The role of the FHA domain-containing protein family in pollen development of Brassica rapa L

The utilisation of male sterility is an ideal method for hybrid seed production in Brassica rapa L. Previously, we identified Bra015018, which encodes a forkhead-associated (FHA) domain-containing protein, as a candidate gene for genetic male sterility (GMS) in B. rapa. Here, we aimed to further explore the role of the FHA domain-containing protein family in the growth and development of B. rapa. For this, we screened the FHA domain-containing protein family at the whole-genome level. Phylogenetic and sequence composition analysis distributed the 26 identified B. rapa FHA domain-containing proteins (BrFHAs) into five groups (clades I-V), which were distributed on chromosomes 1 to 10. We further explored gene structural characteristics, conserved motifs, and cis-regulatory elements of the 26 genes. The identified BrFHA genes were predicted to contain defence, stress, light response, and hormone-responsive regulatory elements in their promoter regions. Three miRNAs related to pollen development, miR414, miR5021, and miR408-5p, targeting three BrFHA genes, were predicted. The online gene expression profiles of the 26 BrFHA family genes revealed that they were highly expressed in different tissues of B. rapa, and 10 genes were highly expressed in flowers. Quantitative PCR analysis showed that 14 BrFHA genes were upregulated in male fertile buds compared with that in male sterile buds. Furthermore, eight genes were highly expressed in the early stages of pollen development, while six genes were highly expressed in the middle stage of pollen development in male fertile buds. This study provides an overview of the BrFHA family, which will assist molecular breeding for GMS in B. rapa.

Automated summary

This study identified and characterized a family of FHA domain-containing proteins in Brassica rapa, which are highly expressed in different tissues and flowers, with some genes showing differential expression in male fertile and sterile buds. The research also predicted miRNAs targeting BrFHA genes related to pollen development. This information can assist in molecular breeding for genetic male sterility in Brassica rapa.