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

Abstract

<i>Aegilops tauschii</i> (2n = 2x = 14, genome DD), also known as Tausch's goatgrass, is the D genome donor of bread or hexaploid wheat <i>Triticum aestivum</i> (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 <i>Ae. tauschii</i> 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 <i>waxy</i> 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 <i>Ae. tauschii</i> reference genome sequence, will facilitate gene discoveries and validations of agronomically important traits and their eventual fine transfer in bread wheat.