Chromosome-Level Genome Assembly Provides New Insights into Genome Evolution and Tuberous Root Formation of Potentilla anserina

Potentilla anserina is a perennial stoloniferous plant with edible tuberous roots in Rosaceae, served as important food and medicine sources for Tibetans in the Qinghai-Tibetan Plateau (QTP), China, over thousands of years. However, a lack of genome information hindered the genetic study. Here, we presented a chromosome-level genome assembly using single-molecule long-read sequencing, and the Hi-C technique. The assembled genome was 454.28 Mb, containing 14 chromosomes, with contig N50 of 2.14 Mb. A total of 46,495 protein-coding genes, 169.74 Mb repeat regions, and 31.76 Kb non-coding RNA were predicted. P. anserina diverged from Potentilla micrantha ∼28.52 million years ago (Mya). Furthermore, P. anserina underwent a recent tetraploidization ∼6.4 Mya. The species-specific genes were enriched in Starch and sucrose metabolism and Galactose metabolism pathways. We identified the sub-genome structures of P. anserina, with A sub-genome was larger than B sub-genome and closer to P. micrantha phylogenetically. Despite lacking significant genome-wide expression dominance, the A sub-genome had higher homoeologous gene expression in shoot apical meristem, flower and tuberous root. The resistance genes was contracted in P. anserina genome. Key genes involved in starch biosynthesis were expanded and highly expressed in tuberous roots, which probably drives the tuber formation. The genomics and transcriptomics data generated in this study advance our understanding of the genomic landscape of P. anserina, and will accelerate genetic studies and breeding programs.

Relationship between bud number in seed branches and yield aspects of sweet potato

ABSTRACT Planting sweet potato branches with the appropriate bud number and disposition, below and above ground, can favor vegetative growth and yield that better fit the marketable standards. This study aimed to explore the influence of the number of buds and their distribution ratio, above and below ground level, on the agronomic and marketable components of sweet potato tuberous roots. The experiment was carried out in a randomized complete block design with three replications. The treatments were arranged in a factorial scheme (3 x 5), with 2, 4, and 8 above-ground buds combined with 2, 4, 6, 8, and 10 below-ground buds. Branches from the UZBD 06 accession (Canadense standard) were used. Vegetative, productive, and marketable traits of roots were evaluated. The use of branches with a greater number of buds above and below ground increased shoot dry biomass. Planting seed branches with 8 buds above and 8 buds below ground provided a greater number and production of marketable roots. The use of 10 buried buds increased root number and yield in the 150-450 g marketable classes, which the consumer market values the most.

Storage Property Is Positively Correlated With Antioxidant Capacity in Different Sweet Potato Cultivars

Sweet potato decays easily due to its high respiration rate and reactive oxygen species (ROS) accumulation during postharvest storage. In this study, we explored the relationship between antioxidant capacity in leaves and storage properties in different sweet potato cultivars, the tuberous roots of 10 sweet potato cultivars were used as the experimental materials to analyze the storage property during storage at 11–15°C. According to the decay percentage after 290 days of storage, Xu 32 was defined as a storage-tolerant cultivar (rot percentage less than 25%); Xu 55-2, Z 15-1, Shangshu 19, Yushu, and Zhezi 3 as above-moderate storage-tolerant cultivars (rot percentage ranging from 25 to 50%); Sushu 16, Yanshu 5, and Hanzi as medium-storable cultivars (rot percentage 50–75%); and Yan 25 as a storage-sensitive cultivar (rot percentage greater than 75%). Meanwhile, analysis of the α-amylase activity in root tubers of the 10 sweet potato cultivars during storage indicated that α-amylase activity was lowest in the storage-tolerant cultivar Xu 32 and highest in the storage-sensitive cultivar Yan 25. Evaluation of antioxidant enzyme activities and ROS content in the leaves of these 10 cultivars demonstrated that cultivar Xu 32, which showed the best storage property, had higher antioxidant enzyme activity [superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and peroxidase (POD)] but lower lipoxygenase (LOX) activity, hydrogen peroxide (H2O2) and malondialdehyde (MDA) contents, and superoxide anion radical (O2⋅–) production rates compared with those of the storage-sensitive cultivar Yan 25 and the medium-storability cultivars Hanzi, Yanshu 5, and Sushu 16. Additionally, principal component analysis (PCA) suggested that sweet potato cultivars with different storage properties were clustered separately. Correlation and heat map analysis further indicated that CAT, APX, POD, and SOD activities were negatively correlated with α-amylase activity, while LOX activity and MDA and H2O2 contents were negatively correlated with the storage property of sweet potato. Combined, our findings revealed that storage property is highly correlated with antioxidant capacity in sweet potato leaves and negatively correlated with α-amylase activity in tuberous roots, which provides a convenient means for the screening of storage-tolerant sweet potato cultivars.

