New and Emerging Disease Threats to Forest Plantations in Sarawak Borneo, Malaysia

The planted forest area in Sarawak is the largest planted forest in Malaysia, which has been developed since 1997 to sustain the decline in the production of natural forests. As of December 2021, the total area of plantation forests reached 551,704 hectares (ha), dominated by fast-growing exotic species mainly Acacia species (55%), Falcataria moluccana (15%) and Eucalyptus (14%). The study showed Acacia was infected with red root rot disease of Ganoderma philippii and brown root rot of Phellinus noxius, Ceratocystis wilt disease caused by Ceratocystis. fimbriata sensu stricto (s.s) complex and pink disease caused by Erythricium salmonicolor, while F. moluccana was infected by gall disease namely Uromycladium falcatarium. Eucalyptus pellita diseases were infected namely by G. philippii red root rot disease, stem canker disease caused by Botryosphaeriaceae pathogen and bacterial wild disease caused by Ralstonia solanacearum. Ceratocystis wilt disease of Acacia mangium shows disease incidence (DI) accounted at 68% (serious) as compared with other diseases observed in this study. This will be the first baseline study that is conducted to observe and assess the diversity of the present, new and emerging pathogens and the damage they cause to exotic planted species of Sarawak

Catharanthus roseus extract as bio-fungicide for controlling Fusarium oxysporum on selected vegetable seedlings

Catharanthus roseus extracts were studied to evaluate their potentials replacing chemical fungicide which give a bad impact on human health and cause environmental pollution problems. The samples of C. roseus were extracted with different extraction solvents including dichloromethane (DCM), acetone, ethanol, and methanol at 5, 10, 15 and 20 mg/mL concentrations. The solvents without the plant extract were used as the controls. After 6 days of incubation, the inhibition zone of the fungal pathogen on PDA media was measured. The extracts were significantly effective (p ≤ 0.05) in limiting the antifungal activities. The DCM extract of C. roseus was the most effective against Fusarium oxysporum with 8.06 mm compared to acetone (0.055 mm), ethanol (0.15 mm), methanol (0.41 mm), and water (0.06 mm). Among of the concentrations, 20 mg/mL gave the best effect to control the fungal pathogen compared to 5, 10 and 15 mg/mL. The C. roseus extract was also effective in controlling F. oxysporum on the selected vegetable seedlings based on leaf number and disease suppression (%) results. However, without treated with the extract; mortality due to F. oxysporum increased. The C. roseus extract was effective and may to be developed as a bio-fungicide agent to control F. oxysporum in the field

Functional Analysis of Mating Type Genes and Transcriptome Analysis during Fruiting Body Development of Botrytis cinerea

Botrytis cinerea is a plant-pathogenic fungus producing apothecia as sexual fruiting bodies. To study the function of mating type (MAT) genes, single-gene deletion mutants were generated in both genes of the MAT1-1 locus and both genes of the MAT1-2 locus. Deletion mutants in two MAT genes were entirely sterile, while mutants in the other two MAT genes were able to develop stipes but never formed an apothecial disk. Little was known about the reprogramming of gene expression during apothecium development. We analyzed transcriptomes of sclerotia, three stages of apothecium development (primordia, stipes, and apothecial disks), and ascospores by RNA sequencing. Ten secondary metabolite gene clusters were upregulated at the onset of sexual development and downregulated in ascospores released from apothecia. Notably, more than 3,900 genes were differentially expressed in ascospores compared to mature apothecial disks. Among the genes that were upregulated in ascospores were numerous genes encoding virulence factors, which reveals that ascospores are transcriptionally primed for infection prior to their arrival on a host plant. Strikingly, the massive transcriptional changes at the initiation and completion of the sexual cycle often affected clusters of genes, rather than randomly dispersed genes. Thirty-five clusters of genes were jointly upregulated during the onset of sexual reproduction, while 99 clusters of genes (comprising >900 genes) were jointly downregulated in ascospores. These transcriptional changes coincided with changes in expression of genes encoding enzymes participating in chromatin organization, hinting at the occurrence of massive epigenetic regulation of gene expression during sexual reproduction

Pest and disease incidence of coniferous species in Taman Saujana Hijau, Putrajaya urban park, Malaysia

Taman Saujana Hijau (TSH), Putrajaya is a 41-ha urban park planted with various coniferous species from around the world. Insect pests and disease incidences of this park are unknown and there is a need for an evaluation of the health status of this urban park. This study assessed the level of pest and disease incidents of coniferous species in 12 plots of 7 species (Araucaria bidwilii, Araucaria haterophylla, Araucaria cunninghamii, Pinus caribaea, Pinus merkusii, Podocarpus polystachyus, and Podocarpus costalis). Termites, canker disease, and foliar disease are three major problems. The highest pest and disease incidence (PnDI) was foliar disease with a 0.49 coefficient correlation between the total number of trees and the PnDI, followed by canker disease with 0.40, and termites with 0.36. Of the seven conifers, A. haterophylla was the most infected followed by A. bidwilii and A.cunninghamii. It was concluded that the incidence of pests and diseases in TSH was moderate. To our knowledge, this may be the first baseline inventory of pests and diseases of coniferous species in Malaysia

Falcataria moluccana (Miq.) root distribution seedlings in response to nitrogen concentrations and tillage

