Cenci Alberto, Chantret Nathalie, Rouard Mathieu
Bioversity International, Parc Scientifique Agropolis II, Montpellier, France.
AGAP, INRA, CIRAD, Université de Montpellier, Montpellier, France.
Front Plant Sci. 2018 Dec 11;9:1843. doi: 10.3389/fpls.2018.01843. eCollection 2018.
Plant cell walls play a fundamental role in several plant traits and also influence crop use as livestock nutrition or biofuel production. The Glycosyltransferase family 61 (GT61) is involved in the synthesis of cell wall xylans. In grasses (Poaceae), a copy number expansion was reported for the GT61 family, and raised the question of the evolutionary history of this gene family in a broader taxonomic context. A phylogenetic study was performed on GT61 members from 13 species representing the major angiosperm clades, in order to classify the genes, reconstruct the evolutionary history of this gene family and study its expansion in monocots. Four orthogroups (OG) were identified in angiosperms with two of them displaying a copy number expansion in monocots. These copy number expansions resulted from both tandem and segmental duplications during the genome evolution of monocot lineages. Positive selection footprints were detected on the ancestral branch leading to one of the orthogroups suggesting that the gene number expansion was accompanied by functional diversification, at least partially. We propose an OG-based classification framework for the GT61 genes at different taxonomic levels of the angiosperm useful for any further functional or translational biology study.
植物细胞壁在多种植物性状中发挥着重要作用，并且还会影响作物作为牲畜饲料或生物燃料生产的用途。糖基转移酶61家族（GT61）参与细胞壁木聚糖的合成。在禾本科植物中，已报道GT61家族存在拷贝数扩增现象，这在更广泛的分类背景下引发了该基因家族进化历史的问题。对代表主要被子植物分支的13个物种的GT61成员进行了系统发育研究，以便对这些基因进行分类，重建该基因家族的进化历史，并研究其在单子叶植物中的扩增情况。在被子植物中鉴定出四个直系同源组（OG），其中两个在单子叶植物中显示出拷贝数扩增。这些拷贝数扩增是由单子叶植物谱系基因组进化过程中的串联重复和片段重复导致的。在导致其中一个直系同源组的祖先分支上检测到正选择足迹，这表明基因数量的扩增至少部分伴随着功能多样化。我们提出了一个基于OG的分类框架，用于被子植物不同分类水平的GT61基因，这对任何进一步的功能或转化生物学研究都很有用。
