Effects of Variety and Growing Location on Physicochemical Properties of Starch from Sweet Potato Root Tuber

Three sweet potato varieties with purple-, yellow-, and white-fleshed root tubers were planted in four growing locations. Starches were isolated from their root tubers, their physicochemical properties (size, iodine absorption, amylose content, crystalline structure, ordered degree, lamellar thickness, swelling power, water solubility, and pasting, thermal and digestion properties) were determined to investigate the effects of variety and growing location on starch properties in sweet potato. The results showed that granule size (D[4,3]) ranged from 12.1 to 18.2 μm, the iodine absorption parameters varied from 0.260 to 0.361 for OD620, from 0.243 to 0.326 for OD680 and from 1.128 to 1.252 for OD620/550, and amylose content varied from 16.4% to 21.2% among starches from three varieties and four growing locations. Starches exhibited C-type X-ray diffraction patterns, and had ordered degrees from 0.634 to 0.726 and lamellar thicknesses from 9.72 to 10.21 nm. Starches had significantly different swelling powers, water solubilities, pasting viscosities, and thermal properties. Native starches had rapidly digestible starch (RDS) from 2.2% to 10.9% and resistant starch (RS) from 58.2% to 89.1%, and gelatinized starches had RDS from 70.5% to 81.4% and RS from 10.8% to 23.3%. Two-way ANOVA analysis showed that starch physicochemical properties were affected significantly by variety, growing location, and their interaction in sweet potato.

Comparative Transcriptome Sequencing of Taro Corm Development With a Focus on the Starch and Sucrose Metabolism Pathway

Taro (Colocasia esculenta) is an important tuber crop and staple food. Taro corms have higher nutritional value and starch contents as compared to most of the other root/tuber crops. However, the growth and development of the taro rhizome have not been critically examined in terms of transcriptomic signatures in general or specific to carbohydrates (starch and sucrose) accumulation. In current study, we have conducted a comprehensive survey of transcripts in taro corms aged 1, 2, 3, 4, 5, and 8 months. In this context, we have employed a whole transcriptome sequencing approach for identification of mRNAs, CircRNAs, and miRNAs in corms and performed functional enrichment analysis of the screened differentially expressed RNAs. A total of 11,203 mRNAs, 245 CircRNAs, and 299 miRNAs were obtained from six developmental stages. The mRNAs included 139 DEGs associated with 24 important enzymes of starch and sucrose metabolism. The expression of genes encoding key enzymes of starch and sucrose metabolism pathway (GBSS, AGPase, UGPase, SP, SSS, βFRUCT and SuSy) demonstrated significant variations at the stage of 4 months (S4). A total of 191 CircRNAs were differentially expressed between the studied comparisons of growth stages and 99 of these were associated with those miRNA (or target genes) that were enriched in starch and sucrose metabolism pathway. We also identified 205 miRNAs including 46 miRNAs targeting DEGs enriched in starch and sucrose biosynthesis pathway. The results of current study provide valuable resources for future exploration of the molecular mechanisms involved in the starch properties of Taro.

Application of Optimal Combined Microfertilizers of Boron, Molybdenum, and Copper Improves Root Tuber Yield Trait and Photosynthetic Response Characteristics in Pseudostellaria heterophylla

In the actual cultivation process, blind fertilizer application was widespread, resulting in a serious decline in the yield of Pseudostellaria heterophylla. We used the 3414 fertilizer experiment design to study the effects of combined Boron (B), Molybdenum (Mo), and Copper (Cu) on the growth indexes, diurnal changes of photosynthesis, and rapid fluorescence induction dynamics in P. heterophylla. Our results show that the optimal combination of B, Mo, and Cu simultaneously promoted the growth of underground and aboveground parts, and significantly improved the quality of single root tuber and yield per unit area. The best combination was treatment 9 (T9 = B, 1 g/L; Mo, 0.08 g/L; Cu, 0.05 g/L), and resulted in a 35.1% increase in yield per unit area compared with the control group (T1). Although the optimal combined application of microfertilizers did not change the bimodal trend of diurnal variation of photosynthesis, it effectively increased the daily average, peak, and valley values of the photosynthetic rate by alleviating the nonstomatal limitation and the photosynthetic midday depression. Pseudostellaria heterophylla leaves showed greater photochemical activity and less photoinhibition of photosystem II in T9. Major effects were that it helped protect the activity of the oxygen-evolving complex to reduce the oxidative damage of chloroplasts and prevent the dissociation of thylakoid. The microfertilizer application also enhanced the electron receiving ability of the QB and plastoquinone (PQ) electronic pools, thereby increasing the ability of electron transfer from QA to QB. The number of reaction centers per unit area was promoted notably by the fertilization treatment.

