Lipid Composition of Citrus Leaves from Plants Resistant and Susceptible to Citrus Bacterial Canker

The contents and composition of lipids in citrus leaves in relation to their general resistance to infection by strains of Xanthomonas campestris pv. citri (Xcc) were determined. The composition and contents of total polar lipids and phospholipids and the degree of fatty acid unsaturation were significantly different between resistant and susceptible species. Leaves from resistant plants had less phospholipids, but more free sterols than those from susceptible plants. The predominant fatty acids in the phospholipids were palmitic (16:0), linoleic (18:2) and α-linolenic acid (18:3). The degree of fatty acid unsaturation was higher in susceptible plants than in resistant plants. Major phospholipids in citrus leaves were phosphatidylchloline (PC), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), and phosphatidylinositol (PI). β-Sitosterol, campesterol and lanosterol were major sterols in the leaves of citrus plants with resistant species having a higher ratio of free sterols to total phospholipids than susceptible species. Differences in lipid metabolism may contribute to differences in Xcc-resistance of citrus leaves.     

Organelle-specific Isozymes of Aspartate-alpha-Ketoglutarate Transaminase in Spinach Leaves

Four distinct isozymes of aspartate-α-ketoglutarate transaminase in a spinach (Spinacia oleracea L.) leaf extract were separated by starch gel electrophoresis. Of the total aspartate-α-ketoglutarate transaminase activity, approximately 45% was represented by the chloroplast isozyme, 26% by the cytosol isozyme, 19% by the mitochondrial isozyme, and 3 to 10% by the peroxisomal isozyme. The aspartate-α-ketoglutarate transamination activity in the four subcellular compartments behaved similarly. It was freely reversible and α-ketoglutarate was preferred to pyruvate or glyoxylate as the amino group acceptor. With glutamate as the amino group donor, oxaloacetate was superior to pyruvate or glyoxylate as the acceptor in chloroplasts, mitochondria, and cytosol, while pyruvate or glyoxylate was preferred to oxaloacetate as the acceptor in peroxisomes.     

A Study on Glutamate Oxaloacetate Transaminase Isozymes of Citrus Germplasm Resources

The glutamate oxaloacetate transaminase isozymes (GOT) extracted from 125 biotypes of Citrus and its relatives, Fortunella, Poncirus and Microcitrus were analyzed using polyacrylamide gel electrophoresis to investigate the taxonomic relationships among citrus plants. Besides all the isozymes reported before, two new bands were detected and designated their putative alleles B and C in GOT-l. Among pummelo cultivars wide variations were found. Most of the mandarins were identical, having SS for GOI-1 and MM for GOT-2 except for Zou-Pi-Gan and Yao-Gan, which both had FS at GOT-1 and might be hybrids. This finding suggests that all of the mandarins may have originated from a common ancestor. Sour orange biotypes showed a considerable variation in GOT isozymes. Most of the sour oranges in China were assumed to be hybrids between pummelo and mandarin based on GOT isozyme patterns, but two biotypes, Xiao-Hong-Cheng and Zhu-lan, had FS at GOT-1 and MB at GOT-2, which strongly suggests that they be hybrids of pummelo and Ichang papeda because B allele of GOT-2 occurs only in Ichang papeda and its close relatives Yuzu and Ichang lemon. From this study Yuzu is assumed to be derived from hybridizationof Ichan, papeda and mandarin.     

The Chemical Components of Essential Oils from the Leaves of 110 Species and Cultivars of Citrus Plants

Seventy-two chemical components of essential oils from the leaves of 110 species and cultivars of Citrus were analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Among the plants analyzed, there are 3 species in papeda, 12 species and cultivars in Osmocitrus, 18 cultivars in C. aurantium L., 15 cultivars in C. sinensis Osbeck, 16 species and cultivars in Citrophorum, 16 species and cuhivars in Cephalocitrus, 30 species and cultivars in Acrumen. As resources of essential oils, some valuable plants were found such as Citrus hystrix D. C., C. junos (Sieb.) Tan. cv. Xiecheng, C. junos (Sieb.) Tan. cv. Luohancheng and C. tankan Hayata. Our study has provided systematic data of the chemical components of the essential oils for the taxonomic work of Citrus plants.     

无融合生殖与柑橘多胚现象的研究进展

植物无融合生殖是指植物的胚珠组织不经历正常的减数分裂和受精作用,而直接进行胚发育形成种子的无性生殖方式。无融合生殖植物完全继承了母体的全部基因型,因而具有独特研究与育种意义。芸香科柑橘属植物具有独特的多胚现象,其珠心组织能够发育成不定胚(称为珠心胚)进行无融合生殖。文中介绍了柑橘类植物的珠心胚生殖现象、细胞学和遗传学研究进展。珠心胚现象虽然对柑橘杂交后代获得有较大影响,但在生产上可产生性状整齐一致的后代,可以培育无病毒苗木。     

Rearing Migratory Endoparasitic Nematodes in Citrus Callus and Roots Produced from Citrus Leaves

Radopholus similis and Pratylenchus coffeae were reared on callus and roots developed from citrus leaves. Callus formed best when leaf petioles were immersed in Astatula fine sand and the leaves were sprayed daily with 4 ppm 2,4-D solution and maintained at 25 or 30 C. The nematodes completed one generation in 20 days at 25 C. Highest populations of R. similis (1,127) occurred after 50 days, and the highest for P. coffeae (619) after 70 days. Leaf-callus cultures from R. similis-resistant citrus rootstocks showed the same degree of infection as susceptible rough lemon callus after 30 days.     

