A laranjeira ‘Pera’ é das principais variedades cultivadas e praticamente a única com maturação na meia-estação no Brasil. Outras variedades similares ou superiores implicariam ganhos na cadeia de processamento de sumo. Avaliaram-se 29 variedades de laranja introduzidas de países mediterrâneos em dois experimentos separados. O porta-enxerto utilizado foi a tangerineira ‘Sunki’ e o delineamento experimental foi em blocos ao acaso, com duas plantas por parcela e três repetições. A plantação de sequeiro foi realizada em maio de 2001, em Bebedouro, Norte do Estado de São Paulo, Brasil, em clima subtropical. Nos anos de 2005 a 2008, avaliaram-se os seguintes parâmetros: crescimento da árvore, produção e qualidade físico-química dos frutos. As seleções ‘Do Tua Graúda’/146, ‘Do Tua Sr. Mamede’/148, ‘Do Tua’/149, ‘Do Tua’/160, ‘Do Tua’/176, ‘Convento’/155, ‘Grada’/158, ‘De Setúbal’/174, ‘De Setúbal’/180, ‘Pera da Vidigueira Sr. Antunes’/159, ‘Sanguínea’/144, Amares’/150, ‘Prata da Ponte’/151, ‘Prata Lima’/152, ‘Pala’/153, ‘Portela’/154, ‘Évora’/157, ‘De Vale dos Besteiros’/161, ‘Biondo Corigliano’/164, ‘Vera’/166, ‘Entrefina’/168, ‘De Vale dos Besteiros’/175, ‘Laranja R.A.H.’/177 e ‘Maçã’/182 são adequadas para cultivo em sequeiro em região de clima subtropical no Brasil visando processamento para produção de suco. ‘Pardilhó’/169 poderia ser explorada para o mercado de fruta fresca, uma vez que se trata de uma cultivar do grupo das laranjas-de-umbigo ou “navel”.

‘Pera’ is one of the major sweet orange commercial varieties and it is the only one being harvested in the mid-season in Brazil. Similar or superior mid-season cultivars could improve the gains in the juice processing chain. In this work, we evaluated 29 sweet orange selections introduced in Brazil from Mediterranean countries. Several sweet orange varieties were evaluated in two distinct experiments. In both trials, the rootstock was Sunki mandarin and the experimental design was in randomized blocks, with three replications and two trees in the unit. The experimental plots were planted on May 2001 in Bebedouro, northern São Paulo State, Brazil, in an oxisol under rain-fed cultivation in subtropical climate. Collected data included tree growth, yield, and physical and chemical fruit traits from 2005 thru 2008. ‘Do Tua Graúda’/146, ‘Do Tua Sr. Mamede’/148, ‘Do Tua’/149, ‘Do Tua’/160, ‘Do Tua’/176, ‘Convento’/155, ‘Grada’/158, ‘De Setúbal’/174, ‘De Setúbal’/180, ‘Pera da Vidigueira Sr. Antunes’/159, ‘Sanguínea’/144, Amares’/150, ‘Prata da Ponte’/151, ‘Prata Lima’/152, ‘Pala’/153, ‘Portela’/154, ‘Évora’/157, ‘De Vale dos Besteiros’/161, ‘Biondo Corigliano/164’, ‘Vera’/166, ‘Entrefina’/168, ‘De Vale dos Besteiros’/175, ‘Laranja R.A.H.’/177 and ‘Maçã’/182 are suitable for rain-fed cultivation in a subtropical region of Brazil, aiming to juice processing. ‘Pardilhó’/169 could be used for fresh market because it is a navel orange.

To date, seven species of viroids have been described infecting Citrus. However, only Citrus exocortis viroid (CEVd), Hop stunt viroid (HSVd) and Citrus dwarfing viroid (CDVd) have been reported in this crop in Brazil. The aim of our work was to identify and characterize viroids infecting plants of 'Navelina ISA 315' sweet orange cultivar grafted on 'Rangpur' lime from field experiments located in Bebedouro, SP, that showed gumming in the bark and wood symptoms. Biological indexing was done on the indicator host 'Clemelin 1120' tangor plants that reacted with typical gumming symptoms. Viroid infection was assessed by graft-inoculation of buds from the field trees on 'Etrog' citron plants grafted on 'Rangpur' lime, followed by RNA extraction and sPAGE analysis. RNAs were subjected to RT-PCR with primers for citrus viroids. The full-length amplified products were sequenced and compared to those available in the GenBank. The trees were found to be infected with cachexia (Ca) variants of HSVd-Ca or HSVd-Ca plus CDVd. The results indicate that efforts have to be made to increase and stimulate the indexing programs, to maintain plants healthy and to develop sanitary programs focused on reducing the spread of viroids and other graft-transmissible agents.

