Overexpression of rice thaumatin-like protein (Ostlp) gene in transgenic cassava results in enhanced tolerance to Colletotrichum gloeosporioides f. sp. manihotis
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Date
2018
Authors
Ojola, Patroba Odeny
Nyaboga, Evans N.
Njiru, Paul N.
Orinda, George
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier
Abstract
Cassava (Manihot esculenta Crantz) is the most important staple food for more than 300 million people in
Africa, and anthracnose disease caused by Colletotrichum gloeosporioides f. sp. manihotis is the most
destructive fungal disease affecting cassava production in sub-Saharan Africa. The main objective of this
study was to improve anthracnose resistance in cassava through genetic engineering. Transgenic cassava
plants harbouring rice thaumatin-like protein (Ostlp) gene, driven by the constitutive CaMV35S promoter,
were generated using Agrobacterium-mediated transformation of friable embryogenic calli (FEC) of cultivar
TMS 60444. Molecular analysis confirmed the presence, integration, copy number of the transgene all
the independent transgenic events. Semi-quantitative RT-PCR confirmed high expression levels of Ostlp in
six transgenic lines tested. The antifungal activity of the transgene against Colletotrichum gloeosporioides
pathogen was evaluated using the leaves and stem cuttings bioassay. The results demonstrated significantly
delayed disease development and reduced size of necrotic lesions in leaves and stem cuttings of
all transgenic lines compared to the leaves and stem cuttingss of non-transgenic control plants.
Therefore, constitutive overexpression of rice thaumatin-like protein in transgenic cassava confers
enhanced tolerance to the fungal pathogen C. gloeosporioides f. sp. manihotis. These results can therefore
serve as an initial step towards genetic engineering of farmer-preffered cassava cultivars for resistance to
anthracnose disease.
Description
Research Article
Keywords
Colletotrichum gloeosporioides f. sp. manihotis, Thaumatin-like protein, Transgenic cassava