Capacité germinative des graines et aptitude au bouturage des tiges, des racines tubéreuses de l’espèce Ampelocissus multistriata(Baker) Planch.

Cette étude s’inscrit dans le contexte de la valorisation des espèces végétales spontanées ayant des valeurs nutritives et économiques afin de contribuer à leur domestication. Cette étude a consisté à tester les capacités germinatives des graines de l’Ampelocissus multistriata par les procédés physiques, chimiques et mécaniques d’une part et tester l’aptitude au bouturage des tiges feuillées, des tiges feuillées avec des racines tubéreuses d’autre part. Pour cela, une surface de 400 m2 a été délimitée au sein de la Faculté des Sciences Exactes et Appliquées de l’Université de N’Djamena pour les deux tests. Par ailleurs, les procédés physiques, chimiques et mécaniques ont été menés à l’Université de Ouagadougou. Les résultats obtenus, ont montré que les tiges feuillées n’ont pas bouturé. Par contre, les tiges feuillées munies des racines tubéreuses ont bouturé à 73,23 %. En ce qui concerne la germination des graines, tous les procédés des traitements physiques, chimiques et mécaniques n’ont pas pu lever la dormance de ces graines. Leurs téguments, très durs, n’ont pas été scarifiés et cela n’a pas permis à l’eau et l’oxygène d’y entrer pour que les graines puissent germer. Seules, les graines ayant séjourné dans le tube digestif des animaux et qui ont été scarifiées par les enzymes intestinales et les sucs digestifs ont toutes germé. Il s’agit d’une endozoochorie. La connaissance des modalités de la propagation par les graines ou par les boutures peut apporter une importante contribution à la conservation de la diversité végétale, à la domestication et à la valorisation de cette plante. English title: Germinative capacity of seeds and aptitude for cutting of stems, tuberous roots of the species Ampelocissus multistriata (Baker) Planch This study is part of the context of valuing spontaneous plant species with nutritional and economic values in order to contribute to their domestication. This study consisted in testing the germination capacities of the seeds of Ampelocissus multistriata by physical, chemical and mechanical methods on the one hand and testing the aptitude for cuttings of leafy stems, leafy stems with tuberous roots on the other hand. For this, an area of 400 m2 has been defined within the Faculty of Exact and Applied Sciences of the University of N’Djamena for the two tests. In addition, the physical, chemical and mechanical processes were carried out at the University of Ouagadougou. The results obtained showed that the leafy stems did not cuttings. In contrast, the leafy stems with tuberous roots cut at 73.23%. Regarding seed germination, not all physical, chemical and mechanical treatment processes were able to break the dormancy of these seeds. Their very hard seed coats were not scarified, and this did not allow water and oxygen to enter them for the seeds to germinate. Only the seeds which have stayed in the digestive tract of animals and which have been scarified by intestinal enzymes and digestive juices have all germinated. It is an endozoochory. Knowing the methods of propagation by seeds or cuttings can make an important contribution to the conservation of plant diversity, to the domestication and enhancement of this plant.

