Relevant case studies for major crops
In our quest to ensure food security and sustainable agricultural practices, it is essential to examine real-world examples of successful strategies for enhancing disease resistance in major crops. Case studies provide valuable insights into the practical applications of various crop improvement methods, shedding light on the effectiveness of these approaches in combating plant diseases. In this discussion, we will delve into several noteworthy case studies showcasing the deployment of innovative techniques to bolster disease resistance in key agricultural crops. These case studies serve as living proof of the impact of scientific research and agricultural innovation, highlighting the potential for addressing global food challenges through practical, field-tested solutions.
Here are some studies on major crops that have used various plant breeding techniques to improve disease resistance:
Wheat
Wheat is one of the most important staple crops in the world, and wheat stem rust fungus is a major threat to its production. In 1998, a new virulent strain of the fungus emerged in Uganda, posing a significant threat to global wheat production. To counter this threat, researchers at the International Maize and Wheat Improvement Center (CIMMYT) have developed a series of wheat varieties resistant to the new strain of the fungus using traditional plant breeding methods.
New wheat varieties were created by selecting plants with desirable traits, such as resistance to fungus, crossing them with other plants and creating offspring with those traits. This process was repeated over several generations, and the resulting plants with desired traits were selected for further breeding. New wheat varieties were extensively tested in the field to ensure their effectiveness in disease control.
These disease-resistant wheat varieties have been widely adopted in East Africa and other parts of the world, contributing to improved food security and livelihoods. For example, in Ethiopia, the adoption of these varieties led to a 36% increase in wheat yield and a 23% increase in farmer income (Singh et al., 2015).
Maize
Maize lethal necrosis (MLN) is a viral disease that can cause significant yield losses in maize crops, particularly in East Africa. To address this issue, researchers at the International Maize and Wheat Improvement Center (CIMMYT) used marker-assisted selection to develop maize varieties resistant to MLN.
Marker-assisted selection identifies genetic markers linked to genes responsible for disease resistance and uses those markers to select plants with desired traits. This approach allows breeders to more efficiently and accurately select resistant plants without the need for time-consuming and expensive phenotypic screening.
The new MLN-resistant maize varieties developed by CIMMYT were extensively field-tested to ensure their efficacy in controlling the disease. These varieties are widely adopted by farmers in East Africa and contribute to improved food security and livelihoods in the region. For example, in Kenya, the adoption of these varieties led to a 15–25% increase in maize yield and a 30–50% reduction in MLN incidence (Makumbi et al., 2015).
Tomato
Tomato yellow leaf curl virus (TYLCV) is a major threat to tomato production worldwide, causing significant yield loss and economic damage. To solve this problem, researchers at the Hebrew University of Jerusalem used genetic engineering to introduce a gene from the wild tomato species Solanum haprosites, which confers resistance to TYLCV, into commercial tomato varieties.
The introduced gene encodes a protein that inhibits replication of the TYLCV virus, thereby conferring resistance to the virus. The resulting genetically engineered tomato plants were resistant to TYLCV and showed improved yields in field trials. Researchers also found that engineered tomatoes did not exhibit any negative effects on their growth or fruit quality (Gafni et al., 2015).
This approach, which uses genetic engineering to introduce disease resistance genes into commercial crops, has the potential to significantly improve crop yields and reduce losses due to disease.
Rice
Bacterial blight is a devastating disease affecting rice crops worldwide, causing significant yield loss and economic damage. To solve this problem, researchers at the International Rice Research Institute (IRRI) used CRISPR-Cas9 gene editing to modify a rice gene called OsSWEET14, which is essential for the growth and development of bacterial pathogens.
The modified gene in the resulting rice plants prevented the bacterial pathogen from using the plant’s sugars as a food source, limiting the bacteria’s ability to grow and cause disease. Engineered rice plants are resistant to several types of bacterial blight and have shown improved yields in field trials. Researchers also found that engineered rice did not exhibit any negative effects on their growth or grain quality (Jiang et al., 2018).
