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The large-scale genomic resource for kelampayan was generated from a developing xylem cDNA library. A total of 6,622 high quality expressed sequence tags (ESTs) were generated through high-throughput 5' EST sequencing of cDNA clones. The ESTs were analyzed and assembled to generate 4,728 xylogenesis unigenes distributed in 2,100 contigs and 2,628 singletons. About 59.3 % of the ESTs were assigned with putative identifications whereas 40.7 % of the sequences showed no significant similarity to any sequences in GenBank. Interestingly, most genes involved in lignin biosynthesis and several other cell wall biosynthesis genes were identified in the kelampayan EST database. The identified genes in this study will be candidates for functional genomics and association genetic studies in kelampayan aiming at the production of high value forests.

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A complementary DNA (cDNA) library was constructed from the developing xylem tissues of Neolamarckia cadamba. A total of 10,368 single-pass sequences was generated through high-throughput 5′-expressed sequence tag (EST) sequencing of the cDNA clones, and 6622 highquality ESTs were obtained after removing the low-quality sequences; this gave approximately 3.17 Mb of data. Clustering of the high-quality ESTs revealed 4728 unigenes, consisting of 2100 consensus and 2628 singletons. A total of 2405 ESTs were successfully annotated with 7753 gene ontology (GO) terms that distributed among three main GO categories, which were biological processes (2333), molecular function (3056) and cellular component (2364). Simple sequence repeat (SSR) mining revealed that the frequency of SSR in the N. cadamba EST database (NcbdEST) was 3.3 %, with the GCT/AGC motif being the most abundant repeat motif. The most abundant transcript with known function found in this database was 60S ribosomal protein followed by 40S ribosomal protein. Some of the important genes involved in xylogenesis and lignin biosynthesis were found in NcdbEST; these include tubulin genes, cellulose synthase (CesA), xyloglucan endotransglycosylase (XET), arabinogalactan, cinnamate 4-hydroxylase (C4H), caffeoylcoenzyme A O-methyltransferase (CCoAOMT) and peroxidase. The data obtained from this study will provide a powerful means for identifying mechanisms controlling wood formation pathways of kelampayan and supply many new cloned genes for future endeavours to modify wood and fibre properties.

Polyploidization has played a crucial role in plant breeding and crop improvement. However, studies on the polyploidization of tropical tree species are still very scarce in this region. This paper described the in vitro induction and identification of polyploid plants of Neolamarckia cadamba by colchicine treatment. N. cadamba belongs to the Rubiaceae family is a natural tetraploid plant with 44 chromosomes (2n = 4x = 44). Nodal segments were treated with colchicine (0.1%, 0.3% and 0.5%) for 24 h and 48 h before transferring to shoot regeneration medium. Flow cytometry (FCM) and chromosome count were employed to determine the ploidy level and chromosome number of the regenerants, respectively. Of 180 colchicine-treated nodal segments, 39, 14 and 22 were tetraploids, mixoploids and octoploids, respectively. The highest percentage of polyploidization (20% octoploids; 6.7% mixoploids) was observed after treated with 0.3% colchicine for 48 h. The DNA content of tetraploid (4C) and octoploid (8C) was 2.59 ± 0.09 pg and 5.35 ± 0.24 pg, respectively. Mixoploid plants are made up of mixed tetraploid and octoploid cells. Chromosome count confirmed that tetraploid cell has 44 chromosomes and colchicine-induced octoploid cell has 88 chromosomes. Both octoploids and mixoploids grew slower than tetraploids under in vitro conditions. Morphological characterizations showed that mixoploid and octoploid leaves had thicker leaf blades, thicker midrib, bigger stomata size, lower stomata density, higher SPAD value and smaller pith layer than tetraploids. This indicates that polyploidization has changed and resulted in traits that are predicted to increase photosynthetic capacity of N. cadamba. These novel polyploid plants could be valuable resources for advanced N. cadamba breeding programs to produce improved clones for planted forest development.