Chinese bacon is highly esteemed by consumers worldwide due to its unique aroma. The composition of volatile organic compounds (VOCs) varies significantly among different types of Chinese bacon. This study analyzed the VOCs of Chinese bacon from Sichuan, Hunan, Guangxi, and Shaanxi provinces using gas chromatography-mass spectrometry (GC-MS), an electronic nose (E-nose), and gas chromatography-ion mobility spectrometry (GC-IMS). The results demonstrate that the combination of GC-MS and GC-IMS effectively distinguishes Chinese bacon from different regions. Notably, Guangxi bacon lacks a smoky aroma, which sets it apart from the other types. However, it contains many esters that play a crucial role in its flavor profile. In contrast, phenols, including guaiacol, which is typical in smoked bacon, were present in the bacon from Sichuan, Hunan, and Shaanxi but were absent in Guangxi bacon. Furthermore, Hunan bacon exhibited a higher aldehyde content than Sichuan bacon. 2-methyl-propanol and 3-methyl-butanol were identified as characteristic flavor compounds of Zhenba bacon. This study provides a theoretical foundation for understanding and identifying the flavor profiles of Chinese bacon. Using various analytical techniques to investigate the flavor compounds is essential for effectively distinguishing bacon from different regions.

Tea is an important woody crop whose cultivation is severely limited by cold stress. Although 5-aminolevulinic acid (ALA) is known to be effective in alleviating abiotic stresses in plants, knowledge of the detailed metabolic response of tea plants to exogenous ALA-induced cold resistance is still limited—a lack which restricts our ability to protect tea plants from cold stress. In the present study, we performed an in-depth metabolomics analysis to elucidate the metabolic responses of tea plants to cold stress and explore the role of ALA in improving tea plants’ cold-resistance capability. Metabolic profiles showed that cold stress altered various metabolisms in tea plants, especially galactose composition and flavonoid contents. Furthermore, exogenous ALA application altered a series of metabolisms associated with cold stress. Importantly, increases in metabolites, including catechin, 3,4-dihydroxyphenylacetic acid and procyanidin B2, involved in the mechanisms of ALA improved tea plants’ cold resistance. Overall, our study deciphered detailed metabolic responses of tea plants to cold stress and elucidated the mechanisms of ALA in enhancing cold resistance through rebuilding compositions of soluble carbohydrates and flavonoids. Therefore, we have provided a basis for exogenous usage of ALA to protect tea plants from cold stress.

Southern Shaanxi is one of China’s high-quality congou black tea production areas. However, the differences in geography, cultivation, and management techniques and production processes lead to uneven qualities of southern Shaanxi congou black tea in different production areas. This study used sensory analysis combined with gas chromatography–ion mobility spectrometry (GC-IMS) to determine southern Shaanxi congou black teas’ geographical origin and volatile fingerprints to prevent economic losses caused by fraudulent labeling. A total of 61 volatile compounds were identified and quantified by GC-IMS. Three main aroma types were found by sensory analysis coupled with significant difference analysis, and a clear correlation between volatile compounds, aroma type, and geographical origin was found by sensory and gallery plot analysis. The black tea with a green/grassy-roast aroma type was mainly distributed in production areas with an altitude of 400–800 m and 1-pentanol, cyclohexanone, 1-penten-3-one, 2-heptanone, dihydroactinidiolide and butyrolactone were the key aroma markers. The black teas produced in production areas with an altitude of 800–1000 m mainly presented strong honey and caramel-like aromas, and sotolone, furaneol, and phenylacetaldehyde played an important role. These results will be helpful for discriminating black tea from different tea production areas in southern Shaanxi.

