Dataset Information

Characterising shoot and root system trait variability and contribution to genotypic variability in juvenile cassava (Manihot esculenta Crantz) plants.

ABSTRACT: The development of cassava genotypes with root system traits that increase soil resource acquisition could increase yields on infertile soils but there are relatively few work that has quantified cassava root system architecture (RSA). We used an easily adaptable and inexpensive protocol to: (i) measure genotypic variation for RSA and shoot traits of a range of cassava genotypes; and (ii) identify candidate variables that contribute the largest share of variance. Cassava genotypes were grown in soil-filled pots, maintained at 70% field capacity. Shoot and RSA traits were measured on plants grown up to 30, 45 and 60 days. Multivariate analysis was used to determine major traits contributing to variation. The study showed that cassava roots are adventitious in origin consisting of a main root axis and orders of lateral roots, and therefore the historically used term "fibrous roots" are redundant currently not contributing to clarity. There were significant differences (P < 0.05) for traits evaluated. The highest relative root growth rate occurred over the first 30 days and ranged from 0.39 to 0.48 cm day-1. Root fresh weight was significantly correlated with other traits, including root length (r = 0.79), leaf area (r = 0.72), number of lower nodal roots (r = 0.60), indicating that direct selection based on these traits might be sufficient to improve root biomass. Up to the first six principal components explained over 80% of the total variation among the genotypes for the traits measured at 30, 45 and 60 days. Leaf area, root diameter and branching density-related traits were the most important traits contributing to variation. Selection of cassava genotypes based on shoot and root biomass, root diameter and branching density at juvenile growth stage could be successful predictors of nutrient and water-use efficiency in the field. Further studies are required to relate studied juvenile cassava root traits with the performance of field-grown-mature plant with regard to drought, nutrient-use efficiency and yield.

SUBMITTER: Adu MO

PROVIDER: S-EPMC6039752 | biostudies-literature | 2018 Jun

REPOSITORIES: biostudies-literature

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Characterising shoot and root system trait variability and contribution to genotypic variability in juvenile cassava (<i>Manihot esculenta</i> Crantz) plants.

Adu Michael Osei MO Asare Paul Agu PA Asare-Bediako Elvis E Amenorpe Godwin G Ackah Frank Kwekucher FK Afutu Emmanuel E Amoah Mishael Nyarko MN Yawson David Oscar DO

Heliyon 20180628 6

The development of cassava genotypes with root system traits that increase soil resource acquisition could increase yields on infertile soils but there are relatively few work that has quantified cassava root system architecture (RSA). We used an easily adaptable and inexpensive protocol to: (i) measure genotypic variation for RSA and shoot traits of a range of cassava genotypes; and (ii) identify candidate variables that contribute the largest share of variance. Cassava genotypes were grown in ...[more]

PMID: 30003159

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Project description:Cassava is an important source of food security and livelihoods for millions of consumers daily. Water deficit conditions are one of the major factors that affect the development of root system architecture (RSA) and consequently, crop productivity, and yet, due to its long maturity periods and bulky storage root systems, RSA studies in cassava are uncommon. The objective of this study was to identify traits that are responsible for the variability and plastic responses of cassava in response to drought at the juvenile stage of growth. Eight cassava genotypes were grown in soil-filled pots under well-watered and droughted conditions for up to 45 days and multivariate analyses employed to determine the major contributory traits to variability and the relative distance plasticity index (RDPI) was computed to evaluate plasticity. There were significant genotypic variations for most of the traits measured. Drought generally inhibited root production and development and the degree of inhibition was between 2 and 22%. Regardless of the soil moisture condition, traits which differentiated the RSA included root biomass, root numbers, root branching density, and total root length, and these were also the important contributory traits to variability under well-watered soil conditions. Important contributory traits to variability traits under drought were shoot-related traits such as leaf area and shoot biomass, and also root system traits such as nodal root number, root biomass, diameter and branching density. Phenotypic plasticity was found in most traits where the number, branching density and diameter of upper nodal roots presented the highest RDPI. These traits corresponded with the traits contributing greatly to variation. Plastic responses of cassava to drought were dependent on trait and genotype. It is concluded that upper nodal roots-related traits could have importance in breeding cassava to better tolerate water deficit conditions. The secondary growth and ability to maintain or increase the upper nodal root count or density under limited soil moisture may be related to good growth and yield performance of cassava under drought conditions. Upper nodal roots could be used to screen and select cassava genotypes adapted to drought at the juvenile stage but as a potential indirect selection strategy, the persistence and pertinence of these traits and their relationship with yield and yield components under drought conditions in the field must be confirmed.

