Abstract
Chromosomal translocations in wheat derived from alien species are a valuable source of genetic diversity that have provided increases in resistance to various diseases and improved tolerance to abiotic stresses in wheat. These alien genomic segments can also affect multiple traits, with a concomitant ability to alter yield potential in either a positive or negative fashion. The aim of this work was to characterize the effects on yield of two types of translocations, namely T4-derived translocations from Thinopyrum ponticum, carrying the leaf rust resistance gene Lr19, and the TC14 translocation from Th. intermedium, carrying the barley yellow dwarf virus resistance gene Bdv2, in Australian adapted genetic backgrounds and under Australian conditions. A large range of germplasm was developed by crossing donor sources of the translocations into 24 Australian adapted varieties producing 340 genotypes. Yield trials were conducted in 14 environments to identify effects on yield and yield components. The T4 translocations had a positive effect on yield in one high yielding environment, but negatively affected yield in low-yielding environments. The TC14 translocation was generally benign, however, it was associated with a negative impact on yield and reduced height in two genetic backgrounds. The translocation was also associated with a delayed maturity in several backgrounds. The T4 translocations results were consistent with previously published data, whilst this is the first time that such an investigation has been undertaken on the TC14 translocation. Our data suggests a limited role for each of these translocations in Australia. The T4 translocations may be useful in high yielding environments, such as under irrigation in NSW and in the more productive high rainfall regions of south-eastern Australia. Traits associated with the TC14 translocation, such as BYDV resistance and delayed maturity, would make this translocation useful in BYDV-prone areas that experience a less pronounced terminal drought (e.g., south-eastern Australia).
Highlights
Hexaploid wheat (Triticum aestivum L.) has recently been estimated to have formed between230,000 and 430,000 years ago through rare hybridization events between diploid and tetraploid progenitors [1] with domestication occurring approximately 10,000 years ago
We investigated the effects of the T4 and TC14 translocations on yield in Australian genetic backgrounds under Australian conditions
Two sets of germplasm were developed to investigate the effects of the T4 translocation series, which consisted of the original yellow floured T4 translocation and two white floured mutants, Agatha
Summary
Hexaploid wheat (Triticum aestivum L.) has recently been estimated to have formed between230,000 and 430,000 years ago through rare hybridization events between diploid and tetraploid progenitors [1] with domestication occurring approximately 10,000 years ago. An effective method to increase genetic diversity is to introgress chromosomal segments into the wheat genome from wild relatives. These chromosomal translocations have been used to enhance resistance to various wheat diseases. Any deleterious genes that are introgressed along with the useful trait can be difficult to remove. One specific translocation on the 7DL chromosome of wheat, called variously 7Ag.7DL, Agatha or T4 [3,4,5], from Thinopyrum ponticum (tall wheatgrass), contained a number of characterized genes including Lr19 for leaf rust resistance, Sr25 for stem rust resistance, Sd1, a segregation distortion gene, and a linked gene deleterious for yellow pigment endosperm colour
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