Participants:

1. Coordinator: Mikocheni Agricultural Research Institute – , Dar es Salaam, Tanzania – Joseph Ndunguru

2.   Jomo Kenyatta University of Agriculture and Technology (KUAT) – Department of Horticulture – JKUAT, Nairobi, Kenya – Elijah Ateka

3. NEIKER – Instituto Vasco de Investigación y Desarrollo Agrario, Vitoria-Gasteiz, Spain – Enrique Ritter

 

Introduction

Cassava (Manihot esculenta), also called yuca or manioc, is extensively cultivated as an annual crop in tropical and subtropical regions for its edible starchy tuberous root, a major source of carbohydrates. Cassava is the third largest source of food carbohydrates in the world. Cassava plays a particularly important role in agriculture in developing countries—especially in sub-Saharan Africa—because it does well on poor soils and with low rainfall, and because it is a perennial that can be harvested as required. Its wide harvesting window allows it to act as a famine reserve and is invaluable in managing labor schedules. It also offers flexibility to resource-poor farmers because it serves as either a subsistence or a cash crop (FAO 2008).

The effects of global climate change such as heat, coldness, drought or flooding are threatening also sustainable cassava cultivation . Moreover, changes in their affecting pathogen spectrums have been observed. Cassava cultivation is affected by a number of serious diseases, such as cassava bacterial blight or cassava mosaic virus. But recently a new virus causing brown streak disease has been identified as a major threat to cassava cultivation worldwide.

Therefore, it is necessary to develop new cultivars that are adapted to these threats by applying marker assisted selection (MAS) or genetic transformations based on useful candidate genes.

The aim of this project is to characterize this valuable Cassava germplasm with respect to resistance and tolerance to different biotic and abiotic stresses and exploit it through breeding to obtain new Cassava varieties adapted to climate change for sustainable agriculture.

Genomic studies offer the possibility to characterize germplasm efficiently at the molecular level and to accelerate considerably breeding programmes. The detection of candidate genes for useful traits offers the possibility to apply them in marker assisted selection (MAS) within breeding programmes. The survey of allelic diversity of such genes within cultivated and wild accessions of a species and analyses of their particular effects, permits to select the most efficient allele combinations. Within this project, we want to identify in cassava useful candidate genes for different biotic and abiotic stresses using various molecular tools, characterize the allelic variation of this germplasm and use markers and models in marker assisted breeding in order to speed up the obtainment of improved varieties.

 

Project objectives: Overall and specific objectives

The General Objective consists of identifying Cassava accessions adapted to biotic and abiotic threats of climate change, and to identify the underlying candidate genes for developing molecular markers and models, which will speed up the breeding of improved and adapted Cassava cultivars for sustainable agriculture.

In order to meet this general objective the following Specific Objectives are envisaged:

1. Evaluation of Cassava accessions (cultivars, accessions, breeding clones) for resistance or tolerance to abiotic and biotic stresses related to global climate change.
2. Detection of useful candidate genes (CG) for abiotic and associated biotic stresses applying different molecular Tools.
3. Molecular characterization of the allelic variation in these CG and determination of allelic composition in the evaluated accessions.
4. Association mapping to detect the effects of specific CG alleles or CG allele combinations on the tolerance levels of the analysed stresses, development of molecular markers for Marker-assisted selection and Model building to assign parental breeding values and predict progeny performances.
5. Pre-breeding activities in Cassava to combine favourable characteristics and to improve adaptation to climate change applying the developed markers and models.
6. Dissemination and Transfer of Project results and Products (accessions and breeding clones).