Storage Roots Research Articles

Influence of exposure to light and storage period on color changes in gari produced from bio-fortified cassava (Manihot esculenta Crantz) varieties

Light degrades carotenoids and thus the color of bio-fortified gari during storage. This study was therefore conducted to evaluate the effect of exposure of bio-fortified gari to light during storage on its color. Gari samples obtained from the processing of fresh storage roots of three yellow root cassava varieties (TMSI011368, TMSI010593, and TMSI010539) and a white root variety (TMS30572) as check were packaged in three replicates in transparent white plastics containers (light condition) and blue plastics containers wrapped in black polythene bags (dark condition). These were stored on an open shelf in the laboratory in a 4 × 2 × 13 factorial experiment in a randomized complete block design. Immediately after processing and monthly for 12 months, the gari samples were evaluated for color using a scale of 1 (white) to 8 (pink). The result showed that yellowness of the gari from bio-fortified cassava varieties decreased over the storage period from 5.5 (TMS010539) immediately after processing to 2.5 (TMS010593, under both storage conditions) at 12 Months After Storage (MAS). The change was significantly (p < 0.05) influenced by variety, storage duration and storage condition. Gari from varieties TMSI011368 and TMSI010593 had the least (38.3%) and highest (50.2%) percentage reduction in yellowness, respectively at the end of the storage period (12 months). Across the storage period, the mean color of gari samples stored in the dark condition (3.37) was significantly higher than the mean color of gari samples exposed to light (3.22). Therefore, the proper selection of cassava variety and the use of packaging containers that screen light from bio-fortified gari during storage can best preserve its color and ensure the availability of a reasonable amount of carotenoids to consumers after long-term storage (12 months).

Quality characteristics of non‐gluten biscuit developed from optimized cream and orange‐fleshed sweetpotato flour

AbstractOrange‐fleshed sweetpotato (OFSP; Ipomoea batatas L.) is a new variety of sweetpotato widely accepted as a staple food in African countries due to its nutritional and health benefits. The aim of this study was to determine the quality characteristics of value added biscuit developed from optimized non‐gluten blends. King J orange‐fleshed sweetpotato (UMUSPO1), Mother's Delight orange‐fleshed sweetpotato (UMUSPO2) and cream‐fleshed sweetpotato were used. Sweetpotato storage roots were processed into flour and were incorporated with soy concentrate, date palm and sweetpotato starch. The blends were optimized using an experimental design of response surface methodology; the optimized blends were used to produce biscuits, and the biscuits were evaluated for total phenol, total flavonoid, ferric reducing antioxidant power (FRAP) and effective concentration (EC50), which is a concentration of the sample required to obtain a 50% antioxidant effect. The physical qualities and consumer acceptability of the developed and control biscuits were also assessed. The results obtained showed that the total phenolic values ranged from 2.32 to 12.54 mg GAE/g, total flavonoid values ranged from 1.11 to 12.20 mg QE/g, and FRAP values ranged from 4.38 to 22.54 mg AEE/g; EC50 of some antioxidant properties was observed to be less than (<) 2; the weight of the biscuit ranged between 4.50 and 5.59 g, diameter of the biscuit ranged between 5.30 and 6.70 cm, and the spread ratio ranged from 8.83 to 12.89. The sensory properties of the biscuit varied significantly (p < 0.05) with one another in terms of the aroma, appearance, crunchiness, taste and overall acceptability. This research showed that the optimized OFSP flour (OFSPK2) produced a good quality biscuit with the highest total phenolic, total flavonoid, and FRAP, and it exhibited good physical qualities. OFSPK2 biscuit had the highest score for its overall acceptability and compared favourably with the 100% wheat flour biscuit (control sample).

