Open Access AJPS The Wheat Plastochron Mutant, fushi-darake, Shows Transformation of Reproductive Spikelet Meristem into Vegetative Shoot Meristem

Copyright © 2013 Chikako Tahira et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. In wheat plants at the vegetative growth stage, the shoot apical meristem (SAM) produces leaf primordia. When repro-ductive growth is initiated, the SAM forms an inflorescence meristem (IM) that differentiates a series of spikelet meris-tem (SM) as the branch. The SM then produces a series of floret meristem (FM) as the branch. To identify the mecha-nisms that regulate formation of the reproductive meristems in wheat, we have investigated a leaf initiation mutant, fu-shi-darake (fdk) which was developed by ion beam mutagenesis. The morphological traits were compared in wild type (WT) and fdk mutant plants grown in the experimental field. WT plants initiated leaves from SAM at regular intervals in spiral phyllotaxy, while fdk plants had 1/2 alternate phyllotaxy with rapid leaf emergence. The fdk plants have in-creased numbers of nodes and leaves compared with WT plants. The time interval between successive leaf initiation events (plastochron) was measured in plants grown in a growth chamber. The fdk plants clearly show the rapid leaf emergence, indicating a shortened plastochron. Each tiller in fdk plants branches at the upper part of the culm. The fine structure of organ formation in meristems of fdk plants was examined by scanning electron microscopy (SEM). The SEM analysis indicated that fdk plants show transformation of spikelet meristems into vegetative shoot meristems. I