Xylella fastidiosa inhabits the plant xylem, a nutrient-poor environment, so that mechanisms to sense and respond to adverse environmental conditions are extremely important for bacterial survival in the plant host. Although the complete genome sequences of different Xylella strains have been determined, little is known about stress responses and gene regulation in these organisms. In this work, a DNA microarray was constructed containing 2,600 ORFs identified in the genome sequencing project of Xylella fastidiosa 9a5c strain, and used to check global gene expression differences in the bacteria when it is infecting a symptomatic and a tolerant citrus tree. Different patterns of expression were found in each variety, suggesting that bacteria are responding differentially according to each plant xylem environment. The global gene expression profile was determined and several genes related to bacterial survival in stressed conditions were found to be differentially expressed between varieties, suggesting the involvement of different strategies for adaptation to the environment. The expression pattern of some genes related to the heat shock response, toxin and detoxification processes, adaptation to atypical conditions, repair systems as well as some regulatory genes are discussed in this paper. DNA microarray proved to be a powerful technique for global transcriptome analyses. This is one of the first studies of Xylella fastidiosa gene expression in vivo which helped to increase insight into stress responses and possible bacterial survival mechanisms in the nutrient-poor environment of xylem vessels.

Os viroides têm sido empregados em diversos países como agentes indutores de nanismo transmissíveis por enxertia ("graft transmissible dwarfing agents", GTDA), principalmente visando à diminuição do porte das plantas, o que permite o adensamento do pomar. No Estado de São Paulo, Brasil, plantas de limeira ácida 'Tahiti' são normalmente enxertadas com gemas contendo GTDA, presumivelmente viroides. Portanto, o presente trabalho visou à identificação e caracterização molecular dos viroides presentes em plantas de limeira ácida 'Tahiti' apresentando caneluras nos ramos (bark-cracking), conhecido como "Quebra galho". Os viroides foram identificados e caracterizados por meio de indexação biológica em cidreira 'Etrog', hibridização por Northern Blot, e RT-PCR seguida de clonagem e sequenciamento completo dos genomas. Identificaram-se Citrus exocortis viroid (CEVd), Hop stunt viroid (HSVd) e Citrus dwarfing viroid (CDVd) em diferentes combinações. Embora não tenha havido associação direta entre desempenho agronômico e severidade dos sintomas com a presença de um determinado viroide ou combinação de viroides, as diferenças na severidade dos sintomas de "Quebra-galho" está associada com a presença (ou ausência) do CEVd, e as interações do CEVd com outros viroides deve ser, provavelmente, determinante nas diferenças fenotípicas observadas em campo.

Viroids have been used as "graft transmissible dwarfing agents" (GTDA) in several countries, mainly to reduce growth of citrus trees, thus increasing their density in orchards. In the State of São Paulo, Brazil, plants of the acid lime 'Tahiti' are usually grafted with a complex of GTDA, presumably viroids. The aim of the present work was the identification and molecular characterization of the viroids infecting trees of acid lime 'Tahiti' displaying "Quebra galho" (bark-cracking). Viroids were identified and characterized by biological indexing in 'Etrog' citron, Northern-blot hybridization, RT-PCR, cloning and complete sequencing of the RNA genomes. Citrus exocortis viroid (CEVd), Hop stunt viroid (HSVd) and Citrus dwarfing viroid (CDVd) were found in different combinations. Although we have not been able to infer a direct relationship between the agronomical performance and symptom severity with the presence of a specific viroid or viroid combination, the differences in the severity of "Quebra-galho" symptoms among different trees is probably associated with the presence (or absence) of CEVd, with its interaction with other viroids perhaps determining the different phenotypes observed in the field.