CHROMOSOME ENGINEERING AND NEXT GENERATION SEQUENCING ASSISTED TRANSFER AND DEPLOYMENT OFALIEN GRASS SPECIES RESISTANCE TO FHB IN WHEAT

摘要

The successful transfer of effective resistance to FHB from the perennial grass Elymus tsukushiensis Honda (2n=6x=42, S~(ts)S~(ts)H~(ts)H~(ts)Y~(ts)Y~(ts), syn. Roegneria kamoji C. Koch) into wheat is the culmination of a research effort that began with the funding of a project by the McKnight Foundation between Nanjing Agricultural University (NAU) and Kansas State University (KSU) in 1995. In the 1990s, NAU scientists reported on the production of wheat x E. tsukushiensis hybrids and the disomic addition (DA) lines lE~(ts)#l and its derivative TWL 1E~(ts)#1 S with effective resistance to FHB in greenhouse and field nurseries in China. The TWL- 1E,S#1S chromosome consists of the short arm of chromosome 1E~(ts)#1 joined to an unknown chromosome armof wheat at the centromere. We crossed DATWL- 1E~(ts)1S with the ph1 ph1 (a mutant of Ph1 gene that allows pairing between wheat and alien chromosomes) stock of wheat and identified plant progenies that were homozygous ph1 ph1 and carried one copy of TWL1E~(ts)#1S. In these plants, we expected the 1 E~(ts)# 1S arm of TWL-1 E~(ts)# 1S to pair randomly with one of the short arms of the group-1, wheat chromosomes 1A, IB or ID. To monitor recombination, we designed primers from 50 ESTs mapped to group-lS arms of wheat. One proximal (BF202643/HaeIII) and one distal (BE591682/HaeIII) EST-STS polymorphic markers were identified. We screened 488 progenies using the EST-STS marker and identified one proximal (#74) and one distal (#107) recombinant. To further characterize the recombinant chromosomes, we designed 20 SNPs using IAS, comparative sequence analysis, and KASParTM marker assays. Recombinant #74 carried the unidentified wheat arm from TWL1E~(ts)#1S and proved to be agronomically undesirable. The distal recombinant #107 involved chromosome 1A of wheat, where the distal tip of 1 AS was substituted by a homoeologous segment from 1 E~(ts)# 1S of TWL 1 E~(ts)# 1S and was designated as T1 AL 1 AS-1 E~(ts)# 1S. Plants where T1 AL 1 AS-1 E~(ts)# 1S substituted for chromosome lAofwheat were fully fertile. Recombinant #107, together with susceptible (Overley) and moderately susceptible (Everest, Chinese Spring and Karl 92) controls, was screened in greenhouse tests for FHB resistance using a single-point inoculation method. The FHB index ratings of recombinant #107 carrier progenies ranged from 4.2 to 13.3%, compared to 31.7-42.5% for noncarrier progenies from the same cross, similar to the susceptible controls. The gene symbol Fhb6 has been assigned to designate this source of resistance. We developed two KASPar SNP markers to monitor the introgression of Fhb6 into adapted wheats. The material has been released as KS14WGRC61 (W-ELTSU Tl AL-1 AS-1E~(ts)#1 S (TA5655//CSph1B MUT (TA3809)*2//FULLER*2 F_3))and distributed to breeders. Further prebreeding and evaluation of Fhb6 wheat lines in field nurseries is underway. (This research was supported by a grant from the USBWSI.)