Identification of the key morphological sweetpotato weevil resistance predictors in Ugandan sweetpotato genotypes using correlation and path‐coefficient analysis

AbstractSweetpotato weevils (SPWs) can cause up to 100% yield losses in sweetpotato (Ipomoea batatas). Nevertheless, there has been limited success in breeding for SPW resistance globally. This is attributed partly to difficulty in screening for resistance because resistance to the SPW is complex and is mediated by several resistance indicators. Measuring all these resistance indicators is costly and time consuming. To enhance efficiency in selection for SPW resistance, there is need to profile and identify key resistance indicators. Potentially, this will better enable breeders to timely and precisely select for SPW resistance. The objective of this study was to identify the most efficient morphological resistance indicators against SPW. Thirty sweetpotato genotypes that varied in resistance to SPW comprising local collections, released varieties, and breeding lines were evaluated at three locations for two seasons in Uganda using an alpha lattice design. Data were collected on storage root yield, SPW root and stem damage, and weevil resistance indicators such as vine vigor (VV), ground cover (GC), vine weight (VW), storage root neck length (NL), latex content, cortex thickness (CT), and dry matter content (DM). Genotype means for all measured traits varied significantly except for CT. Negative relationships were observed between SPW root damage and GC, VW, CT, VV, NL, and DM. However, path coefficient analysis showed storage root NL (direct effect of −0.43, p < 0.001) as the most important morphological resistance indicator. Therefore, NL could be the most reliable predictor of resistance to SPW among breeding clones, especially at early breeding stages.

Modulation of anthocyanin accumulation in storage roots of sweetpotato by transcription factor IbMYB1-2 through direct binding to anthocyanin biosynthetic gene promoters

The storage roots of purple-fleshed sweetpotato rich in anthocyanins are considered nutrient-rich foods with health effects. However, the molecular mechanism underlying anthocyanin biosynthesis and regulation remains to be revealed. In this study, IbMYB1-2 was isolated from purple-fleshed sweetpotato “Xuzishu8”. The phylogenetic and sequence analysis indicated that IbMYB1-2 belongs to the SG6 subfamily with a conserved bHLH motif. Subcellular localization analysis and transcriptional activity assay revealed that IbMYB1-2 is a key transcriptional activator and is specific to the nucleus. Agrobacterium rhizogenes-mediated overexpression of IbMYB1-2 in sweetpotato through in vivo root transgenic system led to an increase in anthocyanins in the root of sweetpotato. qRT-PCR and transcriptome analysis depicted that the transcript levels of IbMYB1-2, IbbHLH42, and eight structural genes that are associated with the synthesis of anthocyanin were upregulated in overexpressed IbMYB1-2 transgenic roots. Dual-luciferase reporter (DLR) assay and yeast one-hybrid (Y1H) assay demonstrated IbMYB1-2 binding to the promoter regions of IbbHLH42 and other anthocyanin biosynthetic genes, including IbCHS, IbCHI, IbF3H, IbDFR, IbANS, IbGSTF12, IbUGT78D2, and IbUF3GT. Moreover, IbbHLH42 was shown to be an active enhancer for the formation of MYB-bHLH-WD40 (MBW) complex, which strongly supports the promoter activities of the IbCHS, IbANS, IbUGT78D2, and IbGSTF12 genes to induce anthocyanin accumulation. Taken together, our findings not only revealed the underlying regulatory molecular mechanism of IbMYB1-2 for anthocyanin accumulation in the storage roots of sweetpotato but also uncovered a potential mechanism by which IbbHLH42 modulated anthocyanin biosynthesis through a positive feedback regulatory loop.

Crop model determined mega-environments for cassava yield trials on paddy fields following rice

The Cropping System Model (CSM)-MANIHOT-Cassava provides the opportunity to determine target environments for cassava (Manihot esculenta Crantz) yield trials by simulating growth and yield data for various environments. The aim of this research was to investigate whether cassava production on paddy fields in Northeast, Thailand could be grouped into mega-environments using the model. Simulations for four different cassava genotypes grown on paddy field following rice harvest was conducted for various soil types and the weather data from 1988 to 2017. The genotype main effect plus genotype by environment interaction (GGE biplot) technique was used to group the mega-environments. The analyses of yearly data showed inconsistent results across years for environment grouping and for the winning genotypes of the individual environment group. An analysis using GGE biplot with the average value of the simulated storage root dry weight (SDW) for 30 years indicated that all 41 environments were grouped into two different mega-environments. This study demonstrated the ability of the CSM-MANIHOT-Cassava to help identify the mega-environments for cassava yield trials on paddy field during off-season of rice that could help reduce both time and resources.

