Distribution and re-transportation of sodium in three Malus species with different salt tolerance.

Abstract To further dissect the mechanism of salt tolerance in Malus , the comparison was made regarding the differences between the salt-tolerant and salt-sensitive species in sodium accumulation and extrusion capability in the roots and stem base as well as the sodium re-transportation from shoot to roots by using 22Na labeling-based feeding of leaves and roots-split experiments. The results demonstrated that the salt-tolerant Malus species could accumulate more 22Na in the main roots, lateral roots, stem base phloem and xylem, and extrude more sodium out than the salt-sensitive one. In addition, the salt-tolerant Malus species had the higher sodium re-transportation rate from shoot to roots. Altogether, it is concluded that the stronger sodium accumulation and extrusion in the roots and the stronger sodium re-transportation from shoot to roots in the salt-tolerant species play important roles in salt tolerance of Malus species. Highlights • The salt-tolerant Malus species could accumulate more sodium in the main roots, lateral roots, stem base phloem and xylem than the salt-sensitive one. • The salt-tolerant Malus species could extrude more sodium out than the salt-sensitive one. • The salt-tolerant Malus species had the higher sodium re-transportation rate from shoot to roots than the salt-sensitive one. • The stronger sodium re-transportation from shoot to roots in the salt-tolerant species plays important role in salt tolerance of Malus species. [ABSTRACT FROM AUTHOR]