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Biofortification of Cassava

Almqvist, Linnea LU (2018) KBKM05 20181
Pure and Applied Biochemistry
Computational Chemistry
Abstract
Cassava, Manihot esculenta, is the third most important staple crop in tropical re-
gions. Cassava is a fibrous root that is tolerant to drought and has a flexible harvest
period making it a reliable crop under poorer farming conditions (FAO, 2008). The
content of provitamin A, also known as β-carotene, is unfortunately low in cassava
even though there are varieties bred for a higher content. Since vitamin A deficiency,
VAD, is a large problem of the regions where cassava is of major importance for calo-
rie intake, an increase of the β-carotene content would be of great interest to address
malnutrition.
The main idea of this project is to increase the amount of β-carotene accumulated
in the cassava root. This is accomplished by... (More)
Cassava, Manihot esculenta, is the third most important staple crop in tropical re-
gions. Cassava is a fibrous root that is tolerant to drought and has a flexible harvest
period making it a reliable crop under poorer farming conditions (FAO, 2008). The
content of provitamin A, also known as β-carotene, is unfortunately low in cassava
even though there are varieties bred for a higher content. Since vitamin A deficiency,
VAD, is a large problem of the regions where cassava is of major importance for calo-
rie intake, an increase of the β-carotene content would be of great interest to address
malnutrition.
The main idea of this project is to increase the amount of β-carotene accumulated
in the cassava root. This is accomplished by using the knowledge of the cassava
genome and the carotenoid pathway, in order to block specific enzymes through
genome editing techniques . The trials will though take many years and this Master
Thesis will cover only a fragment of the entire project. Cassava needs to grow in the
field for at least nine months, which will create a long time frame to consider. After
creating genetic constructs and transforming the cassava plants, the carotenoid and
starch content will be analysed.
Methods for analysing starch and carotenoids for cassava were developed during
this Master Thesis by literature research and laboratory trials. (Less)
Popular Abstract
At the Swedish University of Agricultural Sciences, SLU, in Alnarp, Erik Alexan-
dersson is leading a project that focuses on biofortification of cassava. Cassava is a
staple crop grown in tropical regions and serves as the third most important source
of calorie intake in these regions (FAO, 2008). Cassava is a root tolerant to drought
and can be harvested when needed, which makes it a favorable crop for impover-
ished families. Cassava can be cooked in several different ways, but one in particular
popular method is to dry it and mill to a flour that can be stored and later used for
porridge, known as garri. One major issue with cassava, however, is that it produces
little β-carotene naturally. β-carotene is active as provitamin A,... (More)
At the Swedish University of Agricultural Sciences, SLU, in Alnarp, Erik Alexan-
dersson is leading a project that focuses on biofortification of cassava. Cassava is a
staple crop grown in tropical regions and serves as the third most important source
of calorie intake in these regions (FAO, 2008). Cassava is a root tolerant to drought
and can be harvested when needed, which makes it a favorable crop for impover-
ished families. Cassava can be cooked in several different ways, but one in particular
popular method is to dry it and mill to a flour that can be stored and later used for
porridge, known as garri. One major issue with cassava, however, is that it produces
little β-carotene naturally. β-carotene is active as provitamin A, which is essential in
our diets. If the main calorie intake consists of cassava, the lack of β-carotene in the
root can cause vitamin A deficiency, leading to blindness and death.
In this project, the β-carotene and starch content in cassava was evaluated in or-
der to understand the genes controlling the biosynthesis. The overall project goal is
to enhance the β-carotene content with retained starch levels in cassava (Alexander-
sson, 2017).
CRISPR/Cas9 is a powerful tool to edit plant genomes which can create new valu-
able crops. The gene editing is stable and heritable. The method is also user-friendly
and not hard-line considered as GMO, which would ease public acceptance. For a
growing population and a harsher environment, the method holds promise to be
revolutionary (Khatodia et al., 2016). In this project, CRISPR/Cas9 was used to deac-
tivate enzymes in the carotenoid pathway hopefully leading to β-carotene accumu-
lation in the mature root.
The carotenoid content varies in plants due to for example species, genotype, ripen-
ing stage and environmental conditions. Previously genetic and metabolic engineer-
ing has been successful to enhance the carotenoid levels in different plants, for ex-
ample in the famous so called Golden rice. The carotenoid content can be analysed
using high performance liquid chromatography, HPLC, in biological samples. The
long conjugated double-bonds will absorb light in at a specific wavelength and the
content of specific carotenoids like β-carotene is possible to measure (Saini et al.,
2015). The starch content can be analysed by using enzymatic methods that will hy-
drolyse the starch to glucose, which further can be measured by using spectropho-
tometry.
In this thesis, the β-carotene and starch content was measured for 13 wild cassava
genotypes in order to present a recommendation on which of these genotypes that
produced the most favorable levels. These recommended genotypes could further
be used as targets for the genetic modifications, creating a more revolutionary cas-
sava variety than ever before. (Less)
Please use this url to cite or link to this publication:
author
Almqvist, Linnea LU
supervisor
organization
course
KBKM05 20181
year
type
H2 - Master's Degree (Two Years)
subject
keywords
Biofortification, GMO, CRISPR/Cas9, Vitamin A, Cassava, CRISPR, Gene editing, Beta carotene, Genetic engineering, Applied biochemistry
language
English
id
8950149
date added to LUP
2022-06-30 10:45:24
date last changed
2022-06-30 10:45:24
@misc{8950149,
  abstract     = {{Cassava, Manihot esculenta, is the third most important staple crop in tropical re-
gions. Cassava is a fibrous root that is tolerant to drought and has a flexible harvest
period making it a reliable crop under poorer farming conditions (FAO, 2008). The
content of provitamin A, also known as β-carotene, is unfortunately low in cassava
even though there are varieties bred for a higher content. Since vitamin A deficiency,
VAD, is a large problem of the regions where cassava is of major importance for calo-
rie intake, an increase of the β-carotene content would be of great interest to address
malnutrition.
The main idea of this project is to increase the amount of β-carotene accumulated
in the cassava root. This is accomplished by using the knowledge of the cassava
genome and the carotenoid pathway, in order to block specific enzymes through
genome editing techniques . The trials will though take many years and this Master
Thesis will cover only a fragment of the entire project. Cassava needs to grow in the
field for at least nine months, which will create a long time frame to consider. After
creating genetic constructs and transforming the cassava plants, the carotenoid and
starch content will be analysed.
Methods for analysing starch and carotenoids for cassava were developed during
this Master Thesis by literature research and laboratory trials.}},
  author       = {{Almqvist, Linnea}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Biofortification of Cassava}},
  year         = {{2018}},
}