Aluminum inhibits phosphatidic acid formation by blocking the phospholipase C pathway

Abstract

Aluminum (Al(3+)) has been recognized as a main toxic factor in crop production in acid lands. Phosphatidic acid (PA) is emerging as an important lipid signaling molecule and has been implicated in various stress-signaling pathways in plants. In this paper, we focus on how PA generation is affected by Al(3+) using Coffea arabica suspension cells. We pre-labeled cells with [(32)P]orthophosphate ((32)Pi) and assayed for (32)P-PA formation in response to Al(3+). Treating cells for 15 min with either AlCl(3) or Al(NO(3))(3) inhibited the formation of PA. In order to test how Al(3+) affected PA signaling, we used the peptide mastoparan-7 (mas-7), which is known as a very potent stimulator of PA formation. The Al(3+) inhibited mas-7 induction of PA response, both before and after Al(3+) incubation. The PA involved in signaling is generated by two distinct phospholipid signaling pathways, via phospholipase D (PLD; EC: 3.1.4.4) or via Phospholipase C (PLC; EC: 3.1.4.3), and diacylglycerol kinase (DGK; EC 2.7.1.107). By labeling with (32)Pi for short periods of time, we found that PA formation was inhibited almost 30% when the cells were incubated with AlCl(3) suggesting the involvement of the PLC/DGK pathway. Incubation of cells with PLC inhibitor, U73122, affected PA formation, like AlCl(3) did. PLD in vivo activation by mas-7 was reduced by Al(3+). These results suggest that PA formation was prevented through the inhibition of the PLC activity, and it provides the first evidence for the role of Al toxicity on PA production.

Low pH, Aluminum, and Phosphorus Coordinately Regulate Malate Exudation through GmALMT1 to Improve Soybean Adaptation to Acid Soils

“…These active Al species, primarily Al 3+ , can cause root damage and root growth inhibition by targeting the cell wall , the cytoskeleton , callose production (Sivaguru et al, 2000), DNA (Yamaguchi et al, 1999;Meriga et al, 2004), and the plasma membrane (Elstner et al, 1988) and disturbing stress-signaling pathways including the regulation of cytosolic free Ca 2+ activities (Ramos-Díaz et al, 2007). Consequently, the inhibition of root growth and function on acid soils results in the severe impairment of water and nutrient acquisition by roots, leading to a significant reduction in crop yields (Ryan et al, 2001;Kochian et al, 2004).…”

INFLUENCE OF ALUMINUM ON MINERAL NUTRIENT UPTAKE AND ACCUMULATION INURTICA PILULIFERAL.

“…Aluminum modifies composition, physical properties, and structure of the cell wall and plasma membrane (Wagatsuma et al, 1995;Zhang et al, 1997;Ishikawa and Wagatsuma, 1998) and affects phosphate and/or nucleotide metabolism (Matsumoto and Morimura, 1980;Wallace and Anderson, 1984). Aluminum interference with the signal transduction pathway could also play a role in Al toxicity (Jones and Kochian, 1995;Jones et al, 1998;Ramos-Diaz et al, 2007). Al may cause oxidative stress, which could be involved in Al inhibition of root growth (Yamamoto et al, 2002).…”

Composição de ácidos graxos em raízes de sorgo sob estresse de alumínio

“…A importância das alterações na composição lipídica das membranas e dos seus ácidos graxos constituintes em resposta ao Al tem sido recentemente reforçada (RAMOS-DÍAZ et al, 2007;RYAN et al, 2007;LIU et al, 2008). No presente experimento ficou claro que os ácidos graxos mais abundantes foram, pela seqüência, linoléico > palmítico.…”