BIODIVERSITAS ISSN: 1412-033X Volume 23, Number 2, February 2022 E-ISSN: 2085-4722 Pages: 793-800 DOI: 10.13057/biodiv/d230225 Effects of plant growth regulator from seaweed extracts on expression of genes regulating the oil and related metabolites productions in oil palm IRMA KRESNAWATY 1,2, , DJOKO SANTOSO 1 , SUMI HUDIYONO 2 1 Indonesian Research Institute for Biotechnology and Bioindustry. Jl. Taman Kencana No. 1, Bogor 16128, West Java, Indonesia 2 Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Indonesia. Jl. Lingkar Kampus Raya, Depok 16424, West Java, Indonesia. Tel.: +62-21-7270027,  email: Irma.kresnawaty@yahoo.com Manuscript received: 24 November 2021. Revision accepted: 22 January 2022 Abstract. Kresnawaty I, Santoso D, Hudiyono S. 2022. Effects of plant growth regulator from seaweed extracts on expression of genes regulating the oil and related metabolites productions in oil palm. Biodiversitas 23: 793-800. Plant growth regulators (PGRs) have been used in agricultural practices to regulate various processes, such as germination, vegetative growth, reproduction, maturation, leaf senescence and post-harvest. Seaweed extract as natural PGRs source contains auxin, cytokines, and gibberellins. Although PGRs have been used for decades, the effects of these compounds on the production of secondary metabolites, proteins and related gene-expression are not yet well known in some perennial crops. To study those, treatments consist of trunk injection of oil palm trees with biostimulant that contain PGRs from seaweed extract. Effects of treatments compared were biostimulant (B), biostimulant with activator for oil accumulation (BA) and control (C). The results indicated that the biostimulant treatments affected ACCase Biotin Carboxylase and HMG-CoA genes expression ratio and were maximum at 4 weeks after treatments (WAT) for biostimulant with activators treatments and 8 WAT for biostimulants without activator. Effect of biostimulants treatments in inducing the gene expression was not significant after 8 WAT. Moreover samples with addition biostimulant in 1 and 7 had the highest values of the gibberellin (GID) gene expression. Oil accumulation showed increase in 4 WAT dan had optimum level in 8 WAT because of activators addition, especially increased of palmitic and linoleic acid. Keywords: ACCase, gene expression, biostimulants, seaweed extracts, fatty acids INTRODUCTION Metabolite biosynthesis in plants does not only depend on genetic factors and stages of plant development, but also on plant growth regulators (PGR) added as a supplement. PGR treatments produce biochemical and physiological changes which can modify the quantity and quality of oil production (Prins et al. 2010). The use of PGRs in agricultural practices is currently escalated because of the positive effects on the productivity and quality of agricultural products. The PGR technology can be applied in agriculture areas, where better products and yield are needed (Povh and Ono 2006). Several studies have shown that the application of PGR to some crops can increase their oil production, including in mint and aromatic oil- producing plants (Bano et al. 2016), Mentha arvensis L (Naeem et al. 2012), canola (Ullah et al. 2012), maize (Zhang et al. 2014), jatropha (Abdelgadir et al. 2010), soybean (Sari et al. 2018) and oil palm (Santoso et al. 2018). Since 1940, natural and synthetic plant growth regulators have been used in agriculture to regulate various processes, such as germination, vegetative growth, reproduction, maturation, leaf senescence and post-harvest. One of natural sources that contain growth regulator is seaweed extract (Sunarpi et at. 2010). Seaweed extracts are known to contain: auxin (Krajnc et al. 2013), cytokines (Mondal et al. 2015), and gibberellins (Stirk et al. 2014). Although PGRs have been used for decades, the effects of these compounds on the production of secondary metabolites, proteins and related genes expression are not yet well known (Hussain et al. 2012). Several studies investigating biosynthetic pathways comparing plants with high productivity with those with low productivity were reported on some oil-producing plants, such as rapeseed (Li et al. 2013), soybeans (Liu et al. 2008), corn (Liu et al. 2009) and sunflower (Troncoso-Ponce et al. 2010). For this reason, this research examined the expression of important genes in oil biosynthesis in oil palm, namely ACCase, KAS III, and the stearoil enzyme ACP desaturase (FAD). In addition to genes encoded regulatory proteins were also reported to increase during oil production. To et al (2012) concluded from their research that the transcription factor WRINKLED1 (WRI1) increased its expression in line with oil biosynthesis in Arabidopsis plants. Bourgis et al. (2011) reported similar findings/regulatory gene WRI1 in oil palm and date palms. But, Sing and Cheah (2000) concluded that certain enzymes involved in fatty acid synthesis only exist or increase in significant amount in the period of oil synthesis, whereas regulatory proteins that regulate the expression of enzymes encoding genes exist near the active period of oil synthesis. In addition to oil, oil palm also produces secondary metabolites, such as beta carotene, vitamin E and cholesterol whose biosynthesis are regulated by the