Anatomical aspects of IBA-treated microcuttings of Gomphrena macrocephala St.-Hil

• Main Authors: Míriam F. Moreira, Beatriz Appezzato-da-Glória, Lilian B.P. Zaidan
• Format: Article
• Language: English
• Published: Instituto de Tecnologia do Paraná (Tecpar) 2000-01-01
• Series: Brazilian Archives of Biology and Technology
• Subjects: Gomphrena; root anatomy; in vitro rooting; indol butiric acid; vascular connection
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132000000200012
• ISSN: 1516-8913; 1678-4324

Gomphrena macrocephala St.-Hil. (Amaranthaceae) is a perennial herb from the cerrado with medicinal properties and ornamental interest. Plants can be micropropagated through nodal segments, but acclimatization is difficult. The aim of this study was to establish a relationship between anatomical aspects of the roots and the acclimatization process. When cultures were supplemented with IBA, callus and thick and frangible roots appeared at the base of the microcuttings. A fragile vascular connection between roots and shoots was observed. Abnormal adventitious roots showing alteration in the vascular cylinder and hypertrophy of the cortical cells were also noted. These roots interfere in the transfer to extra vitrum conditions. When no growth regulator was used, no callus was formed, the adventitious roots were similar to those found in seedlings, and acclimatization could proceed. The results show that the origin and the structure of roots formed in the microcuttings play an important role in the acclimatization process and thus in the establishment of the micropropagated plants.<br>G. macrocephala St.-Hil.(Amaranthaceae) é uma espécie herbácea perene do cerrado com propriedades farmacológicas e ornamentais. Pode ser micropropagada através de segmentos nodais, mas as novas plantas sobrevivem por pouco tempo. O presente estudo visou relacionar os efeitos de IBA na anatomia das raízes e a resposta de aclimatização das plantas micropropagadas. Na presença de IBA, a base das microestacas forma calo e raízes adventícias espessas e quebradiças, dificultando a transferência para as condições extra vitrum. Ocorre uma frágil conexão vascular entre o sistema radicular e a microestaca, além de raízes adventícias mal formadas, com alterações no cilindro vascular e hipertrofia das células corticais. Na ausência de IBA, as microestacas não formam calo, as raízes adventícias são morfologicamente similares às de plantas obtidas de sementes e o processo de aclimatização é bem sucedido. Os resultados indicam que as características das raízes formadas podem vir a comprometer a aclimatização e o estabelecimento das novas plantas.