Aluminum tolerance in Centipedegrass (Eremochloa ophiuroides [Munro] Hack.): Excluding Al from root

Centipedegrass (Eremochloa ophiuroides [Munro] Hack.) is a C4 perennial grass and well adapted to acid soils. Centipedegrass accession E041 (Lingchuan, Guangxi Province, China) was found to be more tolerant to Aluminum (Al) than E006 (Nanjing, Jiangsu Province, China). The objective of this study was to identify possible mechanisms associated with centipedegrass. After exposure to Al, citrate was detected in both E041 and E006 roots secretion. Phosphorous (P) starvation and La3+ (Lanthanum) treatment did not induce organic acid secretion. Secretion of organic acid of both E041 and E006 need an initial lag phase of 6 h, and increased significantly after 6 h exposure to Al, which suggested that centipedegrass showed a pattern II-type organic acid secretion. Secretion of citrate increased with increasing external Al concentration, but the amount of citrate secreted was higher in E041 than in E006 which also accumulated more Al than E041. Al accumulated in the epidermal and sub epidermal cortical of root apices. The results suggested that secretion of citrate may be one of Al exclusion mechanisms in centipedegrass, and other mechanism may help to prevent Al from entering into central cylinder.

► Our previous study indicated centipedegrass is a high Aluminum (Al) resistance species.
► In this study we analyzed the possible mechanisms associated with Al tolerance centipedegrass.
► We found that the citrate secretion is an aluminum tolerant mechanism of centiedegrass.
► There is a marked lag phase between the addition of Al and the onset of organic acid release.
► We speculated that other mechanism may help to prevent Al from entering into central cylinder.