Carica papaya L. or commonly known as papaya, is a major tropical crop consumed worldwide either as a vegetable or fresh fruit or processed products. In Malaysia, papaya was initially planted as a smallholder crop throughout the country. Eventually after 15 years of breeding and selection, a new variety, named C. papaya L. var. Eksotika, was released by the Malaysian Agricultural Research and Development Institute (MARDI) in 1987. This event changed the outlook of papaya planting from a smallholder crop to a plantation crop. Despite the blooming papaya business, the industry faced various disease issues that jeopardize its future. The most devastating was the papaya dieback disease, which affected approximately 800 hectares of plantation, destroyed approximately 1 million trees nationwide with total losses estimated at US$ 58 million. Even though Eksotika is a favored commercial variety with good eating and aesthetic quality fruit, its potential for more lucrative distant markets is tarnished with its short-shelf life fruits. Several strategies had been reported to address the challenges faced by Eksotika specifically against the dieback disease and the fruit’s short shelf-life. This review focuses on C. papaya L. var. Eksotika particularly on the strategies to address the challenges faced in order to sustain the economic value of this crop plant, which had contributed significantly to the Malaysian economy.

Dieback disease caused by Erwinia mallotivora is the most devastating disease of papaya in Malaysia. Most papaya cultivars here are susceptible to the disease, indicating a compatible relationship between the cultivars and the pathogenic strains of the bacteria. In this study, we evaluated early responses of a susceptible cultivar to a virulent strain of the bacteria by monitoring the disease symptoms, measuring the expression patterns and activities of the oxidative enzymes superoxide dismutase (SOD) and peroxidase (POD), and profiling the leaf proteome. Water-soaked lesions and necrotic spots were evidenced on the inoculated leaves at 6 days post-inoculation (dpi) which were deteriorated rapidly with death at 12 dpi. The two oxidative enzymes were responsive to the infection as shown by their induced enzymatic activities and gene expressions in the leaves of the infected plants. The 2D-PAGE profile of the leaf proteome exhibited a significant increase in the intensity of the SOD spot, confirming its involvement in the response. In addition, differential expressions of the protein spots known to be related to stress response, energy production and photosynthesis provided insights into the plant's global response to the infection. Overall, this study suggested that the early response to E. mallotivora inoculation in the susceptible papaya cultivar was likely to be mediated by the antioxidant defense system but the effectiveness of the defense could have been compromised with the down-regulation of important proteins required for normal plant growth and development. This study provides the basis for studying the defect in the defense mechanism that turned this cultivar susceptible to the infection.

Biofortification is the process of improving the bioavailability of essential nutrients in food crops either through conventional breeding or modern biotechnology techniques. Rice is one of the most demanding staple foods worldwide. Most global population live on a diet based on rice as the main carbohydrate source that serve as suitable target for biofortification. In general, polished grain or white rice contains nutritionally insufficient concentration of iron (Fe) to meet the daily requirements in diets. Therefore, iron biofortification in rice offers an inexpensive and sustainable solution to mitigate iron deficiency. However, understanding on the mechanism and genes involved in iron uptake in rice is a prerequisite for successful iron biofortification. In this chapter, the overview of iron uptake strategies in plants and as well as different iron-biofortified approaches used in rice will be outlined. Then, the challenges and future prospects of rice iron biofortification to improve global human health will also be discussed.

Antibiotic–adjuvant combinatory therapy serves as a viable treatment option in addressing antibiotic resistance in the clinical setting. This study was carried out to assess and characterize the adjuvant potential and mode of action of linalool against carbapenemase-producing Klebsiella pneumoniae (KPC-KP). Linalool exhibited bactericidal activity alone (11,250 μg/ml) and in combination with meropenem (5,625 μg/ml). Comparative proteomic analysis showed significant reduction in the number of cytoplasmic and membrane proteins, indicating membrane damage in linalool-treated KPC-KP cells. Upregulation of oxidative stress regulator proteins and downregulation of oxidative stress-sensitive proteins indicated oxidative stress. Zeta potential measurement and outer membrane permeability assay revealed that linalool increases the bacterial surface charge as well as the membrane permeability. Intracellular leakage of nucleic acid and proteins was detected upon linalool treatment. Scanning and transmission electron microscopies further revealed the breakage of bacterial membrane and loss of intracellular materials. Linalool induced oxidative stress by generating reactive oxygen species (ROS) which initiates lipid peroxidation, leading to damage of the bacterial membrane. This leads to intracellular leakage, eventually killing the KPC-KP cells. Our study demonstrated that linalool possesses great potential in future clinical applications as an adjuvant along with existing antibiotics attributed to their ability in disrupting the bacterial membrane by inducing oxidative stress. This facilitates the uptake of antibiotics into the bacterial cells, enhancing bacterial killing.

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