Transcriptome analyses of leaf architecture in Sansevieria support a common genetic toolkit in the parallel evolution of unifacial leaves in monocots

Abstract

Planar structures dramatically increase the surface‐area‐to‐volume ratio, which is critically important for multicellular organisms. In this study, we utilize naturally occurring phenotypic variation among three Sansivieria species (Asperagaceae) to investigate leaf margin expression patterns that are associated with mediolateral and adaxial/abaxial development. We identified differentially expressed genes (DEGs) between center and margin leaf tissues in two planar‐leaf species Sansevieria subspicata and Sansevieria trifasciata and compared these with expression patterns within the cylindrically leaved Sansevieria cylindrica. Two YABBY family genes, homologs of FILAMENTOUS FLOWER and DROOPING LEAF, are overexpressed in the center leaf tissue in the planar‐leaf species and in the tissue of the cylindrical leaves. As mesophyll structure does not indicate adaxial versus abaxial differentiation, increased leaf thickness results in more water‐storage tissue and enhances resistance to aridity. This suggests that the cylindrical‐leaf in S. cylindrica is analogous to the central leaf tissue in the planar‐leaf species. Furthermore, the congruence of the expression patterns of these YABBY genes in Sansevieria with expression patterns found in other unifacial monocot species suggests that patterns of parallel evolution may be the result of similar solutions derived from a limited developmental toolbox.

Leaf form diversity and evolution: a never-ending story in plant biology

“…A subsequent study revealed that the proper placement of auxin induces DL ortholog expression, leading to initial leaf flattening (Nukazuka et al 2021 ). A similar mechanism was reported in other independently acquired unifacial leaves, and the importance of thickening meristem is worth emphasizing (Golenberg et al 2023 ). Therefore, understanding each leaf meristem in detail and recapturing the complexity and specialization of leaf morphology through changes in these will help us understand the process of morphological change and the molecular mechanisms behind them more precisely.…”