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The flavin monooxygenases (FMO) encoded by plant YUCCA genes are thought to catalyze a rate-limiting step in the tryptamine pathway for indole-3-acetic acid biosynthesis. Recent experiments with different plant models have indicate that YUCCA genes play essential roles in growth and development through their contribution to the local pool of free auxin. In this study we have characterized five new genes that encode YUCCA-like FMOs in the tomato genome (ToFZY2 to ToFZY6), including gene structure, conserved motifs and phylogenetic analyses. As a first step towards clarifying the individual functions of ToFZY genes, we have used quantitative real-time RT-PCR to conduct a systematic comparison of the steady-state mRNA levels of 6 ToFZY genes, in 33 samples representing major organs and the entire tomato life cycle. We followed an absolute quantification strategy which allowed us to cross-compare transcript levels among different ToFZY genes in a given spatiotemporal coordinate. Our results indicate that expression of ToFZY genes is temporally and spatially regulated, and that the distinctive expression pattern of each ToFZY gene partially overlaps with other members of the multigenic family. We compare our data with previous results in other plant species and make some predictions about the role of tryptamine pathway in tomato growth and development., This work was partially funded by an INVESCAN, S.L. grant (No. OTT2001438) to the CSIC. The first author was supported by a research contract from the Agencia Canarias de Investigación, Inovación y Sociedad de la Información (Gobierno de Canarias). The authors thank CajaCanarias for research support.

Indole-3-acetic acid (IAA), the main endogenous auxin, has been known for decades to be a key regulator for plant growth and development. Multiple routes have been proposed for IAA biosynthesis but physiologic roles or relevance of the different routes are still unclear. Recently, four members of the Arabidopsis thaliana YUC gene family have been implicated in an additional requirement of IAA involved in floral organ and vascular tissue formation. The loss-of-function yuc1yuc4 double mutants in Arabidopsis displayed phenotypes similar to the previously described loss-of-function floozy mutants in petunia (fzy). Moreover, it has been demonstrated that YUC1 encodes a flavin monooxygenase (FMO) that catalyzes a rate-limiting step of a tryptophan-dependent auxin biosynthesis pathway: the conversion of tryptamine to N-hydroxyl-tryptamine. Here we report on the genetic study of ToFZY, the putative tomato ortholog of YUC4 and FZY, including gene and cDNA sequence comparison and a preliminary expression analysis. In addition, we describe a novel conserved amino acid motif that may be considered a hallmark potentially useful for the identification of new YUC-like FMOs. We also demonstrate that ToFZY encodes a protein with the same enzymatic activity as YUC1. Finally, we provide evidence suggesting that the ToFZY gene belongs to a multigenic family whose members may exhibit a temporal and spatial specialization similar to that described in A. thaliana., This work was funded by an INVESCAN, S.L. grant (No. 402.01) to the CSIC and supported by a fellowship to MER, a kind gift from the same firm.

Introduction. The causal agent of Panama disease in banana is Fusarium oxysporum f. sp. cubense (FOC). The authors put forward a hypothesis to account for certain disturbances of the natural defence mechanisms of banana plants against Panama disease as a consequence of very low Zn levels which could alter the mechanism of tylose formation. Materials and methods. A long-term experiment was carried out with 2-month-old banana plants in a growth chamber at 23 °C using three different levels of Zn nutrition. The nutrient solutions were inoculated with FOC 1 and FOC 4. Results and discussion. None of the total plants growing in a nutrient solution inoculated with FOC 1 showed infected rhizomes at the end of the experiment, but 75% of the plants growing in pots inoculated with FOC 4 had infected rhizomes. On the other hand, rhizome infection by FOC 4 was influenced by the nutrient solutions. The data showed that the number of plants with damaged rhizomes was significantly higher in the Zn-deficient treatments (100% of plants) than in the normal Zn solution (25% of plants), these internal symptoms being seen to worsen as the presence of Zn decreased in the nutrient solution. Conclusions. The results obtained seem to confirm the role played by Zn nutrition of banana plants in the appearance of Panama disease and are in accordance with our hypothesis concerning the relationships among plant Zn nutrition, plant IAA level, tylose formation and the incidence of the disease. Likewise, under our experimental conditions, race 1 of FOC is confirmed to be non-pathogenic against this banana cultivar, while race 4 is indeed pathogenic. Spain / Musa / fungal diseases / pathogens / Fusarium oxysporum / plant nutrition / zinc Reponse de plantules de bananiers Dwarf Cavendish, soumises a differents niveaux de nutrition en Zn, vis-a-vis d'une inoculation par les races 1 et 4 du Fusarium oxysporum f. sp. cubense.