Project description:Cassava is the 6th most important source of dietary energy in the world but its root system architecture (RSA) had seldom been quantified. Ability to select superior genotypes at juvenile stages can significantly reduce the cost and time for breeding to bridge the large yield gap. This study adopted a simple approach to phenotyping RSA traits of juvenile and mature cassava plants to identify genotypic differences and the relationships between juvenile traits and harvest index of mature plants. Root classes were categorised and root and shoot traits of eight (8) juvenile pot-grown cassava genotypes, were measured at 30 and 45 days after planting (DAP). The same or related traits were measured at 7 months after planting of the same genotypes grown in the field while yield and yield components were measured in 12-months old field-grown plants. The field experiment was done in 2017 and repeated in 2018. Differences between genotypes for the measured traits were explored using analysis of variance (ANOVA) while traits in juvenile plants were correlated or regressed onto traits measured in 7- and 12-months old plants. The results show significant genotypic variations for most of the traits measured in both juvenile and 7-months old plants. In the 12-months old plants, differences between genotypes were consistent for both 2017 and 2018. Broad-sense heritability was highest for the number of commercial roots (0.87) and shoot fresh weight (0.78) and intermediate for the total number of roots (0.60), harvest index (0.58), fresh weight of roots (0.45). For all the sampling time points or growth stages, there were greater correlations between traits measured at a particular growth stage than between the same traits at different growth stages. However, some juvenile-mature plant trait relationships were significant, positive and consistent for both 2017 and 2018. For example, total root length and the total number of roots in 30 DAP, and branching density of upper nodal roots in 45 DAP, positively correlated with harvest index of 12-months old plants in both 2017 and 2018. Similarly, the diameter of nodal roots, for example, had a negative, significant correlation with fresh shoot biomass of mature plants in both 2017 and 2018. Regression of traits measured in 30 DAP explained up to 22% and 36% of the variation in HI of mature plants in 2017 and 2018, respectively. It is concluded that the simple, rapid, inexpensive phenotyping approach adopted in this study is robust for identifying genotypic variations in juvenile cassava using root system traits. Also, the results provide seminal evidence for the existence of useful relationships between traits of juvenile and mature cassava plants that can be explored to predict yield and yield components.

Project description:External application of acetic acid has been recently reported to enhance the survival to drought in plants such as Arabidopsis, rapeseed, maize, rice and wheat, but the effects of acetic acid application on increased drought tolerance in woody plants such as a tropical crop “cassava” remain elusive. A molecular understanding of acetic acid-induced drought avoidance in cassava will contribute to the development of technology that can be used to enhance drought tolerance without resorting to transgenic technology or advancements in cassava cultivation. In the present study, morphological, physiological and molecular responses to drought were analyzed in cassava after the treatment with acetic acid. Results indicated that the acetic acid-treated cassava plants had a higher level of drought avoidance than water-treated, control plants. Specifically, higher leaf relative water content, and chlorophyll and carotenoid levels were observed as soils dried out during the drought treatment. Leaf temperatures in acetic acid-treated cassava plants were higher relative to leaves on plants pretreated with water and the increase of ABA content was observed in leaves of acetic acid-treated plants, suggesting that stomatal conductance and the transpiration rate in leaves of acetic acid-treated plants decreased to maintain relative water contents and avoid drought. Transcriptome analysis revealed that the acetic acid treatment increased the expression of ABA signaling-related genes, such as OPEN STOMATA 1　(OST1) and protein phosphatase 2C; as well as drought response and tolerance-related genes, such as outer membrane tryptophan-rich sensory protein (TSPO), and heat shock proteins. Collectively, the external application of acetic acid enhances drought avoidance in cassava through the upregulation of ABA signaling pathway genes and several stress response- and tolerance-related genes. These data support the idea that adjustments of the acetic acid application to plants is useful to enhance drought tolerance in order to minimize the growth inhibition in the agricultural field.

Project description:BACKGROUND:Proteomics is increasingly becoming an important tool for the study of many different aspects of plant functions, such as investigating the molecular processes underlying in plant physiology, development, differentiation and their interaction with the environments. To investigate the cassava (Manihot esculenta Crantz) proteome, we extracted proteins from somatic embryos, plantlets and tuberous roots of cultivar SC8 and separated them by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). RESULTS:Analysis by liquid chromatography-electrospray ionisation-tandem mass spectrometry (LC-ESI-MS/MS) yielded a total of 383 proteins including isoforms, classified into 14 functional groups. The majority of these were carbohydrate and energy metabolism associated proteins (27.2%), followed by those involved in protein biosynthesis (14.4%). Subsequent analysis has revealed that 54, 59, 74 and 102 identified proteins are unique to the somatic embryos, shoots, adventitious roots and tuberous roots, respectively. Some of these proteins may serve as signatures for the physiological and developmental stages of somatic embryos, shoots, adventitious roots and tuberous root. Western blotting results have shown high expression levels of Rubisco in shoots and its absence in the somatic embryos. In addition, high-level expression of alpha-tubulin was found in tuberous roots, and a low-level one in somatic embryos. This extensive study effectively provides a huge data set of dynamic protein-related information to better understand the molecular basis underlying cassava growth, development, and physiological functions. CONCLUSION:This work paves the way towards a comprehensive, system-wide analysis of the cassava. Integration with transcriptomics, metabolomics and other large scale "-omics" data with systems biology approaches can open new avenues towards engineering cassava to enhance yields, improve nutritional value and overcome the problem of post-harvest physiological deterioration.

