Abstract
ABSTRACT Germination is a physiological process that begins with hydration. Specific channels known as aquaporins are responsible for water uptake through biological cell membranes. The mercuric chloride (HgCl2) reversibly inhibits water transport during germination through the aquaporins and can changes deoxyribonucleic acid (DNA) integrity, which can result in aquaporins deficiency. The aim of this study was to evaluate the effect of HgCl2 and dithiothreitol (DTT) on aquaporins activity and on the integrity/degradation of DNA in embryonic axes of Schizolobium parahyba (Vell.) Blake during the germination process. Isolated axes were exposed to different concentrations of HgCl2 or DTT; and aquaporins activity, embryo hydration, and DNA integrity were evaluated during embryonic axes imbibition. Growth and changes in axis fresh weight were quantified. We found that the heavy metal affects seed hydration by inhibition of aquaporins activity and does not cause changes in DNA integrity.
Highlights
Water represents more than 90% of the fresh weight of most plant tissues in the growth phase and it is essential for maintaining turgidity and cell expansion (Steinbrecher and Leubner-Metzger, 2017)
The mercuric chloride (HgCl2) reversibly inhibits water transport during germination through the aquaporins and can changes deoxyribonucleic acid (DNA) integrity, which can result in aquaporins deficiency
Isolated axes were exposed to different concentrations of HgCl2 or DTT; and aquaporins activity, embryo hydration, and DNA integrity were evaluated during embryonic axes imbibition
Summary
Water represents more than 90% of the fresh weight of most plant tissues in the growth phase and it is essential for maintaining turgidity and cell expansion (Steinbrecher and Leubner-Metzger, 2017). The hydration process results from the difference in water potentials between cells and the medium, and this varies from one type of seed to another. This imbibition is fundamental for activating seed metabolism, directly affecting the physiological processes that precede root protrusion, such as respiration, mitochondrial multiplication and repair, mobilization of reserves, and DNA synthesis and repair (Nonogaki, et al, 2010). Water movement in the tissues occurs through three routes: the apoplastic, symplastic, and transcellular pathways (Kshetrimayum, et al, 2017). Water movement occurs through plasmodesmata that interconnect the membranes of neighboring cells, creating cytoplasmic bridges. The transcellular pathway involves the movement of water through the cell membranes, in water selective channels known as aquaporins (Preston, et al, 1992; Martínez-Ballesta, et al, 2016; Qi, et al, 2016)
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