Submitted to: Tropical Plant Biology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/1/2014
Publication Date: 6/8/2014
Citation: Hudson, K.A., Hudson, M. 2014. The basic helix-loop-helix transcription factor family in the sacred lotus, Nelumbo nucifera. Tropical Plant Biology. 7(2):65-70. Interpretive Summary: This paper describes a specific family of control genes from the plant Nelumbo nucifera, also known as the sacred lotus. These genes control a variety of processes in all plant species. The lotus has very long-lived seeds and flowers that produce heat to attract pollinating insects. The recent genome sequence of Nelumbo nucifera makes it an interesting plant to use for evolutionary analysis of regulatory genes, because it has a slow rate of DNA sequence change and is from one of the earliest evolutionary lineages of land plants. Although Nelumbo possesses the structures of a land plant, it is adapted to an aquatic lifestyle and tolerates root submergence. Interestingly, some of genes that are involved in root development in other plants are missing or different in Nelumbo, which could help to explain how the lotus adapted to an aquatic environment. This information is used by scientists to understand how gene families evolve and how different plants use similar genes to make different structures or control different processes.
Technical Abstract: Nelumbo nucifera (Sacred Lotus) is a basal eudicot with exceptional physiological and metabolic properties including seed longevity, adaptations for an aquatic habit, and floral thermiogenesis. It also occupies a unique position in the phylogeny of land plants and can be a useful species for studies of conserved plant gene families. The basic-helix-loop-helix (bHLH) proteins represent one of the largest transcription factor families in plants and has undergone extensive duplication and expansion during plant evolution. One hundred and seventeen transcript models encoding canonical bHLHs were identified in the Nelumbo genome, as well as several “atypical” bHLH-encoding genes. The canonical bHLH proteins fall into 23 previously characterized subfamilies also present in other sequenced plant genomes, and are expressed as mRNA. Analysis of bHLHs from lotus and other sequenced angiosperms indicates most of these families of bHLHs, along with secondary motifs associated with the bHLH domain, were likely present in the progenitor of flowering plants. The absence of a bHLH subfamily involved in root development in Nelumbo is consistent with the possibility that the development of specialized root structures may be mediated in part by changes in the bHLH families that regulate root development in dicots.