Hydrogen peroxide induced phenylpropanoids pathway eliciting a defensive response in plants micropropagated in Temporary Immersion Bioreactors (TIBs).

The relation between the oxidative burst and phenylpropanoid pathways has been studied using the sugarcane cultivar C86-56, which does not release phenolics in agar-base micropropagation systems. In stationary liquid culture, a significant production of phenolic compounds and plant survival were determined in sugarcane plants treated with 5mM H(2)O(2). The spectrophotometer determinations and the gene expression analysis corroborated that releasing of phenolics and soluble θ-quinones was induced during the first 24h of treatment. In comparison with the control treatments, sugarcane plants treated with H(2)O(2) demonstrated differences in the micropropagation-related variables when multiplied in Temporary Immersion Bioreactors (TIBs) supplemented with polyethyleneglycol (PEG 20%). Expression of selected genes related to photosynthesis, ethylene, auxins, oxidative burst, and defense pathways were confirmed during the entire PEG 20% stress in the plants coming from the 5mM H(2)O(2) treatment; whereas, much more heterogeneous expression patterns were evidenced in plants stressed with PEG but not previously treated with H(2)O(2). RT-PCR expression analysis supports the hypothesis that while H(2)O(2) induces the oxidative burst, the phenylpropanoids pathways elicit and maintain the defensive response mechanism in micropropagated sugarcane plants.

Differential expression analysis by cDNA-AFLP of Saccharum spp. after inoculation with the host pathogen Sporisorium scitamineum.

A differential expression study on the Saccharum spp.-Sporisorium scitamineum pathogenic interaction was carried out in the susceptible Ja60-5 and the resistant M31/45 genotypes. Using cDNA-AFLP analysis, a total of 64 transcript-derived fragments (TDFs) was found to be differentially expressed, with the majority (67.2%) of the differential TDFs up-regulated in the resistant M31/45 cultivar. The plant response against S. scitamineum infection was complex, representing major genes involved in oxidative burst, defensive response, ethylene and auxins pathways during the first 72 h post-inoculation. Results obtained suggest a key role for genes involved in the oxidative burst and the lignin pathways in the initial sugarcane defense against the S. scitamineum infection.

Gluconacetobacter diazotrophicus Elicits a Sugarcane Defense Response Against a Pathogenic Bacteria Xanthomonas albilineans

A new role for the plant growth-promoting nitrogen-fixing endophytic bacteria Gluconacetobacter diazotrophicus has been identified and characterized while it is involved in the sugarcane-Xanthomonas albilineans pathogenic interactions. Living G.diazotrophicus possess and/or produce elicitor molecules which activate the sugarcane defense response resulting in the plant resistance to X. albilineans, in this particular case controlling the pathogen transmission to emerging agamic shoots. A total of 47 differentially expressed transcript derived fragments (TDFs) were identified by cDNA-AFLP. Transcripts showed significant homologies to genes of the ethylene signaling pathway (26percent), proteins regulates by auxins (9 percent), β-1,3 Glucanase proteins (6percent) and ubiquitin genes (4percent), all major signaling mechanisms. Results point toward a form of induction of systemic resistance in sugarcane-G. diazotrophicus interactions which protect the plant against X. albilineans attack(AU)

Un nuevo papel para el crecimiento de las plantas de promoción de la fijación de nitrógeno Gluconacetobacter diazotrophicus endofíticos bacterias se ha identificado y caracterizado al mismo tiempo que se dedica a la caña de azúcar-patógena Xanthomonas albilineans interacciones. Vida G.diazotrophicus poseer y / o elicitor producir moléculas que activan la respuesta de defensa como consecuencia de caña de azúcar en la planta la resistencia a X. albilineans, en este caso particular el control de la transmisión de patógenos a los nuevos brotes agamic. Un total de 47 diferencialmente expresadas transcripción fragmentos derivados (TDFs) fueron identificados por cDNA-AFLP. Las transcripciones muestran importantes homologías a los genes de la vía de señalización de etileno (26 por ciento), proteínas regula por las auxinas (9 por ciento), β-1, 3 glucanasa proteínas (6 por ciento) y los genes ubiquitina (4 por ciento), los principales mecanismos de señalización. Los resultados apuntan hacia una forma de inducción de resistencia sistémica en la caña de azúcar-G. diazotrophicus interacciones que proteger la planta contra el ataque X

Gluconacetobacter diazotrophicus Elicits a Sugarcane Defense Response Against a Pathogenic Bacteria Xanthomonas albilineans.

A new role for the plant growth-promoting nitrogen-fixing endophytic bacteria Gluconacetobacter diazotrophicus has been identified and characterized while it is involved in the sugarcane-Xanthomonas albilineans pathogenic interactions. Living G.diazotrophicus possess and/or produce elicitor molecules which activate the sugarcane defense response resulting in the plant resistance to X. albilineans, in this particular case controlling the pathogen transmission to emerging agamic shoots. A total of 47 differentially expressed transcript derived fragments (TDFs) were identified by cDNA-AFLP. Transcripts showed significant homologies to genes of the ethylene signaling pathway (26%), proteins regulates by auxins (9%), beta-1,3 Glucanase proteins (6%) and ubiquitin genes (4%), all major signaling mechanisms. Results point toward a form of induction of systemic resistance in sugarcane-G. diazotrophicus interactions which protect the plant against X. albilineans attack.