Role of aluminum-binding ligands in aluminum resistance of Eucalyptus camaldulensis and Melaleuca cajuputi

Abstract

We investigated the roles of Al-binding ligands in Al exclusion from roots and in internal Al detoxification in roots as Al resistance mechanisms in two Al-resistant Myrtaceae trees, Eucalyptus camaldulensis Dehnh. and Melaleuca cajuputi Powell. The amounts of ligands secreted from roots and contained in root tips of these species were compared with those of an Al-sensitive species, Melaleuca bracteata F. Muell., after the roots were exposed to 0 or 1 mM AlCl 3 solution. Secretion of well-known ligands (citrate, oxalate, and malate) from roots under Al treatment was low in all species. However, in E. camaldulensis, the Al-binding capacity of root exudates under Al treatment was considerable and was higher than that in M. bracteata. Gel filtration chromatography revealed that a low-molecular-weight Al-binding ligand was secreted from roots in response to Al only in E. camaldulensis. On the other hand, the Al-binding capacity of cell sap in root tips under Al treatment was similar for the resistant and sensitive species. These results suggest that Al exclusion by secretion of the unknown low-molecular-weight Al-binding ligand from roots contributes to the Al resistance of E. camaldulensis, whereas M. cajuputi has developed Al-resistance mechanisms other than secretion of ligands from roots or concentration of internal ligands in root tips.

Identification of a Hydrolyzable Tannin, Oenothein B, as an Aluminum-Detoxifying Ligand in a Highly Aluminum-Resistant Tree, Eucalyptus camaldulensis

“…However, the amounts of organic acid anions, including citrate, secreted from roots and contained within the root tips are lower than those of more sensitive species (Tahara et al, 2008a). Therefore, the high Al resistance of E. camaldulensis cannot be explained only by the presence of organic acid anions.…”

“…In E. camaldulensis, citrate secretion from roots and its content in the root tips are increased by exposure to Al, suggesting that citrate may contribute to its Al resistance (Tahara et al, 2008a). However, the amounts of organic acid anions, including citrate, secreted from roots and contained within the root tips are lower than those of more sensitive species (Tahara et al, 2008a).…”

BIOMASSA E NUTRIENTES EM POVOAMENTO DE Eucalyptus dunnii Maiden NO PAMPA GAÚCHO1

“…As espécies do gênero Eucalyptus apresentam tolerância a altas concentrações de alumínio na solução do solo (SILVA et al, 2004;POSCHENRIEDER et al, 2008;TAHARA et al, 2008), à baixa fertilidade natural e a níveis de cálcio e magnésio inferiores aos estabelecidos como críticos para a maioria das culturas (BARROS; NOVAIS, 1990;RIBEIRO et al, 1999). Os mecanismos de tolerância ao Al são vários, podendo ser fisiológicos (SILVA et al, 2004;POSCHENRIEDER et al, 2008) e, ou, indiretos, pela complexação do Al pela fração orgânica (VIEIRA, et al, 2008).…”

Temporal dynamics of the response to Al stress in Eucalyptus grandis × Eucalyptus camaldulensis

“…2010, Soares et al 2014. However, unlike annual crops, some species of Eucalyptus have demonstrated tolerance to acidic soils (Tahara et al 2005(Tahara et al , 2008, which demonstrates the potential for this crop to be an economic alternative for producers whose annual crop productivity is adversely affected by Al.…”