First products of DNA marker-assisted selection in sorghum released for cultivation by farmers in sub-saharan Africa

Abstract

Striga hermonthica (Del.) Benth. is the major biotic constraint to sorghum production. Its control is difficult and can only be achieved through integrated management strategies that depend mainly on host plant resistance and enhanced soil fertility. However, breeding for resistance is hampered by the complexity of host parasite interactions and lack of reliable screening methods. The invention of molecular markers has enhanced the effectiveness of breeding for resistance. Five genomic regions (QTLs) with linked markers associated with Striga resistance were mapped in sorghum variety N13 by [10]. In this study, to increase the efficiency of marker-assisted selection (MAS), 27 EST-SSR markers in close association with Striga resistance QTLs were also identified and mapped. Populations of backcross (BC 3 S 4 ) derived from N13 (Striga resistant) X three farmer preferred sorghum cultivars: Tabat, Wad Ahmed and AG-8 (Striga susceptible) were generated. Thirty-one lines (BC 3 S 4 ) with confirmed Striga field resistance were genotyped with foreground and background selection makers. Twenty resistant lines, with two or more major QTLs were selected for regional evaluation. Of these 10 lines were selected and advanced for multi-location testing, together with Wad Ahmed, Tabat, AG-8, N13, SRN39 and IS9830 as checks. Standard variety trials were conducted in Striga sick plots over three seasons (2009)(2010)(2011) in Sudan, Gezira Research Station, Damazine, Sinnar, and Gedarif. Results revealed that four lines (T1BC 3 S 4 , AG6BC 3 S 4 , AG2BC 3 S 4 and W2BC 3 S 4 ) were Striga resistant and agronomically superior with yields ranging from 180% to 298% higher relative to their recurrent parents. This Striga resistance coupled with superior attributes of the recurrent parent (including very high yield potentials, high grain quality and drought tolerance) will provide adaptation and stability across a wide range of environments. These are the first products of DNA markerassisted selection (MAS) in sorghum released for cultivation by farmers in sub-Saharan Africa.

Recent research progress in combatting root parasitic weeds

“…Microsatellite markers linked to the low germination stimulant gene (lgs) for S. hermonthica were identified in sorghum and were supposed to be useful in breeding S. hermonthica-resistant sorghum varieties [14]. In breeding projects in Sudan and Eritrea, S. hermonthica resistance of sorghum was successfully improved by markerassisted selection [15,16]. Resistance to S. hermonthica in wild sorghum accessions was reported as novel sources for sorghum breeding, in which the resistance was ascribed to incompatibility [17].…”

Marker-assisted introgression improves Striga resistance in an Eritrean Farmer-Preferred Sorghum Variety

“…Breeders practice MAS when an important trait that is difficult to assess phenotypically, is tightly linked to a Mendelian trait or molecular markers that can be easily scored (Lammerts van Bueren et al, 2010). The use of molecular markers to breed for Striga resistance in sorghum has recently been shown to be possible (Ejeta and Gressel, 2007;Gammar and Mohamed, 2013;Mohamed et al, 2014). Haussmann et al (2004) identified molecular markers linked to Striga resistance QTLs having mechanisms over and above the "low germination stimulant" trait.…”

Genotypic Variation for Low Striga Germination Stimulation in Sorghum “<i>Sorghum bicolor</i> (L.) Moench” Landraces from Eritrea

“…Sorghum (Sorghum bicolour (L.) Moench) is an important staple crop in Sub-Saharan Africa (SSA) that can meet the increasing demand of food [1]. Although, sorghum consumption is high in most SSA countries, the grain yield at the farm level is low due to the effect of biotic and abiotic stresses [2] [3].…”