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Drought is the most prominent limiting factor to crop productivity. Banana, one of the most important food crops globally, is highly susceptible to drought. However, how banana plants respond to drought stress and post-drought recovery remains unclear. Therefore, this study determined the morphological and protein responses of banana plants (Musa acuminata cultivar Berangan) affected by drought stress, followed by recovery. The results showed that drought significantly reduced the leaf area, plant height, fresh weight, stem circumference, leaf relative water content, chlorophyll contents, and root length of the bananas. In contrast, relative electrolyte leakage, proline, malondialdehyde (MDA) and hydrogen peroxide contents, and the activities of antioxidant enzymes, including catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR), peroxidase, and superoxide dismutase, were induced in the drought-treated banana leaves. However, after recovering from drought stress, the relative water content, MDA, hydrogen peroxide, and antioxidant enzyme activities, including CAT, APX, and GR, were comparable with well-watered plants. To determine the protein responses of bananas toward drought stress, the well-watered, drought-stressed, and recovered banana leaves were sampled for tandem mass tags-based quantitative proteomics analysis. Of the 1018 differentially abundant proteins, 274 were significantly changed. The identified proteins differing between the treatments were mainly related to carbohydrate, energy and amino acid metabolisms, genetic information processing, and secondary metabolite biosynthesis. Our data may assist in developing a complete proteome dataset which could be valuable for developing drought-tolerant bananas. [ABSTRACT FROM AUTHOR]

Banana (Musa acuminata) is an important fruit crop and source of income for various countries, including Malaysia. To date, current agrochemical practice has become a disputable issue due to its detrimental effect on the environment. λ-carrageenan, a natural polysaccharide extracted from edible red seaweed, has been claimed to be a potential plant growth stimulator. Hence, the present study investigates the effects of λ-carrageenan on plant growth using Musa acuminata cv. Berangan (AAA). Vegetative growth such as plant height, root length, pseudostem diameter, and fresh weight was improved significantly in λ-carrageenan-treated banana plants at an optimum concentration of 750 ppm. Enhancement of root structure was also observed in optimum λ-carrageenan treatment, facilitating nutrients uptake in banana plants. Further biochemical assays and gene expression analysis revealed that the increment in growth performance was consistent with the increase of chlorophyll content, protein content, and phenolic content, suggesting that λ-carrageenan increases photosynthesis rate, protein biosynthesis, and secondary metabolites biosynthesis which eventually stimulate growth. Besides, λ-carrageenan at optimum concentration also increased catalase and peroxidase activities, which led to a significant reduction in hydrogen peroxide and malondialdehyde, maintaining cellular homeostasis in banana plants. Altogether, λ-carrageenan at optimum concentration improves the growth of banana plants via inducing metabolic processes, enhancing nutrient uptake, and regulation of cell homeostasis. Further investigations are needed to evaluate the effectiveness of λ-carrageenan on banana plants under field conditions. [ABSTRACT FROM AUTHOR]

Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4) is a destructive necrotrophic fungal pathogen afflicting global banana production. Infection process involves the activation of programmed cell death (PCD). In this study, seven Musa acuminata vacuolar processing enzyme (MaVPE1 – MaVPE7) genes associated with PCD were successfully identified. Phylogenetic analysis and tissue-specific expression categorized these MaVPEs into the seed and vegetative types. Foc TR4 infection induced the majority of MaVPE expressions in the susceptible cultivar "Berangan" as compared to the resistant cultivar "Jari Buaya." Consistently, upon Foc TR4 infection, high caspase-1 activity was detected in the susceptible cultivar, while low level of caspase-1 activity was recorded in the resistant cultivar. Furthermore, inhibition of MaVPE activities via caspase-1 inhibitor in the susceptible cultivar reduced tonoplast rupture, decreased lesion formation, and enhanced stress tolerance against Foc TR4 infection. Additionally, the Arabidopsis VPE -null mutant exhibited higher tolerance to Foc TR4 infection, indicated by reduced sporulation rate, low levels of H2O2 content, and high levels of cell viability. Comparative proteomic profiling analysis revealed increase in the abundance of cysteine proteinase in the inoculated susceptible cultivar, as opposed to cysteine proteinase inhibitors in the resistant cultivar. In conclusion, the increase in vacuolar processing enzyme (VPE)-mediated PCD played a crucial role in modulating susceptibility response during compatible interaction, which facilitated Foc TR4 colonization in the host. [ABSTRACT FROM AUTHOR]