* kobafumi@affrc.go.jp

Wild wheat relatives carry abundant natural variations and have been used for wheat breeding through synthetic hexaploids and alien chromosome introgression lines. We have newly generated about 200 synthetic polyploids through interspecific crossing between a tetraploid wheat accession Triticum turgidum L. ssp. durum cv.

‘Langdon’ [AABB genome] as the female parent and various wild relatives as the pollen parents. The synthetic polyploids include hexaploids, octoploids and decaploids, and their pollen parents are diploids (Ae. tauschii Cosson [DD genome], Ae. umbellulata Zhuk. [UU genome], Ae. uniaristata Vis. [NN genome], Ae. commosa Sm. In Sibth. & Sm. [MM genome], T. monococcum ssp. aegilopoides (Link) Thell. [AmAm genome] and T. urartu Tumanian ex Gandilyan [AA genome]), tetraploids (Ae. biuncialis Vis. [UUMM genome], Ae. columnaris Zhuk. [UUMM genome], Ae. kotschyi Boiss. [SSUU genome], Ae. geniculate Roth [UUMM genome] and Ae. peregrina (Hackel in J. Fraser) Maire & Weille [UUSS genome]) and hexaploids (Ae. juvenalis (Thell.) Eig [DDMMUU genome] and Ae. vavilovii (Zhuk.) Chenn. [DDMMSS genome]), respectively.

In general, Ae. tauschii is the most frequent parent of the synthetic polyploids, but we have succeeded in generating novel synthetic polyploids using other wild relatives. In this study, we investigated the characteristics of these lines and analyzed the effects of genomes derived from wild relatives on tested traits. We evaluated several agronomic traits of synthetic polyploids under field conditions. In the synthetic hexaploids, alterations in traits occurred depending on the genome of the wild relatives.

For example, the AABBDD and AABBAmAm lines had longer culm and spike lengths and more spikelets and grain number per spike than the other lines. The AABBUU, AABBNN and AABBMM lines had higher numbers of effective tillers than the others. On the other hand, no clear differences in traits were observed depending on the genome of the wild relatives in the synthetic octoploids.

We have succeeded in screening salt-tolerant lines through salt stress test during germination.

In the future studies, we plan to evaluate the agronomic traits of synthetic polyploids under dry conditions. It is thus expected that the resources we have generated can contribute to improving wheat in response to recent and future climate changes. This study was supported by Cabinet Office, Government of Japan, Moonshot R&D Program for Agriculture, Forestry and Fisheries (funding agency: Bio-oriented Technology Research Advancement Institution).