The Ectopic Expression of Btr2 in Aegilops tauschii Switches the Disarticulation Layer From Above to Below the Rachis Node

Xiaoxue Zeng; Akemi Tagiri; Shinji Kikuchi; Hidenori Sassa; Takao Komatsuda

doi:10.3389/fpls.2020.582622

The Ectopic Expression of Btr2 in Aegilops tauschii Switches the Disarticulation Layer From Above to Below the Rachis Node

Front Plant Sci. 2020 Nov 9:11:582622. doi: 10.3389/fpls.2020.582622. eCollection 2020.

Authors

Xiaoxue Zeng^{1

2}, Akemi Tagiri¹, Shinji Kikuchi², Hidenori Sassa², Takao Komatsuda^{1

2}

Affiliations

¹ Institute of Crop Science, National Agriculture and Food Research Organization (NARO), Tsukuba, Japan.
² Graduate School of Horticulture, Chiba University, Matsudo, Chiba, Japan.

Abstract

Seed dispersal among wild species belonging to the tribe Triticeae is typically achieved by the formation of a brittle rachis. The trait relies on the development of a disarticulation layer, most frequently above the rachis node (resulting in wedge type dispersal units), but in some species below the rachis node (resulting in barrel type dispersal units). The genes responsible for the former type are the complementary pair Btr1 and Btr2, while the genetic basis of the latter type has yet to be determined. Aegilops tauschii forms barrel type dispersal units and previous study showed this species lacked an intact copy of Btr1. Here it has been demonstrated that Ae. tauschii carries two of Btr2; and that Btr2 transcript is present in a region below the rachis node where the abscission zone forms. The implication is that in this species, the Btr2 product is involved in the formation of barrel type dispersal units.

Keywords: abscission zone; barrel type dispersal units; cell wall; ectopic expression; lignin; triticeae.