Main conclusion <p><i> Commelina erecta</i> L. leaf sheaths fuse postgenitally without KN1 ortholog expression, indicating a distinct molecular mechanism for sheath fusion in <i>Commelinaceae</i>, contrasting it from sheath formation in <i>Poaceae</i>.</p> Abstract <p>Leaf sheaths are common structures within monocotyledonous, being open or closed depending on the separation of their margins. In Commelinaceae, a family of monocotyledonous plants with simple leaves and alternate phyllotaxy, their sheaths are closed. In Poaceae, which often have open sheaths, there has been evidence of <i>KNOX</i> genes affecting the fusion in sheaths in this family. The present study, therefore, investigated the nature of the sheath fusion and the expression of <i>KN1</i> ortholog at the leaf sheaths in <i>Commelina erecta</i> L. Samples of the shoot apex and leaf primordia were subjected to scanning electron microscopy and optical microscopy techniques with serial sections in paraffin. Samples of apical meristems from specimens of <i>C. erecta</i> were also subjected to in situ hybridization to verify the expression of <i>KNOX</i> within its leaves, with the probe sequence established by degenerate RT-PCR. The anatomical analysis revealed that sheaths of <i>C. erecta</i> undergo post-genital fusion. In situ hybridizations in <i>C. erecta</i> revealed no expression of <i>KN1</i> ortholog at the region of the fused sheath margins<i>.</i> The post-genital fusion indicates, therefore, the previous separation of the sheath margins, which, associated with lack of expression of <i>KN1</i> at this region, suggests a distinct molecular mechanism of leaf fusion in Commelinaceae, contrasting it from sheath formation in Poaceae.</p> Graphic abstract <p></p>

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Ontogeny of postgenital leaf sheath fusion in Commelina erecta L. (Commelinaceae)

  • Arthur K. Chan,
  • Michael J. Scanlon,
  • Gladys F. A. Melo-de-Pinna

摘要

Main conclusion

Commelina erecta L. leaf sheaths fuse postgenitally without KN1 ortholog expression, indicating a distinct molecular mechanism for sheath fusion in Commelinaceae, contrasting it from sheath formation in Poaceae.

Abstract

Leaf sheaths are common structures within monocotyledonous, being open or closed depending on the separation of their margins. In Commelinaceae, a family of monocotyledonous plants with simple leaves and alternate phyllotaxy, their sheaths are closed. In Poaceae, which often have open sheaths, there has been evidence of KNOX genes affecting the fusion in sheaths in this family. The present study, therefore, investigated the nature of the sheath fusion and the expression of KN1 ortholog at the leaf sheaths in Commelina erecta L. Samples of the shoot apex and leaf primordia were subjected to scanning electron microscopy and optical microscopy techniques with serial sections in paraffin. Samples of apical meristems from specimens of C. erecta were also subjected to in situ hybridization to verify the expression of KNOX within its leaves, with the probe sequence established by degenerate RT-PCR. The anatomical analysis revealed that sheaths of C. erecta undergo post-genital fusion. In situ hybridizations in C. erecta revealed no expression of KN1 ortholog at the region of the fused sheath margins. The post-genital fusion indicates, therefore, the previous separation of the sheath margins, which, associated with lack of expression of KN1 at this region, suggests a distinct molecular mechanism of leaf fusion in Commelinaceae, contrasting it from sheath formation in Poaceae.

Graphic abstract