Fig. 1

OsRKD3 is closely related to embryonic RKDs. A Phylogenetic tree of RWP-RK proteins. Left panel; Phylogenetic tree computed with MEGA7, representing the evolutionary history, was inferred using the minimum evolution method. An optimal tree with the sum of branch length = 8.65634175 is shown. The ME tree was generated using the Close-Neighbour-Interchange (CNI) algorithm at a search level of 1. The percentage of replicate trees in which the associated taxa clustered together in the bootstrap test (500 replicates) are shown next to the branches. The analysis involved 17 amino acid sequences. All positions containing gaps and missing data were eliminated. Right panel: Schematic diagrams for structures of RWP-RK proteins. Green boxes represented RWP-RK domain. Blue box on OsRKD5 represented tetratricopeptide repeats (TPR) and pentatricopeptide repeats (PPR). Red box highlights AtRKD4, MpRKD and OsRKD3, which group together in the phylogenetic tree. Os, Oryza sativa; At, Arabidopsis thaliana; Mp, Marchantia polymorpha. B Protein alignment of RWP-RK domains. The alignment computed by MAFFT using Jalview. A black coloured box represented the RWP-RK conserved motif. C Expression profiling, as normalised FPKM RNA-seq reads, of RKD genes in various rice organs. Red box indicates the expression profile for OsRKD3. D Expression profile of OsRKD3 in different reproductive tissues. RNA-seq data was obtained from the rice genome annotation project (http://rice.uga.edu/expression.shtml) and the rice RNA-seq database (http://ipf.sustech.edu.cn/pub/ricerna/)