Floral-stimulus activity in tobacco stem pieces

Abstract

Abstract. The growth patterns of axillary buds of dayneutral tobacco (Nicotiana tabacum L. cv. Wisconsin 38) plants were assessed by using explants of single buds attached to leafless stem cuttings and allowing the buds to grow to flowering without additional manipulation. Buds located 5, 10 and 15 nodes below the inflorescence were employed. For a given bud position, when a cutting had few internodes the growth pattern of a bud tended to fall into one of two groups: buds that produced few-noded shoots and buds that produced many-noded shoots. For example, in a group of 13 cuttings composed of bud 5 with 2 associated internodes, 11 buds produced 14.2 nodes (range, 11-17) and 2 buds produced 32.0 nodes (range, 30-34). As the number of internodes on the cutting increased, the number of buds producing few-noded shoots increased and the number of nodes produced decreased (e.g. in contrast to the data above, all 5th buds with 6 internodes produced 12.8 nodes; range 11-15). When cuttings from the 3 positions had the same number of internodes, the more apical cuttings had buds that produced fewer nodes (e.g. for cuttings with 6 internodes all 5th buds produced 12.8 nodes, all 10th buds produced 15.5 nodes and 85% of 15th buds produced few-noded shoots with 19.3 nodes). The number of nodes produced by a bud was a function of the original position of the stem piece and not the original position of the bud. That is, bud 5 associated with the 6 internodes below it produced 12.8 nodes and bud 10 associated with essentially the same 6 internodes (i.e. the 6 above it) produced 12.9 nodes while bud 10 associated with the 6 internodes below it produced 15.5 nodes. Thus, the number of nodes produced by a bud was dependent upon the original main-axis position of the cutting as well as the number of internodes on the cutting. Buds forced to grow out in situ on main axes devoid of leaves produced substantially more nodes than similar buds on cuttings. Buds isolated without associated internodes produced many-noded plants with a number of nodes similar to that of plants grown from seed. The simplest interpretation of theseCorrespondence to: C.N. McDaniel; FAX: 1(518)27685 54 data is that stem pieces contain floral-stimulus activity and that this activity is present in a gradient with the highest activity being located in the apical part of the stem.

Regulatory dephosphorylation of CDK at G2/M in plants: yeast mitotic phosphatase cdc25 induces cytokinin-like effects in transgenic tobacco morphogenesis

“…In accordance with published data (e.g. McDaniel and Hartnett, 1993), in WT tobacco an acropetal floral capacity gradient was observed when apical as opposed to basal nodes were cultured in vitro (Teichmanová et al, 2007). Surprisingly, in Spcdc25 plants with verified gene expression there was no significant difference between numbers of leaves formed and days-to-flowering in basal compared with apical cultured nodes.…”

The Arabidopsis homeotic genes APETALA3 and PISTILLATA are sufficient to provide the B class organ identity function

“…This is supported by the acropetally decreasing severity of the floral meristem identity defects of lfy-6 and ap1-1 (Irish and Sussex, 1990;Weigel et al, 1992). The presence of a gradient of floral quality has also been previously suggested by work on tobacco (McDaniel and Hartnett, 1993). In these studies, explants of axillary buds were attached to stem cuttings, and the number of nodes produced by the bud before flowering were counted.…”

The fission yeast mitotic activator cdc25 and sucrose induce early flowering synergistically in the day‐neutral Nicotiana tabacum cv. Samsun

“…Surprisingly, the acropetal floral potential (McDaniel & Hartnett, 1993) observed when younger as opposed to older nodes were cultured was not evident in cdc25 plants (Figs 2, 3). The consensus view is that the floral gradient results from integrated signals of numerous chemical components.…”