RESUMEN
Pumpkin (Cucurbita pepo) seeds are nutritious and valued as a source of vegetable oil, protein, healthy fatty acids, and minerals. Pumpkin seeds that are naturally devoid of the seedcoat (hull-less) are preferred by the industry as they eliminate the need for de-hulling prior to use. A single recessive gene, designated as n or h, controls the hull-less seed trait in pumpkin. Visual selection for the trait is easy, however, it is resource intensive when applied to large breeding populations. High throughput genotyping assays can aid in the identification of suitable individuals in segregating populations through marker-assisted selection. In the current study, the QTL-seq approach was used to identify genetic loci, SNP markers and candidate genes associated with the hull-less trait in a segregating F2 population (n = 143) derived from a cross between Kakai (hull-less) × Table Gold Acorn (hulled). The segregation of the hull-less trait in the F2 population fit a 3:1 ratio (p < 0.05). QTL-seq analysis detected a single QTL on chromosome 12 (Qtlhull-less-C12) which was significantly associated with the hull-less trait in C. pepo. Twenty-eight SNPs were genotyped in the population, two among which (Ch12_3412046 and Ch12_3417142) were significantly associated (p < 0.05) with the hull-less trait in cultivars and accessions of diverse genetic background. Several candidate genes fall within the Qtlhull-less-C12 interval, among them is the No Apical meristem (NAC) domain-containing protein and a Fiber Protein fb11 gene involved in lignin accumulation and cell wall deposition across plant species, respectively. The findings of this study will facilitate the marker-assisted selection for the hull-less seed trait in pumpkin and further our understanding of the functional mechanisms underlying the trait across cucurbit crops.
RESUMEN
BACKGROUND: Bacillus cereus is an environmental pathogen whose spores resist the usual cleaning procedure applied by the food industry and hospitals. We reported a cluster of severe intestinal infections due to B cereus in 2 very low birth weight neonates from a neonatal intensive care unit. METHODS: Environmental sampling and bacteriological analysis of pooled breast milk (PBM) were performed. Practices for preparation and administration of milk were observed and additional laboratory experiments performed. Strains were typed using M13-polymerase chain reaction and their virulence tested using cellular and insect models. RESULTS: B cereus strains were exclusively isolated from intestinal tracts and PBM. No environmental culture yielded any viable B cereus. Although genotypically diverse, both clinical and food strains exhibited high virulence potency. These findings pointed out the pathogenic potency of B cereus in neonates; the putative role of PBM as a reservoir for pathogenic B cereus and the triggered effect of a defective care procedure, which allowed the growth of bacteria in pasteurized PBM. Well described from dried formula, the presence of pathogenic B cereus strains in PBM was not previously reported. CONCLUSIONS: Careful monitoring of conditions during collection, conservation, and administration of PBM should be implemented in high-risk populations such as premature neonates.
