* To whom correspondence should be addressed. Malays. Appl. Biol. (2016) 45(2): 1–10 SEXING IN RATTANS CHOONG, C.Y. * and WICKNESWARI, R. School of Environmental and Natural Resource Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia * E-mail: cychoong@ukm.edu.my Accepted 14 October 2016, Published online 21 December 2016 ABSTRACT In Malaysia, rattans belonging to Calamus species are regarded as the most economically important non-wood resource from forest after timber. However, the genetic resource of rattans in the wild is much depleted due to over exploitation and lose of forest habitat. Therefore, there is a need to establish large scale plantation to produce enough canes for furniture and handicraft industries. Large scale planting requires sufficient planting materials, and the establishment of seed orchards for seed production is important for supplying sufficient planting materials. However, the dioecy in rattan limits its breeding and cultivation. The dioecious Calamus species have distinct male and female plants, and gender is identified only after the first flowering. Early identification of male and female individuals by molecular markers can help to address the limitation of dioecy for large scale planting. In this paper, we address the dioecy and sex ratio in Calamus species. Subsequently, we discuss the functional genomics of Calamus manan and C. palustris in understanding the sex determination and flower development in rattans. Key words: Calamus, dioecy, floral genes, genomics, rattans INTRODUCTION Rattan is a spiny climbing plant belonging to the family Arecaceae, and classified in the large subfamily Calamoidea for its scaled fruits. Approximately 600 different rattan species in 13 genera ( Calamus , Calospatha , Ceratolobus , Daemonorops , Eremospatha , Korthalsia , Laccosperma , Myrialepis , Oncocalamus , Plectocomia , Plectocomiopsis , Pogonotium and Retispatha) are distributed through the tropical and subtropical regions worldwide. The rattan species are dominated by the genus Calamus with roughly 370 species (Dransfiled, 1992). In Peninsular Malaysia alone, there are more than 100 species (Aminuddin, 1995), indicating the high biodiversity of rattan resources in this geographical area. Of these, roughly 25 species are of commercial value, including Calamus manan, C. caesius, C. ornatus, C. palustris , C. scipionum and Korthalsia spp. (Aminuddin, 1995). The rattan canes are used in matting, furniture, fish trap and handicraft; the leaves are traditionally used as cigarette paper, thatching; and the fruits of some species are edible and fruits from a few species of Daemonorops produce Dragon’s blood, a deep maroon resin, used as dye, vanish and Chinese medicine (Dransfield, 1979). However, the real commercial use of rattan is of its canes for furniture making. Therefore, it is not surprising to note that rattan represents the most important non-wood forest product after timber. According to the rattan furniture statistics (data up to year 2011) by Malaysian Timber Industry Board, the total export value of rattan furniture for year 2011 was just over RM21 million, and Singapore, Australia, Belgium, China and the United Kingdom were the main export destinations (MTIB, 2016). However, there was a trend of decreasing export value from RM55 million in 2005 to RM21 million in 2011 (MTIB, 2016), and this may indicate that the rattan cane resources for furniture industry are depleting. Therefore, there is an urgent need of large scale rattan plantation for mass production of rattan canes. With the purpose of establishing rattan cultivation, our research focuses on two commercially important species – C. palustris and C. manan (Figure 1). Both the species have been listed as the seven high priority rattan species for regional and international actions (Rao & Ramanatha Rao, 1998). Calamus palustris is locally known as rotan manau Langkawi, with its distribution in the brought to you by CORE View metadata, citation and similar papers at core.ac.uk provided by UKM Journal Article Repository