Project description:Purpose: The plant hormone abscisic acid (ABA) coordinates responses leading to desiccation tolerance in all land plants. RNA-seq was employed to obtain differential expression data in response to ABA, dehydration and mannitol treatments in wild-type tissue. This was compared against the targeted gene knockout line PpanrKO. The ANR gene encodes a novel ABA regulator identified from ABA non-responsive (anr) mutant screens. Methods: RNA-seq on the Illumina HiSeq platform and mapping to the V3.0 genome and transcriptome assemblies using tophat2 enabled gene abundance data to be generated for differential gene expression analysis with edgeR in the Trinity package. Results: We observe a coordinated up-regulation of ca. 900 genes, with extensive overlaps between hormone and stress treatments as well as ca. 900 down-regulated genes. Of the up-regulated genes, those encoding LEA proteins, membrane channel proteins and transporters and oxidative-stress-associated genes comprised a significant fraction while those encoding growth-associated cell wall enzymes (e.g. expansins) and components of secondary metabolism (notably enzymes in the phenylpropanoid pathway) were prominent in the down-regulated genes. The ANR gene, a modular MAP3 kinase comprising an N-terminal PAS domain, a central EDR domain and a C-terminal MAPKKK-like domain unique to basal plant lineages, is found to play a central role in these responses with mutants failing to accumulate the wide spectrum of dehydration tolerance-associated gene products characteristic of the wild-type response and do not acquire ABA-dependent desiccation tolerance. Conclusions: Our study adds considerable data to the stress responses in bryophytes helping understand the mechanisms behind vegetative dehydration tolerance; an important trait for crop species. We also confirmed the vital role that PpANR plays in these responses in the moss Physcomitrella patens likely representing an ancestral mechanism for ABA-mediated dehydration tolerance vital in the conquest of land.

Project description:Purpose: The plant hormone abscisic acid (ABA) coordinates responses leading to desiccation tolerance in all land plants. RNA-seq was employed to obtain differential expression data in response to ABA, dehydration and mannitol treatments in wild-type tissue. This was compared against the targeted gene knockout line PpanrKO. The ANR gene encodes a novel ABA regulator identified from ABA non-responsive (anr) mutant screens. Methods: RNA-seq on the Illumina HiSeq platform and mapping to the V3.0 genome and transcriptome assemblies using tophat2 enabled gene abundance data to be generated for differential gene expression analysis with edgeR in the Trinity package. Results: We observe a coordinated up-regulation of ca. 900 genes, with extensive overlaps between hormone and stress treatments as well as ca. 900 down-regulated genes. Of the up-regulated genes, those encoding LEA proteins, membrane channel proteins and transporters and oxidative-stress-associated genes comprised a significant fraction while those encoding growth-associated cell wall enzymes (e.g. expansins) and components of secondary metabolism (notably enzymes in the phenylpropanoid pathway) were prominent in the down-regulated genes. The ANR gene, a modular MAP3 kinase comprising an N-terminal PAS domain, a central EDR domain and a C-terminal MAPKKK-like domain unique to basal plant lineages, is found to play a central role in these responses with mutants failing to accumulate the wide spectrum of dehydration tolerance-associated gene products characteristic of the wild-type response and do not acquire ABA-dependent desiccation tolerance. Conclusions: Our study adds considerable data to the stress responses in bryophytes helping understand the mechanisms behind vegetative dehydration tolerance; an important trait for crop species. We also confirmed the vital role that PpANR plays in these responses in the moss Physcomitrella patens likely representing an ancestral mechanism for ABA-mediated dehydration tolerance vital in the conquest of land. RNA from 3 biological replicas was bulked per library. 8 libraries were generated from two genotypes, wild-type and PpanrkO, which included 3 treatments and a control sample for each.

Project description:BACKGROUND: The terrestrial habitat was colonized by the ancestors of modern land plants about 500 to 470 million years ago. Today it is widely accepted that land plants (embryophytes) evolved from streptophyte algae, also referred to as charophycean algae. The streptophyte algae are a paraphyletic group of green algae, ranging from unicellular flagellates to morphologically complex forms such as the stoneworts (Charales). For a better understanding of the evolution of land plants, it is of prime importance to identify the streptophyte algae that are the sister-group to the embryophytes. The Charales, the Coleochaetales or more recently the Zygnematales have been considered to be the sister group of the embryophytes However, despite many years of phylogenetic studies, this question has not been resolved and remains controversial. RESULTS: Here, we use a large data set of nuclear-encoded genes (129 proteins) from 40 green plant taxa (Viridiplantae) including 21 embryophytes and six streptophyte algae, representing all major streptophyte algal lineages, to investigate the phylogenetic relationships of streptophyte algae and embryophytes. Our phylogenetic analyses indicate that either the Zygnematales or a clade consisting of the Zygnematales and the Coleochaetales are the sister group to embryophytes. CONCLUSIONS: Our analyses support the notion that the Charales are not the closest living relatives of embryophytes. Instead, the Zygnematales or a clade consisting of Zygnematales and Coleochaetales are most likely the sister group of embryophytes. Although this result is in agreement with a previously published phylogenetic study of chloroplast genomes, additional data are needed to confirm this conclusion. A Zygnematales/embryophyte sister group relationship has important implications for early land plant evolution. If substantiated, it should allow us to address important questions regarding the primary adaptations of viridiplants during the conquest of land. Clearly, the biology of the Zygnematales will receive renewed interest in the future.

Dataset Information

Group A PP2Cs evolved in land plants as key regulators of intrinsic desiccation tolerance.

Publications

Group A PP2Cs evolved in land plants as key regulators of intrinsic desiccation tolerance.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets