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sur le développement des zones arides et semi-arides

Titre : Diversity and genome-wide association in Napier grass (Cenchrus purpureus L.) collections for agronomic and drought-tolerance related traits

Auteur : LIRE HAILU WACHAMO

Université de soutenance : University of Hawassa.

Grade : MSc thesis in Plant Biotechnology. 2022

Résumé
Limited access to improved forages is one of the major factors affecting livestock performance in sub-Sahara Africa (SSA). Cenchrus purpureus L is a C4 perennial grass species native to SSA and it has attributes high yielding, resistance against most pests and diseases. However, it has received limited research attention and few genomic tools have been developed for it to date. Main aim of this study was for genetic diversity, identification of SNPs and genome wide association analysis on 109 core collections of Napier grass accessions from 16 countries. Results shows that more than a million SNPs were identified for analysis. Among sequenced 84 Napier grass accessions were phenotyped for two seasons, under different water stress conditions normal water condition, moderate water stress (MWS) and severe water stress (SWS). Agronomic traits such as plant height (PH), leaf width (LW) and length (LL), total fresh weight (TFW) and total dry weight (TDW) and nutritional traits such as Acid Detergent fibre (ADF), acid detergent lignin (ADL), Neutral detergent fibre (NDF), crude protein (CP), Metabolizable Energy (ME) and in-vitro organic matter digestibility (IVOMD) were measured. Significant differences for both agronomic and nutritional traits were observed and most traits showed higher mean value under MWS conditions. Furthermore, a genome-wide association study (GWAS) identified more than 100 SNPs, for both agronomic and nutritional traits, that were significantly associated (P < 1.00E-05) with traits of interest. The results obtained in the present study will enhance our understanding of complex agronomic and nutritional traits in Napier grass and these genomic tools will serve as a valuable resource in future breeding programs to select high yielding and drought-tolerant varieties of Napier grass, suited for different agroecological zone

Mots Clés : agronomic characters ; drought ; pennisetum purpureum ; single nucleotide polymorphism ; animal feeding ; forage

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