Voltage-gated K(+) channels (Kv1) are important in glia, being required for cell proliferation. Herein, reactive astrocytes from a rat cerebellar lesion were shown to contain Kv1.1, -1.2, -1.3, -1.4, and -1.6 alpha plus beta1.1 subunits, as well as an unusual beta2.1 constituent; the latter was also found in a glioblastoma C6 cell line, together with Kv1.1, -1.3, and -1.6 and beta1.1 subunits. Reverse transcriptase-polymerase chain reaction revealed a novel product of the beta2 gene in C6 cells and reactive astrocytes, but not in cultured astrocytes or rat normal brain. Its cloning identified a variant, Kvbeta2.1A, alternatively spliced between I24 and Y39. Despite this 14 residue deletion, Kvbeta2.1A assembled cotranslationally with Kv1.1 or -1.2 and, when coexpressed with Kv1. 4 in oocytes, increased the inactivation rate of this K(+) current. Whereas the full-length beta2.1 gave a large increase in the amplitude of the Kv1.1 current in oocytes, the effect of beta2.1A varied from a modest elevation of the current to a slight suppression in some cases. In summary, this is the first report of the existence of an alternatively spliced product of the Kvbeta2.1 gene in C6 cells and reactive astrocytes, and supports the involvement of its core region (residues 39 onward) in assembly with alpha subunits while excluding a contribution of the adjacent 14 residues to accelerating the inactivation of Kv1.4.

IntroductionOver four billion people around the world rely on bread wheat (Triticum aestivum L.) as a major constituent of their diet. The changing climate, however, threatens the food security of these people, with periods of intense drought stress already causing widespread wheat yield losses. Much of the research into the wheat drought response has centred on the response to drought events later in development, during anthesis or grain filling. But as the timing of periods of drought stress become increasingly unpredictable, a more complete understanding of the response to drought during early development is also needed.MethodsHere, we utilized the YoGI landrace panel to identify 10,199 genes which were differentially expressed under early drought stress, before weighted gene co-expression network analysis (WGCNA) was used to construct a co-expression network and identify hub genes in modules particularly associated with the early drought response.ResultsOf these hub genes, two stood out as novel candidate master regulators of the early drought response – one as an activator (TaDHN4-D1; TraesCS5D02G379200) and the other as a repressor (uncharacterised gene; TraesCS3D02G361500).DiscussionAs well as appearing to coordinate the transcriptional early drought response, we propose that these hub genes may be able to regulate the physiological early drought response due to potential control over the expression of members of gene families well-known for their involvement in the drought response in many plant species, namely dehydrins and aquaporins, as well as other genes seemingly involved in key processes such as, stomatal opening, stomatal closing, stomatal morphogenesis and stress hormone signalling.

Triticum aestivum L. (bread wheat) is a crop relied upon by billions of people around the world, as a major source of both income and calories. Rising global temperatures, however, pose a genuine threat to the livelihood of these people, as wheat growth and yields are extremely vulnerable to damage by heat stress. Here we present the YoGI wheat landrace panel, comprising 342 accessions that show remarkable phenotypic and genetic diversity thanks to their adaptation to different climates. We quantified the abundance of 110 790 transcripts from the panel and used these data to conduct weighted co-expression network analysis and to identify hub genes in modules associated with abiotic stress tolerance. We found that the expression of three hub genes, all heat-shock proteins (HSPs), were significantly correlated with early thermotolerance in a validation panel of landraces. These hub genes belong to the same module, with one (TraesCS4D01G207500.1) being a candidate master-regulator potentially controlling the expression of the other two hub genes, as well as a suite of other HSPs and heat-stress transcription factors (HSFs). In this work, therefore, we identify three validated hub genes, the expression of which can serve as markers of thermotolerance during early development, and suggest that TraesCS4D01G207500.1 is a potential master regulator of HSP and HSF expressionpresenting the YoGI landrace panel as an invaluable tool for breeders wishing to determine and introduce novel alleles into modern varieties, for the production of climate-resilient crops.

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