Qualitative and quantitative phytochemical composition, antimicrobial activity, and brine shrimp cytotoxicity of different solvent extracts of Acanthus polystachyus, Keetia gueinzii, and Rhynchosia elegans

Background The root, root bark, and root tubers of Acanthus polystachyus, Keetia gueinzii, and Rhynchosia elegans are used for managing bacterial and fungal infections among the Luo community of Kisumu East Sub County in Kenya. However, data on the efficacy of these plants against common bacterial and fungal pathogens is not available. The safety of these plants is also not known. This study aimed to investigate the phytochemical composition, antimicrobial properties, and safety of different solvent extracts of the roots, root barks, and root tubers of Acanthus polystachyus, Keetia gueinzii, and Rhynchosia elegans. The broth microdilution method evaluated the antimicrobial activities of the root, root bark, and root tuber extracts (water, acetone, and methanol) of Acanthus polystachyus, Keetia gueinzii, and Rhynchosia elegans. Gram-positive (Bacillus cereus, Staphylococcus aureus), gram-negative (Escherichia coli), and fungal (Candida albicans) microorganisms were used in the evaluation. The safety of the extracts was evaluated in Artemia salina. The phytochemical composition of the extracts was determined using qualitative and quantitative assays. Results In general, the extracts of Acanthus polystachyus, Keetia gueinzii, and Rhynchosia elegans displayed poor antimicrobial properties relative to conventional antimicrobial agents including Amoxicillin, Gentamicin, and Nystatin. The aqueous extract of Acanthus polystachyus and the aqueous, acetone, and methanol extracts of Keetia gueinzii were safe in Artemia salina but all other extracts were cytotoxic to Artemia salina. Conclusions These findings suggest that the use of the roots, root barks, and root tubers of Acanthus polystachyus, Keetia gueinzii, and Rhynchosia elegans is limited by poor antimicrobial efficacy and cytotoxicity.

An Overview of the Ethnobotanic, Ethnopharmacological and Medicinal Importance of Edible Wild Root Tuber Orchids in Cameroon

Orchids are well known for their beautiful exotic flowers, and food-flavoring products which make them a resource of great economic importance in the global horticultural and food industries. In Cameroon, orchids are particularly important for their tubers which are used for food and traditional medicine. Orchids are therefore of considerable economic importance, traded within and across the regions and out of the country. Few research works have reported for these orchids in Cameroon exploring mostly identification and taxonomy. It is therefore the responsibility and duty of the local population to valorize the tubers for national use based on their awareness of the hidden potentials for food and medicine. Many people will have eaten orchids without realizing, due to the countless products in international trade that contain the seeds of artificially propagated Vanilla orchids. However, this legal trade is only one example of orchids being used as ingredients in food and drink. One example is the trade in chikanda, a cake made from the ground tubers of terrestrial orchids and consumed in several countries in Central and East Africa. Another product made from the ground tubers of terrestrial species is salep, which is used as an ingredient in hot drinks and ice cream and consumed mainly in Turkey and neighboring countries. The high exploitation with no biodiversity and conservation strategic plan by indigenes is a call for concern about the sustainability as future existence of these wild edible orchids is highly threatened; reason why orchids are on the international red list. This paper reviews the ethnobotanical and medicinal uses of orchid roots and tubers with a focus on Cameroon. The review highlights some of the areas that require more focus in terms of research and policy interventions, namely identification of all edible orchids, domestication of edible orchids, and trade controls. Focusing on Cameroon, this paper reviews and examines the edible root and tuber orchids developments based on information from some of the work that has been done in Cameroon, the ethnobotanic, ethnopharmacological and medicinal uses of these orchids.

