Thuwal, Saudi Arabia, October 07, 2024 — A groundbreaking study conducted by researchers at the King Abdullah University of Science and Technology (KAUST) has unveiled a crucial gene that plays a significant role in enhancing crop resistance to Striga hermonthica, commonly known as purple witchweed, one of the most formidable threats to agricultural crops worldwide. This research specifically focuses on pearl millet, a cereal crop widely cultivated in Saudi Arabia and other arid regions, which has shown vulnerability to this parasitic weed.
The study revealed that certain strains of pearl millet devoid of the gene CLAMT1b, which is responsible for the synthesis of specific hormones, exhibited remarkable resistance to the invasive Striga weed. In contrast, strains expressing this gene were found to be susceptible to parasitism. These findings offer valuable insights into potential breeding strategies aimed at bolstering food security, particularly in regions where food sources are precarious due to environmental challenges.
Pearl millet is not only a staple crop but also holds high nutritional value, serving as a vital food source for nearly 100 million people across Africa and Asia, especially those residing in arid and semi-arid regions. This cereal's ability to withstand extreme heat and drought conditions further underscores its significance, particularly in light of the United Nations' designation of 2023 as the International Year of Millets.
The Striga parasite poses a unique challenge to crops by attaching itself to the host's root system, thereby siphoning off essential water and nutrients. Researchers have identified two primary mechanisms through which plants can resist this parasitic threat. The first involves an immune response that effectively blocks the interaction between host and parasite. The second, which is adopted by pearl millet and several other crops—including rice and maize—relies on a hormone known as strigolactone. The KAUST team analyzed the genomes of two distinct pearl millet lines and discovered that the presence of the CLAMT1b gene resulted in the secretion of four types of strigolactone, which facilitated interactions with Striga. Conversely, the line lacking CLAMT1b did not produce these strigolactones, rendering it resistant to the parasitic weed.
Furthe exploration into other pearl millet varieties revealed that many breeding stocks, including commercial varieties, expressed the CLAMT1b gene. Importantly, the researchers found that the presence of CLAMT1b did not adversely affect the beneficial relationship between pearl millet and arbuscular mycorrhizal fungi. These fungi enhance the plant's ability to absorb water and nutrients while bolstering its resistance to diseases. This discovery paves the way for breeding strategies aimed at eliminating the CLAMT1 gene, thereby protecting the crop against Striga without disrupting the vital ecological relationships that support its growth and resilience.
Professor Salim Al-Babili, who led the study, remarked, “Our study should assist plant breeders in selecting seeds with the resistant allele. More resistant cultivars for both commercial farms in Saudi Arabia and smallholder farmers in Africa would greatly improve food security in these regions.” This research, funded by the Bill and Melinda Gates Foundation, provides a promising avenue for enhancing crop resilience and ultimately contributing to global food security.
The full study is published in the esteemed journal Nature Communications, where it contributes to the ongoing dialogue surrounding sustainable agricultural practices and the imperative of adapting to the challenges posed by parasitic weeds in the quest for food security. As the world faces increasing agricultural pressures, such innovative research is critical for developing resilient food systems that can withstand environmental adversities.