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EXPRESSION OF A SESAME GERANYLGERANYL REDUCTASE cDNA IS INDUCED BY LIGHT BUT REPRESSED BY ABSCISIC ACID AND ETHYLENE

MYOUNG RYOUL PARK¹, EUN AE CHO², SHAFIQ REHMAN³ AND SONG JOONG YUN^1,2*

Abstract: Geranylgeranyl reductase (CHL P) is localized in plastids and catalyzes the reduction of geranylgeranyl diphosphate to phytyl diphosphate, a molecule required for both tocopherol and chlorophyll biosyntheses. To understand the regulation of Chl P expression in sesame, a Chl P cDNA (SiChlP) was isolated and the effects of light and phytohormones on SiChl P expression was investigated. The putative SiChl P cDNA was 1,633 bp and included a 1,394 bp open reading frame encoding a polypeptide of 465 amino acid residues. SiChl P mRNA was expressed most abundantly in leaves and cotyledons, moderately in developing capsules and seeds, but little in flowers, hypocotyls and roots of healthy seedlings and plants. Expression of SiChl P in a cotyledon was induced by light, but the level of induction was higher in red light than in far-red or blue light. However, SiChl P expression was diminished by dark, ethylene and abscisic acid.

¹Institute of Agricultural Science and Technology, Chonbuk National University, Jeonju, 561-756, South Korea

²Department of Crop Science, Chonbuk National University, Jeonju, 561-756, South Korea

³Department of Botany, Kohat University of Science & Technology (KUST), Kohat 26000, Pakistan

^*Corresponding author: E-mail: sjyun@chonbuk.ac.kr; Fax: +82-63-270-2640