Changes in carbohydrate metabolism in sweet orange (Citrus sinensis) infected with 'Candidatus Liberibacter asiaticus', a purported cause of citrus Huanglongbing (HLB), were investigated. Starch levels in HLB-infected leaves with and without symptoms increased 3AE1-and 7AE9-fold, respectively, compared to healthy controls. In symptomless leaves, sucrose and fructose accumulated significantly (P < 0AE05) in both midribs and lobes, and glucose only in the midribs (greater than fivefold); whereas maltose levels were reduced to 64AE6% and 86AE8% in the midribs and foliar lobes, respectively, of the values in healthy leaves. In leaves with symptoms, sucrose and glucose remained at high levels compared to healthy leaves, whilst no accumulation of fructose was observed; by contrast, the maltose content decreased to as low as 49AE6% of that in healthy leaves. Fourfold induction of cell-wall-bound invertase activity was detected in both types of leaves on diseased plants. Additionally, the expression profiles of starch breakdown genes suggested that the transcription of DPE2 and MEX1 was downregulated. Together with the reduction of maltose, it is suggested that the impairment of starch breakdown may contribute to the starch accumulation in infected leaves. The imbalance of carbohydrate partitioning and its relation to disease physiology are discussed.

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TreeGenes and tree fruit Genome Database Resources serve the international forestry and fruit tree genomics research communities, respectively. These databases hold similar sequence data and provide resources for the submission and recovery of this information in order to enable comparative genomics research. Large-scale genotype and phenotype projects have recently spawned the development of independent tools and interfaces within these repositories to deliver information to both geneticists and breeders. The increase in next generation sequencing projects has increased the amount of data as well as the scale of analysis that can be performed. These two repositories are now working towards a similar goal of archiving the diverse, independent data sets generated from genotype/phenotype experiments. This is achieved through focused development on data input standards (templates), pipelines for the storage and automated curation, and consistent annotation efforts through the application of widely accepted ontologies to improve the extraction and exchange of the data for comparative analysis. Efforts towards standardization are not limited to genotype/phenotype experiments but are also being applied to other data types to improve gene prediction and annotation for de novo sequencing projects. The resources developed towards these goals represent the first large-scale coordinated effort in plant Communicated by T. Drudge A contribution to the special issue "The genomes of the giants: a walk through the forest of tree genomes".