Characterization of alcohol acetyltransferases in the ripe flesh of 'Monthong' and 'Chanthaburi 1' durians.

Durian is economically significant in Southeast Asia due to its distinctive aroma and palatability. During fruit ripening, the flesh generates a substantial quantity of esters and some sulfur-containing compounds. This study aimed to analyze the ester profiles and characteristics of alcohol acetyltransferase (AAT; EC. 2.3.1.84) in the ripe flesh of two Thai durian (Durio zibethinus Merr.) cultivars, 'Chanthaburi 1' (a hybrid cultivar with a soft aroma) and 'Monthong' (a renowned cultivar with a medium scent). The primary esters responsible for the aromatic compounds found in durian are ethyl-2-methyl butanoate, ethyl hexanoate, and ethyl octanoate. The AAT's efficacy was assessed in its ability to catalyze the synthesis of acetate esters through the reaction between acetyl CoA and different alcohols. The AAT enzymes extracted from 'Chanthaburi 1' and 'Monthong' cultivars exhibited a notable affinity towards 3-methyl-1-butanol and hexanol as alcohol substrates. Propanol and butanol exhibited moderate activity as AAT substrates, whereas methanol and ethanol demonstrated the lowest. Both durians exhibited favorable enzyme activity at a temperature of 30 °C. However, 'Monthong' AAT demonstrated superior performance across a broader pH range compared to 'Chanthaburi 1' AAT. The partially purified proteins precipitated with ammonium sulfate and subsequently gel-filtered through a DEAE-Sephadex® column enhanced the potency of 'Chanthaburi 1' AAT, resulting in increased purity (1.20-fold) and specificity (1.08-fold) compared to 'Monthong'. The AAT of 'Chanthaburi 1' and 'Monthong' exhibited molecular weights of 39.52 and 41.51 kDa, respectively. This study presents the initial documentation of AAT in durians through an enzyme assay and activity staining technique.

Short-Term Storability of Alginate-Encapsulated Persian Violet Microshoots for Germplasm Exchange.

Microshoots have been widely used for micropropagation. It may be necessary to store microshoots for a short period of time, for example in germplasm exchange needing transport to other research groups. Here, we investigated the short-term storability of alginate-encapsulated Persian violet (Exacum affine Balf. f. ex Regel) microshoots at 4 °C and 25 °C. After storage, the encapsulated microshoots were sown on basal Murashige and Skoog medium for germination and viability determination using tetrazolium chloride staining. The results showed that one or five microshoots encapsulated with a single alginate layer could be stored at 4 °C for up to 30 days, while the percentages of germination and viability of the microshoots encapsulated with two layers of alginate were greatly reduced upon storage. This is the first report on the storability of alginate-encapsulated multiple microshoots, which could be a more efficient way to encapsulate microshoots used for short-term cold storage.

Differing In Vitro Rooting and Flowering Responses of the Persian Violet to Low and High UV-C Irradiation.

Persian violet flowers are considered esthetically attractive, leading to the high economic value of this plant. Plant breeding is fundamental to crop improvement, and the induction of mutation by tissue culture technology in combination with irradiation has been beneficially applied to generate plants with novel desirable characteristics. In this research, single or double rounds of UV-C irradiations were carried out on plant tissue cultures to initiate the in vitro rooting and mutation of Persian violets. It was found that single low-intensity UV-C exposure, when applied to Persian violet microshoots for 4 h, could induce the maximum number of roots and the highest root length without the use of a plant growth regulator. Overall, the single and double UV-C irradiation of Persian violet microshoots led to 44 different types of Persian violet flower mutations. Under single high-intensity UV-C irradiation for 6 h, up to nine petals were initiated, whereas single low-intensity UV-C irradiation did not influence the morphological variation of Persian violet flowers. Thus, Persian violet microshoots respond differently in terms of in vitro rooting and flowering depending on the UV-C intensity and exposure duration. These outcomes may be applied to micropropagation and in vitro plant breeding.