Transcriptomic profiling of citrus fruit peel tissues reveals fundamental effects of phenylpropanoids and ethylene on induced resistance

[EN] Penicillium spp. are the major postharvest pathogens of citrus fruit in Mediterranean climatic regions. The induction of natural resistance constitutes one of the most promising alternatives to avoid the environmental contamination and health problems caused by chemical fungicides. To understand the bases of the induction of resistance in citrus fruit against Penicillium digitatum, we have used a 12k citrus cDNA microarray to study transcriptional changes in the outer and inner parts of the peel (flavedo and albedo, respectively) of elicited fruits. The elicitor treatment led to an over-representation of biological processes associated with secondary metabolism, mainly phenylpropanoids and cellular amino acid biosynthesis and methionine metabolism, and the down-regulation of genes related to biotic and abiotic stresses. Among phenylpropanoids, we detected the over-expression of a large subset of genes important for the synthesis of flavonoids, coumarins and lignin, especially in the internal tissue. Furthermore, these genes and those of ethylene biosynthesis showed the highest induction. The involvement of both phenylpropanoid and ethylene pathways was confirmed by examining changes in gene expression and ethylene production in elicited citrus fruit. Therefore, global results indicate that secondary metabolism, mainly phenylpropanoids, and ethylene play important roles in the induction of resistance in citrus fruit.The technical assistance of Ana Izquierdo (IATA-CSIC, Valencia-Spain) is gratefully acknowledged. This work was supported by Research Grants AGL2002-1227 and AGL2005-04921-C02-01 from the Spanish Ministry of Science and Technology and PROMETEO/2010/010 from the Generalitat Valenciana. A-RB, RCHdV and AGB acknowledge the Centre for Biosystems Genomics, which is part of the Netherlands Genomics Initiative, for additional funding.Ballester, A.; Lafuente, M.; Forment Millet, JJ.; Gadea Vacas, J.; De Vos, RCH.; Bovy, AG.; Gonzalez-Candelas, L. (2011). Transcriptomic profiling of citrus fruit peel tissues reveals fundamental effects of phenylpropanoids and ethylene on induced resistance. Molecular Plant Pathology. 12(9):879-897. https://doi.org/10.1111/J.1364-3703.2011.00721.XS87989712

The Farthest Point Strategy for Progressive Image Sampling

A new method of farthest point strategy (FPS) for progressive image acquisition—an acquisition process that enables an approximation of the whole image at each sampling stage—is presented. Its main advantage is in retaining its uniformity with the increased density, providing efficient means for sparse image sampling and display. In contrast to previously presented stochastic approaches, the FPS guarantees the uniformity in a deterministic min-max sense. Within this uniformity criterion, the sampling points are irregularly spaced, exhibiting anti-aliasing properties comparable to those characteristic of the best available method (Poisson disk). A straightforward modification of the FPS yields an image-dependent adaptive sampling scheme. An efficient O(N log N) algorithm for both versions is introduced, and several applications of the FPS are discussed