Differential Resistance of Two Subtropical Rice Cultivars to Aluminum Toxicity

Abstract

Two contrasting subtropical rice cultivars were selected and tested for aluminum (Al) toxicity by two methods: a fast selection (24 h) using 0.5 mM CaCl₂ solution containing 50 or 100 µM Al and long-term Al treatment in Kimura B culture solution. Xiang Nuo 1 (XN 1) was shown to be much more resistant than Xiangzhong Xian 2 (XX 2) to Al toxicity and consistent and stable results were obtained with the two methods used although much higher Al concentration was needed to cause a similar cultivar difference in the culture solution (2000 µM compared with 50 µM Al³⁺ in CaCl₂ solution). The results indicate that there is considerable potential to screen Al-resistant cultivars from the subtropical germplasm. It was further found that callus formation was markedly induced in response to Al, and a cultivar difference also existed indicating that the induced callus formation may be used as a sensitivity marker for rice cultivar Al stress. Under Al stress, the resistant cultivar accumulated less Al than the sensitive one, corresponding to the induced callus formation over time. Lower Al accumulation in the resistant cultivar suggests that there may be an exclusion mechanism underlying the Al resistance of XN 1.

Acknowledgments

This work was supported by the National Natural Science Foundation of China (NNSFC 30070453).