Movement of Tritiated Water through Young Citrus Plants

Water movement through different organs of 1–2 year oldSour Orange seedlings was studied by using tritium as a tracerinjected into the nutrient solution. The activity of the leaftissue water of plants free to exchange water with the atmospherereached only 60–70% of the nutrient solution even afterlong periods exceeding 30 h, whereas in plants exposed to dryair the activity approached equilibrium with the solution. Turnoverof water was less rapid in the laminae than in the midveinsof the leaves, in both cases the rate being a function of theamount of foliage on the plant. A reduction in transpirationrate effected by plastic covering, silicone coating, or abscisicacid spray was clearly indicated by a lowered level of tritiumactivity in the plant tissue.     

Numerical Chemotaxonomical Study on Citrus Plants Cultivated in China

Soluble proteins were extracted from mature leaves of 83 citrus biotypes. Their protein patterns were obtained by acrylamide gel electrophoresis. The similarity of the protein patterns among the samples was calculated by computer according to the principle and methods of numerical taxonomy. The similarity comparison was made between different species and varieties included in the Swingl’s system. The distance coefficients of similarity (DCS) is 2.13 between species in the genus Citrus, 0.927 in Poncirus and 0.617 among Fortunella species. The DCS of biotypes in Citrus limon, C. paradisi and C. sinensis are zero, and those in C. grandis and C. reticulata are 0.656 and 0.863 respectively. There is no difference among satsuma mandarin, Tankan and King mandarin, which are considered respectively as a good species in Tanaka’s system. Ancestors of some biotypes. whose origin was unknown berore, are postulated in this work. Jiang Bai Shang Cheng is probably a hybrid between C. junos Tanaka and mandarin, rough lemon may be a hybrid of mandarin with citron or lime, but not with lemon. Some so-called lemon biotypes are not in the same cluster as true lemon (Eureka or Lishon). The biotypes. of sour orange, all of which are scattered in the phenetic tree of cluster analysis (PTCA), might have been derived from different ancestors. In the PTCA the evolutionary tendency from Poncirus to Macroacrumen in the citrus plants may be found on the basis of the DCS of different genera, sections and subsections respectively with the subsection Macroacrumen. The present author considers that if Fortunella is recognized as true genus, Cephalocitrus should also be an acceptable genus. The position of Fortunella in the PTCA is between the sections Cephalocitrus and Aurantium, but it does not represent its position in the phylogeny. Taking comprehensive data into consideration it appear to be more reasonable to place C. ichangensis, as member of Papeda originated in the subtropics, in the section Papeda.     

Amino Acid Content of Leaves in Mycorrhizal and Non-mycorrhizal Citrus Rootstocks

Nitrogen status was examined in leaves of sour orange and roughlemon citrus rootstocks grown in a low phosphorus sand inoculatedwith Glomus etunicatus, in sand amended with superphosphateat a rate of 2240 kg ha^–1, and in a sand control leftuntreated. Sour orange was 3.1- and 3.5-fold taller and roughlemon was 1.8- and 2.0-fold taller than the controls in theinoculated and phosphorus treatments, respectively. In the controls,leaf N was up to 2.5-fold higher than in the other treatments.Both total and free amino acids accumulated in leaves of bothrootstocks to higher levels in the control than in the othertreatments. Most total amino acids in the control were lowerthan in the treatments, with the exceptions of arginine (upto 12-fold increase), proline (up to 1.8-fold increase), lysine,and free ammonia. Twenty-two free amino acids, urea, and ammoniawere detected. Both rootstocks grown in control sand had significantincreases in citrulline, ornithine, lysine, histidine, arginineand ammonia. Levels of total and most free amino acids in theinoculated and phosphorus treatments were similar to one another.It is suggested that mineral deficiency caused by the absenceof G. etunicatus causes a reorganization of N-metabolism witha shift to a greater synthesis of ornithine cycle intermediates. Citrus aurantium L., Citrus limon (L.) Burm, amino acid content, citrus rootstocks, mycorrhiza, nitrogen metabolism     

