Introgression Of Stay-Green Trait Into a Kenyan Farmer Prefered Sorghum Variety

Abstract

Backcross breeding enables breeders to transfer a desired trait from a Genetic Improvement of Kenyan sorghum variety for drought resistance donor parent, into the favoured genetic background of a recurrent parent. This study utilised back-cross breeding to transfer stay green quantitative trait locus (QTLs) from the donor parental line E36-1 into a Kenyan farmer-preferred variety, Ochuti as the recurrent parental line. The parental lines E36-1 has 3 stay green QTLs, SBI-01, SBI-07 and SBI-10 located at various chromosomes. The transfer of these QTLs was confirmed with the help of Simple Sequence Repeats (SSRs) molecular markers. Five foreground markers that were polymorphic among the two parental genotypes were used to identify individuals of F1 generation that had stay green QTLs transferred into Ochuti. A maximum of two QTLs, namely, SBI-07 and SBI-10 were identified as having been transferred into three individual genotypes. Two other F1 genotypes had only one QTL (SBI-10) transferred into Ochuti. The heterozygous F1 genotypes were used as the female parents in the generation of BC1F1. About 25% of the BC1F1 progenies that were genotyped had at least One QTL introgressed. As is the case in all marker-assisted back-cross breeding, the rate of success in introgressing QTL from donor to recurrent parental lines depends on the number of plants screened.L'am\ue9loration par croisement en retour permet les am\ue9lirateurs \ue0 transf\ue9rer le trait d\ue9sir\ue9 d'une vari\ue9t\ue9 de sorgho Kenyan g\ue9n\ue9tiquement am\ue9lior\ue9 pour parent donneur de r\ue9sistance \ue0 la s\ue9cheresse, en parent r\ue9current d'un pass\ue9 g\ue9n\ue9tiquement favori. Cette \ue9tude a utilis\ue9 le croisement en retour pour transf\ue9rer le trait quantitatif locus de la persistance chlorophyllienne (QTLs) d'une lign\ue9e de parent donneur E36-1 dans la vari\ue9t\ue9 Kenyan pr\ue9f\ue9r\ue9e par les fermiers, Ochuti comme lign\ue9e parentale r\ue9currente. La lign\ue9e parentale E36-1 a 3 QTL de persistence chlorophyllienne SBI-01, SBI-07 et SBI-10 localis\ue9s sur divers chromosomes. Le transfert de ces QTL \ue9tait confirm\ue9 avec l'aide des marqueurs mol\ue9culaires \ue0 r\ue9p\ue9tition simple de s\ue9quences (RSS). Cinq marqueurs rapproch\ue9s qui \ue9taient polymorphoques parmi les deux g\ue9notypes parentaux \ue9taient utilizes pour identifier les individus de g\ue9n\ue9ration F1 qui avaient le QTL de persistence chlorophyllienne transf\ue9r\ue9e dans Ochuti. Un maximum de deux QTLs appel\ue9s SBI-07 et SBI-10 \ue9taient identifi\ue9 comme ayant \ue9t\ue9 transf\ue9r\ue9s dans trois g\ue9notypes individuels. Deux autres g\ue9notypes F1 avaient un QTL (SBI-10) transf\ue9r\ue9 dans Ochuti. Les g\ue9notypes h\ue9terozygotes F1\ue9taient utilis\ue9s comme de parents femelles dans la g\ue9n\ue9ration de BC1F1. Environ 25 % de prog\ue9nies BC1F1 qui \ue9taient g\ue9notyp\ue9s avaient au moins un QTL introgress\ue9. Comme c'est le cas dans toute amelioration par croisement de retour avec marqueur assist\ue9, le taux de r\ue9ussite en introgressant le QTL du donneur aux lign\ue9es parantales r\ue9currentes d\ue9pend du nombre de plants test\ue9s