Polyethylene mulch film (PEM) is widely utilized in garlic cultivation, significantly enhancing garlic yield. However, the prolonged use of this material leads to serious environmental issues that adversely affect soil health and plant growth. To promote the adoption of biodegradable mulch film (BDM) in garlic cultivation, we investigate the effects of BDMs with thicknesses of 0.006 mm, 0.008 mm, and 0.010 mm on garlic growth and soil properties, comparing them with the commonly used PEM 0.008 mm. The results indicated that the agronomic traits of garlic were significantly improved under both PEM and BDMs compared to no mulching, with yield increases ranging from 75.42% to 90.39%. The highest garlic yield was observed with the BDM 0.008 mm. Most above-ground agronomic traits of garlic did not exhibit significant differences between PEM and BDMs, although a few traits showed slight increases under the BDMs 0.008 mm and 0.010 mm. The quality characteristics of garlic bulbs, including the contents of soluble sugar, vitamin C, and allicin, did not differ significantly between PEM and BDMs. Soil temperature was significantly higher under both PEM and BDMs compared to no mulching. In comparison to PEM 0.008 mm, the application of BDMs 0.006 mm and 0.008 mm significantly enhanced potassium availability in the soil. Furthermore, the activities of catalase, phosphatase, and invertase were notably increased under the BDM 0.008 mm, suggesting that this type of mulch could improve the physicochemical properties of the soil. Additionally, the BDM 0.008 mm remained intact throughout the low-temperature overwintering period, began to partially degrade as temperatures rose in March and April, and exhibited considerable fragmentation during the maturity and harvest periods of garlic. Its degradation rate was well aligned with the growth requirements of garlic. Taken together, these findings suggested that the BDM 0.008 mm is particularly effective, resulting in significant yield increase and an appropriate degradation rate. These results provided a valuable reference for the selection and application of BDM in garlic cultivation.

Multiplier onion (Allium cepa var. aggregatum) is an economically important Allium crop that serves dual purposes as both a culinary ingredient and medicinal resource. Despite its widespread utilization, systematic characterization of its nutrient metabolism components remains limited, which has constrained the development of high-value cultivars with optimized nutritional profiles. In this study, we conducted a comprehensive metabolomic profiling of bulbs from five genetically distinct accessions using a widely targeted metabolomic method based on ultra-performance liquid chromatography–tandem mass spectrometry (UPLC-MS/MS). The analysis identified 659 metabolites, including lipids, flavonoids, phenolic acids, amino acids, saccharides and alcohols, organic acids, alkaloids, nucleotides and derivatives, vitamins, etc. Notably, the bulbs exhibited a high abundance of flavonoids (e.g., quercetin, kaempferol, naringenin, isorhamnetin) and eight essential amino acids (valine, threonine, leucine, isoleucine, lysine, methionine, histidine, and tryptophan). Comparative analysis revealed that 366 differentially accumulated metabolites were identified among these 5 accessions, many of which were significantly enriched in pathways related to flavonoid biosynthesis, as well as amino acid biosynthesis and metabolism. Transcriptome analysis indicated that differentially expressed genes (DEGs) across the five accessions were significantly enriched flavonoid biosynthesis, and various amino acid biosynthesis and metabolism processes, such as “tyrosine metabolism”, “phenylalanine, tyrosine, and tryptophan biosynthesis”, “cysteine and methionine metabolism” and “arginine and proline metabolism”, being consistent with the substantial variations observed in flavonoids, amino acids, and their derivatives in the metabolome analysis. Correlation and network analysis identified several crucial candidate regulatory genes for the biosynthesis and metabolism of lipids, flavonoids, phenolic acids, and amino acids. These findings provide a comprehensive metabolic atlas of multiplier onion, reveal key genetic regulators of nutritional quality, and establish a scientific foundation for nutraceutical development and cultivar improvement strategies.

