Premium
Expression of XET‐related genes and its relation to elongation in leaves of barley ( Hordeum vulgare L.)
Author(s) -
SCHÜNMANN P. H. D.,
SMITH R. C.,
LÅNG V.,
MATTHEWS P. R.,
CHANDLER P. M.
Publication year - 1997
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1046/j.1365-3040.1997.d01-49.x
Subject(s) - hordeum vulgare , biology , elongation , mutant , complementary dna , gene , gibberellic acid , microbiology and biotechnology , botany , genetics , poaceae , germination , materials science , metallurgy , ultimate tensile strength
Five cDNA clones were isolated from barley ( Hordeum vulgare L.) that encoded mRNAs related to xyloglucan endotransglycosylase (XET). One of the clones encoded a protein with XET activity in vitro. Sequence comparisons revealed five families of XET‐related sequences, one of which (containing two of the barley genes) was novel. Hybridization studies using clone‐specific probes indicated that the corresponding genes were represented once, or possibly twice, in the barley genome. Treatment of dwarf mutants with gibberellic acid (GA 3 ), or homozygosity at the ‘slender’ ( sln1 ) locus, resulted in a 2.5‐fold (approximately) stimulation of blade elongation rate. Three of the five clones detected mRNAs that were maximally expressed towards the base of the blade, and present in greater quantities in GA 3 ‐treated or slender seedlings. The remaining two clones detected mRNAs that were maximally expressed in the middle of the blade. Relative elemental growth rate (REGR) profiles of leaves growing with or without GA 3 treatment revealed similar maximal REGR values despite a 2.5‐fold difference in leaf elongation rate. Segments of GA 3 ‐treated leaves attained their maximal REGR values more rapidly, this being associated with enhanced expression of the three ‘basal’ XET‐related mRNAs. Highest XET activities were detected in the base of the elongation zone, and in GA 3 ‐treated seedlings a second activity peak was observed near the distal end of the elongation zone. We conclude that there are likely to be several XET isoenzymes with different expression patterns, and identify those XET‐related proteins potentially involved in leaf elongation.