Polyamines in buds of apple as affected by temperature and their relationship to bud development

The time course of changes in the concentrations of arginine and polyamines in spur buds of apple (Malus domestica Borkh.) was studied. The trees were exposed to six temperature treatments: 13 degrees and 13 degrees C; 13 deg rees then 20 degrees C; 20 degrees and 20 degrees C; 20 degrees then 27 deg rees C; 27 degrees and 27 degrees C, and 27 degrees then 13 degrees C in tw o successive periods of 6-7 and 12 weeks, starting at full bloom. Shoot gro wth and flowering were recorded as well. In the first six weeks. the argini ne concentration in spur buds did not differ much between temperatures, but thereafter an increase occurred, especially at the 27-27 degrees C and 20- 27 degrees C regimes. The drop in temperature from 27 degrees to 13 degrees C at 6-7 weeks after bloom resulted in an increase of arginine that surpas sed the 13-13 degrees C and even the 27-27 degrees C values. In general, the time course of changes in the concentration of total polyam ines (PAs) was not pronounced and lacked consistency. The relation to tempe rature was the inverse of that of arginine; the level became lower with the rise in temperature. More than 80% of PAs were accounted for by spermidine and spermine. The pattern for concentrations for spermidine and putrescine in relation to temperature was generally similar to that for total polyami nes, but the reverse holds for spermine. The rise of temperature at 6-7 wee ks after bloom reduced the contents of spermidine and putrescine, but did n ot influence spermine. Conversely, the drop of temperature (27 degrees to 1 3 degrees C) increased the spermidine and putrescine levels, and produced a decline in spermine. The results are discussed in terms of a 'passive' storage function for argi nine and a more 'active' function for polyamines in modulating bud growth a ctivity. The relationship between polyamines and flower-bud formation is al so discussed. (C) 1999 Elsevier Science B.V. All rights reserved.