Project description:The external application of acetic acid has recently been reported to enhance survival of drought in plants such as Arabidopsis, rapeseed, maize, rice, and wheat, but the effects of acetic acid application on increased drought tolerance in woody plants such as a tropical crop "cassava" remain elusive. A molecular understanding of acetic acid-induced drought avoidance in cassava will contribute to the development of technology that can be used to enhance drought tolerance, without resorting to transgenic technology or advancements in cassava cultivation. In the present study, morphological, physiological, and molecular responses to drought were analyzed in cassava after treatment with acetic acid. Results indicated that the acetic acid-treated cassava plants had a higher level of drought avoidance than water-treated, control plants. Specifically, higher leaf relative water content, and chlorophyll and carotenoid levels were observed as soils dried out during the drought treatment. Leaf temperatures in acetic acid-treated cassava plants were higher relative to leaves on plants pretreated with water and an increase of ABA content was observed in leaves of acetic acid-treated plants, suggesting that stomatal conductance and the transpiration rate in leaves of acetic acid-treated plants decreased to maintain relative water contents and to avoid drought. Transcriptome analysis revealed that acetic acid treatment increased the expression of ABA signaling-related genes, such as OPEN STOMATA 1 (OST1) and protein phosphatase 2C; as well as the drought response and tolerance-related genes, such as the outer membrane tryptophan-rich sensory protein (TSPO), and the heat shock proteins. Collectively, the external application of acetic acid enhances drought avoidance in cassava through the upregulation of ABA signaling pathway genes and several stress responses- and tolerance-related genes. These data support the idea that adjustments of the acetic acid application to plants is useful to enhance drought tolerance, to minimize the growth inhibition in the agricultural field.

Project description:The mealybug, Phenacoccus manihoti, is a leading pest of cassava (Manihot esculenta Crantz), damaging this crop globally. Although the biological control of this mealybug using natural predators has been established, resistance breeding remains an important means of control. Understanding plant responses to insect herbivory, by determining and identifying differentially expressed genes (DEGs), is a vital step towards the understanding of molecular mechanisms of defence responses in plants and the development of resistant cultivars by gene editing. Morphological and molecular analysis confirmed the mealybug identity as Phenacoccus manihoti (Matile-Ferrero). The transcriptome response of the green mite resistant cassava genotype AR23.1 was compared to P40/1 with no known resistance at 24 and 72 hours of mealybug infestation compared to non-infested mock. A total of 301 and 206 genes were differentially expressed at 24 and 72 of mealybug infestation for AR23.1 and P40/1 genotypes respectively, using a log2 fold change and P-value ? 0.05. Gene ontology functional classification revealed an enrichment of genes in the secondary metabolic process category in AR23.1 in comparison with P40/1, while genes in the regulation of molecular function, cellular component biogenesis and electron carrier categories were more significantly enriched in P40/1 than in AR23.1. Biological pathway analysis, based on KEGG, revealed a significant enrichment of plant-pathogen interaction and plant hormonal signal transduction pathways for a cohort of up-regulated and down-regulated DEGs in both genotypes. Defence-related genes such as 2-oxogluterate, gibberellin oxidase and terpene synthase proteins were only induced in genotype AR23.1 and not in P40/1, and subsequently validated by RT-qPCR. The study revealed a difference in response to mealybug infestation in the two genotypes studied, with AR23.1 showing a higher number of differentially expressed transcripts post mealybug infestation at 24 and 72 hours. Candidate defence-related genes that were overexpressed in the AR23.1 genotype post mealybug infestation will be useful in future functional studies towards the control of mealybugs.

Dataset Information

Characterising shoot and root system trait variability and contribution to genotypic variability in juvenile cassava (Manihot esculenta Crantz) plants.

Publications

Characterising shoot and root system trait variability and contribution to genotypic variability in juvenile cassava (<i>Manihot esculenta</i> Crantz) plants.

Similar Datasets

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