No abstract

Genome information from model species such as rice can assist in the cloning of genes in a complex genome, such as maize. Here, we identified a maize ortholog of rice GS5 that contributes to kernel development in maize. The genomewide association analysis of the expression levels of ZmGS5, and 15 of its 26 paralogs, identified a trans-regulator on chromosome 7, which was a BAK1-like gene. This gene that we named as ZmBAK1-7 could regulate the expression of ZmGS5 and three of the paralogs. Candidate-gene association analyses revealed that these five genes were associated with maize kernel development-related traits. Linkage analyses also detected that ZmGS5 and ZmBAK1-7 co-localized with mapped QTLs. A transgenic analysis of ZmGS5 in Arabidopsis thaliana L.showed a significant increase in seed weight and cell number, suggesting that ZmGS5 may have a conserved function among different plant species that affects seed development.

Rift Valley fever virus (RVFV) belongs to the order Bunyavirales and is the type species of genus Phlebovirus , which accounts for over 50% of family Phenuiviridae species. RVFV is mosquito-borne and causes severe diseases in both humans and livestock, and consists of three segments (S, M, L) in the genome. The L segment encodes an RNA-dependent RNA polymerase (RdRp, L protein) that is responsible for facilitating the replication and transcription of the virus. It is essential for the virus and has multiple drug targets. Here, we established an expression system and purification procedures for full-length L protein, which is composed of an endonuclease domain, RdRp domain, and cap-binding domain. A cryo-EM L protein structure was reported at 3.6 Å resolution. In this first L protein structure of genus Phlebovirus , the priming loop of RVFV L protein is distinctly different from those of other L proteins and undergoes large movements related to its replication role. Structural and biochemical analyses indicate that a single template can induce initiation of RNA synthesis, which is notably enhanced by 5’ viral RNA. These findings help advance our understanding of the mechanism of RNA synthesis and provide an important basis for developing antiviral inhibitors. Importance The zoonosis RVF virus (RVFV) is one of the most serious arbovirus threats to both human and animal health. RNA-dependent RNA polymerase (RdRp) is a multifunctional enzyme catalyzing genome replication as well as viral transcription, so the RdRp is essential for studying the virus and has multiple drug targets. In our study, we report the structure of RVFV L protein at 3.6 Å resolution by cryo-EM. This is the first L protein structure of genus Phlebovirus. Strikingly, a single template can initiate RNA replication. The structure and assays provide a comprehensive and in-depth understanding of the catalytic and substrate recognition mechanism of RdRp.