Pollen-Expressed Transcription Factor 2 Encodes a Novel Plant-Specific TFIIB-Related Protein that Is Required for Pollen Germination and Embryogenesis in Arabidopsis

Pollen germination and embryogenesis are important to sexual plant reproduction. The processes require a large number of genes to be expressed. Transcription of eukaryotic nuclear genes is accomplished by three conserved RNA polymerases acting in association with a set of auxiliary general transcription factors （GTFs）, including B-type GTFs. The roles of B-type GTFs in plant reproduction remain poorly understood. Here we report functional characterization of a novel plant-specific TFIIB-related gene PTF2 in Arabidopsis. Mutation in PTF2 caused failure of pollen germination. Pollen-rescue revealed that the mutation also disrupted embryogenesis and resulted in seed abortion. PTF2 is expressed prolifically in developing pollen and the other tissues with active cell division and differentiation, including embryo and shoot apical meristem. The PTF2 protein shares a lower amino acid sequence similarity with other known TFIIB and TFIIB-related proteins in Arabidopsis. It can interact with TATA-box binding protein 2 （TBP2） and bind to the double- stranded DNA （dsDNA） as the other known TFIIB and TFIIB-related proteins do. In addition, PTF2 can form a homodimer and interact with the subunits of RNA polymerases （RNAPs）, implying that it may be involved in the RNAPs transcription. These results suggest that PTF2 plays crucial roles in pollen germination and embryogenesis in Arabidopsis, possibly by regulating gene expression through interaction with TBP2 and the subunits of RNAPs.

Medial Preoptic Area Modulates Courtship Ultrasonic Vocalization in Adult Male Mice

Adult male mice emit highly complex ultrasonic vocalizations(USVs)in response to female conspecifics.Such US Vs,thought to facilitate courtship behaviors,are routinely measured as a behavioral index in mouse models of neurodevelopmental and psychiatric disorders such as autism.While the regulation of US Vs by genetic factors has been extensively characterized,the neural mechanisms that control USV production remain largely unknown.Here,we report that optogenetic activation of the medial preoptic area(mPOA)elicited the production of USVs that were acoustically similar to courtship US Vs in adult mice.Moreover,mPOA vesicular GABA transporter-positive(Vgat +)neurons were more effective at driving USV production than vesicular glutamate transporter 2-positive neurons.Furthermore,ablation of mPOA Vgat+ neurons resulted in altered spectral features and syllable usage of USVs in targeted males.Together,these results demonstrate that the mPOA plays a crucial role in modulating courtship USVs and this may serve as an entry point for future dissection of the neural circuitry underlying USV production.