Convergent evolution of shoots in land plants: lack of auxin polar transport in moss shoots.
The shoot is a repeated structure made up of stems and leaves and is the basic body plan in land plants. Vascular plants form a shoot in the diploid generation, whereas nonvascular plants such as mosses form a shoot in the haploid generation. It is not clear whether all land plants use similar molecular mechanisms in shoot development or how the genetic networks for shoot development evolved. The control of auxin distribution, especially by polar auxin transport, is essential for shoot development in flowering plants. We did not detect polar auxin transport in the gametophytic shoots of several mosses, but did detect it in the sporophytes of mosses without shoot structure. Treatment with auxin transport inhibitors resulted in abnormal embryo development, as in flowering plants, but did not cause any morphological changes in the haploid shoots. We fused the soybean auxin-inducible promoter GH3 with a GUS reporter gene and used it to indirectly detect auxin distribution in the moss Physcomitrella patens. An auxin transport inhibitor NPA did not cause any changes in the putative distribution of auxin in the haploid shoot. These results indicate that polar auxin transport is not involved in haploid shoot development in mosses and that shoots in vascular plants and mosses are most likely regulated differently during development.
Fujita
Tomomichi
T
National Institute for Basic Biology, Okazaki 444-8585, Japan.
Sakaguchi
Hisako
H
Hiwatashi
Yuji
Y
Wagstaff
Steven J
SJ
Ito
Motomi
M
Deguchi
Hironori
H
Sato
Toshiyuki
T
Hasebe
Mitsuyasu
M
D001483:Base Sequence; D005075:Biological Evolution; D001693:Biological Transport, Active; D019068:Bryopsida / Q000033:anatomy & histology* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D017931:DNA Primers / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D004171:Diploidy; D017343:Genes, Plant; D006238:Haploidy; D007210:Indoleacetic Acids / Q000378:metabolism*; D018520:Plant Shoots / Q000033:anatomy & histology* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic; D015398:Signal Transduction
D017931:DNA Primers; D018744:DNA, Plant; D007210:Indoleacetic Acids