© 2000 Heron Publishing—Victoria, Canada
Genes expressed in the latex of Hevea brasiliensis
Kyung-Hwan Han (1, 3), Dong Ho Shin (1), Jaemo Yang (1), In Jeong Kim (1), Soo Kyung Oh (1) and K. S. Chow (2)
1. Kumho Life and Environmental Science Laboratory, 572 Ssangam-Dong, Kwangsan-Gu, Kwangju, 506-712, Korea / 2. Biotechnology and Strategic Research Unit, Rubber Research Institute of Malaysia, P.O. Box 10150, 50908 Kuala Lumpur, Malaysia / 3. Department of Forestry, Michigan State University, 126 Natural Resources Building, East Lansing, MI 48824-1222, USA / Received October 8, 1999
Summary
Rubber (cis-1,4-polyisoprene), an important raw material for many industrial uses, is synthesized in the latex of Hevea brasiliensis (Willd. ex A. Juss.) Müll. Arg. We postulated that the genes uniquely or preferentially expressed in the latex may be important for
rubber biosynthesis. We constructed cDNA libraries from the latex of H. brasiliensis to investigate the genes expressed in the latex by single-run partial sequencing of the cDNA clones. Sequence analyses identified
245 expressed sequence tags (ESTs), of which 57% showed homology to previously described sequences in public databases. About
16% of the database-matched ESTs encode rubber biosynthesis-related proteins such as rubber elongation factor (REF) and small
rubber particle protein (SRPP). The second most frequent transcripts next to rubber biosynthesis-related genes were defense
genes and protein metabolism-related genes (12.6% each). About 27% of the database-matched ESTs had sequence homology with
genes of unknown function. Among the redundantly expressed genes, REF was the most frequently expressed (6.1%), followed by
SRPP (3.7%) and HbLAR (2.9%). Northern blot analyses showed that ten (71%) of the 14 ESTs studied were expressed at a higher
level in latex than in leaves.
Keywords:
biosynthesis, EST, genetic engineering, rubber.
