*Wx* **Gene in** *Hordeum chilense:* **Chromosomal Location and Characterisation of the Allelic Variation in the Two Main Ecotypes of the Species**

### **Juan B. Alvarez \*, Laura Castellano, Rocío Recio and Adoración Cabrera**

Departamento de Genética, Escuela Técnica Superior de Ingeniería Agronómica y de Montes, Edificio Gregor Mendel, Campus de Rabanales, Universidad de Córdoba, CeiA3, ES-14071 Córdoba, Spain; a02caall@uco.es (L.C.); rorecas@gmail.com (R.R.); ge1cabca@uco.es (A.C.)

**\*** Correspondence: jb.alvarez@uco.es

Received: 17 April 2019; Accepted: 17 May 2019; Published: 22 May 2019

**Abstract:** Starch, as the main grain component, has grea<sup>t</sup> importance in wheat quality, with the ratio between the two formed polymers, amylose and amylopectin, determining the starch properties. Granule-bound starch synthase I (GBSSI), or waxy protein, encoded by the *Wx* gene is the sole enzyme responsible for amylose synthesis. The current study evaluated the variability in *Wx* genes in two representative lines of *Hordeum chilense* Roem. et Schult., a wild barley species that was used in the development of tritordeum (×*Tritordeum* Ascherson et Graebner). Two novel alleles, *Wx-Hch*1*a* and *Wx-Hch*1*b*, were detected in this material. Molecular characterizations of these alleles revealed that the gene is more similar to the *Wx* gene of barley than that of wheat, which was confirmed by phylogenetic studies. However, the enzymatic function should be similar in all species, and, consequently, the variation present in *H. chilense* could be utilized in wheat breeding by using tritordeum as a bridge species.

**Keywords:** starch; tritordeum; waxy proteins; wheat quality; wild barley
