Two Pine Endo-
-1,4-Glucanases Are Associated with Rapidly
Growing Reproductive Structures
Carol A. Loopstra,
Aidyn Mouradov*,
Adam Vivian-Smith,
Tina V. Glassick,
Beth V. Gale,
Simon G. Southerton,
Heidi Marshall, and
Robert D. Teasdale
Department of Forest Science and Crop Biotechnology Center, Texas
A&M University, College Station, Texas 77843-2135 (C.A.L.); and ForBio Research, P.O. Box 1729, Toowong, Queensland 4066, Australia
(A.M., A.V.-S., T.V.G., B.V.G., S.G.S., H.M., R.D.T.)
Two cDNA clones encoding
endo-
-1,4-glucanases (EGases) were isolated from a radiata pine
(Pinus radiata) cDNA library prepared from immature
female strobili. The cDNAs PrCel1 (
inus
adiata cellulase
) and PrCel2 encode
proteins 509 and 515 amino acids in length, respectively, including
putative signal peptides. Both proteins contain domains conserved in
plant and bacterial EGases. The proteins PRCEL1 and PRCEL2 showed
strong similarity to each other (76% amino acid identity), and higher
similarity to TPP18 (73 and 67%, respectively), an EGase cloned from
tomato (Lycopersicon esculentum) pistils, than to any
other reported EGases. Northern-blot analyses indicated that both genes
displayed a similar pattern of expression. The only significant
difference was in the level of expression. In situ
hybridizations were used to demonstrate that, within
differentiating pine reproductive structures, PrCel1 expression was
greatest in microsporangia in pollen strobili and near the developing
ovule in the seed strobili. Expression was also found in vegetative
tissues, especially in regions experiencing cell elongation, such as
the elongating region of root tips. Both proteins have an ability to
degrade carboxymethylcellulose in vitro. Genomic-blot analysis
indicated the presence of a family of EGase genes in the radiata pine
genome, and that PrCel1 and PrCel2 are transcribed from
distinct one-copy genes.
*
Corresponding author; e-mail a.mouradov{at}forbio.com.au; fax
61-7-3870-5777.
Plant Physiol. (1998) 116: 959-967
Copyright Clearance Center: 0032-0889/98/116/0959/09
© 1998 American Society of Plant Physiologists