Summer dormancy in Elymus scaber and its hybridity with wheat

This study examined the nature of summer dormancy in E. scaber and reports on hybridisation attempts with a range of wheat genotypes to determine the suitability of E. scaber as a donor species in the development of ‘perennial wheat’. In a field experiment, E. scaber populations sourced from agro-ecologically diverse sites in south-eastern Australia, were subjected to three irrigation treatments to test their level of summer dormancy. The tillering reaction to opportunistic summer moisture was the same across all populations and suggests that summer dormancy is facultative in populations of E. scaber, rather than complete as previously reported. Using E. scaber as a pollen source, attempts were made to fertilise 16 wheat cultivars, used as emasculated female parents. Two rescue techniques were used to recover immature embryos at 24–48 h and 14 days post-pollination. Pollinated wheat spikes showed high proportions of early seed set, indicating fertilisation was taking place, however embryo recovery was very low. Several putative hybrid plants were recovered from both rescue techniques. PCR testing of the recovered plants was unable to detect E. scaber DNA and surviving plants were entirely like the wheat parent and fully fertile, suggesting either these plants were the result of rare self-pollination or doubled haploids following E. scaber chromosome elimination. The short lived nature of E. scaber along with challenges associated with crossing this species to wheat, has led the authors to conclude that E. scaber is not a priority candidate to be used as a perennial donor species in perennial grain development.