The Brassicaceae species Braya humilis shows broad adaptation to different climatic zones and latitudes. However, the molecular adaptation mechanism of B. humilis is poorly understood. In China, B. humilis is mainly d...The Brassicaceae species Braya humilis shows broad adaptation to different climatic zones and latitudes. However, the molecular adaptation mechanism of B. humilis is poorly understood. In China, B. humilis is mainly distributed on the QinghaiTibetan Plateau(QTP) and in the adjacent arid region. Previous transcriptome analysis of B. humilis has revealed that 39 salt and osmotic stress response genes are subjected to purifying selection during its speciation. To further explore the adaptation mechanism of B. humilis to an arid environment, OrthoMCL program was employed in this study and 6,268 pairs of orthologous gene pairs with high confidence were obtained between B. humilis and Arabidopsis thaliana. A comparative evolutionary analysis based on nonsynonymous to synonymous substitution ratio(Ka/Ks) was then conducted. There were 64 pairs exhibiting a Ka/Ks ratio more than 0.5 and among which, three instrumental candidate genes, T20487,T22576, and T23757, were identified with strong selection signatures(Ka/Ks >1). The corresponding A. thaliana orthologs are double-stranded RNA-binding domain protein, MADS-box family protein, and NADH-dehydrogenase subunit6, which is encoded by mitochondria genome. This report not only demonstrates the adaptation contribution of fast evolving nuclear genes, but also highlights the potential adaptive value of mitochondria gene to the speciation and adaptation of B. humilis toward the extreme environment in an arid region.展开更多
Species of the red algal order Acrochaetiales mostly inhabit marine environments,with only two freshwater taxa Audouinella and Ottia.A new genus and species are described for freshwater red alga Pauciramus yunnanensis...Species of the red algal order Acrochaetiales mostly inhabit marine environments,with only two freshwater taxa Audouinella and Ottia.A new genus and species are described for freshwater red alga Pauciramus yunnanensis from Ailao Mountain,Yunnan,China.It is closely related to Ottia and a new order Ottiales was proposed for these genera.Pauciramus has unique combination of morphological characteristics including the following:plants caespitose and densely pulvinate,slender uniseriate filaments with well-developed rhizoids,rarely branched,cylindrical vegetative cell with a single,ribbon-shaped and parietal chloroplast,reproduction by tetrasporangia,and dense sporangial branchlet only at the upper portion of filaments.Phylogenetic analysis of sequence data from the plastid ribulose-1,5-bisphosphate carboxylase-oxygenase large-subunit(rbc L),small subunit gene of the ribosomal cistron(SSU)and barcode region near the 5′end of the mitochondrial cytochrome oxidase subunit I(COI-5P)indicated that:the new taxon,P.yunnanensis,was in a well-supported clade with Ottia meiospora,and this clade was sister to order Palmariales and Acrochaetiales.To adhere to the principle of monophyly,a new freshwater order Ottiales including Ottia and Pauciramus is proposed.Despite the high sequence interspecific divergences and obvious morphological differences between genera Ottia and Pauciramus,seems impractical to establish a new family for a monospecific genus.Therefore,we temporarily classified Pauciramus into the family Ottiaceae,and made necessary revisions to the description to accommodate this genus.展开更多
基金supported by National Natural Science Foundation of China (No. 41201048)by the Youth Innovation Promotion Association of Chinese Academy of Sciences (2018463)
文摘The Brassicaceae species Braya humilis shows broad adaptation to different climatic zones and latitudes. However, the molecular adaptation mechanism of B. humilis is poorly understood. In China, B. humilis is mainly distributed on the QinghaiTibetan Plateau(QTP) and in the adjacent arid region. Previous transcriptome analysis of B. humilis has revealed that 39 salt and osmotic stress response genes are subjected to purifying selection during its speciation. To further explore the adaptation mechanism of B. humilis to an arid environment, OrthoMCL program was employed in this study and 6,268 pairs of orthologous gene pairs with high confidence were obtained between B. humilis and Arabidopsis thaliana. A comparative evolutionary analysis based on nonsynonymous to synonymous substitution ratio(Ka/Ks) was then conducted. There were 64 pairs exhibiting a Ka/Ks ratio more than 0.5 and among which, three instrumental candidate genes, T20487,T22576, and T23757, were identified with strong selection signatures(Ka/Ks >1). The corresponding A. thaliana orthologs are double-stranded RNA-binding domain protein, MADS-box family protein, and NADH-dehydrogenase subunit6, which is encoded by mitochondria genome. This report not only demonstrates the adaptation contribution of fast evolving nuclear genes, but also highlights the potential adaptive value of mitochondria gene to the speciation and adaptation of B. humilis toward the extreme environment in an arid region.
基金Supported by the National Natural Science Foundation of China (No.41871037 to Shulian XIE and No.31800172 to Fangru NAN)the Fund for Shanxi"1331 Project"
文摘Species of the red algal order Acrochaetiales mostly inhabit marine environments,with only two freshwater taxa Audouinella and Ottia.A new genus and species are described for freshwater red alga Pauciramus yunnanensis from Ailao Mountain,Yunnan,China.It is closely related to Ottia and a new order Ottiales was proposed for these genera.Pauciramus has unique combination of morphological characteristics including the following:plants caespitose and densely pulvinate,slender uniseriate filaments with well-developed rhizoids,rarely branched,cylindrical vegetative cell with a single,ribbon-shaped and parietal chloroplast,reproduction by tetrasporangia,and dense sporangial branchlet only at the upper portion of filaments.Phylogenetic analysis of sequence data from the plastid ribulose-1,5-bisphosphate carboxylase-oxygenase large-subunit(rbc L),small subunit gene of the ribosomal cistron(SSU)and barcode region near the 5′end of the mitochondrial cytochrome oxidase subunit I(COI-5P)indicated that:the new taxon,P.yunnanensis,was in a well-supported clade with Ottia meiospora,and this clade was sister to order Palmariales and Acrochaetiales.To adhere to the principle of monophyly,a new freshwater order Ottiales including Ottia and Pauciramus is proposed.Despite the high sequence interspecific divergences and obvious morphological differences between genera Ottia and Pauciramus,seems impractical to establish a new family for a monospecific genus.Therefore,we temporarily classified Pauciramus into the family Ottiaceae,and made necessary revisions to the description to accommodate this genus.