Effect of L-Tryptophan and L-Glutamic Acid on Carrot Yield and Its Quality

Positively affecting crop quality and yields, amino acids used as plant stimulants play a special role in ensuring global food security. L-tryptophan (L-Try) and L-glutamic acid (L-Glu) are important biostimulants that increase the yield of field crops and vegetables. Carrot is one of the most important vegetables due to its production volume in the world (sixth most consumed vegetable) and its nutritional value. The response of different plant species to amino acid application varies. The literature mainly deals with the effects of ready-made products containing a mixture of several amino acids, with no exhaustive studies on the effects of individual amino acids on carrot quality and yield. This paper is based on a two-year field experiment (2019–2020), in which the effect of two amino acids, L-Trp (7.5 g·ha−1) and L-Glu (60.0 g·ha−1), on carrot (Daucus carota L.) was investigated. They were applied to the leaves (FA) or both to the soil and to the leaves (S + FA), separately, (L-Trp or L-Glu) or as a mixture (L-Trp + L-Glu). The control plot was treated with mineral fertilizers only. The research was conducted as a field experiment in a split-block design. The yield of carrot storage roots and their content of dry matter, protein, sugars, total soluble solids (TSS), and ascorbic acid were determined. The amino acids positively affected the yield of carrots compared to the control, but only the synergistic action of L-tryptophan and L-glutamic acid increased it significantly. On average, for both amino acids the S + FA application increased the protein content and the marketable yield of storage roots significantly more than in response to FA treatment. A significant increase in marketable yield compared to the control was found after the combined soil and foliar application (S + FA) of all amino acid combinations, but the L-Trp + L-Glu mixture worked best. The storage roots of carrots grown on the plot with L-Trp + L-Glu contained significantly more protein and TSS than those on the control plot. The content of TSS was also positively affected by L-Trp used on its own, while L-Glu increased the content of ascorbic acid. Amino acids applied to the leaves (FA) increased the content of total sugars in the carrot roots more than when applied both to the soil and to the leaves (S + FA). Of all treatment combinations, the synergistic action of L-Trp and L-Glu made it possible to obtain the highest yields of carrot storage roots, containing the most protein and total soluble solids.

Influence of flower bud removal on the growth and anti-inflammatory properties of Platycodon grandiflorus roots

Platycodon grandiflorus roots have been used as a popular food additive and traditional medicinal product because of their therapeutic effects. During cultivation of this crop, flower bud removal has been used to increase root yield. However, the underlying mechanisms by which flower bud removal increases the yield of P. grandiflorus roots are still unknown. In this study, to investigate the effect of flower bud removal, we analyzed the level of gibberellic acid 3 (GA3) production, anti-inflammatory properties, and polyphenolic compounds in P. grandiflorus roots. Flower bud removal led to reduced GA3 content, resulting in increased root yield. In addition, we found that the accumulation of polyphenolic compounds through induction of the phenylpropanoid pathway is presumably a positive effect of flower bud removal that improves the anti-inflammatory properties of P. grandiflorus roots. Our results revealed that flower bud removal is a promising strategy for improving yield and quality of storage roots by rebalancing the assimilate exchange between sink organs.

Cooking sweetpotato roots increases the in vitro bioaccessibility of phytochemicals and antioxidant activities, but not vitamin C

The percent bioaccessibility of phytochemicals and antioxidant activities (ABTS and FRAP) of cooked sweetpotato storage roots (peeled and unpeeled) of varying flesh colours was assessed in vitro. Generally, the phytochemicals’ bioaccessibility increased with cooking compared to the raw roots, except in vitamin C. The raw roots had vitamin C bioaccessibility of 92 %, while for cooked, it ranged between 61 % (baking) and 73 % (frying). For phenolics and flavonoids, peeling the roots significantly (P < 0.001) increased bioaccessibility by 11 % and 4 %, respectively. For the other phytochemicals, the bioaccessibility of peeled roots did not differ significantly (P > 0.05) from unpeeled ones. Cooked roots had higher antioxidant activities than in raw. Vitamin C may have acted as a pro-oxidant as it was the only phytochemical with inverse relation with antioxidant activities. Boiling, steaming, baking, frying, or microwaving sweetpotato roots increases the in vitro bioaccessibility of phytochemicals and antioxidant activities, but not vitamin C.

Mechanical Properties of Sugar Beet Roots under Impact Loading Conditions.