Kiwifruit bacterial cankers caused by Pseudomonas syringae pv. actinidiae (Psa) are a serious threat to the kiwifruit industry. Salicylic acid (SA) regulates plant defense responses and was previously found to enhance kiwifruit’s resistance to Psa. However, the underlying mechanisms of this process remain unclear. In this study, we used 4D proteomics to investigate how SA enhances kiwifruit’s resistance to Psa and found that both SA treatment and Psa infection induced dramatic changes in the proteomic pattern of kiwifruit. Psa infection triggered the activation of numerous resistance events, including the MAPK cascade, phenylpropanoid biosynthesis, and hormone signaling transduction. In most cases, the differential expression of a number of genes involved in the SA signaling pathway played a significant role in kiwifruit’s responses to Psa. Moreover, SA treatment upregulated numerous resistance-related proteins, which functioned in defense responses to Psa, including phenylpropanoid biosynthesis, the MAPK cascade, and the upregulation of pathogenesis-related proteins. We also found that SA treatment could facilitate timely defense responses to Psa infection and enhance the activation of defense responses that were downregulated in kiwifruit during infection with Psa. Thus, our research deciphered the potential mechanisms of SA in promoting Psa resistance in kiwifruit and can provide a basis for the use of SA to enhance kiwifruit resistance and effectively control the occurrence of kiwifruit bacterial cankers.

Basic WD40 proteins, which are characterized by a conserved WD40 domain, comprise a superfamily of regulatory proteins in plants and play important roles in plant growth and development. However, WD40 genes have been rarely studied in apple (Malus × domestica Borkh.). In this study, 346 WD40 genes classified in 12 subfamilies, were identified in the apple genome. Evolutionary analysis of WD40 proteins in apple and Arabidopsis revealed that the genes were classifiable into 14 groups, and the exon/intron structure of each group showed a similar structure. Analysis of collinearity showed that the large-scale amplification of WD40 genes in apple was largely attributable to recent whole-genome replication events. Nineteen candidate stress-related genes, selected by GO annotation and comparison with Arabidopsis homologs, showed different expression profiles in six organs at different developmental stages in response to exogenous abscisic acid (ABA), drought, and low temperature. Eight genes (MdWD40-17, 24, 70, 74, 219, 256, 283, and 307) showed a distinct response to one or more treatments (ABA, drought, and low temperature) as indicated by quantitative real-time PCR analysis. Taken together, these data provide rich resources for further study of MdWD40 genes and their potential roles in stress responses in apple.

Tea (Camellia sinensis L.) is an important perennial cash crop and a typical subtropical plant. It is widely concerned because of its unique flavor and health benefits. In recent years, low temperatures have severely restricted the growth of tea plants and quality of tea products, especially in spring. As a common precursor for all porphyrin compounds, 5-aminolevulinic acid (ALA) is involved in photosynthesis and respiration and plays an active role in improving salt, drought and low-temperature tolerance in plants. However, it is not yet clear what affect exogenous ALA has on tea plants’ tolerance under low temperature. In the present study, we collected and deciphered the transcriptome profiles from Shaancha No. 1 leaf tissues under low temperature (−4 °C) treatment (T-4), exogenous ALA application (T-A), pretreated ALA before low temperature (T-A-4) and untreated control (T-CK). Results showed that 4990 (2375 up- and 2615 down-regulated), 223 (103 up- and 120 down-regulated) and 92 (13 up- and 79 down-regulated) differentially expression genes (DEGs) were identified at T-CK vs. T-4, T-CK vs. T-A and T-4 vs. T-A-4, respectively. Both T-4 and T-A treatments triggered a myriad of stress resistance genes up-regulated related to multiple signaling pathways by means of Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. This included MAPK, a toll-like receptor that signals pathways involved in cold resistance. However, gene ontology (GO) analysis showed that the DEGs in T-4 treatment were mainly enriched in the phenylpropanoid metabolic and redox processes that were relevant to membrane structure damage response. In contrast, the DEGs in T-A treatment were mainly enriched in cell recognition and amylase activity. Furthermore, in pairwise comparison of T-A-4 vs. T-4, the DEGs were enriched in ascorbate and aldarate, retionol, taurine and hypotaurine, glutathione metabolic pathways and two biosynthesis process including zeatin, diterpenoid biosynthesis, which might contribute to mitigating the damage caused by low temperature. Overall, these results indicated that exogenous ALA application may improve the biochemical attributes and enhance the tolerance to low temperature, which provides a valuable strategy to improve tea quality and cold stress.