Abstract only

Striga 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 resistant 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 elements 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 which 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 that 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 germination 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 was severely impaired resulting in a low incidence of emergence. Work is currently underway to: develop molecular markers to aid in the introgression of this trait into other maize lines; to clone and identify the gene underlying the trait; to investigate the physiological basis of Striga growth retardation and to; evaluate other interesting maize families in the laboratory.

Conservation Agriculture Program|Genetic Resources Program

English

0409|AGRIS 0401|AL-Maize Program

Juan Carlos Mendieta

INT3287|INT2340

CIMMYT Staff Publications Collection