Influence of Water Deficit on Gene Products in Pinus Halepensis
Investigators (most current known information)
Two different approaches were used to identify genes or proteins induced by drought stress in Pinus halepensis, allepo pine. One approach used young seedlings to examine proteins induced by water-deficit-stress. Seedlings were subjected to a rapid stress treatment by withholding water or to a slow induction by subjecting them to varying concentrations of glycerol. In roots of seedlings subjected to the rapid stress, total protein content was reduced to 20% that of unstressed within 18 hours. The protein content of hypocotyls decreased at a slower rate. Coomassie staining of total proteins separated by SDS-PAGE did not show differences between stressed and unstressed seedlings. However, SDS-PAGE of hypocotyl boiling-stable proteins did identify bands induced by stress. When biotin was incorporated into proteins produced during treatments, it was possible to detect additional proteins induced by stress. The various bands reached their maximums at different stress levels. An antibody to a peptide found in LP3, a protein induced by drought stress in loblolly pine, was used to examine induction of dehydrins. The antibody was not specific and reacted with several proteins between 15 and 90 kDa. Some of the bands decreased or increased during stress treatments. The second approach used approximately six-month-old seedlings and differential screening of a cDNA library to isolate clones of induced genes. The library was made using roots of stressed seedlings and was screened using probes generated from stressed and unstressed roots. Of the 21,500 clones examined, we identified 156 that represent genes induced by stress. Fifteen of the identified genes were sequenced and northern blot analyses were used to examine the expression of seven of those genes. The genes induced by stress include those encoding a LEA-like protein (late-embryogenesis-abundant), a lignin biosynthetic enzyme (4-coumarate CoA ligase), a cyclophilin, an endochitinase, a sucrose synthase-type protein and some not similar to previously identified genes. Some of the above proteins are similar to those induced by stress in other species. It will be interesting to determine which, if any, of the characterized genes encode the induced proteins identified with our first approach.
Articles in Journal
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