Striga-Resistant Corn Performance in Controlled Crosses

Greg Howard
8th April, 2024

Striga-Resistant Corn Performance in Controlled Crosses

Diagram for the setup of testing Striga hermonthica seed germination; conditioned Striga seed laid out in double layer watchman filter paper on petri dish to measure germination capacity.

Image adapted from: Zebire et al. / CC BY (Source)

Key Findings

  • In Africa, a study improved maize resistance to the parasitic weed Striga, which affects crop yields
  • Using a specific breeding method with a 'tester' plant, researchers developed maize hybrids resistant to Striga and with high yields
  • The study showed that selecting the right tester is crucial for both Striga resistance and crop output
In the agricultural sector, particularly in Africa, one of the most challenging problems is the infestation of crops by parasitic weeds, notably Striga hermonthica. This weed is known for its devastating impact on the yield of staple crops like maize and rice. Addressing this issue, a new study[1] by the International Institute of Tropical Agriculture has focused on improving maize resistance to Striga hermonthica and enhancing yield-related traits through the use of a specific breeding method. The method involves selecting a 'tester'—a plant variant used to cross with a series of other plants to evaluate their genetic potential. The right tester can help to amplify genetic differences among test crosses from new inbred lines of maize, which are pure lines obtained through self-pollination and selection. The ultimate goal is to identify maize hybrids that not only resist Striga hermonthica but also maintain high yields. Previous research[2] highlighted the significance of genetic variation in host resistance and tolerance to different Striga species and ecotypes. It was discovered that rice genotypes exhibited varying degrees of resistance and tolerance, which are two distinct strategies plants use to cope with Striga infestation. Resistance refers to a plant's ability to ward off Striga attacks, while tolerance is the plant's capacity to endure the presence of the parasite without substantial loss to its growth and yield. Understanding these traits is crucial for breeding programs aimed at developing crop varieties that can thrive in Striga-prone areas. Building on this foundation, the recent study sought to examine how different levels of resistance in the tester influence the performance of resulting maize hybrids. The researchers evaluated the testcross progeny for their resistance to Striga hermonthica and for traits related to yield. By using testers with varying resistance levels, they were able to assess which combinations would lead to the most Striga-resistant and high-yielding hybrids. The study's methodology involved crossing a set of new inbred maize lines with testers that have been classified according to their Striga resistance levels. The resulting hybrids were then grown in Striga-infested fields, where their performance was meticulously recorded. Traits such as the number of emerged Striga plants, the timing of their emergence, and the overall yield of the maize were measured. The results showed that using a tester with high resistance to Striga hermonthica was instrumental in developing hybrids with enhanced resistance to the weed. Moreover, these hybrids also demonstrated favorable yield traits, suggesting that the choice of tester can have a significant impact on both Striga resistance and the potential output of the crop. This study is particularly important as it provides a practical breeding strategy that can be implemented to combat Striga infestation. By carefully selecting the right tester, breeders can create maize hybrids that are better equipped to withstand the adverse effects of Striga, thereby securing food production in regions where the parasite is endemic. Furthermore, the findings support the notion that resistance and tolerance are genetically determined and that breeding for these traits can be a predictive and strategic approach to developing new crop varieties. The study also reinforces the need for ongoing research to understand the complex interactions between crops and parasites like Striga, which can vary widely across different species and ecotypes. In conclusion, the research conducted by the International Institute of Tropical Agriculture offers a promising avenue for improving maize cultivation in Striga-affected areas. By leveraging genetic differences through the use of a suitable tester, it is possible to produce maize hybrids that are not only resistant to Striga hermonthica but also have the potential to yield abundantly. This approach could be a game-changer for farmers in regions plagued by Striga, offering them a sustainable solution to protect their crops and livelihoods.

AgricultureGeneticsPlant Science

References

Main Study

1) Testcross performance of Striga-resistant maize inbred lines and testers with varying levels of Striga reaction

Published 5th April, 2024

https://doi.org/10.1186/s43170-024-00239-w

Related Studies

2) Genetic variation and host-parasite specificity of Striga resistance and tolerance in rice: the need for predictive breeding.

https://doi.org/10.1111/nph.14451


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