Physiological and molecular characterization of drought responses and identification of candidate tolerance genes in cassava

Turyagyenda, Laban F.; Kizito, Elizabeth Balyejusa; Ferguson, Morag; Baguma, Yona; Agaba, Morris; Harvey, Jagger; Osiru, D.S.O.

doi:10.1093/aobpla/plt007

Cited by 66 publications

(52 citation statements)

References 55 publications

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“…Thus, it is important to characterize the various mechanisms displayed by cassava and develop tools that will allow selections to be easily made under certain specific mechanisms. In addition, most of the studies have been focused on understanding the plants reaction to physical stress such as moisture stress (Turyagyenda et al, 2013, Utsumi et al, 2012, moisture and cold stress (Zhang et al, 2010) and stress due to low soil water status (El-Sharkawy, 2007) under controlled conditions that are different from field conditions. There is, therefore, need to characterize the level and type of tolerance under field stress to allow for specific selections in particular environments.…”

Section: Introductionmentioning

confidence: 99%

Biochemical and secondary metabolites changes under moisture and temperature stress in cassava (Manihot esculenta Crantz)

Nuwamanya¹,

Rubaihayo²,

Mukasa³

et al. 2014

Afr. J. Biotechnol.

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Cassava's (Manihot esculenta Crantz) importance as a food security crop in Sub Saharan Africa is enhanced by its special traits such as tolerance to drought and high yields under drought stress. However, full understanding of tolerance mechanisms under hydrothermal stress in cassava is a key in developing highly tolerant varieties with increased yield. In our study, the effects of low soil moisture and increased temperature on cassava physiology were investigated. Twenty (20) cassava varieties were evaluated in a Randomized Complete Block Design in western Uganda. Hydrothermal stress was described as a period of no rainfall for a period of eight weeks leading to low soil moisture (contents between 28 to 35%) and average daily temperatures of ≥35°C. The average daily relative humidity during this period was considerably low (≤40%) further complementing already enhanced stress conditions. As such, the contents of important biochemicals and secondary metabolites in the plants were altered in a bid to counteract the effects of stress. Significant differences occurred in accumulation of main biochemicals such as soluble proteins (P<0.05), free reducing sugars (P<0.05) and bound reducing sugars (P<0.05) while reductions in the total starch yield by 70 to 100% of the original composition before stress were observed in all the test varieties. Changes in pigment properties were also observed with a decrease in the total carotenoid content (~65%) and chlorophyll a (Chla) (~40%) but no significant changes were observed for chlorophyll b (Chlb). Secondary metabolites such as phenolics and tannins too depicted varied but non-significant changes and they existed in low quantities. There were also significant changes in the phenotype (foliar portion of the plant) with at least two mechanisms of tolerance identified. The study showed the importance of carbohydrate and nitrogen cycle related metabolites in mediating tolerance in cassava by affecting their phenotypic expression in the plant.

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Section: Introductionmentioning

confidence: 99%

Biochemical and secondary metabolites changes under moisture and temperature stress in cassava (Manihot esculenta Crantz)

Nuwamanya¹,

Rubaihayo²,

Mukasa³

et al. 2014

Afr. J. Biotechnol.

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“…For cassava, a number of studies have been carried out to understand plant response to abiotic stresses such as moisture stress (Turyagyenda et al, 2013;Alves and Setter, 2004), soil salinity and related stresses (Okgbenin et al, 2010;Fregene and Setter, 2007), but still, the development of drought tolerant varieties remains a challenge. One way of solving challenges related to moisture and salinity stress susceptibility is the selec-tion of varieties that exhibit tolerance characteristics.…”

Section: Introductionmentioning

confidence: 99%

“…One way of solving challenges related to moisture and salinity stress susceptibility is the selec-tion of varieties that exhibit tolerance characteristics. Most of these characteristics are phenotypic in nature (Turyagyenda et al, 2013) and are related to leaf morphology and leaf response to light (Okgbenin et al, 2010). Light mediates a number of responses including leaf growth and development which are important factors in the deployment of stress tolerance mechanisms and manifestations such as the stay green trait.…”

Section: Introductionmentioning

confidence: 99%

Influence of spectral properties on cassava leaf development and metabolism

Nuwamanya¹,

Rubaihayo²,

Mukasa³

et al. 2014

Afr. J. Biotechnol.

