S. Ramanjulu et al., Salt and drought stress differentially affect the accumulation of extracellular proteins in barley, Z NATURFO C, 54(5-6), 1999, pp. 337-347
Citations number
35
Categorie Soggetti
Biochemistry & Biophysics
Journal title
ZEITSCHRIFT FUR NATURFORSCHUNG C-A JOURNAL OF BIOSCIENCES
Barley (Hordeum vulgare) was grown for eight days in the presence of a rang
e of salt concentrations or subjected to repeated cycles of wilting and reh
ydration. Changes in apoplastic protein content, protein pattern, enzymic a
ctivities and ion composition were investigated under salinity and drought.
The protein content of intercellular washing fluid (IWF) increased 2.5- to
3.0-fold when the NaCl concentration in the growth medium was increased fr
om 0 to 100 mM. The elevated protein content was the result of a general in
crease in most polypeptides and a pronounced increase in the abundance of s
pecific polypeptides of apparent molecular masses of 15, 21, 22, 26, 36, 40
and 62 kDa. Conversely, the IWF protein content decreased during wilting s
imilar as after application of colchicin, cytochalasin B or cycloheximide s
uggesting that inihibition of protein synthesis or vesicle transport may be
the cause for the decrease in apoplastic protein content and enzyme activi
ties in dehydrating plant tissue. The changes in apoplastic protein content
were accompanied by stress-specific alterations in activities of apoplasti
c enzymes. The greater apoplastic protein content was the consequence of st
imulated protein synthesis in the presence of NaCl, as evidenced by increas
ed incorporation of [S-35]-methionine into IWF protein. The results demonst
rate that the leaf apoplast is a compartment which sensitively and differen
tially responds to drought and salinity with consequences for plant growth.