Production and Characterization of Interspecific Hybrids Between Allium fistulosum and Allium przewalskianum Regel

This study aims to obtain interspecific hybrid plants and analyze the botanical characteristics of hybrids between Zhangqiudawutong welsh onions (A. fistulosum) and Qingganjiu (A. przewalskianum Regel), so as to provide a basis for the efficient utilization of wild resources in the Allium genus.

Taking Zhangqiudawutong welsh onion and Qingganjiu as experimental materials, flowering induction and reciprocal cross were conducted on both parents. Ovary cultivation techniquewas applied to obtain F₁ hybrid plants. The authenticity of hybrid F₁ was identified by means of chloroplast genome sequencing, flow cytometry detection, karyotype analysis, ITS analysis, and phenotypic characteristics. The botanical characteristics of hybrids were observed at the seedling stage, vegetative growth stage, and bolting-flowering stage. Their fertility was identified through observation and self-pollination. The color, texture and taste of the product were assessed via sensory assessment to determine its potential as an emerging vegetable. Differential metabolites between hybrid varieties and their parental lines were analyzed using widely-targeted metabolomics.

There was a significant difference in the seedling rates between reciprocal crosses of Zhangqiudawutong welsh onion and Qingganjiu. Ovaries from the cross of Zhangqiudawutong welsh onions (♀) × Qingganjiu (♂) expanded normally, whereas those from the reciprocal cross failed to expand and instead wilted and dried out. Ten days after pollination, natural ovaries ceased swelling, gradually turned grayish-white, became soft-textured, and eventually withered. Through ovary culture, 36 F₁ hybrid plants were obtained, with a germination rate of 46.25% and a seedling rate of 22.50%. The chloroplast genome sequence of hybrid F_1-16 was consistent with that of the maternal parent (Zhangqiudawutong welsh onion), indicating maternal inheritance of the cytoplasm. The peak of chromosome fluorescence intensity was 32.90×10⁵, which was between the two parents. The karyotype formula of chromosomes was 2n=2x=16=16m (1SAT), belonging to type 1A. The ITS sequence haplotypes included two types, which were identical to those of the two parents, respectively. The MAPI_1 molecular marker was developed, and the detection results showed that Zhangqiudawutong welsh onions (♀) had a single 124 bp band, while Qingganjiu (♂) had a single 289 bp band. Both bands were amplified in all 36 F₁ hybrid individuals. F₁ hybrid plants showed strong heterosis, with an average of 17.50 tillers per plant. Notably, their biomass yield reached 387.52 g per tiller group, which was significantly higher than that of their parents. All F₁ individuals were pollen-sterile, exhibiting male sterility, and propagated vegetatively via tillering and aerial bulbils instead. A total of 1208 metabolites were detected in both parents and hybrid F_1-16, and 153 metabolites showed significant differences between F_1-16 and its parents. Among these, 97 metabolites were upregulated and 56 metabolites were downregulated in F_1-16 compared to the parents. Additionally, F_1-16 produced a novel metabolite, Phloretin-2'-O-glucoside (Phloreizin), which has extremely high medicinal and health value.

Interspecific hybrid F₁ between Zhangqiudawutong and Qingganjiu was successfully obtained using ovary culture technology. F₁ exhibited obvious heterosis and male sterility. A method for developing molecular markers to identify distant hybrid species was designed and validated.