The Brittle Rachis Trait in Species Belonging to the Triticeae and Its Controlling Genes Btr1 and Btr2

Xiaoxue Zeng; Kohei Mishina; Juqing Jia; Assaf Distelfeld; Peter Jeff Maughan; Shinji Kikuchi; Hidenori Sassa; Takao Komatsuda

doi:10.3389/fpls.2020.01000

The Brittle Rachis Trait in Species Belonging to the Triticeae and Its Controlling Genes Btr1 and Btr2

Front Plant Sci. 2020 Jul 22:11:1000. doi: 10.3389/fpls.2020.01000. eCollection 2020.

Authors

Xiaoxue Zeng^{1

2}, Kohei Mishina¹, Juqing Jia¹, Assaf Distelfeld³, Peter Jeff Maughan⁴, 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, Japan.
³ School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv, Israel.
⁴ Department of Plant & Wildlife Sciences, Brigham Young University, Provo, UT, United States.

Abstract

In many non-cultivated angiosperm species, seed dispersal is facilitated by the shattering of the seed head at maturity; in the Triticeae tribe, to which several of the world's most important cereals belong, shattering takes the form of a disarticulation of the rachis. The products of the genes Btr1 and Btr2 are both required for disarticulation to occur above the rachis nodes within the genera Hordeum (barley) and Triticum/Aegilops (wheat). Here, it has been shown that both Btr1 and Btr2 are specific to the Triticeae tribe, although likely paralogs (Btr1-like and Btr2-like) are carried by the family Poaceae including Triticeae. Aegilops tauschii (the donor of the bread wheat D genome) lacks a copy of Btr1 and disarticulation in this species occurs below, rather than above the rachis node; thus, the product of Btr1 appears to be required for disarticulation to occur above the rachis node.

Keywords: Triticeae; disarticulation; duplication; phylogeny; seed dispersal.