Retrotransposon and gene activation in wheat in response to mycotoxigenic and non-mycotoxigenic-associated Fusarium stress

Abstract

Despite inhibition of protein synthesis being its mode of action, the trichothecene mycotoxin deoxynivalenol (DON) induced accumulation of transcripts encoding translation elongation factor 1alpha (EF-1alpha), class III plant peroxidase (POX), structure specific recognition protein, basic leucine zipper protein transcription factor (bZIP), retrotransposon-like homologs and genes of unknown function in the roots of wheat cultivars CM82036 and Remus. Fusarium head blight (FHB) studies using Fusarium graminearum and its trichothecene-minus (Tri5 ( - )) mutant derivative and adult plant DON tests showed that these transcripts were responsive to both mycotoxigenic- and non-mycotoxigenic-associated Fusarium stress. In tests using the parents 'CM82036', 'Remus' and 14 double-haploid progeny that segregated for quantitative trait locus (QTL) Fhb1 on chromosome 3BS (syn. Qfhs.ndsu-3BS) (from 'CM82036' that confers DON tolerance), bZIP expression was significantly more DON-up-regulated in lines that inherited this QTL. Basal accumulation of the bZIP transcript in spikelets treated with Tween20 (control), DON and in DON-relative to Tween20-treated spikelets was negatively correlated with DON-induced bleaching above (but not below) the treated spikelets (AUDPC(DON)) (r = -0.41, -0.75 and -0.72, respectively; P < or = 0.010). bZIP-specific PCR analysis of 'Chinese spring' and its 3BS deletion derivatives indicated that bZIP is located in chromosomal region(s) other than 3BS. These results, and the fact that a homologous cold-regulated wheat bZIP (wLIP19) maps to group 1 chromosomes suggests that wheat bZIP may participate in defence response cascades associated with Fhb1 and that there is a cross-talk between biotic and abiotic stress signalling pathways.

TaFROG encodes a Pooideae orphan protein that interacts with SnRK1 and enhances resistance to the mycotoxigenic fungus Fusarium graminearum

“…For detached leaf gene expression studies, wheat plants were cultivated under contained environment conditions at 20°C to 22°C with a 16-h-light/8-hdark photoperiod at 300 mmol m 22 s 21 and 70% relative humidity, as previously described (Ansari et al, 2007). The second leaves (growth stage 10; Zadoks et al, 1974) were collected, and 8-cm sections were placed in a square petri dish on moist Whatman No.…”

Deoxynivalenol resistance as a component of FHB resistance

“…Like FHB, DON has also been shown to cause premature bleaching of plant tissue: it causes premature bleaching of both wheat heads and barley leaf tissues (Bushnell et al 2003(Bushnell et al , 2010Lemmens et al 2005;Schweiger et al 2010;Diamond et al 2013). Application of DON to the central spikelets of wheat heads led to the premature bleaching of florets in both the antipetal and basipetal direction (Lemmens et al 2005;Ansari et al 2007). …”

Diversity of Long Terminal Repeat Retrotransposon Genome Distribution in Natural Populations of the Wild Diploid WheatAegilops speltoides

“…It is possible that populations with enhanced TE activity are more likely to survive as new forms, or even new species, during environmental fluctuations due to the production of an extended number of genomic variants for natural selection (Grant 1981;Raskina et al 2004a;Belyayev et al 2010). This is one of the key problems in understanding the mechanisms of speciation because, in a certain sense, intraspecific genome diversification, particularly the genesis of differences across eco-geographical gradients, could be regarded as a speciation precursor.Dobzhansky's central-marginal model (Da Cunha and Dobzhansky 1954) assumes that populations near the center of a species' range usually display high levels of genetic and phenotypic variation, while populations on the margin of the range are monomorphic (for review see Eckert et al 2008 Extrapolating the central-marginal model onto the TE fraction and given the fact that TEs are sensitive to changes in the external environment (Wessler 1996;Kashkush et al 2003;Grandbastien et al 2005;Ansari et al 2007;Martienssen 2008), it is possible to speculate that the TE quantity and structural distribution across the genome may perceptibly vary between populations. Indeed, the environment can have a decisive influence on the structure of the genome, changing it in a certain direction that could be heritable (Martienssen 2008).…”

“…Dobzhansky's central-marginal model (Da Cunha and Dobzhansky 1954) assumes that populations near the center of a species' range usually display high levels of genetic and phenotypic variation, while populations on the margin of the range are monomorphic (for review see Eckert et al 2008 Extrapolating the central-marginal model onto the TE fraction and given the fact that TEs are sensitive to changes in the external environment (Wessler 1996;Kashkush et al 2003;Grandbastien et al 2005;Ansari et al 2007;Martienssen 2008), it is possible to speculate that the TE quantity and structural distribution across the genome may perceptibly vary between populations. Indeed, the environment can have a decisive influence on the structure of the genome, changing it in a certain direction that could be heritable (Martienssen 2008).…”

“…Extrapolating the central-marginal model onto the TE fraction and given the fact that TEs are sensitive to changes in the external environment (Wessler 1996;Kashkush et al 2003;Grandbastien et al 2005;Ansari et al 2007;Martienssen 2008), it is possible to speculate that the TE quantity and structural distribution across the genome may perceptibly vary between populations. Indeed, the environment can have a decisive influence on the structure of the genome, changing it in a certain direction that could be heritable (Martienssen 2008).…”