Chinese scientists identify strigolactone transporter critical for parasitic weed resistance and tomato yield

Date:02-18-2025

A recent breakthrough by researchers led by Prof. LI Jiayang from the Institute of Genetics and Developmental Biology (IGDB) of the Chinese Academy of Sciences offers new hope in the battle against parasitic weeds that cause global agricultural losses exceeding $10 billion annually. The researchers have identified a key gene, strigolactone transporter SlABCG45, in tomatoes that plays a crucial role in balancing the host resistance to parasitic weeds and fruit yield in tomato.

The study, published on January 29 in The Innovation, highlights how SlABCG45, a strigolactone (SL) transporter, mediates the plant's defense against broomrape species (Orobanche and Phelipanche) without affecting crop yield. This discovery is seen as a significant step toward developing crops with durable, broad-spectrum resistance to parasitic weeds.

Striga, a parasitic weed attacking monocot cereals like maize, sorghum, and millet, and broomrapes, which target crops such as tomatoes, sunflowers, potatoes, and chickpea, present major challenges to global agriculture. Management of parasitism is challenging, and very few resistance genes have been cloned and characterized in plants. 

To identify key genes that confer resistance to broomrapes, the researchers performed a genome-wide association study using 152 tomato accessions and identified SlABCG45 as a crucial gene that mediates host resistance to Phelipanche aegyptiaca.

A proposed model for SlABCG45-mediated improvement of broomrape resistance and fruit yield in tomato (Image by IGDB)

They found that SlABCG45 and its close homolog SlABCG44 were membrane-localized SL transporters with essential roles in exudation of SLs to the rhizosphere, transport of SLs from the roots to the shoots and mediation of broomrape seeds germination.

Interestingly, SlABCG45 and SlABCG44 exhibit functional differentiation. SlABCG45 expression was strongly responsive to phosphorus deficiency, an environmental signal that induces parasitism, SL biosynthesis and exudation, whereas SlABCG44 was weakly responsive to phosphorus deficiency. Furthermore, the SlABCG45 mutation had a relatively weak effect on fruit size, but the slabcg44 mutant produces smaller fruits.

The research team systematically evaluated the potential of SlABCG45 genome editing in broomrape resistance, and showed that knocking out SlAGCG45 confers durable and broad-spectrum resistance to broomrape species in tomato.

Importantly, field experiments over two successive years in Xinjiang Province demonstrate that knocking out SlABCG45 significantly improved tomato resistance to broomrape, resulting in a yield increase of over30% in a Phelipanche-infested field.

Finally, they proposed that crops deficient in SL biosynthesis, such as Slccd8, exhibit resistance to broomrapes. However, the agricultural application of this strategy has been hampered by the accompanying undesirable traits, including dwarfing, excessive branch numbers, smaller and fewer fruit, and reduced fruit yield. Knockout of SlABCG45 significantly improved resistance to Phelipanche and Orobanche without sacrificing fruit development, thus elevating fruit yield in a Phelipanche-infested field. 

These findings demonstrate that SlABCG45 is a critical target for breeding crops that can resist parasitic weeds without compromising yield, paving the way for more sustainable agricultural practices in the future.