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Root apical meristem diversity in extant lycophytes and implications for root origins
Author(s) -
Fujinami Rieko,
Yamada Toshihiro,
Nakajima Atsuko,
Takagi Shoko,
Idogawa Ai,
Kawakami Eri,
Tsutsumi Maiko,
Imaichi Ryoko
Publication year - 2017
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.14630
Subject(s) - selaginella , extant taxon , meristem , biology , division (mathematics) , botany , apical cell , cell division , evolutionary biology , cell , genetics , shoot , arithmetic , mathematics
Summary Root apical meristem ( RAM ) organization in lycophytes could be a key to understanding the early evolution of roots, but this topic has been insufficiently explored. We examined the RAM organization of lycophytes in terms of cell division activities and anatomies, and compared RAM s among vascular plants. RAM s of 13 species of lycophytes were semi‐thin‐sectioned and observed under a light microscope. Furthermore, the frequency of cell division in the RAM of species was analyzed using thymidine analogs. RAM s of lycophytes exhibited four organization types: type I ( Lycopodium and Diphasiastrum ), II ( Huperzia and Lycopodiella ), III ( Isoetes ) and RAM with apical cell ( Selaginella ). The type I RAM found in Lycopodium had a region with a very low cell division frequency, reminiscent of the quiescent center ( QC ) in angiosperm roots. This is the first clear indication that a QC ‐like region is present in nonseed plants. At least four types of RAM are present in extant lycophytes, suggesting that RAM organization is more diverse than expected. Our results support the paleobotanical hypothesis that roots evolved several times in lycophytes, as well as in euphyllophytes.