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Cassava's importance as a food security crop in Sub Saharan Africa will be enhanced by its special traits such as tolerance to drought and high yields under hydrothermal stress. Some of the special traits which include the light reflective and absorptive properties of the leaves that depend on the surface characteristics of the leaves, are variety dependent and may influence the plants' reaction to light; hence, its photosynthetic capacity. We investigated the differences in the leaf spectral properties in different cassava varieties and related them to leaf biochemical properties using 20 cassava varieties established in a randomized complete block design in Kasese, western Uganda. Time dependent changes in leaf spectral characteristics were studied using Digimizer software and related to changes in sugar and pigment properties. Changes in the amount of reflected light were observed for the three main wavelengths used by plants (blue, green and red) with the blue being the most preferred. Total soluble free sugars exhibited a diurnal pattern from lower values (0.07 mg/g) after the dark period to higher values (0.313 mg/g) as the day progressed and was different from those of translocatable sugars such as sucrose. Chlorophyll a exhibited a curved pattern in all varieties increasing with increase in light intensity from 09:00 h (0.18 ug/g), peaking at 15:00 h (0.22 ug/g) and dropping down in concentration by 18:00 h (0.16 ug/g). Significant differences were observed in cassava varieties for the concentration of chlorophylls and carotenes. The results were obtained at a time of optimal growth conditions (four months after planting) and were used to classify these varieties into three broad groups showing that studies on spectral properties of leaves can still give a lot of insights in selection for stress tolerance under less optimal stress. The significant changes observed in the phenotype especially the foliar portion of the plant with the stay green and early recovering mechanisms of tolerance identified also tarried well with observed spectral differences. The results show that studies on plant spectral properties can be important in making inferences on the plants physiological and growth status.

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“…In most cassava growing regions of the world, the cassava growth cycle is typically interrupted by months of drought, influencing various plant physiological processes and resulting in depressed growth, development and yield [43,44]. Although cassava is a drought tolerant crop, there is a range of drought-tolerance levels in available germplasm.…”

Section: Tolerance To Droughtmentioning

confidence: 99%

Recent Biotechnological Advances in the Improvement of Cassava

Fondong¹,

Rey²

2018

Cassava

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Cassava (Manihot esculenta Crantz) is the fourth most important source of carbohydrates for human consumption in the tropics and thus occupies a uniquely important position as a food security crop for smallholder farmers. Consequently, cassava improvement is of high priority to most national agricultural research institutions in the tropics. With advances in functional genomics and genome editing approaches in this post genomics era, there are unprecedented opportunities and potential to accelerate the improvement of this important crop. These new technologies will need to be directed toward addressing major cassava production constraints, notably virus resistance, protein content, tolerance to drought and reduction of hydrogen cyanide content. Here, we discuss the important role novel functional genomics and genome editing technologies have and will continue to play in cassava improvement efforts. These approaches, including artificial miRNA (amiRNA), trans-acting small interfering RNA (tasiRNA), clustered regularly interspaced short palindromic repeat (CRISPR)-associated protein 9 (Cas9), and Targeting Induced Local Lesions IN Genomes (TILLING), have been shown to be effective in addressing major crop production constraints. In addition to reviewing specific applications of these technologies in cassava improvement, this chapter discusses specific examples being deployed in the amelioration of cassava or of other crops that could be applied to cassava in future.

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Physiological and molecular characterization of drought responses and identification of candidate tolerance genes in cassava

Cited by 66 publications

References 55 publications

Biochemical and secondary metabolites changes under moisture and temperature stress in cassava (Manihot esculenta Crantz)

Biochemical and secondary metabolites changes under moisture and temperature stress in cassava (Manihot esculenta Crantz)

Influence of spectral properties on cassava leaf development and metabolism

Recent Biotechnological Advances in the Improvement of Cassava

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