Garlic is a widely utilized condiment and health product. However, garlic bulbs are prone to quality deterioration resulting in decrease of economic value during postharvest. In this study, the storability of 501 garlic accessions worldwide was evaluated based on the examination of decay index (DI), decay rate, sprouting rate, and bud-to-clove ratio in two consecutive years. The DI was employed as a primary index for evaluating the storability of garlic. Among these garlic, 43 accessions exhibited strong storability with DI of 0%–5%. Phenotypic and cytological observations revealed that strong storability accessions displayed delayed sprouting and decay, a slow rate of nutrient transfer to vascular bundles. Through genome-wide association study (GWAS), 234 single-nucleotide polymorphism loci (SNPs) were associated with the storability, which were located in or near 401 genes, which were annotated the functions of resistance, storage substances transport, etc. A total of 44 genes were screened using selective sweep analysis. Transcriptomic analysis was performed at four periods after storage in the 8N035 accession with strong storability and 8N258 accession with weak storability. Compared with 8N035, the upregulated genes in the 8N258 were enriched in photosynthesis and stress response, whereas the downregulated genes were enriched in response of biotic and abiotic stress and defense response. A co-expression network and GWAS identified three hub genes as key regulatory genes. Conjoint analysis of GWAS, selective sweep, and transcriptomic analysis identified 21 important candidate genes. These findings provided excellent resources with storability and vital candidate genes regulating storability for biological breeding of garlic.

Multiplier onion (Allium cepa L. var. aggregatum) is an important bulbous vegetable widely utilized for culinary, condimental, and medicinal purposes. However, limited research on its genetic diversity and phenotypic variation has hindered the development and utilization of superior cultivars. In this study, we conducted full-length transcriptome profiling to obtain unique transcripts and develop large-scale simple sequence repeat (SSR) markers. Subsequently, we employed integrative analysis to characterize the genetic and phenotypic variation of 263 multiplier onion accessions in China. Full-length transcriptome sequencing utilizing PacBio technology generated 61,108 high-quality non-redundant transcripts with an average length of 1816 bp, from which we developed 4124 SSR markers encompassing 100 motif types. Population structure, principal component analysis, and neighbor-joining phylogenetic analysis classified the 263 multiplier onion accessions into two distinct subpopulations: Pop1, consisting of 236 accessions primarily from Heilongjiang Province, and Pop2, comprising 27 accessions mostly from Shaanxi Province. Phenotypic evaluation demonstrated significant variation in bulb traits, with single bulb weight (SBW) exhibiting the highest variability (0.75–29.94 g; CV = 70.10%), followed by total bulb weight per plant (BW) (5.00–168.83 g; CV = 58.34%), indicating considerable potential for breeding high-yield varieties. Correlation analysis indicated that the SBW and BW had significantly positive correlations with multiple traits, including bulb height, bulb transverse diameter, diameter of basal plate of bulb, diameter of bulb neck, and number of cloves per bulb. Our findings provide a valuable genetic and phenotypic resource for the conservation and utilization of multiplier onion germplasms.

Doubled haploid (DH) technology based on in vivo haploid induction (HI), which is used to obtain true-breeding lines within a single generation, is a technique that significantly increases modern crop-breeding efficiency. Recently, dicot Arabidopsis thaliana lines containing mutations in DMP8/9 were used as haploid inducer lines, but the use of this new HI mechanism is limited in Brassicaceae species, which include many important vegetable, oil, and fodder crops. Here, we investigated the phylogenetic distribution of the DMP8 and DMP9 homologous genes from 26 sequenced Brassicaceae species. We found that DMP8 only exists in the tribe Arabideae, while multiple copies of the DMP9 gene are presenting in all the investigated Brassicaceae species. The syntenic DMP9 genes were divided into two groups derived from the S genomic block and R genomic block, respectively. We further investigated the duplication, structure variations, and expression of the DMP9 genes in Brassica species that had undergone an extra whole-genome triplication. Our results revealed that DMP9 was lost in the most fractionated (MF2) subgenome, and the retained DMP9s in the least fractionated (LF) subgenome and medium fractionated (MF1) subgenome showed diversified expression patterns, indicating their functional diversification. Our results will be useful for obtaining the target DMP genes for the establishing of HI lines in Brassicaceae crops.