Abstract
Currently maize production in the East and Central Africa (ECA) region is at 1.3 tonnes per hectare compared to the potential of up to 7.0 tonnes per hectare because of biotic and abiotic constraints, and this has resulted in prevalence of famine in sub-Saharan Africa. Drought is the most important abiotic stress affecting productivity of maize in Sub Saharan Africa leading to up to 70% crop loss and in certain cases total crop loss. Previous work has shown that Mitogenic Activated Protein Kinase (MAPKKK) gene activated an oxidative signal cascade, which led to tolerance to adverse condition. To analyze the role of the oxidative signal cascades on tropical maize, 4 transgenic tropical maize plants were developed through an Agrobacterium-mediated transformation with a MAPKKK homology from tobacco Nicotiana Protein Kinase 1 (npk1) and the insert was confirmed using Southern and Northern blot hybridization analysis. Fertile To maize plants were obtained which were planted to generate T1 plants, which were used for comparison with non-transgenic plants. The T1 plantlets of tropical inbred TL08-(2)4, single hybrid cross of a PTL001, a multiple cross hybrid DH01 and a dry land cultivar DLC1 genotypes were planted in the greenhouse and assessed for morphological and physiological changes associated with increase in drought stress tolerance when under water stress condition. The results showed that npk1 effectively enhanced drought tolerance in TL08-(2)4 and PTL001, and there was no significant morphological difference between transgenic controls (well watered) and transgenic tests (subjected to moderate drought stress). Overall, there were between 20%-35% enhancements of yield of the transgenic stressed events compared with non-transgenic stressed control.
Highlights
Despite maize being the staple food for most of the population in the East and Central Africa (ECA) region and an important crop as a source of income, animal feed, manure and industrial uses, maize production has often been inadequate
The plants labeled TL08-3, TL08-4, DHO1-1, DH01-2, DH01-4, DLC1-6, DLC1-8 and PTL001-17 were positive for npk1 gene
Previous studies have shown that Agrobacterium tumefaciens transformed events had similar copy number of the npk1 gene and bar gene with a correlation coefficient of 0.9098 [12]
Summary
Despite maize being the staple food for most of the population in the ECA region and an important crop as a source of income, animal feed, manure and industrial uses, maize production has often been inadequate. In Kenya for example, maize yield and production are 1.7 tons/ha and 2.7 million tons annually which are not adequate to meet its demand due to rapid population growth, making it a net importer of 427,000 tons of maize per annum [1] [2] This inadequacy is due to abiotic stress, such as drought, aluminum toxicity, or scarcity of nutrients; biotic stress being mainly pests and diseases [2]-[5]. Drought is a major abiotic stress affecting productivity of maize in Africa leading to up to 70% crop loss and in certain cases total crop loss [6]. It causes up to 24 million tons of yield loss in maize worldwide annually with the greatest impact being in Sub Saharan Africa (SSA) where erratic rain pattern and poor farming methods are common [7]. A correlation between agronomical traits and the rate of photosynthesis has been reported in several studies [9]-[11]
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