Abscission zone development in Setaria viridis and its domesticated relative, Setaria italica

Abstract

The AZ in Setaria is developmentally and anatomically different from that characterized in rice, barley, and many eudicots. In particular, no set of small, densely cytoplasmic cells is obvious. This difference in anatomy could point to differential genetic control of the structure.

Divergent gene expression networks underlie morphological diversity of abscission zones in grasses

“…In Setaria, cells in the AZ lack lignin entirely except in the epidermis, confirming previous data ( Fig. 2c) (Hodge & Kellogg, 2016). TEM shows that cells in the rice AZ are thin-walled and cytoplasmically dense, while the adjacent cells are thick-walled, indicating secondary cell wall deposition (Fig.…”

“…The AZ of rice and Brachypodium is located in the rachilla, although Brachypodium has multiple fertile florets and therefore multiple AZs within a spikelet while rice has only one. 2c) (Hodge & Kellogg, 2016). 1b).…”

“…One possible explanation is that these genes might be expressed in the AZ but at times different from the two captured by our RNA-Seq experiment. 6i-l), presumably the secondary AZ of Setaria, in which abscission occurs less frequently and later than at the pedicel AZ (Hodge & Kellogg, 2016). Therefore, we used in situ hybridisation at three stages of development in which the oldest (Stage 3, S3 hereafter) is the young stage of our RNA-Seq experiment (Figs 6-9).…”

TheSetaria viridisgenome and diversity panel enables discovery of a novel domestication gene

“…A zone of specialized cells, the abscission zone (AZ), forms below the spikelet during seed maturation, and loss of connections between the cells of the AZ result in cell separation and seed drop. Setaria italica (foxtail millet) is the domesticated form of S. viridis; like most domesticates it fails to form an AZ and thus is non-shattering 8 . While loss of shattering has been an important early step in the domestication of all cultivated grasses, the genes involved generally differ among species 7,[9][10][11][12] .…”

Setaria: A Food Crop and Translational Research Model for C4 Grasses

“…Mutant populations have been characterized in both foxtail millet and green foxtail millet, and the identity of candidate genes was revealed by novel high-throughput sequencing approaches (Li et al, 2016; Liu et al, 2016; Martins et al, 2016; Xue et al, 2016). S. italica and S. viridis have been used in the characterization of important agronomic traits, including yield-related architectural traits such as height, branching, biomass, flowering time and domestication-related traits such as shattering (Qian et al, 2012; Jia et al, 2013; Mauro-Herrera et al, 2013; Wang et al, 2013; Doust et al, 2014; Gupta et al, 2014; Layton and Kellogg, 2014; Qie et al, 2014; Fahlgren et al, 2015; Fang et al, 2016; Hodge and Kellogg, 2016; Liu et al, 2016; Mauro-Herrera and Doust, 2016). …”