Root damages due to mechanical impacts result in deterioration in commercial sugar beet quality. In order to determine the mechanical characteristics of roots, a stand equipped with a pendulum enabling impact investigations of whole beets was used. The roots were stored in a monitored environment for up to 5 days (temperature 15 ± 2 °C, 40 ± 2%). During the tests, the beets were struck against a flat steel resistant surface with the velocities Vimp = 0.5, 1.0 and 1.5 m·s-1. The measurements of local root curvatures in three chosen impact areas and the deformation (dmax) allowed modelling of the volume of contact (CV) by means of the ellipsoid cap. These investigations enabled the determination of the relations between the maximal impact force, Fmax, the impact energy, Eimp, and the absorbed energy, Eabs, as well as the contact volume and impact velocity, taking into account the root storage time, St. It was found that the maximal impact force increased with increasing impact velocity and decreased with the storage time for each group of roots. With increasing velocity, there were also increases in the following: impact energy, absorbed energy, contact volume and maximal deformation, as well as absorbed energy, referred to as the mass Eabs-v from Vimp. The mean values of the stresses (σmax), being the quotients of the impact force (Fmax) and the surface area of the ellipsoid cap base (ABE), were 0.81-1.17 MPa, 1.064-1.59 MPa and 1.45-1.77 MPa for the velocities of 0.5, 1.0 and 1.5 m·s-1, respectively. It was confirmed that the statistical significance of the mentioned parameters changes depending on the impact velocity.

The transcription factor IbNAC29 positively regulates the carotenoid accumulation in sweet potato.

Carotenoid is a tetraterpene pigment beneficial for human health. Although the carotenoid biosynthesis pathway has been extensively studied in plants, relatively little is known about their regulation in sweet potato. Previously, we conducted the transcriptome database of differentially expressed genes between the sweet potato (Ipomoea batatas) cultivar 'Weiduoli' and its high-carotenoid mutant 'HVB-3'. In this study, we selected one of these candidate genes, IbNAC29, for subsequent analyses. IbNAC29 belongs to the plant-specific NAC (NAM, ATAF1/2, and CUC2) transcription factor family. Relative IbNAC29 mRNA level in the HVB-3 storage roots was ~1.71-fold higher than Weiduoli. Additional experiments showed that the contents of α-carotene, lutein, β-carotene, zeaxanthin, and capsanthin are obviously increased in the storage roots of transgenic sweet potato plants overexpressing IbNAC29. Moreover, the levels of carotenoid biosynthesis genes in transgenic plants were also up-regulated. Nevertheless, yeast one-hybrid assays indicated that IbNAC29 could not directly bind to the promoters of these carotenoid biosynthesis genes. Furthermore, the level of IbSGR1 was down-regulated, whose homologous genes in tomato can negatively regulate carotene accumulation. Yeast three-hybrid analysis revealed that the IbNAC29-IbMYB1R1-IbAITR5 could form a regulatory module. Yeast one-hybrid, electrophoretic mobility shift assay, quantitative PCR analysis of chromatin immunoprecipitation and dual-luciferase reporter assay showed that IbAITR5 directly binds to and inhibits the promoter activity of IbSGR1, up-regulating carotenoid biosynthesis gene IbPSY. Taken together, IbNAC29 is a potential candidate gene for the genetic improvement of nutritive value in sweet potato.

Biofortification to avoid malnutrition in humans in a changing climate: Enhancing micronutrient bioavailability in seed, tuber, and storage roots.

Malnutrition results in enormous socio-economic costs to the individual, their community, and the nation's economy. The evidence suggests an overall negative impact of climate change on the agricultural productivity and nutritional quality of food crops. Producing more food with better nutritional quality, which is feasible, should be prioritized in crop improvement programs. Biofortification refers to developing micronutrient -dense cultivars through crossbreeding or genetic engineering. This review provides updates on nutrient acquisition, transport, and storage in plant organs; the cross-talk between macro- and micronutrients transport and signaling; nutrient profiling and spatial and temporal distribution; the putative and functionally characterized genes/single-nucleotide polymorphisms associated with Fe, Zn, and β-carotene; and global efforts to breed nutrient-dense crops and map adoption of such crops globally. This article also includes an overview on the bioavailability, bioaccessibility, and bioactivity of nutrients as well as the molecular basis of nutrient transport and absorption in human. Over 400 minerals (Fe, Zn) and provitamin A-rich cultivars have been released in the Global South. Approximately 4.6 million households currently cultivate Zn-rich rice and wheat, while ~3 million households in sub-Saharan Africa and Latin America benefit from Fe-rich beans, and 2.6 million people in sub-Saharan Africa and Brazil eat provitamin A-rich cassava. Furthermore, nutrient profiles can be improved through genetic engineering in an agronomically acceptable genetic background. The development of "Golden Rice" and provitamin A-rich dessert bananas and subsequent transfer of this trait into locally adapted cultivars are evident, with no significant change in nutritional profile, except for the trait incorporated. A greater understanding of nutrient transport and absorption may lead to the development of diet therapy for the betterment of human health.

