Dataset Information

Specific peroxidases differentiate Brachypodium distachyon accessions and are associated with drought tolerance traits.

ABSTRACT:

Background and aims

Brachypodium distachyon (Brachypodium) is a model system for studying cereal, bioenergy, forage and turf grasses. The genetic and evolutionary basis of the adaptation of this wild grass species to drought stress is largely unknown. Peroxidase (POD) may play a role in plant drought tolerance, but whether the allelic variations of genes encoding the specific POD isoenzymes are associated with plant response to drought stress is not well understood. The objectives of this study were to examine natural variation of POD isoenzyme patterns, to identify nucleotide diversity of POD genes and to relate the allelic variation of genes to drought tolerance traits of diverse Brachypodium accessions.

Methods

Whole-plant drought tolerance and POD activity were examined in contrasting ecotypes. Non-denaturing PAGE and liquid chromatography-mass spectrometry were performed to detect distinct isozymes of POD in 34 accessions. Single nucleotide polymorphisms (SNPs) were identified by comparing DNA sequences of these accessions. Associations of POD genes encoding specific POD isoenzymes with drought tolerance traits were analysed using TASSEL software.

Key results

Variations of POD isoenzymes were found among accessions with contrasting drought tolerance, while the most tolerant and susceptible accessions each had their own unique POD isoenzyme band. Eight POD genes were identified and a total of 90 SNPs were found among these genes across 34 accessions. After controlling population structure, significant associations of Bradi3g41340.1 and Bradi1g26870.1 with leaf water content or leaf wilting were identified.

Conclusions

Brachypodium ecotypes have distinct specific POD isozymes. This may contribute to natural variations of drought tolerance of this species. The role of specific POD genes in differentiating Brachypodium accessions with contrasting drought tolerance could be associated with the general fitness of Brachypodium during evolution.

SUBMITTER: Luo N

PROVIDER: S-EPMC4970367 | biostudies-literature | 2016 Aug

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Specific peroxidases differentiate Brachypodium distachyon accessions and are associated with drought tolerance traits.

Luo Na N Yu Xiaoqing X Nie Gang G Liu Jianxiu J Jiang Yiwei Y

Annals of botany 20160620 2

<h4>Background and aims</h4>Brachypodium distachyon (Brachypodium) is a model system for studying cereal, bioenergy, forage and turf grasses. The genetic and evolutionary basis of the adaptation of this wild grass species to drought stress is largely unknown. Peroxidase (POD) may play a role in plant drought tolerance, but whether the allelic variations of genes encoding the specific POD isoenzymes are associated with plant response to drought stress is not well understood. The objectives of thi ...[more]

PMID: 27325900

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Project description:Background and aimsCold is a major constraint for cereal cultivation under temperate climates. Winter-hardy plants interpret seasonal changes and can acquire the ability to resist sub-zero temperatures. This cold acclimation process is associated with physiological, biochemical and molecular alterations in cereals. Brachypodium distachyon is considered a powerful model system to study the response of temperate cereals to adverse environmental conditions. To date, little is known about the cold acclimation and freezing tolerance capacities of Brachypodium. The main objective of this study was to evaluate the cold hardiness of seven diploid Brachypodium accessions.MethodsAn integrated approach, involving monitoring of phenological indicators along with expression profiling of the major vernalization regulator VRN1 orthologue, was followed. In parallel, soluble sugars and proline contents were determined along with expression profiles of two COR genes in plants exposed to low temperatures. Finally, whole-plant freezing tests were performed to evaluate the freezing tolerance capacity of Brachypodium.Key resultsCold treatment accelerated the transition from the vegetative to the reproductive phase in all diploid Brachypodium accessions tested. In addition, low temperature exposure triggered the gradual accumulation of BradiVRN1 transcripts in all accessions tested. These accessions exhibited a clear cold acclimation response by progressively accumulating proline, sugars and COR gene transcripts. However, whole-plant freezing tests revealed that these seven diploid accessions only have a limited capacity to develop freezing tolerance when compared with winter varieties of temperate cereals such as wheat and barley. Furthermore, little difference in terms of survival was observed among the accessions tested despite their previous classification as either spring or winter genotypes.ConclusionsThis study is the first to characterize the freezing tolerance capacities of B. distachyon and provides strong evidence that some diploid accessions such as Bd21 have a facultative growth habit.

Project description:Brachypodium distachyon as an annual species that colonises broken ground is a highly appropriate model to define drought tolerance mechanisms. We have previously identified accessions exhibiting drought tolerance, high susceptibility and intermediate tolerance to drought; respectively, ABR8, KOZ1 and ABR4, from a screen of 138 genotypes. To define the mechanisms of tolerance, the responses to drought were assessed using transcriptomic and metabolomic approaches. Analysis of RNA-seq before and following drought suggested relatively few differentially expressed genes in ABR8. Linking these to gene ontology (GO) terms revealed an enrichment for biological processes related to “regulated stress response”, “plant cell wall” and “oxidative stress”. Interestingly, drought tolerance also appeared to correlate with pre-existing differences in gene expression linked to GO terms associated with the cell wall. These included glycoside hydrolases involved in cell wall remodelling, pectin methylesterases, expansins and a pectin acetylesterase. Metabolomic assessments of the same samples also indicated few statistically significant changes in ABR8 with drought. Instead, pre-existing differences in the cell-wall associated metabolites appeared to correlate with drought tolerance. Our data suggests two different modes/levels at which cell wall characteristics can play a role in conferring drought tolerance: (i) an active response mode/level which involves stress induced changes in cell wall features to help the plant cope with drought and (ii) an intrinsic mode in which innate differences in cell wall composition and architecture between genotypes are important in determining tolerance to drought stress. Both modes seem to contribute to the drought tolerance of ABR8. Identification of the exact mechanisms through which the cell wall confers drought tolerance will be important to fully exploit the contribution of the cell wall in the development of drought tolerant cereals and other grasses.

Dataset Information

Specific peroxidases differentiate Brachypodium distachyon accessions and are associated with drought tolerance traits.

Background and aims

Methods

Key results

Conclusions

Publications

Specific peroxidases differentiate Brachypodium distachyon accessions and are associated with drought tolerance traits.

Similar Datasets

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