Location: Crop Improvement and Genetics Research
Project Number: 2030-21430-015-011-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Jul 1, 2026
End Date: Dec 30, 2027
Objective:
The objectives of this cooperative research project are to: (1) perform metabolomic and transcriptomic analyses to identify differential signaling molecules activated by the two resistance genes (HA and HB) that underlie enhanced broad-spectrum resistance to Hessian fly; (2) express the HB gene in yeast to determine whether the HB protein functions as an enzyme catalyzing de novo cytokinin biosynthesis; and (3) identify the unknown gene that interacts with HA to cause hybrid lethality (HL) and elucidate the underlying biological mechanisms.
Approach:
We previously identified two closely linked Hessian fly resistance genes, HA and HB, in Aegilops tauschii, the D-genome progenitor of bread wheat. Pyramiding these two genes confers enhanced broad-spectrum resistance. Field trials further demonstrated that both genes significantly increase grain yield in near-isogenic lines. Notably, one of the genes, HA, induces hybrid lethality through interaction with an unknown gene (HL) present in certain wheat cultivars, such as Faller.
To elucidate the molecular mechanisms underlying enhanced broad-spectrum resistance conferred by stacking the two genes, we will conduct metabolomic and transcriptomic analyses to identify differential signaling molecules and resistance pathways activated by the two R genes (HA and HB) in near-isogenic lines, with and without infestation, followed by validation through exogenous application. We have demonstrated that HA and HB enhance cytokinin homeostasis, thereby increasing grain yield and improving resilience to multiple biotic and abiotic stresses in both near-isogenic and transgenic lines. To determine whether these genes function directly as enzymes catalyzing cytokinin biosynthesis or indirectly regulate cytokinin homeostasis, we will express HA and HB proteins in the GS115 strain of Pichia pastoris under the control of the AOX1 promoter and quantify cytokinin production.