A CHECKLIST OF FREE-LIVING MARINE NEMATODES AT DIFFERENT ECOSYSTEM IN NORTHERN STRAITS OF MALACCA, MALAYSIA

Nematodes present in all substrates and sediment types with an enormous number of species. The studies on free-living marine nematodes are still limited in Malaysia. The present study provides general information on genus checklist of free-living marine nematodes in the northern part of Peninsular Malaysia in a different ecosystem which are intertidal zones of estuarine, sandy beach and mangrove ecosystems. Samples were randomly collected at three stations in each ecosystem. A total of 34 genera (22 families and ten suborders) were recorded in three ecosystems. Each ecosystem had common genera which also commonly found worldwide. Viscosia genus was observed in all three ecosystems. The nematode genera of Estuary and mangrove ecosystems had greater similarities than those in the sandy beach.

PRELIMINARY OBSERVATION OF TROPICAL DIATOM Thalassiosira spp. FROM TELUK BAHANG, PENANG

This study describes the morphological structure of Thalassiosira spp. found in coastal water and intertidal area of Teluk Bahang, Penang. Examination of the samples collected from January 2015 to June 2016 showed that these species were the common genera in both benthic and surface seawater at Teluk Bahang. To obtain phytoplankton samples, five liters of seawater were filtered through the plankton net (35 µm). While for benthic samples, the samples were collected at sediment surface of 1 mm depth. Samples of Thalassiosira spp. were obtained from both phytoplankton and benthic samples. Scanning electron microscope (SEM) was used to study the morphology of Thalassiosira spp. Results from the SEM showed distinct differences in areolae pattern, sizes, position and number of processes among Thalassiosira spp. (Thalassiosira nanolineata, Thalassiosira densannula, and Thalassiosira gravida). Thalassiosira densannula and Thalassiosira nanolineata were found in both habitats, coastal and benthic area while Thalassiosira gravida was found only in coastal water. Thalassiosira spp. contribute approximately 15% of the total benthic community and approximately 35% of the total phytoplankton community.

CHARACTERIZATION OF 18S RIBOSOMAL RNA FRAGMENT FROM Solanum tuberosum L. var. Granola POTATO

Potato (Solanum tuberosum L.) is a prime horticultural commodity. One of the varieties of potato that widely cultivated in Indonesia is Granola. This study characterized the variety Granola based on the 18S sequences of rRNA gene fragment. The 18S sequences were used to distinguish the Granola and determine the differentiating characters from other Solanum based on those sequences data. The characterization was completed in three main steps including DNA isolation from potato leaf using Doyle & Doyle method, amplification of the 18S gene fragment, and DNA sequencing. The amplification of 18S gene fragment by a PCR method obtained 528 bp sequences. The BLAST search using NCBI web service confirmed that Granola potato has 99% matching sequence with S. tuberosum. The phylogenetic reconstruction further indicates the S. tuberosum var. Granola used in this study deeply nested with the reference sequence X67238.1, a potato from Europe.

KERAGAMAN GENETIK VARIETAS PADI japonica DAN indica BERDASARKAN MARKA DNA TERKAIT MUTU RASA

PCR-based markers and evaluation of physicochemical properties should be addressed for the improvement of rice varieties with good eating dan eating quality (EQ). This study aimed to examine the genetic diversity of rice varieties based on DNA markers related to physicochemical properties determining EQ. A total of 46 rice varieties consisting of 22 japonica varieties and 24 indica varieties were examined using 43 PCR-based markers. The results showed that polymorphic information content (PIC) ranged from 0.04 to 0.38, in support of genetic diversity indices which ranged from 0.04 to 0.50 across total markers. Pairwise genetic similarity matrix ranged from 0.40 to 0.98 with the closest genetic distance was observed between two japonica varieties (Dongjin and Hwaseong) and the most distant one was between japonica and indica (Onnuri/Manmi with Cigeulis/Fatmawati). The unweighted neighbor-joining tree clustered the rice varieties into two major clades, indica and japonica, and subsequent subclades were differentiating according to the individual genetic background. The genetic diversity of rice from different subspecies and DNA markers for EQ can effectively be utilized for basic information and marker-assisted selection (MAS) for the development of improved varieties with good EQ in rice breeding program.