Reaction of introduced orange fleshed sweetpotato (Ipomoea batatas L.) genotypes for virus disease resistance and storage root yield performance under field conditions in Dilla and Hawassa, southern Ethiopia

Reaction of introduced orange fleshed sweetpotato (Ipomoea batatas L.) genotypes for virus disease resistance and storage root yield performance under field conditions in Dilla and Hawassa, southern Ethiopia

Macronutrient omission influences morphological parameters, growth, and yield in Arracacia xanthorrhiza Bancroft

Mineral nutrition in arracacha is a critical production factor that conditions harvest yield. Few studies have been developed in nutrition and physiology, this does not allow to the design of ideal fertilization programs; consequences are increased production costs, soil degradation, and low-quality storage roots. Therefore, this study aimed to characterize the symptoms associated with macronutrient deficiency in arracacha plants and its effect on morphological parameters, the accumulation of fresh and dry biomass, and the distribution of dry matter in the different organs. Under greenhouse conditions, the experiment was conducted in Cajamarca, Tolima, Colombia. A completely randomized design was implemented, with seven treatments and six replicates (6 solutions lacking N, P, K, Ca, Mg, and S and Hoagland complete solution). Forty-two seedlings were transplanted, to which the complete solution was applied for 75 days, increasing the concentrations from 0.25 M to 1 M, and then nutritional deficiencies were induced. Deficiencies caused by macronutrients in arracacha plants exhibited visual symptoms and changes in their morphology. The omission of N, Ca, and S generated the most severe symptoms, drastically affecting plant height, leaf width, number of leaves, and plant mass accumulation. In the case of P, leaves became small and intense green with a violet margin. The Mg and K generated leaves with interveinal and margin chlorosis. Plants with the omission of macronutrients allocated dry mass in the following order: stem, storage roots, propagules, and leaves.

A method for rapid and homogenous initiation of post-harvest physiological deterioration in cassava storage roots identifies Indonesian cultivars with improved shelf-life performance

Cassava is the most cultivated and consumed root crop in the world. One of the major constraints to the cassava value chain is the short shelf life of cassava storage roots which is primarily due to the so-called post-harvest physiological deterioration (PPD). The identification of natural sources of PPD tolerance represents a key approach to mitigating PPD losses by generating farmer- and industry-preferred cassava cultivars with prolonged shelf life. In the present study, a PPD assessment method was developed to screen for PPD tolerance in the cassava germplasm. The proposed PPD assessment method displayed a reduced rate of microbial infection and allowed a rapid and homogenous development of typical PPD symptoms in the cassava storage roots. We successfully used the PPD assessment method in combination with an image-based PPD scoring method to identify and characterize PPD tolerance in 28 cassava cultivars from the Indonesian cassava germplasm. Our analysis showed a significant and positive correlation between PPD score and dry matter content (r = 0.589–0.664, p-value < 0.001). Analysis of additional root parameters showed a significant and positive correlation between PPD scores at 2 days post-harvest (dph) and root length (r = 0.388, p-value < 0.05). Our analysis identified at least 4 cultivars displaying a significantly delayed onset of PPD symptoms as compared to the other selected cultivars. The availability of cassava cultivars contrasting for tolerance to PPD will be particularly instrumental to understanding the molecular mechanisms associated with delayed PPD in cassava roots.

