Hydraulic conductance and mercury-sensitive water transport for roots of Opuntia acanthocarpa in relation to soil drying and rewettingPlant Physiology (2001)
AbstractDrought-induced changes in root hydraulic conductance (L P) and mercury-sensitive water transport were examined for distal (immature) and mid-root (mature) regions ofOpuntia acanthocarpa. During 45 d of soil drying,L P decreased by about 67% for distal and mid-root regions. After 8 d in rewetted soil,L P recovered to 60% of its initial value for both regions. Axial xylem hydraulic conductivity was only a minor limiter of L P. Under wet conditions, HgCl2 (50 μM), which is known to block membrane water-transport channels (aquaporins), decreasedL P and the radial hydraulic conductance for the stele (L R, S) of the distal root region by 32% and 41%, respectively; both L P andL R, S recovered fully after transfer to 2-mercaptoethanol (10 mM). In contrast, HgCl2 did not inhibit L P of the mid-root region under wet conditions, although it reducedL R, S by 41%. Under dry conditions, neitherL P nor L R, S of the two root regions was inhibited by HgCl2. After 8 d of rewetting, HgCl2 decreased L Pand L R, S of the distal region by 23% and 32%, respectively, but L P andL R, S of the mid-root region were unaltered. Changes in putative aquaporin activity accounted for about 38% of the reduction in L P in drying soil and for 61% of its recovery for the distal region 8 d after rewetting. In the stele, changes in aquaporin activity accounted for about 74% of the variable L R, S during drought and after rewetting. Thus, aquaporins are important for regulating water movement for roots of O. acanthocarpa.
Citation InformationP. Martre, Gretchen North and P. S. Nobel. "Hydraulic conductance and mercury-sensitive water transport for roots of Opuntia acanthocarpa in relation to soil drying and rewetting" Plant Physiology Vol. 126 (2001)
Available at: http://works.bepress.com/gretchen_north/13/