Developmental stages during the rooting of in-vitro-cultured Quercus robur shoots from material of juvenile and mature origin

Abstract

In-vitro-cultured shoots of clones initiated from shoots of the basal parts (BS) and the crown (C) of two mature Quercus robur L. trees were subjected to rooting experiments to relate rooting with shoot topophysical origin. The BS shoots exhibited morphologically juvenile characteristics and rooted more easily after indole-3-butyric acid (IBA) treatment than C shoots. When naphthylphthalamic acid (NPA) was applied to BS shoots, rooting capacity decreased and root emergence was delayed at least 2 days compared with shoots treated with IBA only. During the first days of the rooting process, endogenous indole-3-acetic acid (IAA) concentration was higher in C shoots than in BS shoots, regardless of whether the shoots were treated with NPA. Mitotic figures were observed in cells from the basal part of both BS and C shoots 24 h after IBA treatment. After 4 days of IBA treatment, the occurrence of histological events differed between BS shoots and C shoots. Cells of BS shoots became meristematic, giving rise to meristemoids and root primordia, whereas no differentiation of root meristemoids occurred in cells of C shoots. Thus, although adult oak material (C shoots) is capable of responding to the initial stimulus of auxin during the adventitious rooting process, the endogenous IAA concentration is not the factor limiting rooting in adult material.

Stimulation of Root Growth Induced by Aluminum in <i>Quercus serrata</i> Thunb. Is Related to Activity of Nitrate Reductase and Maintenance of IAA Concentration in Roots

“…In the present study, we also confirmed IAA concentration (87.3 pmol/g fw) in Q. serrata roots was comparable with that of rice (82.1 pmol/g fw) [18]. IAA concentration in in vitro cultured shoots of Q. robur was about 300 to 700 nmol/g dry weight (dw) in basal area and about 10 to 70 nmol/g dw in apical section [20]. IAA concentration in roots of Q. serrata was about 82 to 88 pmol/g fw in the present study, so the IAA concentration in Q. serrata roots was very low compared with that of Q. robur shoots.…”

Plant regeneration: cellular origins and molecular mechanisms

“…Histological studies using woody species Castanea sativa and Quercus sp. showed that the exogenous application of auxin reactivates cell proliferation but not the formation of new root meristems in mature explants (Ballester et al, 1999;Vidal et al, 2003). A recent study using Pisum sativa suggested that the vegetative-to-reproductive transition is linked to the reduced root regenerative capacity and that this is caused by the loss of auxin responsiveness in reproductive shoots (Rasmussen et al, 2015).…”

Micromorphological response towards altered environmental conditions in subsequent stages of in vitro propagation of Morinda coreia

“…This indicates development of vein density during the rooting stages. Auxin treatment at rooting stage promotes mitotic dedifferentiation and development of secondary vascular tissues, cambial cells and inter-fascicular supporting tissues (Vidal et al 2003). Vein density was gradually increased via an ex vitro rooting mechanism.…”