Root Yield and Starch Synthase Type IV Gene Activity under Different Micro Nutrient Fertilizer and Harvest Ages on Cassava (Manihot esculenta Crantz)

Abstract The important part of cassava root is starch which is probably controlled by starch synthase type IV (SSIV) gene. The information of micro nutrient and harvest age related to the activity starch synthase type IV (SSIV) gene is still very rare. The objectives of this study were to evaluate root fresh weight of cassava, to compare yield of storage root, and to evaluate the activity of starch synthase type IV (SSIV) gene by real-time quantitative polymerase chain reaction (RT-PCR) applied by micro nutrient fertilizer. Treatments were arranged by factorial (3 × 3) in randomized complete block design (RCBD) with three replications used as block. The first factor was three different dosages of micro nutrient fertilizer as 0, 20, and 40 kg/ha. The second factor was harvest ages as 7, 8, and 10 months after planting (MAP). The micro nutrient fertilizer mainly contents of 5,888 ppm Fe and 1,368 ppm Zn. Variables were leaf number (LN), leaf fresh weight (LFW), leaf dry weight (LDW), stem fresh weight (SFW), stem dry weight (SDW), root fresh weight (RFW), root dry weight (RDW), skin root fresh weight (SRFW), skin root dry weight (SRDW), starch content, and activity of SSIV gene. The result showed that RDW of cassava applied by 40 kg micro nutrient/ha was significantly increased at 10 MAP. The increase in RDW was due to mainly high SSIV gene activity. Additionally, the SSIV gene activity caused by 20 kg micro nutrient/ha treatment showed almost as twice as those by 40 kg micro nutrient/ha. Keywords: Real-time PCR, Root dry weight, Root yield, Starch, Stem dry weight

Sweetpotato cultivars responses to interactive effects of warming, drought, and elevated carbon dioxide.

Plants are sensitive to changes projected in climates, such as elevated carbon dioxide (eCO2), high temperature (T), and drought stress (DS), which affect crop growth, development, and yield. These stresses, either alone or in combination, affect all aspects of sweetpotato plant growth and development, including storage root development and yield. We tested three sweetpotato cultivars (Beauregard, Hatteras, and LA1188) responses to eight treatments (Control, DS, T, eCO2, DS + T, T + eCO2, DS + eCO2, DS + T + eCO2). All treatments were imposed 36days after transplanting (DAP) and continued for 47days. Treatments substantially affected gas exchange, photosynthetic pigments, growth, and storage root components. Cultivars differed considerably for many of the measured parameters. The most significant negative impact of DS was recorded for the shoot and root weights. The combination of DS + T had a significant negative effect on storage root parameters. eCO2 alleviated some of the damaging effects of DS and high T in sweetpotato. For instance, eCO2 alone or combined with DS increased the storage root weights by 22% or 42% across all three cultivars, respectively. Based on the stress response index, cultivar "Hatteras" was most tolerant to individual and interactive stresses, and "LA 1188" was sensitive. Our findings suggest that eCO2 negates the negative impact of T or DS on the growth and yield of sweetpotato. We identified a set of individual and interactive stress-tolerant traits that can help select stress cultivars or breed new lines for future environments.

A sustainable approach for weed and insect management in sweetpotato: breeding for weed and insect tolerant/resistant clones

AbstractWeed management is consistently ranked among the top priorities of the United States sweetpotato industry. To provide additional weed and insect management strategies for sweetpotato, we initiated development of insect-resistant germplasm that also has weed tolerance by breeding and selecting for sweetpotato clones that are fast growing and have semi-erect to erect canopy architecture. Field studies were conducted in 2018 and 2019 in Charleston, South Carolina, to quantify the effects of weed-free interval and sweetpotato clone on weed counts for naturally occurring weed species, storage root yield, and insect resistance to the major pests of sweetpotato. Weed-free intervals included plots that were weedy all season and weed-free for 2, 3, and 4 wk after transplanting. Sweetpotato clones evaluated included ‘Beauregard’, ‘Covington’, ‘Monaco’, and six advanced selections with semi-erect to erect plant habit. Significant weed-free interval and sweetpotato clone main effects were observed for all variables measured, but not for their interaction. Two sweetpotato clones, USDA-17-037 and USDA-17-077, were consistent across both years and had the lowest weed counts, exhibited enhanced insect resistance, and were the highest yielding entries. These results demonstrate the potential for development of insect-resistant sweetpotato germplasm with a vigorous, erect plant habit that may be less susceptible to weed interference than cultivars with spreading shoot growth. The combination of germplasm that is both resistant to insect pests and competitive with weeds can provide organic and subsistence sweetpotato growers solutions to these critical issues related to sweetpotato production.

