De 2009 à 2014, dans le cadre de la Sorghum Research Initiative du Generation Challenge Programme, deux projets ont été conduits avec l’Institut d’Economie Rurale et l’ICRISAT au Mali, visant à intégrer l’analyse génétique dans les programmes de sélection qui s’y développent. Deux présentations seront proposées faisant le bilan de chacun des deux projets.

 Multi-traits and multi-environments sorghum breeding in Mali through marker assisted recurrent selection.

Jean-Francois Rami – UMR AGAP

Marker assisted recurrent selection (MARS) is a recent approach that integrates molecular markers all along of the breeding process. The approach combines an exhaustive multi-environment bi-parental populations based QTL analysis, for all the traits that define the breeder’s target, with genotypic index definition, and several generations of intercrossing monitored by markers. The genetic material produced by this approach corresponds to one or several ideal genotypes defined based on the QTL results and their variation in different environments. This approach aims at getting the most out of breeding populations, and finally of resources allocated to the breeding program. MARS can be seen as a pipeline of genetic material improvement through enrichment in good alleles for target traits and corresponding identified QTLs.

Since 2008, two populations developed from the crosses of Tiandougou with Keninkeni and Tiandougou with Lata3 have been evaluated in 2010 and 2011 respectively in 6 environments. QTLs have been detected for both populations for a large number of traits (grain productivity, flowering time, plant morphology, grain quality, etc.) in the 6 environments. At the end of the project, 3 cycles of marker-assisted recurrent selection have been accomplished for the two populations. About 900 families have been produced through this process. The evaluation of the germplasm generated through the 3 recurrent cycles has been initiated for one of the two populations. Several MARS families have showed superior and stable (over 4 environments) performance as compared to the elite checks evaluated in the same experiments. Some of these lines are already being tested as candidate varieties.

 Enhancing sorghum grain yield and quality for the Sudano-Sahelian zone of West Africa using the Backcross Nested Association Mapping (BCNAM) approach

 Baptiste Guitton – Icrisat/UMR AGAP

 Loss of genetic diversity is a potential impediment to genetic gain in breeding programs. Despite their high yield potential, elite sorghum varieties resulting from breeding programs have shown poor grain quality and adaptation to the West Africa Sudano-Sahelian region. Local varieties are conversely known for their adaptation and processing qualities attributes and consequently remain the most cultivated varieties in traditional systems of West Africa.

Our approach consists in enriching elite varieties developed recently in Malian breeding programs with alleles originating from sorghum genetic diversity and from African landraces with the aim to develop sorghum cultivars combining high yield performance, grain quality, and adaptation to the sudano-sahelian climatic conditions of Mali.

A multi-parental crossing scheme using 3 elite recurrent parents and 29 donor parents leading to 50 advanced-backcross (BC1F3) populations of 70 to 200 families, representing approximately 6300 families, was implemented to reach our objective. This design combines high-resolution population development for genetic analysis of complex traits, genetic basis enlargement, and opportunities for direct breeding applications.

Genotyping By Sequencing technology has been carried out on this material and yielded around 9000 polymorph SNP per population. Phenotyping was performed from 2012 to 2014 for a wide range of agronomic traits of which yield performance, adaptation to soil fertility, photoperiod sensitivity, grain and stem quality. Various approaches are being explored for detecting marker-trait associations in this multi-parental design combining genetic mapping and genome wide association genetics.

Besides genetic analyses, BCNAM populations have been introduced in conventional breeding pipeline, and promising progenies have been identified, showing that BCNAM approach is an effective method to introduce favourable alleles from adapted sorghum germplasm into elite breeding material, while producing experimental material for genetic analyses. Populations potential as a resource to investigate complex traits architecture and to identify molecular markers linked to agronomic traits will be presented.

Contact :

JF. Rami