up of PS2 electron transport. Photoinhibition of photosynthesis in leaves was modified by NaHSO₃ treatment under high PFD. Hence the increase in leaf dry mass seems to be associated with the mitigation of photoinhibition caused by strong PFD.     

利用细胞松弛素B分离柑橘及金柑植物微核的研究

采用细胞松弛素B(CB)处理结合蔗糖梯度超速离心方法分离柑橘和金柑亚原生质体的结果表明,柑橘和金柑原生质体的直径为20～30μm,采用蔗糖梯度超速离心分离亚原生质体,其适宜离心力是1400000×g;4',6-二脒基-2-苯基吲哚(DAPI)的染色效果最好,细胞核和细胞质可明显区分;愈伤组织经CB处理36h后再分离亚原生质体,可显著提高微原生质体的产量,分离的微原生质体直径为1.8～3.5μm,产量达到2～3×104个·g-1(FW)。     

Characterization of gamma-terpinene synthase from Citrus unshiu (Satsuma mandarin)

Gamma-terpinene is a monoterpene and a major component of essential oils made from citrus fruits and shows strong antioxidant activity in various assay systems. Plant gamma-terpinene synthase is a member of the monoterpene cyclase family, which produces a specific monoterpene through cyclization of geranyl diphosphate (GPP), but the monoterpene cyclases have not been fully characterized. It is necessary to prepare large amounts of gamma-terpinene synthase from Citrus unshiu (Satsuma mandarin) for the characterization, on this purpose we expressed the protein in Escherichia coli (E. coli) cells. As most monoterpene synthases have plastid-targeting signals, a gene lacking these signals was prepared and functionally expressed in E. coli cells harboring extra copies of the argU gene. The purified enzyme was incubated with GPP and the main product was confirmed to be gamma-terpinene by GC/MS.     

In vitro plantlet formation from juice vesicle callus of satsuma (Citrus unshiu Marc.)

Callus was induced from juice vesicles of satsuma mandarin on Murashige & Skoog medium supplemented with -naphthaleneacetic acid (NAA), kinetin (K) and gibberellin (GA). Adventitious embryoids arose from the callus tissue on the medium containing 1 mgl^–1 NAA alone. The embryoids grew into embryos which resulted in a plantlet on medium containing 1 mgl^–1 GA.Abbreviations GA gibberellin - K kinetin - NAA -naphthaleneacetic acid     

Respiratory Response, Ethylene Production, and Response to Ethylene of Citrus Fruit during Ontogeny

The initial respiratory rates at 20 centrigrade of detached oranges (Valencia and navel), grapefruit, and lemons decreased during ontogeny. Small attached oranges respired at the same rate as detached fruits of the same weight, and cutting the pedicel produced no shock or injury stimulus to the respiratory rate. Small oranges and grapefruit (average weight about 15 grams) showed pseudoclimacteric respiratory patterns and produced ethylene. The height of the respiratory rise and the amount of ethylene produced decreased as the fruit increased in weight until the September 4th harvest, when the fruit weights were 120, 64, and 87 grams for grapefruit, Valencia, and navel oranges, respectively; at that time no respiratory rise or ethylene production was observed. The pattern for all subsequent harvest revealed no postharvest rise in the respiratory rates. Lemon fruit, in contrast, had a continuously decreasing respiratory rate at all stages of ontogeny. Exposure to 20 microliters of ethylene per liter induced an increase in the respiratory rate of all varieties at every stage of ontogeny; this was true also in young oranges and grapefruit following their respiratory rise and decline.     

温州蜜柑叶片水提取液的抑菌效果

柑橘除部分品种用于鲜食和加工外,许多品种的果实及下脚料未得到充分的综合利用[1].自20世纪60年代以来,国内外学者对不同柑橘品种中的60多种类黄酮的提取、纯化及结构测定、类黄酮的药理学及其他应用方面进行了研究[2～4].研究发现: 槲皮酮和橘皮苷能显著抑制脊髓灰质炎病毒、单纯性疱疹病毒、副流感病毒等病毒的感染和复制; 多甲基黄酮如橙黄酮、蜜橘黄素和柑橘黄酮具有抗病毒和抗菌的作用[5～8].但尚未见柑橘叶生理活性物质提取及其对常见细菌和真菌的抑菌实验的报道.本文初步研究了温州蜜柑叶片提取液对大肠杆菌、枯草芽孢杆菌、金黄色葡萄球菌、白色念珠菌的抑菌作用,旨在为进一步开发利用柑橘叶提供依据.     

Effects of Exogenous Growth Regulators on Fruit Development in Citrus unshiu

The effects of applied growth regulators on fruit developmenthave been determined in the parthenocarpic Satsuma mandarin(Citrus unshiu Marc.). The application of either gibberellicacid or benzyladenine at flower opening, caused a transientincrease in cell division in the ovary wall, but had no significanteffect on final fruit size. Late fruit growth and final fruitsize were increased by the application of the synthetic auxin2,4,5-trichlorophenoxyacetic acid, which had a specific effecton the enlargement of the juice vesicles. The three growth regulators enhanced vascularization in thepedicel, but the growth effects observed were unrelated to theirinfluence on the transport capacity of the phloem but causedby their direct effects on the fruit tissues. The sensitivityof the fruit tissues to the applied growth regulators changedmarkedly during early fruitlet development, and was characterizedculturing the fruit tissues in vitro.Copyright 1993, 1999 AcademicPress Citrus unshiu Marc., fruit growth, hormone treatment, in vitro culture, phloem formation, phloem transport, xylogenesis