Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Accueil du site → Doctorat → Ethiopie → Marker Assisted Introgression of Striga Resistant and Drought Tolerant Quantitative Trait Loci into Popular Ethiopian Sorghum Cultivars

Addis Ababa University (2021)

Marker Assisted Introgression of Striga Resistant and Drought Tolerant Quantitative Trait Loci into Popular Ethiopian Sorghum Cultivars

Abebe, Teklay

Titre : Marker Assisted Introgression of Striga Resistant and Drought Tolerant Quantitative Trait Loci into Popular Ethiopian Sorghum Cultivars

Auteur : Abebe, Teklay

Université de soutenance : Addis Ababa University

Grade : DOCTOR OF PHILOSOPHY (PhD) IN MICROBIAL, CELLULAR AND MOLECULAR BIOLOGY (APPLIED GENETICS) 2021

Résumé partiel
Sorghum (Sorghum bicolor (L.) Moench) is the fifth important dryland cereal crop worldwide, and a dietary staple food for more than half a billion poor and food-insecure people dwelling in the semi-arid tropics of Africa and Asia. Sorghum is one of the strategic crops in Ethiopia, which provides more than one third of the cereal diet and is almost entirely grown by subsistence farmers to meet needs for food, feed, income, beverage, house and fuel purposes. Despite the multiple uses, its productivity is constrained at least partly by the intense Striga infestation and frequent drought, which causes up to 100% crop loss. The possible approaches to overcome the two prevailing constraints include genetic manipulation of the crop and the growing environment. The use of host-plant resistance offers a potentially cost-effective and environmentally sound complementary management strategy for incorporation into integrated management of Striga and drought. The studies were, therefore, designed to introgress Striga resistance and drought tolerance genes/quantitative trait loci (QTLs) into popular and farmer-preferred cultivars through marker assisted backcrossing (MABC). One-hundred-eighteen and 61 backcrossed lines were developed for Striga and drought, respectively. The 118 backcrossed lines and 15 parental lines were evaluated for Striga resistance based on low Striga seed germination stimulant activity in the agar gel assay (AGA) and under field condition. The AGA study was conducted at Holetta national agricultural biotechnology research center (NABRC) arranged in completely randomized design with four replications, while the field evaluation was conducted at two selected Striga hotspots and two non-infested locations layout in -lattice design with triplicates. The 61 drought tolerant converted and nine parental lines were evaluated under two-contrasting (optimum vis-à-vis stress) environments in -lattice design with three replications. The well-watered experiment was irrigated throughout the season, while the water-limited trial was irrigated well during the early growth stages with irrigation withheld at anthesis in order to allow moisture stress during grain-filling stage. The results from the AGA indicated that genotypes significantly differed (P<0.01) for their low production of Striga germination stimulant activity (lgs). The mean maximum germination distance (MGD) and germination rate (GR) ranged from 0.0 mm to 29.45 mm and 0.0% to 72.4% in the agar, respectively. Of the 118 backcrossed lines, 22.9% showed less than 10 mm of MGD and GR of <30%, revealing provision of low germination stimulant/strigolactones production (lgs). There were significant positive (r = 0.4-0.81) correlations showing the roles of these parameters as selection criteria in breeding for resistance. The existence of higher heritability (h2b = 77-83%) and genetic advance (GA = 62-93%) for the germination parameters indicated possibilities for improving resistance against Striga through selection.

Présentation

Version intégrale (6,3 Mb)

Page publiée le 3 juin 2022