ABA in Roots and Leaves of Flooded Pea Plants

Zhang, J. and Davies, W. J. 1987. ABA in roots and leaves offlooded pea plants.—J. exp. Bot. 38: 649–659. Roots of potted pea (Pisum sativum L. cv. Feltham First) seedlingswere flooded with tap water. Within a few hours of the startof the flooding treatment the content of free ABA in roots increasedcompared to contents of roots of unflooded control plants butthis increase was not statistically significant until the beginningof the second day after flooding. Approximately 36 h after firstflooding significant increases in the free-ABA content of leaveswere detected. This was 14 h after significant increases inthe amount of ABA in the roots of the same plants. There wasmarked diurnal variation in free-ABA content of leaves and rootsof plants that had been flooded for several days, with maximumcontents recorded 3 h or more after the beginning of the lightperiod. Very rapidly after the lights were switched oft ABAcontents declined. On day 3 of the flooding treatment, therewas more than a 5-fold decrease in the free-ABA content of leaveswithin a few hours of the beginning of the dark period. Radio-immunoassaysuggested that a very large proportion of the total ABA in theplant was in a bound form. This form of ABA increased substantiallyas the flooding period progressed. The importance of variation in ABA content for the control ofwater relations and gas exchange of flooded plants is discussed. Key words: Flooding, Pisum sativum, ABA, water relations     

Biotransformations of Terpenes by Fungi from Amazonian Citrus Plants

The biotransformations of (RS)‐linalool ( 1 ), (S)‐citronellal ( 2 ), and sabinene ( 3 ) with fungi isolated from the epicarp of fruits of Citrus genus of the Amazonian forest (i.e., C. limon, C. aurantifolia, C. aurantium, and C. paradisiaca) are reported. The more active strains have been characterized, and they belong to the genus Penicillium and Fusarium. Different biotransformation products have been obtained depending on fungi and substrates. (RS)‐Linalool ( 1 ) afforded the (E)‐ and (Z)‐furanlinalool oxides ( 7 and 8 , resp.; 39 and 37% yield, resp.) with Fusarium sp. (1D2), 6‐methylhept‐5‐en‐2‐one ( 4 ; 49%) with F. fujikuroi, and 1‐methyl‐1‐(4‐methypentyl)oxiranemethanol ( 6 ; 42%) with F. concentricum. (S)‐Citronellal ( 2 ) gave (S)‐citronellol ( 12 ; 36–76%) and (S)‐citronellic acid ( 11 ; 5–43%) with Fusarium species, while diastereoisomeric p‐menthane‐3,8‐diols 13 and 14 (20 and 50% yield, resp.) were obtained as main products with Penicillium paxilli. Finally, both Fusarium species and P. paxilli biotransformed sabinene ( 3 ) to give mainly 4‐terpineol ( 19 ; 23–56%), and (Z)‐ and (E)‐sabinene hydrates ( 17 (3–21%) and 18 (11–17%), resp.).     

柑桔原生质体融合再生叶肉亲本型植株的遗传分析

叶肉亲本（粗柠檬）型植株叶形指数、气孔特征与亲本粗柠檬无异,与同组合体细胞杂种差异显著。染色体计数为二倍体（２ｎ＝２ｘ＝１８）。过氧化物酶（ＰＯＸ）、多酚氧化酶（ＰＰＯ）、谷草转氨酶（ＧＯＴ）同工酶图谱与粗柠檬一致。ＲＡＰＤ分析表明,在具多态性的５４个随机引物中,大多数引物（５２个）上的图谱与粗柠檬相同。但ＯＰＷ－１２上,叶肉亲本型植株含有哈姆林甜检的特征谱带。ＯＰＶ－０４扩增产物显示,叶肉亲本型     

Metabolic Pathway of alpha-Ketoglutarate in Citrus Leaves as Affected by Phosphorus Nutrition

The uptake and metabolism of α-[5-¹⁴C]ketoglutarate by phosphorus-deficient and full nutrient (control) lemon (Citrus limon) leaves were studied over various time intervals. After 45 minutes in P-deficient leaves, the bulk of incorporated ¹⁴C appeared in organic acids and much less in amino acids, while in the control leaves, the ¹⁴C contents of organic and amino acids were equal. In P-deficient leaves, after longer incubation times the ¹⁴C content of organic acids and amino acids increased, while that of CO₂ and residue fractions remained low. In full nutrient leaves the ¹⁴C content of amino acids and organic acids decreased after longer incubation time and increased in the insoluble residue and CO₂. In full nutrient leaves the organic and amino acid metabolism were closely related and accompanied by protein synthesis and CO₂ release, while in P-deficient leaves an accelerating accumulation of arginine and citric acid was linked together with inhibition of protein synthesis and CO₂ liberation.     

SPME-GC-MS分析桃金娘科6种植物的叶片挥发性成分

采用固相微萃取-气质联用技术分析红果仔（Eugenia uniflora Linn.）、海南蒲桃（Syzygium hainanense Chang et Miau）、红鳞蒲桃（Syzygium hancei Merr. et Perry）、黄金香柳（Milleara bracteata F. Muell. c.v. ）、白千层（Melaleuca leucadendron Linn.）、柠檬桉（Eucalyptus citriodora Hook. f.）6种桃金娘科植物叶的挥发性成分。6种桃金娘科植物叶的挥发成分主要为萜烯类,且富含保健性挥发成分,共有成分为(Z)-β-罗勒烯、β-石竹烯、月桂烯、γ-萜品烯和别香橙烯。对这6种桃金娘科植物的叶片挥发性成分进行萃取与分析,对于合理栽培该科植物,有效利用其生态效益来提高人类生活环境和改善健康状况提供科学依据。