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- Author or Editor: Bin Xu x
- Journal of the American Society for Horticultural Science x
Cucumber (Cucumis sativus L.) belongs to the cucumber genus of the Cucurbitaceae family, and the selection of cultivars with minimal or no lateral branches can enhance the cultivation management efficiency. The growth of lateral branches is inhibited by strigolactone. To investigate the regulatory mechanism of strigolactone on the lateral branch development in cucumber, the cultivar LZ1 exhibiting multiple lateral branches was selected as the experimental material. The axillae of the plants were infiltrated with 1, 5, and 10 μmol·L−1 germination releaser 24 (GR24) at the four- to five-leaf stage. It was identified that 1 μmol·L−1 GR24 exhibited the most potent inhibitory effect on cucumber lateral branches. Additionally, exogenous strigolactone decreased the auxin content in the apical bud and axillae and increased the auxin content in the stem. This inhibited polar auxin transport in the axillary bud and promoted polar auxin transport in the apical bud. The content of strigolactone in the axilla region of cucumbers was elevated, whereas the synthesis and expression of cytokinin in the same area were reduced. A low concentration of GR24 induced the expression of cucumber branched 1 (csbrc1), whereas a high concentration of GR24 downregulated the expression of cucumber lateral suppressor (cscls) and blind (csblind), which inhibited the growth of cucumber lateral branches.
Peach (Prunus persica) fruit emit more than 100 volatile organic compounds. Among these volatiles, γ-decalactone is the key compound that contributes to peach aroma. The final step in lactones biosynthesis is catalyzed by alcohol acyltransferases (AATs). In this study, five AAT genes were isolated in the peach genome, and the ways that these genes contribute toward the peach aroma were studied. The sequence analysis of the five AATs showed PpAAT4 and PpAAT5 are truncated genes, missing important residues such as HXXXD. The expressions of PpAATs were investigated to identify the roles in creating the peach aroma. The results indicated that only PpAAT1 is highly expressed during γ-decalactone formation. A functional survey of the five PpAATs, using the oleaginous yeast expression system, suggested that only PpAAT1 significantly increased the γ-decalactone content, whereas the other four PpAATs did not significantly alter the γ-decalactone content. Enzyme assays on PpAATs heterologously expressed and purified from Escherichia coli indicated that only PpAAT1 could catalyze the formation of γ-decalactone. All results indicated that PpAAT1 is a more efficient enzyme than the other four PpAATs during the γ-decalactone biosynthesis process in peach fruit. The results from this study should help improve peach fruit aroma.