Robertson, J. | bioRxiv Science

bioRxiv2018

Genotyping by sequencing of 393 Sorghum bicolor BTx623 x IS3620C recombinant inbred lines improves sensitivity and resolution of QTL detection

We describe a genetic map with a total of 381 bins of 616 genotyping by sequencing (GBS)-based SNP markers in a F6-F8 recombinant inbred line (RIL) population of 393 individuals derived from crossing S. bicolor BTx623 to S. bicolor IS3620C, a guinea line substantially diverged from BTx623. Five segregation distorted regions were found with four showing enrichment for S. bicolor alleles, suggesting possible selection during formation of this RIL population. A quantitative trait locus (QTL) study with this number of individuals, tripled relative to prior studies of this cross, provided resources, validated previous findings, and demonstrated improved power to detect plant height and flowering time related QTLs relative to other published studies. An unexpected low correlation between flowering time and plant height permitted us to separate QTLs for each trait and provide evidence against pleiotropy. Ten non-random syntenic regions conferring QTLs for the same trait suggest that those QTLs may represent alleles at genes functioning in the same manner since the 96 million year ago genome duplication that created these syntenic relationships, while syntenic regions conferring QTLs for different trait may suggest sub-functionalization after duplication. Collectively, this study provides resources for marker-assisted breeding, as well as a framework for fine mapping and subsequent cloning of major genes for important traits such as plant height and flowering time in sorghum.

genetics↗

bioRxiv2017

The Drosophila SK potassium channel negatively regulates nociception.

Inhibition of nociceptor activity is important for the prevention of spontaneous pain and hyperalgesia. To identify the critical K+ channels that regulate nociceptor excitability we performed a forward genetic screen using a Drosophila larval nociception paradigm. Knockdown of three K+ channel loci, the small conductance calcium-activated potassium channel (SK), seizure and tiwaz, resulted in marked hypersensitive nociception behaviors. In more detailed studies of SK, we found that hypersensitive phenotypes could be recapitulated with a genetically null allele. Importantly, the null mutant phenotype could be rescued with tissue specific expression of an SK cDNA in nociceptors. Optical recordings from nociceptive neurons showed a significant increase in mechanically activated Ca2+ signals in SK mutant nociceptors. SK showed expression in peripheral neurons. Interestingly SK proteins localized to axons of these neurons but were not detected in dendrites. Our findings suggest a major role for SK channels in the regulation of nociceptor excitation and they are inconsistent with the hypothesis that the important site of action is within dendrites.\n\nHighlights-Specific potassium channels regulate nociceptor excitability.\n-SK channels have a critical function in nociception.\n-SK channels specifically localize to sensory axons\n-SK channels are not detectable in sensory dendrites.

neuroscience↗