Deep Sequencing Analysis of RNAs from Citrus Plants Grown in a Citrus Sudden Death-Affected Area Reveals Diverse Known and Putative Novel Viruses.

Citrus sudden death (CSD) has caused the death of approximately four million orange trees in a very important citrus region in Brazil. Although its etiology is still not completely clear, symptoms and distribution of affected plants indicate a viral disease. In a search for viruses associated with CSD, we have performed a comparative high-throughput sequencing analysis of the transcriptome and small RNAs from CSD-symptomatic and -asymptomatic plants using the Illumina platform. The data revealed mixed infections that included Citrus tristeza virus (CTV) as the most predominant virus, followed by the Citrus sudden death-associated virus (CSDaV), Citrus endogenous pararetrovirus (CitPRV) and two putative novel viruses tentatively named Citrus jingmen-like virus (CJLV), and Citrus virga-like virus (CVLV). The deep sequencing analyses were sensitive enough to differentiate two genotypes of both viruses previously associated with CSD-affected plants: CTV and CSDaV. Our data also showed a putative association of the CSD-symptomatic plants with a specific CSDaV genotype and a likely association with CitPRV as well, whereas the two putative novel viruses showed to be more associated with CSD-asymptomatic plants. This is the first high-throughput sequencing-based study of the viral sequences present in CSD-affected citrus plants, and generated valuable information for further CSD studies

Evaluation of fruit quality in a lemon cybrid with mandarin mitochondria

Nutritional and organoleptic qualities of fruit are currently very important objectives for plant breeders. Organic acids, sugars and carotenoids were studied by high liquid chromatography on the pulp of a citrus cybrid. This cybrid named 'WLM + EUR' (Citrus deliciosa Ten.) + (Citrus limon (L.) Burm.), inherited nuclear and chloroplasts genomes of Eureka lemon (Citrus limon (L.) Burm.) plus mitochondria from Willow leaf mandarin (Citrus deliciosa Ten.). In our work, impact of new mitochondria on fruit quality was studied during the maturity period. We observed that the cybrid was different from willow leaf mandarin and close to lemon parent. Organic acids level is slightly increased in the cybrid fruit pulp compared to Eureka lemon. No significant difference is observed in sugars and carotenoids between the cybrid and the lemon. The results confirm that mains genetic information for sugars, organic acids and carotenoids biosynthesis are contained in the nucleus. Cybridisation should be used in citrus as a strategy to breed specifie traits associated with mitochondrial genomes such as male sterility without affecting the main organoleptic and nutritional qualities. (Texte intégral

Evaluation of the resistance of few citrus rootstocks to alkalinity by applying a faste test of secreening

Alkalinity of Moroccan soils is the major abiotic constraint on citrus production area. The best choice of citrus rootstocks adequate and resistant is a better solution to avoid this problem. The aim of this study is to develop a fast test of citrus rootstocks screening towards alkalinity. The alkaline stress was applied on ten citrus rootstocks two month old, using irrigation with a Hoagland and Arnon solution added with 1 g CaCO(3)/L and adjusted at various pH levels 6, 7 and 9. Observations concerned symptoms incidence and severity of iron chlorosis after two months of rearing. Results permitted to classify Poncirus trifoliata and Flying dragon as the most sensitive to alkalinity stresses, whereas, Citrus volkameriana and Citrus macrophylla were resistant. These conclusions are equivalent with those obtained with old citrus rootstocks in field trials

The use of kaolin to control Ceratitis capitata in organic citrus groves.

The Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera Tephritidae), is the key pest in some organically managed citrus orchards in Sicily. The effectiveness of processed kaolin (Surround WP) for control of C. capitata damage was tested in field trials carried out in 2003-2004 on two early ripening citrus species: satsuma (Citrus unshiu Markow.) and clementine (Citrus clementina Hort. ex Tan.). Although the number of males captured in trimedlure baited traps was high in both years and in both orchards, the percentage of damaged fruit varied greatly from almost 0% (satsuma 2003) to more than 60% (clementine, both years). Nevertheless, the application of processed kaolin significantly reduced damage caused by C. capitata on both citrus spe- cies on preharvest fruit on some dates and on harvested fruits in both years. The kaolin was easily removed from harvested fruit by washing. Processed kaolin has potential for reducing damage caused by C. capitata in organic and conventional citrus or- chards

Organic Citrus: Challenges in Production and Trade

Organic citrus still is a niche and makes about 1-2% of the global citrus production. However, it is increasing year-by-year in parallel with the increasing demand for organic products. Organic citrus offers creative and circumspect producers and exporters excellent opportunities for success. Key success factors are specific know-how, access to production inputs and to markets. The main production areas of organic citrus – oranges, mandarins, grapefruit, limes and lemons – are Latin America, North America, Europe and Near East. Many tropical countries in the Americas are extending organic citrus production. What are the challenges for organic citrus production and trade

