Changing root system architecture through inhibition of putrescine and feruloyl putrescine accumulation

Abstract

Plant roots provide anchorage and absorb the water and minerals necessary for photosynthesis in the aerial parts of the plant. Since plants are sessile organisms, their root systems must forage for resources in heterogeneous soils through differential branching and elongation [(1988) Funct. Ecol. 2, 345-351;(1991) , in a model system consisting of excised tobacco roots, that both a-or.-difluoromethylornithine (an inhibitor of putrescine biosynthesis) and the rolA gene (from the root-inducing transferred DNA of Agrobacterium rhizogenes) stimulate overall root growth and cause a conversion in the pattern of root system formation, producing a dominant or 'tap' root. These morphological changes are correlated with a depression in the accumulation of polyamines and their conjugates.

Endogenous levels of polyamines in the organs of cucumber plant (Cucumis sativus) and factors affecting leaf polyamine contents

“…For example, putrescine was found most abundantly in the root, while relatively large amounts of spermine were detected in reproductive organs such as the calyx including stamen and the immature fruit (Figs 1 and 2). The participation of putrescine in regulating root development has been reported in the tobacco plant (Ben‐Hayyim et al 1994). Watson et al (1998) also described the role of arginine decarboxylase, an enzyme that catalyzes putrescine formation, in root meristem function in Arabidopsis .…”

BUD2, encoding an S-adenosylmethionine decarboxylase, is required for Arabidopsis growth and development

“…Previous observations revealed that polyamines may be involved in a variety of plant developmental processes, such as cell division, root initiation, somatic embryogenesis, xylogenesis, flower development, fruit ripening and senescence [3]. Recent studies have indicated that polyamines also affect the formation of plant architecture, such as internode elongation [10,11], root branching [12] and shoot apical dominance [13].…”

“…Previous observations revealed that polyamines may be involved in a variety of plant developmental processes, such as cell division, root initiation, somatic embryogenesis, xylogenesis, flower development, fruit ripening and senescence [3]. Recent studies have indicated that polyamines also affect the formation of plant architecture, such as internode elongation [10,11], root branching [12] and shoot apical dominance [13].The plant polyamine biosynthetic pathway is relatively simple [14]. Putrescine is derived either from ornithine catalyzed by ornithine decarboxylase (ODC) or from arginine through several steps catalyzed by arginine decarboxylase (ADC), agmatine iminohydrolase and N-carbamoylputrescine amidohydrolase.…”

Effect of the rol genes from Agrobacterium rhizogenes on polyamine metabolism in tobacco roots

“…Higher levels of soluble Put conjugates were also observed in slow-growing than in fastgrowing callus cultures (Martin-Tanguy et al, 1988), It is known that rolA and rolC genes alter polyamine metabolism and flowering in tobacco plants (Martin-Tanguy et al, 1993). Under the control of its natttral promoter, plants transgenic for rolA displayed an increased accumulation of free polyamines prior to flowering and a reduction in conjugated polyamines (Sun et al, 1991), but no changes in free and conjugated polyamine levels were detected when this gene was driven by the CaMV35S promoter (Martin-Tanguy et al 1993), Ben-Hayyim et al (1994) reported a decrease in the level of both free and conjugated Put in tobacco roots excised from seedlings transformed with rolA under the control of the doubly etihanced CaMV35S promoter. In our root cultures, free and conjugated polyamine accumulation was clearly increased when tobacco roots were transformed by rolA tmder the control of its own promotor (Tab.…”