Transposons and tolerance; teh identification of genes for Striga tolerance in maize. Integrated Approaches to Higher Maize Productivity in the New Millennium.

Abstract

^ AStriga is one of the most severe constraints to cereal production in areas of the semi-arid tropics of Africa where subsistence agriculture is predominant. The development of Striga tolerant or resistant germplasm has been the goal of many maize breeders. However, to date, no esistant maize has been developed and tolerance, though improved, is still limited. Funded by the Rockefeller Foundation, we developed a large population of maize which contained transposable element-induced mutations. The transposon selected was the mutator element system. Mutator lements preferentially insert into coding regions of the genome and are therefore optimal for transposon-tagging. 8000 F2 families from the transposon-tagged maize population were screened in the field in Kibos during 1 998 and 1999. Interesting families were identified as those hich had segregating Striga-free plants (no emergence) within the family. Twenty three families have been identified which have no/low emergence of Striga. All these families displayed 1: 3 segregation for the Striga free trait (25% Striga free, 75% Striga emergence), this indicates hat a single recessive mutation is responsible for the observed phenotype. The progeny of one of these families has been screened in pot experiments in the laboratory and the phenotype observed in the field has been confirmed. The lack of Striga emergence was not due to altered ermination stimulant production or perturbed attachment. However, the biomass of the parasite on this transposon-tagged line was much lower than that on susceptible control lines. As such the growth of Striga attached to the transposon-tagged plants …