A Consumer Test of Citrus Drinks made from Comminuted Whole Citrus Fruit

Consumer, Citrus, Whole Citrus Fruit, Citrus Fruit, Consumer Test, Consumer/Household Economics, Food Consumption/Nutrition/Food Safety,

DNA amplified fingerprinting, a useful tool for determination of genetic origin and diversity analysis in Citrus

We used three short repetitive nucleotide sequences [(GTG)5, (TAC)5, and (GACA)4] either as radiolabeled probes for hybridization with restricted Citrus DNA or as single primers in polymerase chain reaction amplification experiments with total genomic DNA. We tested the ability of the sequences to discriminate between seedlings of zygotic or nuclear origin in the progeny of a Volkamer lemon #Citrus volkameriana# Ten. & Pasq.) tree. The genetic variability within two species [#Citrus sinensis# (L.) Osbeck (sweet oranges) and #Citrus reticulata# Blanco and relatives (mandarins)] was evaluated. DNA amplified figerprinting with single primers was the more successful technique for discriminating between nucellular and zygotic seedlings. Although we were not able to distinguish among 10 cultivars of #C. sinensis#, all 10 #C. reticulata# cultivars tested were distinguishable. However, it still is difficult to identify the putative parents of a hybrid plant when the two parental genomes are closely related. (Résumé d'auteur

First report of Diaphorina citri (Hemiptera: Psyllidae) in Costa Rica

In November 2003, the Asian citrus psyllid (Diaphorina citri) was found for the first time in Costa Rica, in Alajuela, Heredia and San Jose provinces. Figure 1 shows an adult female and nymphal instars of Asiatic citrus psyllid

An Overview of Mexico’s Citrus Industry

This report looks at Mexico’s citrus industry and its relationship to the United States. Information on Mexico’s citrus production, utilization and trade are discussed.Mexico, citrus industry, International Relations/Trade,

Efficiency of different culture mediums and explant types of some Citrus rootstocks on somatic embryogenesis : [21]

Callus induction, somatic embryogenesis and plant regeneration were obtained in ten different Citrus genotypes [Citrus aurantium L. (cv 'Tuzcu 891 '), Citrus aurantium L. (cv 'Tuzcu 31-31'), Citrus aurantium L. (cv 'Gou Tou'), Citrus sinensis (L.) Osb. (cv 'Alanya Dilimli'), Citrus reshni Hort. ex.Tan. (cv 'Cyprus Cleopatra mandarine'), Poncirus trifoliata (L) Raf (cv 'Pomeroy'), Citrus sinensis (L) Osb. x Poncirus trifoliata (L) Raf. (cv 'Tuzcu M2 Citrange'), Citrus sinensis (L) Osb. x Poncirus trifoliata (L) Raf. (cv 'Carrizo Citrange'), Citrus paradisi Macf. x Poncirus trifoliata (L) Raf. (cv 'Swingle Citrumelo'), Citrus volkameriana Tan.& Pasg. (cv 'CRC 01 Volkameriana') from style and ovule explants. Explants were cultured on different culture media. The nutrients of Murashige and Skoog medium (MS) and Murashige and Tucker (MT) vitamins supplemented with 500 mg/l Malt Extract (ME), with 1 mg/l 2, 4-D and three different concentration of BA (0, 0.5, 1 mg/l) were used for first year experiments. MS basal medium was used alone with ME and three different concentration of BA (1, 2, 3 mg/l) for style explants for the second year experiment. MS nutrients and MT vitamins with ME were used alone and 2, 4-D (1 mg/l) and BA (0, 0.5, 1 mg/l) used for ovule culture experiment for the second year experiments. Sucrose was used as a carbon source (50 g/l) for all experirnents. The different genotypes showed different embryogenic frequency from style and ovule experiments. Percentages of style explants producing somatic embryos ranged from 0% (AREC Swingle Citrumelo, M2 Citrange, Volkameriana, Pomeroy trifoliate) to 100% (Gou Tou Sour Orange). Percentages of ovule explants producing somatic embryos ranged from 0% (Carrizo Citrange, Alanya Dilimli Sweet Orange, AREC Swingle Citrumelo) to 100% (Tuzcu 891 and Cleopatra Mandarine). About 4 weeks later somatic embryos developed into plantlets. Genetic stability of callus lines was determined by SSR markers. (Texte intégral