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Two Arabidopsis 3‐ketoacyl CoA synthase genes, KCS20 and KCS2/DAISY, are functionally redundant in cuticular wax and root suberin biosynthesis, but differentially controlled by osmotic stress

Two Arabidopsis 3‐ketoacyl CoA synthase genes, KCS20 and KCS2/DAISY, are functionally redundant... Very‐long‐chain fatty acids (VLCFAs) are essential precursors of cuticular waxes and aliphatic suberins in roots. The first committed step in VLCFA biosynthesis is condensation of C2 units to an acyl CoA by 3‐ketoacyl CoA synthase (KCS). In this study, two KCS genes, KCS20 and KCS2/DAISY, that showed higher expression in stem epidermal peels than in stems were isolated. The relative expression of KCS20 and KCS2/DAISY transcripts was compared among various Arabidopsis organs or tissues and under various stress conditions, including osmotic stress. Although the cuticular waxes were not significantly altered in the kcs20 and kcs2/daisy‐1 single mutants, the kcs20 kcs2/daisy‐1 double mutant had a glossy green appearance due to a significant reduction of the amount of epicuticular wax crystals on the stems and siliques. Complete loss of KCS20 and KCS2/DAISY decreased the total wax content in stems and leaves by 20% and 15%, respectively, and an increase of 10–34% was observed in transgenic leaves that over‐expressed KCS20 or KCS2/DAISY. The stem wax phenotype of the double mutant was rescued by expression of KSC20. In addition, the kcs20 kcs2/daisy‐1 roots exhibited growth retardation and abnormal lamellation of the suberin layer in the endodermis. When compared with the single mutants, the roots of kcs20 kcs2/daisy‐1 double mutantss exhibited significant reduction of C22 and C24 VLCFA derivatives but accumulation of C20 VLCFA derivatives in aliphatic suberin. Taken together, these findings indicate that KCS20 and KCS2/DAISY are functionally redundant in the two‐carbon elongation to C22 VLCFA that is required for cuticular wax and root suberin biosynthesis. However, their expression is differentially controlled under osmotic stress conditions. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Plant Journal Wiley

Two Arabidopsis 3‐ketoacyl CoA synthase genes, KCS20 and KCS2/DAISY, are functionally redundant in cuticular wax and root suberin biosynthesis, but differentially controlled by osmotic stress

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References (63)

Publisher
Wiley
Copyright
Copyright © 2009 Wiley Subscription Services, Inc., A Wiley Company
ISSN
0960-7412
eISSN
1365-313X
DOI
10.1111/j.1365-313X.2009.03973.x
pmid
19619160
Publisher site
See Article on Publisher Site

Abstract

Very‐long‐chain fatty acids (VLCFAs) are essential precursors of cuticular waxes and aliphatic suberins in roots. The first committed step in VLCFA biosynthesis is condensation of C2 units to an acyl CoA by 3‐ketoacyl CoA synthase (KCS). In this study, two KCS genes, KCS20 and KCS2/DAISY, that showed higher expression in stem epidermal peels than in stems were isolated. The relative expression of KCS20 and KCS2/DAISY transcripts was compared among various Arabidopsis organs or tissues and under various stress conditions, including osmotic stress. Although the cuticular waxes were not significantly altered in the kcs20 and kcs2/daisy‐1 single mutants, the kcs20 kcs2/daisy‐1 double mutant had a glossy green appearance due to a significant reduction of the amount of epicuticular wax crystals on the stems and siliques. Complete loss of KCS20 and KCS2/DAISY decreased the total wax content in stems and leaves by 20% and 15%, respectively, and an increase of 10–34% was observed in transgenic leaves that over‐expressed KCS20 or KCS2/DAISY. The stem wax phenotype of the double mutant was rescued by expression of KSC20. In addition, the kcs20 kcs2/daisy‐1 roots exhibited growth retardation and abnormal lamellation of the suberin layer in the endodermis. When compared with the single mutants, the roots of kcs20 kcs2/daisy‐1 double mutantss exhibited significant reduction of C22 and C24 VLCFA derivatives but accumulation of C20 VLCFA derivatives in aliphatic suberin. Taken together, these findings indicate that KCS20 and KCS2/DAISY are functionally redundant in the two‐carbon elongation to C22 VLCFA that is required for cuticular wax and root suberin biosynthesis. However, their expression is differentially controlled under osmotic stress conditions.

Journal

The Plant Journal – Wiley

Published: Nov 1, 2009

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