Falcataria moluccana (Miq.) Barnaby & Grimes is an important species for forest plantation programmes in Malaysia and is widely used in the wood industry. However, its root interactions have not been widely investigated due to the limited methodologies and information about the root distribution of trees and crops in forest plantation and agroforestry systems. This study was conducted to determine the rhizotron-scale root interactions of F. moluccana at different tillage and nitrogen concentrations under four different treatments: control, tillage, fertiliser, and tillage with fertiliser. The rhizotron-scale experiment was conducted at a greenhouse where F. moluccana (Batai) seedlings were transplanted in transparent rhizotron tubes (onemetre-high transparent polycarbonate solid sheet) using topsoil and river sand to simulate natural growing conditions. Root Intensity (RI), Root Length Density (RLD), Specific Root Length (SRL), dried shoot biomass and root biomass were recorded. Root biomass and SRL were notably higher (25–50 cm depth) at 6 WAT (Weeks After Transplanting), and the shoot biomass (tillage + fertiliser) was significantly higher at 14 WAT. However, plants treated with different tillage and nitrogen concentrations showed no significant impact on the RI and RLD. Fertiliser treatment only, and tillage with fertiliser treatment, showed greater root distribution at the rhizotron scale. These findings contribute to forest plantation and natural forest rehabilitation efforts by helping optimise the soil resources within ecosystems for sustainable forest management

Diversity of endophytic fungi isolated from different plant parts of Acacia mangium, and antagonistic activity against Ceratocystis fimbriata, a causal agent of Ceratocystis wilt disease of A. mangium in Malaysia

Acacia mangium is an important wood for commercial products especially pulp and medium-density fibreboard. However, it is susceptible to Ceratocystis fimbriata infection, leading to Ceratocystis wilt. Therefore, the present work aimed to (i) establish the diversity of endophytic fungi in different plant parts of A. mangium,and (ii) evaluate the antifungal potentials of the isolated and identified endophytic fungi against C. fimbriata. Endophytic fungal identification was conducted by PCR amplification and sequencing of the internal transcribed spacer 1 (ITS1) and ITS4 regions of nuclear ribosomal DNA. A total of 66 endophytic fungi were successfully isolated from different parts of A. mangium; leaf (21), stem (13), petiole (12), root (9), flower (6), and fruit (5). The endophytic fungal isolates belonged to Ascomycota (95.5%) and Zygomycota (4.5%). For Ascomycota 13 genera were identified: Trichoderma (28.6%), Nigrospora (28.6%), Pestalotiopsis (12.7%), Lasiodiplodia (9.5%), Aspergillus (6.3%), Sordariomycetes (3%), and Neopestalotiopsis, Pseudopestalotiopsis, Eutiarosporella, Curvularia, Fusarium, Penicillium, and Hypoxylon each with a single isolate. For Zygomycota, only Blakeslea sp. (5%) was isolated. Against C. fimbriata, Trichoderma koningiopsis (AC 1S) from stem, Nigrospora oryzae (AC 7L) from leaf, Nigrospora sphaerica (AC 3F) from the flower, Lasiodiplodia sp. (AC 2 U) from fruit, Nigrospora sphaerica (AC 4P) from petiole, and Trichoderma sp. (AC 9R) from root exhibited strong inhibition for C. fimbriata between 58.33 to 69.23%. Thus, it can be concluded that certain endophytic fungi of A. mangium have the potential to be harnessed as anti-Ceratocystis agent in future biotechnological applications

Alley-cropping system can boost arthropod biodiversity and ecosystem functions in oil palm plantations

Oil palm (Elaeis guineensis) is among the fastest expanding crops, due to high global demand for vegetable oils. Large areas of forest are converted into oil palm plantation to meet the market demand in producing countries which causes rapid decline in tropical biodiversity, including arthropods. The alley-cropping system has the potential to promote faunal biodiversity, related ecosystem services and food security in agricultural landscapes. In alley-cropping, a main crop is intercropped with a secondary crop (often a food crop), secondary crops are cultivated in the alleys in between the main crop. We compared arthropod taxonomic richness, arthropod predators and decomposers between five alley-cropping treatments (pineapple, bamboo, black pepper, cacao, bactris), where oil palm is intercropped with another species. In addition, we sampled two control treatments: monoculture oil palm, aged seven and 15 years old. A total of 50,155 arthropod individuals were recorded using pitfall trap sampling, representing 19 orders and 28 families. Fourteen orders belonging to sub-phylum Insecta, three orders from Arachnida (Araneae; Acarinae; Scorpiones) and two orders from Myriapoda (Chordeumatida; Geophilomorpha). We detected an increase in beta-diversity of oil palm production landscape. Specifically, we found that the number of arthropod orders, families and abundance were significantly greater in alley-cropping farming plots than those in monoculture plots. In addition, alley-cropping treatments contained larger numbers of predators and decomposers. Our findings suggest that the alley-cropping system can become a key management strategy to improve biodiversity and ecosystem functions within oil palm production landscapes

The complete chloroplast genome of Aquilaria malaccensis Lam. (Thymelaeaceae), an important and threatened agarwood-producing tree species

Known for its valuable agarwood, Aquilaria malaccensis Lam. is an evergreen tropical forest tree species endemic to the Indo-malesian region. Indiscriminate damaging and harvesting of the trees in the wild have resulted in it being listed in the CITES Appendix II for controlled trade and in the IUCN Red List as ‘Vulnerable (VU)’. In this study, the complete chloroplast genome of A. malaccensis was assembled using data from high-throughput Illumina sequencing. The chloroplast genome was 174,832 bp in size, which included two inverted repeat regions of 42,091 bp each, separated by a large single copy region of 87,302 bp and a small single copy region of 3,348 bp. A total of 139 genes were predicted, including 39 tRNA, 8 rRNA, and 92 protein-coding genes. Phylogenetic analysis placed A. malaccensis within the family Thymelaeaceae. The chloroplast genome sequence of A. malaccensis offers a useful resource for future studies on the taxonomy and conservation of the threatened Aquilaria trees