Diversity of the Bacterial Microbiome Associated With the Endosphere and Rhizosphere of Different Cassava (Manihot esculenta Crantz) Genotypes

Root-associated microbial communities play important roles in plant growth and development. However, little attention has been paid to the microbial community structures associated with cassava, which is a staple food for approximately 800 million people worldwide. Here, we studied the diversity and structure of tuber endosphere and rhizosphere bacterial communities in fourteen cassava genotypes: SC5, SC8, SC9, SC205, KU50, R72, XL1, FX01, SC16, 4612, 587, 045, S0061, and 1110. The results of bacterial 16S rDNA sequencing showed that the richness and diversity of bacteria in the rhizosphere were higher than those in the tuber endosphere across the 14 cassava genotypes. After sequencing, 21 phyla and 310 genera were identified in the tuberous roots, and 36 phyla and 906 genera were identified in the rhizosphere soils. The dominant phylum across all tuber samples was Firmicutes, and the dominant phyla across all rhizosphere samples were Actinobacteria, Proteobacteria, and Acidobacteria. The numbers of core bacterial taxa within the tuber endospheres and the rhizospheres of all cassava genotypes were 11 and 236, respectively. Principal coordinate analysis and hierarchical cluster analysis demonstrated significant differences in the compositions of rhizosphere soil microbiota associated with the different cassava genotypes. Furthermore, we investigated the metabolic changes in tuber roots of three genotypes, KU50, SC205, and SC9. The result showed that the abundances of Firmicutes, Proteobacteria, and Actinobacteria in tuber samples were positively correlated with organic acids and lipids and negatively correlated with vitamins and cofactors. These results strongly indicate that there are clear differences in the structure and diversity of the bacterial communities associated with different cassava genotypes.

Molecular Mechanisms through Which Short-Term Cold Storage Improves the Nutritional Quality and Sensory Characteristics of Postharvest Sweet Potato Tuberous Roots: A Transcriptomic Study

Sweet potato (Ipomoea batatas (L.) Lam.) is a commercially relevant food crop with high demand worldwide. This species belongs to the Convolvulaceae family and is native to tropical and subtropical regions. Storage temperature and time can adversely affect tuberous roots' quality and nutritional profile. Therefore, this study evaluates the effect of storage parameters using physicochemical and transcriptome analyses. Freshly harvested tuberous roots (Xingxiang) were stored at 13 °C (control) or 5 °C (cold storage, CS) for 21 d. The results from chilling injury (CI) evaluation demonstrated that there was no significant difference in appearance, internal color, weight, and relative conductivity between tuberous roots stored at 13 and 5 °C for 14 d and indicated that short-term CS for 14 d promoted the accumulation of sucrose, chlorogenic acid, and amino acids with no CI symptoms development. This, in turn, improved sweetness, antioxidant capacity, and nutritional value of the tuberous roots. Transcriptome analyses revealed that several key genes associated with sucrose, chlorogenic acid, and amino acid biosynthesis were upregulated during short-term CS, including sucrose synthase, sucrose phosphate synthase, phenylalanine ammonia-lyase, 4-coumarate-CoA ligase, hydroxycinnamoyl-CoA quinate hydroxycinnamoyltransferase, serine hydroxymethyltransferase, alanine aminotransferase, arogenate dehydrogenase, and prephenate dehydratase. These results indicated that storage at 5 °C for 14 d could improve the nutritional quality and palatability of sweet potato tuberous roots without compromising their freshness.

Pharmacognostical and Phytochemical Evaluation of Aconitum heterophyllum Root

The present work aims to study the pharmacognostical and phytochemical characteristics of the roots of Aconitum heterophyllum. The study deals with the macroscopy, microscopy, powder analysis, physicochemical standardization, and preliminary phytochemical screening of Aconitum heterophyllum roots. Anatomical studies of the tuberous roots of Aconitum heterophyllum showed distinct endodermis, a wide zone of secondary phloem, and a ring of 4 to 9 vascular strands. The powder analysis revealed the presence of suberized cells of metaderm, reticulate xylem vessels, and starch grains. Physicochemical standardization such as moisture content, ash values, and extractive values of Aconitum heterophylluym was determined. For the identification of various chemical constituents, preliminary phytochemical screening was also studied.