19 páginas, 6 figuras, 2 tablas., Menadione sodium bisulphite (MSB) is a water-soluble derivative of vitamin K3, or menadione, and has been previously demonstrated to function as a plant defence activator against several pathogens in several plant species. However, there are no reports of the role of this vitamin in the induction of resistance in the plant model Arabidopsis thaliana. In the current study, we demonstrate that MSB induces resistance by priming in Arabidopsis against the virulent strain Pseudomonas syringae pv. tomato DC3000 (Pto) without inducing necrosis or visible damage. Changes in gene expression in response to 0.2 mm MSB were analysed in Arabidopsis at 3, 6 and 24 h post-treatment using microarray technology. In general, the treatment with MSB does not correlate with other publicly available data, thus MSB produces a unique molecular footprint. We observed 158 differentially regulated genes among all the possible trends. More up-regulated genes are included in categories such as 'response to stress' than the background, and the behaviour of these genes in different treatments confirms their role in response to biotic and abiotic stress. In addition, there is an over-representation of the G-box in their promoters. Some interesting functions are represented among the individual up-regulated genes, such as glutathione S-transferases, transcription factors (including putative regulators of the G-box) and cytochrome P450s. This work provides a wide insight into the molecular cues underlying the effect of MSB as a plant resistance inducer., This work was partially funded by an INVESCAN, S.L. grant (No.OTT2001438) to the CSIC and by a BIO2006-02168 grant of MICINN to PT. The microarrays were funded in part by the “Genome España” Foundation. MER was supported by a research contract (ID-TF-06/002) from the Consejería de Industria, Comercio y Nuevas Tecnologías (Gobierno de Canarias). The authors thank CajaCanarias for their research support. We also thank Lorena Perales for her help in performing the bacterial growth curves, Dr. Héctor Cabrera for his useful advice on writing the manuscript, the English translation service of the Universidad Politécnica de Valencia and Mrs. Pauline Agnew whose endeavoured to edit the English translation of this paper.

12 pages, 2 figures, 4 tables.-- PMID: 19102748 [PubMed].-- PMCID: PMC2629474., [Background] The elucidation of gene expression patterns leads to a better understanding of biological processes. Real-time quantitative RT-PCR has become the standard method for in-depth studies of gene expression. A biologically meaningful reporting of target mRNA quantities requires accurate and reliable normalization in order to identify real gene-specific variation. The purpose of normalization is to control several variables such as different amounts and quality of starting material, variable enzymatic efficiencies of retrotranscription from RNA to cDNA, or differences between tissues or cells in overall transcriptional activity. The validity of a housekeeping gene as endogenous control relies on the stability of its expression level across the sample panel being analysed. In the present report we describe the first systematic evaluation of potential internal controls during tomato development process to identify which are the most reliable for transcript quantification by real-time RT-PCR., [Results] In this study, we assess the expression stability of 7 traditional and 4 novel housekeeping genes in a set of 27 samples representing different tissues and organs of tomato plants at different developmental stages. First, we designed, tested and optimized amplification primers for real-time RT-PCR. Then, expression data from each candidate gene were evaluated with three complementary approaches based on different statistical procedures. Our analysis suggests that SGN-U314153 (CAC), SGN-U321250 (TIP41), SGN-U346908 ("Expressed") and SGN-U316474 (SAND) genes provide superior transcript normalization in tomato development studies. We recommend different combinations of these exceptionally stable housekeeping genes for suited normalization of different developmental series, including the complete tomato development process., [Conclusion] This work constitutes the first effort for the selection of optimal endogenous controls for quantitative real-time RT-PCR studies of gene expression during tomato development process. From our study a tool-kit of control genes emerges that outperform the traditional genes in terms of expression stability., This work was partially funded by an INVESCAN, S.L. grant (No. OTT2001438) to the CSIC. The first author was supported by a research contract (ID-TF-06/002) from the Consejería de Industria, Comercio y Nuevas Tecnologías (Gobierno de Canarias). The authors thank CajaCanarias for research support.

3 pages, 1 table.-- Printed version published Dec 2004., The soilborne fungus Fusarium oxysporum f.sp. cubense is the causal agent of banana vascular wilt disease named Panama disease and one of the most serious threats to banana crops worldwide. A water-soluble addition compound of vitamin K3, menadione sodium bisulphite (MSB), first studied as a plant growth regulator, has recently been shown to induce resistance against Panama disease. Effective fungicides are not yet available to control this fatal disease. Here we report on two independent long-term experiments leading to the enhanced resistance response induced by MSB. The results demonstrated that MSB is an effective resistance activator in banana, and a potentially useful agent for the control of Panama disease., The authors would like to thank J.M. Hernández- Hernández fromthe Departamento de Patología Vegetal, Instituto Canario de Investigaciones Agrarias (ICIA), for kindly providing FOC-4 inoculum.

Fusarium wilt of banana (Panama disease), caused by Fusarium oxysporum f.sp. cubense, is a soliborne systemic disease which occludes host vascular system. We report here two experiments on resistance induction with banana plants (cv. Dwarf Cavendish) carried out in glass greehouse with different indoleacetic acid treatments, which are capable of inducing resistance to Panama disease. The results obtained in these experiments suggest that the exogenous application of indoleacetic acid to banana plants induce resistance to Panama disease and that the resistance induction is more effective when performed using low doses and frequent applications. This work seems to confirm the role played by indoleacetic acid according to Beckman's models as, one of the major defence factors of the host plant in vascular wilt diseases., The authors would like to thank J, M, Hermández Hernández from the Departamento de Patología Vegetal, Instituto Canario de Investigaciones Agrarias (ICIA), for kindly providing FOC-4 inoculum. We also acknowledge Mrs. Pauline Agnew who endeavoured to edit the English translation of this paper.