J Syst Evol ›› 2016, Vol. 54 ›› Issue (3): 204-218.DOI: 10.1111/jse.12206

• Research Articles • Previous Articles     Next Articles

Evolution of the leucine-rich repeat receptor-like protein kinase gene family: Ancestral copy number and functional divergence of BAM1 and BAM2 in Brassicaceae

Hao Li1†, Qian Shi1†, Zai-Bao Zhang1, Li-Ping Zeng1, Ji Qi1*, and Hong Ma1,2*   

  1. 1State Key Laboratory of Genetic Engineering and Collaborative Innovation Center for Genetics and Development, Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Plant Biology, Institute of Biodiversity Sciences, Center for Evolutionary Biology, School of Life Sciences, Fudan University, Shanghai 200438, China
    2Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
  • Received:2016-03-11 Published:2016-05-13

Abstract: Gene duplication allows for functional divergence and innovation that provide selective advantages. However, in flowering plants genetic studies have revealed that single-gene mutations affecting one of two or more closely related paralogs often fail to cause detectable morphological defects, suggesting functional redundancy. Flowering plants have hundreds of genes encoding leucine-rich repeat receptor-like protein kinases (LRR-RLKs), several of which play important roles in anther development, but little is known about their evolutionary history and possible functional divergence. We investigated the evolutionary relationship of the LRR-RLK gene family by phylogenetic analysis and found that these closely related paralogs resulted from multiple duplication events, such as the one resulting in BAM1 and BAM2. We further used quantitative real-time reverse transcription–polymerase chain reaction to verify gene expression changes in immature anthers from the bam1/bam2single and double mutants compared with wild type, providing strong evidence that the BAM1 and BAM2 genes have evolved different functions, with differential effects on anther gene expression. Moreover, careful examination of anther development in bam1 and bam2 single mutants revealed previously unrecognized extra cell division in tapetum cell layers. Thus our results from phylogenetic, molecular, and morphological analyses uncover sequence and functional differences between paralogs whose single mutants lack obvious fertility defects, effectively revealing functional divergence of duplicate genes.

Key words: anther development, BAM1/BAM2, Brassicaceae, leucine-rich repeat receptor-like kinases, LRR-RLK, subfunctionalization