Ga. Velikanov et al., The study of the hydraulic conductivity of the plasmodesmal transport channels by the pulse NMR method, RUSS J PL P, 48(3), 2001, pp. 318-325
Radial self-diffusion of water in the absorbing zone of the roots of winter
wheat (Triticum aestivum L.) seedlings was studied by the pulse-gradient-s
pin-echo NMR method. At the fixed time of diffusion observation, the diffus
ion decay of proton spin-echo was nonexponential; however, it could be reli
ably separated into three exponential components differing in the self-diff
usion coefficients (SDC) of water molecules. Our experimental data corrobor
ate the modern concept of two transport channels in plant plasmodesmata, wh
ich connect cytoplasmic and vacuolar (endoplasmic) compartments of adjacent
cells into the unified supracellular continuums. Two SDC obtained by the k
inetic analysis of diffusion decay were shown to depend on the expected cha
nges in the hydraulic conductivity of the two above-mentioned plasmodesmal
channels. To elucidate the role of ATP-dependent actomyosin proteins in the
regulation of the hydraulic conductivity of plasmodesmata, we followed the
changes in the water SDC induced by treating the roots with cytochalasin B
(5 muM, 30 min), the inhibitor of actin polymerization; 2,3-butanedione mo
noxime (10 mM, 1 h), the inhibitor of myosin ATPase activity; and antimycin
A (5 muM, 1 h) and sodium azide (10 mM, 30 min), the inhibitors of energy
generation. The data thus obtained provided the basis for elaborating a new
methodological approach to simultaneously monitoring the functional state
of both plasmodesmal channels without any wound effect impairing their func
tions.