Physiological and environmental control of adventitious root formation in cuttings: An overview

Adventitious Root Formation in Plants: The Implication of Hydrogen Peroxide and Nitric Oxide

“…These cells should then become competent to respond to the rooting stimulus, which in most cases is being played by auxin, thus promoting the formation of root meristemoids (for some researchers, this is considered the early induction phase) [ 6 , 16 ]. During the next phase (the induction or late induction phase), these cells become committed to forming the first root initials [ 9 , 16 ]. Right after, a series of cell divisions occur, where the organized mass of cells is visible, forming the first root meristem, which will gradually develop into root primordium (root initiation) [ 4 , 9 , 19 , 20 , 21 ].…”

“…During the next phase (the induction or late induction phase), these cells become committed to forming the first root initials [ 9 , 16 ]. Right after, a series of cell divisions occur, where the organized mass of cells is visible, forming the first root meristem, which will gradually develop into root primordium (root initiation) [ 4 , 9 , 19 , 20 , 21 ]. The latter will continue to grow in order to connect to the vascular system of the cutting [ 7 ] while at the same time, if the conditions are favorable, it will emerge from the stem as a functional, developing root (expression phase or root emergence) [ 4 , 18 ].…”

“…Both ARs and LRs present similar properties, as both serve for nutrient and water uptake, while they are also sources of endogenous cytokinin production. On the other hand, the formation of ARs is mostly observed under harsh stress conditions, such as flooding or hypoxia, after mechanical wounding or in the case of vegetative plant propagation where the main objective is the formation of ARs on plant parts and organs (propagules) in order to produce a new line of plants [ 8 , 9 , 10 , 11 ]. In clonal propagation nowadays, the most commonly used propagation material is the cutting.…”

“…Adventitious root formation (ARF) in cuttings is a prerequisite step in the clonal propagation of economically important plant species, taking place in nurseries multiplying horticultural, ornamental, forestry, or medicinal plants ( Figure 2 ) [ 4 , 9 , 10 , 13 ]. The aim of ARF is the production of a perfect, complete, and autonomous plant deriving from a cutting.…”

“…For the nursery to be successful, the losses during, as well as after, the ARF should be minimized. Such losses are usually due to either insufficient rooting performance or poor quality of the rooting system produced, which presents a barrier to the successful acclimatization of the rooted plantlets [ 9 , 14 , 15 ].…”