Abstract

Soil acidity, associated with Al toxicity and P deficiency are the major constraints for the yield and quality in grassland systems established on Southern Chile. Advance in the development of P-efficient plants with higher Al-tolerance has become in a key strategy for sustainable agriculture in Chilean Andisols. Nevertheless, to date little is known about the signaling system mediating Al tolerance and P use efficiency in pastures. To further investigate the molecular basis associated to P efficiency and internal Al detoxification in ryegrass (Lolium perenne L.) we analyzed the expression pattern of an Al transporter (LpNrat1). Ryegrass cv. Nui was hydroponically grown with different Al and P doses and the expression level of LpNrat1 was evaluated by quantitative RT-PCR. Aluminium increased the expression level of LpNrat1 in roots irrespective of P supply, suggesting that this transporter is also involved in Al uptake in ryegrass. Additionally, the expression of LpNrat1 showed a rapid induction (24 h) in response to Al, indicating that this gene is needed in initial steps of internal Al detoxification. Interestingly, P deficiency enhanced the expression of LpNrat1 about 3-fold in roots of plant grown with Al at 24 h. Moreover, under P deficiency without Al supply, the expression level of LpNrat1 was up-regulated by about 6-fold compared to normal P conditions. These results could indicate that P deficiency enhanced Al transport by a common signaling mechanism between Al toxicity and P deficiency. Taken together, our outcomes not only improve the understanding about the mechanisms underlying Al-P interaction in ryegrass but also provide an opportunity to select high-yield ryegrass cultivars to be used in these soils.