TILL-D: An Aegilops tauschii TILLING Resource for Wheat Improvement

Aegilops tauschii (2n = 2x = 14, genome DD), also known as Tausch’s goatgrass, is the D genome donor of bread or hexaploid wheat Triticum aestivum (2n = 2x = 42, AABBDD genome). It is a rich reservoir of useful genes for biotic and abiotic stress tolerance for wheat improvement. We developed a TILLING (Targeting Induced Local Lesions In Genomes) resource for Ae. tauschii for discovery and validation of useful genes in the D genome of wheat. The population, referred to as TILL-D, was developed with ethyl methanesulfonate (EMS) mutagen. The survival rate in M1 generation was 73%, out of which 22% plants were sterile. In the M2 generation 25% of the planted seeds showed phenotypic mutations such as albinos, chlorinas, no germination, variegated, sterile and partially fertile events, and 2,656 produced fertile M2 plants. The waxy gene was used to calculate the mutation frequency (1/70 kb) of the developed population, which was found to be higher than known mutation frequencies for diploid plants (1/89–1/1000 kb), but lower than that for a polyploid species (1/24–1/51 kb). The TILL-D resource, together with the newly published Ae. tauschii reference genome sequence, will facilitate gene discoveries and validations of agronomically important traits and their eventual fine transfer in bread wheat

MOLECULAR ISOLATION OF THE MOV-1 LOCUS IN HEXAPLOID BREAD WHEAT

Wheat provides a substantial portion of globally consumed calories, yet faces growing challenges to meet yield needs. Traits affecting floral architecture and grain number hold immense promise for increasing yield potential. Multi-ovary wheat is a unique mutant line that holds potential in improving yields, characterized by the formation of 2-3 grains per floret in a given wheat spike. Described is a multi-approach mapping effort that refines the chromosomal position of the MOV1 locus at high resolution. A radiation hybrid map, linkage map, and refined physical map are reported. Further mutation analysis recovered missense mutations within a candidate gene, displaying a quantitatively reduced phenotype. Expression profiling of the candidate gene reveals up-regulation at crucial developmental stages. Structural investigation of the gene and surrounding locus identified two insertion/deletion events that suggest a pathway for transcriptional regulation. The results presented implicate the candidate gene in the manifestation of the multi-ovary phenotype