Pentaploid Wheat Hybrids: Applications, Characterisation, and Challenges

Abstract

Interspecific hybridisation between hexaploid and tetraploid wheat species leads to the development of F₁ pentaploid hybrids with unique chromosomal constitutions. Pentaploid hybrids derived from bread wheat (Triticum aestivum L.) and durum wheat (Triticum turgidum spp. durum Desf.) crosses can improve the genetic background of either parent by transferring traits of interest. The genetic variability derived from bread and durum wheat and transferred into pentaploid hybrids has the potential to improve disease resistance, abiotic tolerance, and grain quality, and to enhance agronomic characters. Nonetheless, pentaploid wheat hybrids have not been fully exploited in breeding programs aimed at improving crops. There are several potential barriers for efficient pentaploid wheat production, such as low pollen compatibility, poor seed set, failed seedling establishment, and frequent sterility in F₁ hybrids. However, most of the barriers can be overcome by careful selection of the parental genotypes and by employing the higher ploidy level genotype as the maternal parent. In this review, we summarize the current research on pentaploid wheat hybrids and analyze the advantages and pitfalls of current methods used to assess pentaploid-derived lines. Furthermore, we discuss current and potential applications in commercial breeding programs and future directions for research into pentaploid wheat.

Keywords: Triticum aestivum; Triticum turgidium spp. durum; in situ hybridisation; interploidy crosses; pentaploid hybrids.

FIGURE 1

Summary of pentaploid wheat production for bread and durum wheat improvement. BC, back crossing.

FIGURE 2

Summary of D-genome chromosome retention in hexaploid/tetraploid and tetraploid/hexaploid crosses. Durum wheat Group-1 (lines with no or intermediate number of D chromosomes) is indicated in black and bread wheat Group-2 (lines with at least one copy of all seven D chromosomes) in white. The cross which has a tetraploid maternal parent is indicated with a green box. The proportion of D-genome chromosomes retained in each cross is indicated on the X-axis.