ROS and Oxidative Response Systems in Plants Under Biotic and Abiotic Stresses: Revisiting the Crucial Role of Phosphite Triggered Plants Defense Response

Phosphite (Phi) is a chemical analog of orthophosphate [HPO43−]. It is a systemic pesticide generally known to control the prevalence of oomycetes and soil-borne diseases such as Phytophthora, Pythium, and Plasmopora species. Phi can also control disease symptoms and the spread of pathogenic bacteria, fungi, and nematodes. Phi plays critical roles as a fungicide, pesticide, fertilizer, or biostimulator. Overall, Phi can alleviate the severity of the disease caused by oomycete, fungi, pathogenic bacteria, and nematodes (leave, stem, fruit, tuber, and root) in various plants (vegetables, fruits, crops, root/tuber crops, ornamental plants, and forests). Advance research in molecular, physiological, and biochemical approaches has approved the key role of Phi in enhancing crop growth, quantity, and quality of several plant species. Phi is chemically similar to orthophosphate, and inside the cells, it is likely to get involved in different features of phosphate metabolism in both plants and pathogens. In plants, a range of physiobiochemical alterations are induced by plant pathogen stress, which causes lowered photosynthesis activities, enzymatic activities, increased accumulation of reactive oxygen species (ROS), and modification in a large group of genes. To date, several attempts have been made to study plant-pathogen interactions with the intent to minimize the loss of crop productivity. Phi’s emerging function as a biostimulant in plants has boost plant yield and tolerance against various stress factors. This review discusses Phi-mediated biostimulant effects against biotic and abiotic stresses.

Biology, Taxonomy, and Management of the Root-Knot Nematode (Meloidogyne incognita) in Sweet Potato

Sweet potato is the seventh-ranked food crop produced after wheat, rice, maize, potato, barley, and cassava in the world. It is the most important root tuber crop in temperate, subtropical, and tropical areas of the world. It is grown for food, income-generating, and jobs for farmers and retailers. The important nutritional substances of sweet potatoes are ß-carotene and anthocyanins. However, the production and its valuable products are limited due to root-knot nematode parasitism. One of the most important destructive species of root-knot nematode to this crop is Meloidogyne incognita. The most destructive stage to sweet potato is at its second juvenile stage (J2). At this stage, it invades the roots and tubers of sweet potato highly in warm sandy soil conditions. It is an obligate plant-parasitic nematode. M. incognita caused significant yield loss to sweet potato in terms of quality, quantity, disturbing the process of photosynthesis and nutrient uptake through the formation of galling, establishing of its feeding sites, or induced galls that contain giant-feeding cells, and cracking of tubers and roots directly. It also reduces the market values of the infected tuber of sweet potato by downgrading the production values. The problem of quality and quantity losses to sweet potato by this pest is one of the major problems nowadays. It caused this problem alone or interaction with other plant-parasitic pathogens or through synergistic of fungi, bacteria, viruses, and others. Therefore, this review paper is focused on the sweet potato M. incognita biology, taxonomy, geographical distribution, and management measures.

Stimulatory Effect of Fe3O4 Nanoparticles on the Growth and Yield of Pseudostellaria heterophylla via Improved Photosynthetic Performance

Nanomaterials have recently been used as growth stimulants to promote the production of crops in saline-alkali through root application. However, if applied through leaves, little is known about the effect of Fe3O4 nanoparticles (NPs) on the root growth and yield, especially for medicinal crops. To fill this gap, a single factor experiment was conducted to explore the effects of Fe3O4 NPs on growth, yield, the dry matter distribution, chlorophyll content, photosynthetic characteristics, chlorophyll fluorescence parameters, and polysaccharide content of Pseudostellaria heterophylla by foliar spraying under field conditions. Fe3O4 NPs (20–50 mg·L–1) significantly promoted growth, the dry matter distribution of root and root tuber yield per unit area. Fe3O4 NPs enhanced net photosynthetic rate (Pn) by increasing chlorophyll content. And Fe3O4 NPs increased the daily mean and peak value of Pn, and alleviated the phenomenon of “midday depression” by improving nonstomatal limitation. Chlorophyll fluorescence parameters indicating that Fe3O4 NPs promoted the photochemical activity of PSII and alleviated photoinhibition by enhancing the photochemical use of excess excitation energy. Gray correlation analysis showed that Fe3O4 NPs enhanced the adaptability of P. heterophylla photosynthesis to high temperatures and strong light. Of note, Fe3O4 NPs enhanced the polysaccharide content of the root tuber. Phytotoxic effect was recorded at high NPs (100 mg·L–1) doses. Collectively, Fe3O4 NPs could promote performance of P. heterophylla by improving photosynthetic performance, enhancing its adaptability to the environment, and increasing the distribution ratio of photosynthates to the underground part.