Potential toxicity of wild Ipomoea ingested by schoolchildren in remote Northeastern Thailand

Background: Natural plant toxins can cause food poisoning upon intentional or unintentional consumption of wild plants. Some toxic wild plants can be mistaken for edible species because of their morphological resemblance. This study examined a poisoning case report of schoolchildren who consumed a steamed tuberous root of wild Ipomoea, misidentified as I. mauritiana, and experienced gastrointestinal toxicity. Objectives: This study aimed to identify the tuberous root of wild Ipomoea using the internal transcribed spacer (ITS) region as a DNA barcode and characterize compounds obtained using gas chromatography-mass spectrometry (GC-MS). Materials and methods: DNA was extracted from fresh and cooked samples of the storage root. PCR amplification and DNA sequencing of the entire ITS region were performed. FastTree and maximum likelihood analyses were used to obtain phylogenetic trees of the Ipomoea species. Root extracts were prepared for GC-MS analysis, and potentially harmful phytochemicals responsible for poisonous plant exposure were predicted based on a well-established plant toxin database. Results: ITS phylogeny showed a close relationship between wild toxic Ipomoea and edible I. mauritiana. The chemometric profile obtained from GC-MS analysis of the root extracts revealed the presence of 31 phytochemicals. Among them, two putatively toxic compounds identified were β-amyrin and coumarin. Conclusion: Misidentification of the wild poisonous plant reported herein resulted in toxic plant ingestion. Although most poisonous plant exposures are not life threatening, measures should be taken to ensure the safety of the general public.

Characterization of a novel mutant with inhibition of storage root formation in sweet potato.

Sweet potato is a widely cultivated crop with storage roots. Although many studies have been conducted on the mechanism of its storage root formation, the details have not been fully elucidated. We screened mutant lines with inhibition of storage root formation to clarify parts of the mechanism. In this study, the process of storage root formation in one of the mutant lines, C20-8-1, was investigated. The inhibition of storage root formation was observed during the early stages of growth. The roots in C20-8-1 did not show histological differences compared to those in wild type. The transition from fibrous roots to pencil roots, which are the developmental stages prior to mature storage root formation, was delayed or inhibited in C20-8-1. The upregulation of starch biosynthesis-related genes and downregulation of lignin biosynthesis genes with storage root swelling were not confirmed in the root of C20-8-1 during the developmental transition stage, suggesting that most of the roots in C20-8-1 are in the pre-transition state toward the storage root swelling. C20-8-1 showed a mutant phenotype during the critical period of storage root swelling initiation, and further clarification of this mutation is expected to provide new insights into storage root formation.

Multi-year throughfall reduction enhanced the growth and non-structural carbohydrate storage of roots at the expenses of above-ground growth in a warm-temperate natural oak forest

The more frequent occurrence and severer drought events resulting from climate change are increasingly affecting the physiological performance of trees and ecosystem carbon sequestration in many regions of the world. However, our understanding of the mechanisms underlying the responses and adaption of forest trees to prolonged and multi-year drought is still limited. To address this problem, we conducted a long-term manipulative throughfall reduction (TFR, reduction of natural throughfall by 50%–70% during growing seasons) experiment in a natural oriental white oak (Quercus aliena var. acuteserrata Maxim.) forest under warm-temperate climate. After seven years of continuous TFR treatment, the aboveground growth in Q. aliena var. acuteserrata started to decline. Compared with the control plots, trees in the TFR treatment significantly reduced growth increments of stems (−14.2%) and leaf area index (−6.8%). The rate of net photosynthesis appeared to be more susceptible to changes in soil water in trees subjected to the TFR than in the control. The TFR-treated trees allocated significantly more photosynthates to belowground, leading to enhanced growth and nonstructural carbohydrates (NSC) storage in roots. The 7-year continuous TFR treatment increased the biomass, the production and the NSC concentration in the fine roots by 53.6%, 153.6% and 9.6%, respectively. There were clear trade-offs between the aboveground growth and the fine root biomass and NSC storage in Q. aliena var. acuteserrata trees in response to the multi-year TFR treatment. A negative correlation between the fine root NSC concentration and soil water suggested a strategy of preferential C storage over growth when soil water became deficient; the stored NSC during water limitation would then help promote root growth when drought stress is released. Our findings demonstrate the warm-temperate oak forest adopted a more conservative NSC use strategy in response to long-term drought stress, with enhanced root growth and NSC storage at the expenses of above-ground growth to mitigate climate change-induced drought.