Qingchun Yin

Chlorine dioxide (ClO₂) gas has attracted considerable attention due to its safety and efficiency. In this study, we successfully developed a color-variable ClO₂ slow-releasing card for postharvest litchi. The optimal ClO₂ slow-releasing card was prepared as follows: Card A was soaked in 2.5 mol/L NaClO₂ and 0.3 mol/L CaCl₂. Card B was soaked in 1 mol/L oxalic acid, 0.3 mol/L CaCl₂, and natural pigment. Finally, cards A and B were dried and adhered using 60% gelatin. The ClO₂ releasing time of the card was more than 120 h at 5–25 °C, and it could change color from dark yellow to white. The qualities of 3 kg litchi treated with no pieces (CK), half a piece (T1), one piece (T2), two pieces (T3), and three pieces (T4) of ClO₂ slow-releasing card were compared. The results showed that litchi of T1 had significantly (p < 0.05) higher L* and a* values but a lower respiration rate and relative conductivity than CK after 7 days of storage, showing the best pulp qualities and pericarp color. Further correlation analyses revealed a significant positive correlation (R² = 0.971) between Cya-3-O-gal-1 and a*, indicating a sharp decline in Cya-3-O-gal-1 and strong pericarp browning in CK. On the contrary, the low-releasing ClO₂ of T1 effectively inhibited Cya-3-O-gal-1 degradation. This could be one of the reasons for the superior pericarp color of T1. This study provides a visual, efficient, and economical solution for postharvest litchi.

So far, the metabolic differences between tree-ripened and postharvest-ripened mangoes have largely remained unexplored. The aim of this study was to evaluate the chemical composition of nutrient substances in mangoes subjected to different ripening methods. An untargeted metabolomic approach based on ultra performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) was carried out to investigate the differences between artificially ripened and naturally ripened mangoes. The principal component analysis results indicate a clear separation between the different treatment groups. Variance analysis, fold change, and orthogonal partial least squares discriminant analysis (OPLS-DA) were employed to find potential markers. In total, 69 metabolites were identified, with significant variations in the abundance of organic acids, vitamins, carbohydrates, and polyphenols closely related to the ripening methods of mangoes. These results contribute to a better understanding of the metabolic changes in mangoes due to different ripening methods, which could be used to assist in evaluating the quality of mango fruit.

Summary: The high content of cyanogenic glycosides (CG) in cassava storage tubers seriously affects human food safety. CG play crucial roles in plant growth and development and can protect cassava leaves from being masticated by herbivorous predators. Nevertheless, the regulatory mechanism of CG biosynthesis, which results in a low CG content in storage tubers and high CG content in leaves, remains poorly understood. Here, yeast one-hybrid assay was performed using a mixed cDNA library of cassava storage roots and leaves as prey and the promoter of MeCYP79D2 as bait. MeCYP79D2, a cytochrome P450 protein, is the rate-limiting enzyme for CG synthesis in cassava. From this information, a candidate regulator of MeCYP79D2 , that is, transcription factor MePHD1.2, was selected. MePHD1.2, which is located in the nucleus and exhibits a transcription inhibitory activity, can directly bind to PD2 segment in the promoter of MeCYP79D2 , which results in its repressed expression. In cassava, the transcriptional activity of MeCYP79D2 was considerably enhanced in mephd1.2 lines, which caused an increase in the contents of linamarin and lotaustralin. Our findings unveil a novel regulatory module governing CG biosynthesis, wherein mutation of MePHD1.2 attenuates its transcription inhibition on MeCYP79D2 and boosts CGs biosynthesis in cassava.

The metabolite-caused taste variation during rambutan maturation is unknown due to a lack of systematic investigation of all components. In this study, three growing stages, including unripe (S1), half-ripe (S2), and full-ripe (S3) BY2 and BY7 rambutans were compared and profiled by UPLC–MS/MS-based widely targeted metabolomics analysis. We demonstrated that the sugar-acid ratios of two rambutans were greatly improved between the S2 and S3 stages. A total of 821 metabolites were identified, including 232, 205, 204, and 12 differential metabolites (DMs) in BY2-S1 vs. BY2-S2, BY2-S2 vs. BY2-S3, BY7-S1 vs. BY7-S2, and BY7-S2 vs. BY7-S3, respectively. A correlation analysis showed that gamma-aminobutyric acid (GABA) could be the sugar-acid ratio biomarker of BY2 rambutan. Methionine (Met), alanine (Ala), and S-methyl-L-cysteine (SMC) could be total amino acid biomarkers of BY2 and BY7 rambutans. In addition, UPLC-MS/MS-based quantitative verification of the above biomarkers exhibited the same variations as metabolomics analysis. This study not only provides useful nutritive information on rambutans but also valuable metabolic data for rambutan breeding strategies.

Triflumezopyrim, a novel mesoionic insecticide used to control planthoppers, is a potential substitute for imidacloprid. In this study, triflumezopyrim and imidacloprid residues in rice were determined using a quick, easy, cheap, effective, rugged, and safe procedure combined with ultra-high-performance liquid chromatography–tandem mass spectrometry. The limit of quantification of both triflumezopyrim and imidacloprid was 0.01 mg kg⁻¹, and the average recovery values were 94–104% and 91–106%, with relative standard deviations (RSDs) of 1.1–1.4% and 2.1–3.4% (n = 5), respectively. The consumer protection level was assessed by calculating the theoretical maximum daily intake using the reported maximum residue limits of triflumezopyrim and imidacloprid. The established method was successfully applied to 200 commercial rice samples collected from four provinces in China, and their potential public health risks were assessed using triflumezopyrim and imidacloprid residues. The risk associated with triflumezopyrim and imidacloprid dietary intake was assessed by calculating the national estimated short-term intake and the acute reference dose percentage (%ARfD). The results show that the theoretical maximum daily intake (NEDI) values of triflumezopyrim and imidacloprid in different age and gender groups were 0.219–0.543 and 0.377–0.935 μg kg⁻¹ d⁻¹ bw, and the risk quotient (RQ) values were 0.188–0.467% and 0.365–0.906%, respectively. The acute reference dose (%ARfD) of triflumezopyrim and imidaclopridin ranged from 0.615 to 0.998% and from 0.481 to 0.780%, respectively.