Plant cuticle, which covers the plant surface, consists of waxes and cutins, and is associated with plant drought, cold, and salt re-sistance. Hitherto, at least 47 genes participating in the formation of plant cuticle have been cloned from Arabidopsis thaliana, Oryza sativa, Zea mays, Ricinus communis, Brassica napus, and Medicago truncatula; and about 85% of them encode proteins sharing above 50% identities with their rice homologous sequences. These cloned cuticle genes were mapped in silico on different chromosomes of rice and Arabidopsis, respectively.
The mapping results revealed that plant cuticle genes were not evenly distrib-uted in both genomes. About 40% of the mapped cuticle genes were located on chromosome 1 in Arabidopsis, while 20% of the mapped cuticle genes were located on chromosome 2 but none on chromosome 12 in rice. Some cloned plant cuticle genes have several rice homologous sequences, which might be produced by chromosomal segment duplication.
The consensus map of cloned plant cuticle genes will provide important clues for the selection of candidate genes in a positional cloning of an unknown cuticle gene in plants.
Phylogenetic trees of protein families involved in cuticle formation. The protein members of KCS (a), CYP(b), TF(c), GPAT(d) and receptor kinase are shown. The scale bar of 0.1 represents 10% sequence divergence; bootstrap values are given above the branches (Image by Sciences in Cold and Arid Regions) |
(a) In silico mapping of cloned cuticle genes on Arabidopsis (a) and rice (b) chromosomes. CEN represented centromeric regions (Image by Sciences in Cold and Arid Regions) |
Rice synteny regions carrying homologous sequences of cloned cuticle genes Osatt1(a), Osgl8(b), Oshth(c), Oswsl1(d), Oskcs1(e), and Oswbc11(f). The rice homologous sequences are linked by lines (Image by Sciences in Cold and Arid Regions) |
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