Shan Zhao

Sweet potato (Ipomoea batatas (L.) is regarded among the most crucial crops globally because it is abundant in essential nutrients vital for human health. However, limited comprehensive information is available regarding the nutritional composition of sweet potato, which hinders its optimal utilization. This study investigated the nutritional and chemical composition of sweet potato roots and explored their interrelationships. In total, 86 sweet potato accessions, comprising white, yellow, orange, and purple flesh-colored varieties, were used. A total of 34 components, including nutrients, phytochemicals, and minerals, were identified. Multivariate analysis was performed to assess the relationships among these components. The sweet potato roots were rich in carbohydrates, polyphenols, and minerals. Carbohydrates were primarily composed of total starch (22.6–69.7 g/100 g DW), total soluble sugar (TSS) (10.3–40.0 g/100 g DW), and total dietary fiber (TDF) (7.99–26.0 g/100 g DW). Polyphenols included total caffeoylquinic acids (CQAs) (0.478–14.2 g/kg DW), total anthocyanins (0–2003 mg/kg DW), and β-carotene (0–133 mg/kg DW). The mineral content followed the order: potassium > calcium > phosphorus > sodium > magnesium > iron > manganese > zinc > copper > selenium. White-fleshed sweet potato exhibited high total starch levels (50.4 g/100 g DW) but low TSS levels (21.1 g/100 g DW). Orange-fleshed sweet potato contained high levels of TSS (26.5 g/100 g DW), TDF (17.9 g/100 g DW), and β-carotene (61.4 mg/100 g DW) but low levels of protein (2.99 g/100 g DW) and total starch (43.0 g/100 g DW). Purple-fleshed sweet potato had high levels of phytochemicals, particularly total CQAs (8.17 g/kg DW) and anthocyanins (904 mg/kg DW). Cluster analysis categorized sweet potato accessions into six clusters with unique characteristics. Furthermore, principal component analysis identified accessions with exceptionally high nutritional content. The correlation analysis indicated that starch was negatively correlated with soluble sugar and TDF, whereas CQAs and anthocyanins were highly positively correlated. These findings offer a solid theoretical foundation for sweet potato breeding and utilization.

The sequences of x-type high-molecular-weight glutenin promoter (x-HGP) from 21 diploid Triticeae species were cloned and sequenced. The lengths of x-HGP varied from 897 to 955 bp, and there are 329 variable sites including 105 singleton sites and 224 polymorphic sites. Genetic distances of pairwise X-HGP sequences ranged from 0.30 to 16.40% within 21 species and four outgroup species of Hordeum. All five recognized regulatory elements emerged and showed higher conservation in the x-HGP of 21 Triticeae species. Most variations were distributed in the regions among or between regulatory elements. A 22 bp and 50 bp insertions which were the copy of adjacent region with minor change, were found in the x-HGP of Ae. speltoides and Ps. Huashanica, and could be regarded as genome specific indels. The phylogeny of media-joining network and neighbour-joining tree both supported the topology were composed of three sperate clusters. Especially, the cluster I comprising the x-HGP sequences of Aegilops, Triticum, Henrardia, Agropyron and Taeniatherum was highly supporting by both network and NJ tree. As conferring to higher level and temporal and spatial expression, x-HGP can used as the source of promoter for constructing transgenic plants which allow endosperm-specific expression of exogenous gene on higher level. In addition, the x-HGP has enough conservation and variation; so it should be valuable in phylogenetic analyses of Triticeae family members.

Background: High molecular weight glutenin subunits (HMW-GSs), encoded by the genes at Glu-1 loci in wheat and its related species, are significant in the determination of grain processing quality. However, the diversity and variations of HMW-GSs are relatively low in bread wheat. More interests are now focused on wheat wild relatives in Triticeae. The genus Aegilops represents an important germplasm for novel HWM-GSs and other useful genes for wheat genetic improvement. Results: Six novel Glu-1 alleles and HMW-GSs were identified and characterized from three species of Aegilops section Sitopsis (S genome). Both open reading frames (ORFs) and promoter regions of these Glu-1 alleles were sequenced and characterized. The ORFs of Sitopsis Glu-1 genes are approximately 2.9 kb and 2.3 kb for x-type and y-type subunits, respectively. Although the primary structures of Sitopsis HMW-GSs are similar to those of previously reported ones, all six x-type or y-type subunits have the large fragment insertions. Our comparative analyses of the deduced amino acid sequences verified that Aegilops section Sitopsis species encode novel HMW-GSs with their molecular weights larger than almost all other known HMW-GSs. The Glu-1 promoter sequences share the high homology among S genome. Our phylogenetic analyses by both network and NJ tree indicated that there is a close phylogenetic evolutionary relationship of x-type and y-type subunit between S and D genome. Conclusions: The large molecular weight of HMW-GSs from S genome is a unique feature identified in this study. Such large subunits are resulted from the duplications of repetitive domains in Sitopsis HMW-GSs. The unequal crossover events are the most likely mechanism of variations in glutenin subunits. The S genome-encoded subunits, 1Dx2.2 and 1Dx2.2* have independent origins, although they share similar evolutionary mechanism. As HMW-GSs play a key role in wheat baking quality, these large Sitopsis glutenin subunits can be used as special genetic resources for wheat quality improvement.