AUTHOR=Guo Hongyan , Zhang Wei , Tian Hainan , Zheng Kaijie , Dai Xuemei , Liu Shanda , Hu Qingnan , Wang Xianling , Liu Bao , Wang Shucai 

TITLE=An auxin responsive CLE gene regulates shoot apical meristem development in Arabidopsis

JOURNAL=Frontiers in Plant Science

VOLUME=6

YEAR=2015

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2015.00295

DOI=10.3389/fpls.2015.00295

ISSN=1664-462X

ABSTRACT=<p>Plant hormone auxin regulates most, if not all aspects of plant growth and development, including lateral root formation, organ pattering, apical dominance, and tropisms. Peptide hormones are peptides with hormone activities. Some of the functions of peptide hormones in regulating plant growth and development are similar to that of auxin, however, the relationship between auxin and peptide hormones remains largely unknown. Here we report the identification of <italic>OsCLE48</italic>, a rice (<italic>Oryza sativa</italic>) <italic>CLE</italic> (<italic>CLAVATA3/ENDOSPERM SURROUNDING REGION</italic>) gene, as an auxin response gene, and the functional characterization of <italic>OsCLE48</italic> in <italic>Arabidopsis</italic> and rice. <italic>OsCLE48</italic> encodes a CLE peptide hormone that is similar to <italic>Arabidopsis</italic> CLEs. RT-PCR analysis showed that <italic>OsCLE48</italic> was induced by exogenously application of IAA (indole-3-acetic acid), a naturally occurred auxin. Expression of integrated <italic>OsCLE48p:GUS</italic> reporter gene in transgenic <italic>Arabidopsis</italic> plants was also induced by exogenously IAA treatment. These results indicate that <italic>OsCLE48</italic> is an auxin responsive gene. Histochemical staining showed that <italic>GUS</italic> activity was detected in all the tissue and organs of the <italic>OsCLE48p:GUS</italic> transgenic <italic>Arabidopsis</italic> plants. Expression of <italic>OsCLE48</italic> under the control of the <italic>35S</italic> promoter in <italic>Arabidopsis</italic> inhibited shoot apical meristem development. Expression of <italic>OsCLE48</italic> under the control of the <italic>CLV3</italic> native regulatory elements almost completely complemented <italic>clv3-2</italic> mutant phenotypes, suggesting that OsCLE48 is functionally similar to CLV3. On the other hand, expression of <italic>OsCLE48</italic> under the control of the <italic>35S</italic> promoter in <italic>Arabidopsis</italic> has little, if any effects on root apical meristem development, and transgenic rice plants overexpressing <italic>OsCLE48</italic> are morphologically indistinguishable from wild type plants, suggesting that the functions of some CLE peptides may not be fully conserved in <italic>Arabidopsis</italic> and rice. Taken together, our results showed that <italic>OsCLE48</italic> is an auxin responsive peptide hormone gene, and it regulates shoot apical meristem development when expressed in <italic>Arabidopsis</italic>.</p>