ROS BAKAR

Erwinia mallotivora is a Gram-negative bacterium that causes the papaya dieback disease in Malaysia. Currently, no effective disease control method is documented. In this regard, the adoption of harpin proteins in promoting plant defense mechanisms has been reported to be a promising control method for this disease. This study used, two recombinant harpin proteins, Hrp I and Hrp II, to control the disease in the glasshouse and field conditions. The results of foliar application in the glasshouse showed protective index of 70.8% and 35.7% for Hrp I and Hrp II, respectively. Meanwhile, the field trial for Hrp I showed a promising protection index of 72.3%. Moreover, the plant growth-promoting attributes were also significantly improved in the case of the Hrp I -treated plants. The effectiveness of Hrp I and II as inducers of systemic acquired resistance (SAR) was further validated by profiling defense-related genes using RT-qPCR analysis. The results showed that the treated papaya pla...

In Malaysia, bacterial wilt has been identified as one of the main constraints for banana production. Blood Disease Bacterium (BDB) is a gram negative bacteria that caused Banana Blood Disease (BBD) which identified as one of the most important pathogen of banana (Musa sp.) which could infect almost all cultivated banana varieties. On the other hand, BDB is grouped into Phylotype IV which placed in a subgroup of the R. solanacearum species complex. BDB was reported to be pathogenic to a single host, banana. Hence, the first objectives of this study is to determine the host range and symptomatology study of BDB on selected hosts. Results from this study showed that BDB only pathogenic to banana not to other tested hosts such as tomato (Solanum lycopersicum) and heliconia (Heliconia sp.) and confirmed to be virulence and able to infect banana. The disease symptoms were wilting of leaves, discoloration of vascular tissues and eventually leads to plant death. The second objectives of th...

Bacterial wilt disease is one of the major diseases in banana. In Malaysia, banana blood disease (BBD) is caused by the blood disease bacterium (BDB) A2 HR MARDI (Ralstonia syzygii subsp. celebensis). This disease bears similarities in symptomatology with Moko disease which caused by Ralstonia solanacearum and BBD in Indonesia, which caused by BDB R229. To determine the symptoms and host range of BDB, a pathogenicity test and host range study were carried out. In this study, there are four stages of external and internal symptoms which were observed. The pathogenicity of the bacterium cultures was then tested on banana, tomato and heliconia plantlets to determine the host range for BDB. To reconfirm that the banana was infected with BDB, re-isolation of BDB from the infected banana plants and Koch’s postulates test were performed. The results showed that there were symptoms of wilting and yellowing of leaves, which eventually caused plants death in the banana plantlets but no sympto...

Similar to animals, plants possess ‘immune memory’ in response to invading pathogens that lead to enhanced defense reaction following pathogen exposure. Systemic acquired resistance (SAR) is a well-characterized type of plant immunity and is associated with coordinated expression of a set of pathogenesis-related (PR) genes and proteins also known as SAR markers. Induction of SAR in plants was shown to be initiated by group of chemicals and biological compounds known as SAR inducers that can be used for the management of important plant diseases. Elucidation and characterization of potential SAR inducers as potential elicitors that can protect papaya from the papaya dieback disease pathogen were carried out using HRPX protein, which was produced as a recombinant protein in an Escherichia coli system. Disease severity analysis in a glasshouse experiment indicated lower disease infection rates in the HRPX-treated plants than in water-treated plants. Selected SAR-associated defense gene...

Sabah snake grass or Clinacanthus nutans has drawn public interest having significant economic benefits attributable to the presence of phytochemicals and several interesting bioactive constituents that may differ according to harvesting age and harvesting frequency. The current study was aimed to evaluate the effect of harvesting age and harvesting frequency towards herbal yield, antioxidant activities, phytochemicals synthesis, and bioactive compounds of C. nutans. A factorial randomized completely block design with five replications was used to illustrate the relationship between herbal yield, DPPH (2, 2-diphenyl-1-picrylhydrazyl) and ferric reducing antioxidant power (FRAP) assays, total phenolic and flavonoid content affected by harvesting age (week 8, 12, and 16 after transplanting), and harvesting frequency (harvest 1, 2, and 3). The bioactive compounds by HPLC were also determined to describe the interaction effect between both harvesting age and harvesting frequency. The yi...