The role of endogenous auxin in root initiation

Abstract

This paper describes the process of the formation of adventitious roots . There appears to be good agreement that this consists of four stages, dedifferentiation coupled with the formation of a meristematic locus, cell division to form a radially symmetrical cluster of cells, further divisions coupled with organisation into a bilaterally symmetrical meristem and finally growth of cells in the basal part of the meristem which causes its protursion through the epidermis. Evidence for the involvement of auxins in these various stages is reviewed and the extent to which rooting of easy-and hard-to-root species can be accounted for in terms of auxin content discussed. Peaks of IAA occur soon after excision of cuttings in some species and there is some evidence suggesting that this is correlated with changes in peroxidase activity . The possible involvement of cytokinins with auxins is briefly considered.

Juvenile stockplant material enhances root development through higher endogenous auxin level

“…These differences probably occurred because we were comparing results of experiments in which different species had been used. After the decrease of IAA level in the late initiation phase (Jarvis 1986;Blakesley et al 1991) the renewed increase of IAA is known in the phase of growth and development of root primordia (Tartoura et al 2004) which is supported by our results. There were no differences in auxin dynamics between the mature and juvenile stockplant material which suggests that the differences in endogenous IAA between both types of material at the time of severance are the most important factor for the subsequent root formation.…”

“…Although, the differences were not significant the use of juvenile cutting material with higher amounts of IAA in tendency demonstrated how important the endogenous auxin level could be when examining better rooting results of this material. Blakesley et al (1991) have already summarised that endogenous auxin level in cuttings should be very important for the later root formation, but this question was rarely included in the experiments. Later on, various authors (Spethmann 1997;Hartmann et al 1997) have already underlined endogenous auxin level in the cutting bases as the central point in the successful rooting process in plants, but they also mentioned the exogenous auxin which can serve as a counterpart in the rooting process.…”

Involvement of polyamines in the adventitious rooting of micropropagated shoots of the apple rootstock MM106

“…The results indicated a typical increase-decrease variation in free IAA concentration during the first 5 d that correspond to the induction of rooting; this variation is similar to that observed in other rooting materials (Maldiney et al 1986;Blakesley et al 1991;Gaspar et al 1992Gaspar et al , 1994Blakesley 1994). Moncousin et al (1988, and Noiton et al (1992) have shown that this transitory IAA peak corresponded to the end of the rooting inductive phase.…”

Endogeneous levels of indole-3-acetic acid and abscisic acid during the rooting of Cotinus coggygria cuttings taken at different times of the year

“…It is considered that the optimum concentration of IAA for the initiation of rooting is markedly supraoptimal for root extension. Thus IAA can be stimulatory at an early stage but inhibitory at a later one [14,6] . Maldiney et al, [17] have suggested a similar interpretation of the stimulatory and inhibitory effects of ABA .…”