The MYB33, MYB65, and MYB101 transcription factors affect Arabidopsis and potato responses to drought by regulating the ABA signaling pathway.

Drought is one of the main climate threats limiting crop production. Potato is one of the four most important food crop species worldwide and is sensitive to water shortage. The CBP80 gene was shown to affect Arabidopsis and potato responses to drought by regulating the level of microRNA159 and, consequently, the levels of the MYB33 and MYB101 transcription factors (TFs). Here, we show that three MYB TFs, MYB33, MYB65, and MYB101, are involved in plant responses to water shortage. Their downregulation in Arabidopsis causes stomatal hyposensitivity to abscisic acid (ABA), leading to reduced tolerance to drought. Transgenic Arabidopsis and potato plants overexpressing these genes, with a mutated recognition site in miR159, show hypersensitivity to ABA and relatively high tolerance to drought conditions. Thus, the MYB33, MYB65, and MYB101 genes may be potential targets for innovative breeding to obtain crops with relatively high tolerance to drought.

Mouse model of the human serotonin transporter-linked polymorphic region.

Genetic factors play a significant role in risk for mood and anxiety disorders. Polymorphisms in genes that regulate the brain monoamine systems, such as catabolic enzymes and transporters, are attractive candidates for being risk factors for emotional disorders given the weight of evidence implicating monoamines involvement in these conditions. Several common genetic variants have been identified in the human serotonin transporter (5-HTT) gene, including a repetitive sequence located in the promoter region of the locus called the serotonin transporter-linked polymorphic region (5-HTT-LPR). This polymorphism has been associated with a number of mental traits in both humans and primates, including depression, neuroticism, and harm avoidance. Some, but not all, studies found a link between the polymorphism and 5-HTT levels, leaving open the question of whether the polymorphism affects risk for mental traits via changes in 5-HTT expression. To investigate the impact of the polymorphism on gene expression, serotonin homeostasis, and behavioral traits, we set out to develop a mouse model of the human 5-HTT-LPR. Here we describe the creation and characterization of a set of mouse lines with single-copy human transgenes carrying the short and long 5-HTT-LPR variants. Although we were not able to detect differences in expression between the short and long variants, we encountered several technical issues concerning the design of our humanized mice that are likely to have influenced our findings. Our study serves as a cautionary note for future studies aimed at studying human transgene regulation in the context of the living mouse.

Genomewide identification of genes involved in the potato response to drought indicates functional evolutionary conservation with Arabidopsis plants.

Potato is one of the four most important food crop plants worldwide and is strongly affected by drought. The following two pairs of potato cultivars, which are related in ancestry but show different drought tolerances, were chosen for comparative gene expression studies: Gwiazda/Oberon and Tajfun/Owacja. Comparative RNA-seq analyses of gene expression differences in the transcriptomes obtained from drought-tolerant versus drought-sensitive plants during water shortage conditions were performed. The 23 top-ranking genes were selected, 22 of which are described here as novel potato drought-responsive genes. Moreover, all but one of the potato genes selected have homologues in the Arabidopsis genome. Of the seven tested A. thaliana mutants with altered expression of the selected homologous genes, compared to the wild-type Arabidopsis plants, six showed an improved tolerance to drought. These genes encode carbohydrate transporter, mitogen-activated protein kinase kinase kinase 15 (MAPKKK15), serine carboxypeptidase-like 19 protein (SCPL19), armadillo/beta-catenin-like repeat-containing protein, high-affinity nitrate transporter 2.7 and nonspecific lipid transfer protein type 2 (nsLPT). The evolutionary conservation of the functions of the selected genes in the plant response to drought confirms the importance of these identified potato genes in the ability of plants to cope with water shortage conditions. Knowledge regarding these gene functions can be used to generate potato cultivars that are resistant to unfavourable conditions. The approach used in this work and the obtained results allowed for the identification of new players in the plant response to drought.

Construction of Artificial miRNAs to Prevent Drought Stress in Solanum tuberosum.

The use of artificial microRNAs (amiRNAs) is still a relatively new technique in molecular biology with a wide range of applications in life sciences. Here, we describe the silencing of the CBP80/ABH1 gene in Solanum tuberosum with the use of amiRNA. The CBP80/ABH1 protein is part of the Cap Binding Complex (CBC), which is involved in plant responses to drought stress conditions. Transformed plants with a decreased level of CBP80/ABH1 display increased tolerance to water shortage conditions. We describe how to design amiRNA with the Web MicroRNA Designer platform in detail. Additionally, we explain how to perform all steps of a procedure aiming to obtain transgenic potato plants with the use of designed amiRNA, through callus tissue regeneration and Agrobacterium tumefaciens strain LBA4404 as a transgene carrier.

Serotonin 1A auto-receptors are not sufficient to modulate anxiety in mice.

The neurotransmitter serotonin plays an important role in modulating diverse behavioral traits. Mice lacking the serotonin 1A receptor (Htr1a) show elevated avoidance of novel open spaces, suggesting that it has a role in modulating anxiety behavior. Htr1a is a Gαi -coupled G-protein-coupled receptor expressed on serotonin neurons (auto-receptor), where it mediates negative feedback of serotonin neuron firing. Htr1a is also expressed on non-serotonin neurons (hetero-receptor) in diverse brain regions, where it mediates an inhibitory effect of serotonin on neuronal activity. Debate exists about which of these receptor populations is responsible for the modulatory effects of Htr1a on anxiety. Studies using tissue-specific transgenic expression have suggested that forebrain Htr1a hetero-receptors are sufficient to restore normal anxiety behavior to Htr1a knockout mice. At the same time, experiments using tissue-specific transgenic suppression of Htr1a expression have demonstrated that Htr1a auto-receptors, but not forebrain hetero-receptors, are necessary for normal anxiety behavior. One interpretation of these data is that multiple Htr1a receptor populations are involved in modulating anxiety. Here, we aimed to test this hypothesis by determining whether Htr1a auto-receptors are sufficient to restore normal anxiety to Htr1a knockout animals. Transgenic mice expressing Htr1a under the control of the tryptophan hydroxylase 2 (Tph2) promoter showed restored Htr1a-mediated serotonin negative feedback and hypothermia, but anxiety behavior indistinguishable from that of knockout mice. These data show that, in the absence of Htr1a hetero-receptors, auto-receptors are unable to have an impact on anxiety. When combined with previous data, these findings support the hypothesis that Htr1a auto-receptors are necessary, but not sufficient, to modulate anxiety.

Down-regulation of CBP80 gene expression as a strategy to engineer a drought-tolerant potato.

Developing new strategies for crop plants to respond to drought is crucial for their innovative breeding. The down-regulation of nuclear cap-binding proteins in Arabidopsis renders plants drought tolerant. The CBP80 gene in the potato cultivar Desiree was silenced using artificial microRNAs. Transgenic plants displayed a higher tolerance to drought, ABA-hypersensitive stomatal closing, an increase in leaf stomata and trichome density, and compact cuticle structures with a lower number of microchannels. These findings were correlated with a higher tolerance to water stress. The level of miR159 was decreased, and the levels of its target mRNAs MYB33 and MYB101 increased in the transgenic plants subjected to drought. Similar trends were observed in an Arabidopsis cbp80 mutant. The evolutionary conservation of CBP80, a gene that plays a role in the response to drought, suggests that it is a candidate for genetic manipulations that aim to obtain improved water-deficit tolerance of crop plants.