Levels of indole-3-acetic acid in vigorous and genetic dwarf apple trees

Abstract

Abstract. Seasonal levels of indole-3-acetic acid (IAA) present in buds, meristematic tissues, and leaves of 1-year-old shoots of two selections (vigorous and dwarf) of a F2 generation apple population with original "Goldspur" × "Redspur" parentage were determined using gas chromatography-selected ion monitoring-mass spectrometry (GC-SIM-MS) with a 13C-IAA internal standard. A comparison of IAA levels through one growing season was made in the shoots of two trees differing in growth. The levels of IAA in the leaves of the vigorous tree were higher in the early and late growing seasons, as compared to those in the dwarf tree. Levels of IAA in buds of the dwarf tree shoots were found to be higher than in those of the vigorous tree shoots.Over the past 30 years there has been a dramatic increase in the planting of dwarfed apple trees. Tree size is controlled by grafting genetically vigorous cultivars onto size-controlling clonal rootstocks. Recently, interest has been expressed in the production of genetically reduced-sized apple trees by breeding dwarf cultivars (Faust and Zagaja 1984). The mechanism responsible for dwarfing of these trees is not yet understood. The existing knowledge concerning the role of auxins (IAA) in the dwarfing of the grafted apple tree has been summarized by Lockard and Schneider (1981). Some studies of growth Substances in genetically dwarfed trees have been done, including the measurement of auxin-like substances for two growing seasons by the Avena curVature bioassay in shoots and vascular tissues of apple hybrids having different

Control of longitudinal and cambial growth by gibberellins and indole-3-acetic acid in current-year shoots of Pinus sylvestris

“…(Zakrzewski 1975, Carpita and Tarmann 1982, Terry et al 1982 and to inhibit the elongation of currentyear Pinus sylvestris L. shoots when applied around the circumference of the subjacent previous-year (1-year-old) shoot (Sundberg and Little 1990). In addition, both a positive relationship and no relationship have been reported between the concentration of endogenous IAA and the rate of shoot elongation in woody species (Dunberg 1976, Wood 1983, Sandberg and Ericsson 1987, Buta et al 1989, Rodríguez et al 1991, Browning et al 1992, Yang et al 1992, Rinne et al 1993.…”

Role of phytohormones in the formation of dwarf and tall Siberian crabapple (Malus bаccata L. Borkh.)

“…Grochowska et al (1984) showed that the auxin level in leaves and buds of tall apple trees was higher than in dwarf ones. On the other hand, in the experiment with these plants, the gas chromatography-mass spectrometry (GC-MS) assay showed that the IAA level was higher in the buds and lower in the leaves of dwarf plants than in tall plants (Buta et al, 1989). No difference was revealed between auxin contents in the apical part of scions of normal and column-shaped apple species during the period of intense growth of new scions (Watanabe et al, 2004).…”

Indole-3-acetic acid level in wood, bark and cambial sap of apple rootstocks differing in growth vigour

“…Using the Avena curvature test for auxin measurement, Grochowska et al (1984) showed that IAA levels in leaves and buds of sib crossings of the apple cultivars Goldspur and Redspur were higher in vigorous than in dwarf trees. Buta et al (1989) used a GC-SIM-MS method for auxin measurement in the same apple population and showed that IAA levels in buds were higher in dwarf than in vigorous trees, whereas in leaves the relationship was just the opposite. In contrast, Wlosek-Stangret et al (2000) did not find any significant differences in free or bound IAA levels in leaves of 'Jonagold' apple trees grafted on various rootstocks.…”