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

First author: Yunqing Yu; Affiliations: Donald Danforth Plant Science Center (Donald Danforth植物科学中心): St Louis, USA

Corresponding author: Elizabeth A. Kellogg

Abscission is a process in which plants shed their parts, and is mediated by a particular set of cells, the abscission zone (AZ). In grasses (Poaceae), the position of the AZ differs among species, raising the question of whether its anatomical structure and genetic control are conserved. The ancestral position of the AZ was reconstructed. A combination of light microscopy, transmission electron microscopy, RNA‐Seq analyses and RNA in situ hybridisation were used to compare three species, two (weedy rice and Brachypodium distachyon) with the AZ in the ancestral position and one (Setaria viridis) with the AZ in a derived position below a cluster of flowers (spikelet). Rice and Brachypodium are more similar anatomically than Setaria. However, the cell wall properties and the transcriptome of rice and Brachypodium are no more similar to each other than either is to Setaria. The set of genes expressed in the studied tissues is generally conserved across species, but the precise developmental and positional patterns of expression and gene networks are almost entirely different. Transcriptional regulation of AZ development appears to be extensively rewired among the three species, leading to distinct anatomical and morphological outcomes.

脱落是指植物取出其部分器官组织的过程，该过程由一系列特定的细胞所介导，这类细胞就叫做离区。在草类植物禾本科中，离区的位置在不同物种之间各不相同，这不禁让人想到草类植物离区的解剖学结构和遗传调控机制是否保守。作者重建了草类植物祖先种中离区的位置。通过结合光学显微镜、透射电子显微镜、转录组测序分析以及RNA原位杂交，作者比较了三个草类植物的离区，其中两个杂草稻和短柄草的离区位置与祖先种保持一致，另外一个狗尾草的离区有所不同，其位置处于一簇小穗下。三者之间，水稻和短柄草离区的解剖学结构更加相近。然而，细胞壁特性与转录组特征并不表明水稻与短柄草离区之间的相似性要比更狗尾草的更加相似。不同物种，同一组织表达的基因通常都是保守的，但基因表达的时空模式以及基因网络通常都完全不同。这三个物种离区发育的转录调控显然都具有各自的特征，进而导致了解剖学和形态上的差异性。

通讯：Elizabeth A. Kellogg（https://www.danforthcenter.org/scientists-research/principal-investigators/Elizabeth-Kellogg?__sw_csrfToken=3QEuXgk2kcANrA0N8PkME2rYNaru4ghE)

个人简介：1973年，哈佛大学，学士；1977年，爱达荷大学，硕士；1983年，哈佛大学，博士。

研究方向：谷类作物及其野生近缘种。

doi: https://doi.org/10.1111/nph.16087

Journal: New Phytologist

Published online: August 28, 2019