Ta K N, Adam H, Staedler Y M, Schönenberger J, Harrop T, Tregear J, Do N V, Gantet P, Ghesquière A, Jouannic S
UMR DIADE, IRD, 911, Avenue Agropolis, BP 64501, 34394 Montpellier Cedex 5, France.
LMI RICE, IRD, USTH, National Key Laboratory for Plant Cell Biotechnology, Agronomical Genetics Institute, Pham Van Dong Road, Hanoi, Vietnam.
Evodevo. 2017 Jan 28;8:2. doi: 10.1186/s13227-017-0065-y. eCollection 2017.
The African rice was domesticated from its wild relative about 3000 years ago. During the domestication process, panicle complexity changed from a panicle with low complexity in , to a highly branched panicle carrying more seeds in . To understand the basis of this differential panicle development between the two species, we conducted morphological and molecular analyses of early panicle development.
Using X-ray tomography, we analyzed the morphological basis of early developmental stages of panicle development. We uncovered evidence for a wider rachis meristem in than in . At the molecular level, spatial and temporal expression profiles of orthologs of genes related to meristem activity and meristem fate control were obtained using in situ hybridization and qRT-PCR. Despite highly conserved spatial expression patterns between and , differences in the expression levels of these early acting genes were detected.
The higher complexity of the panicle compared to that of its wild relative is associated with a wider rachis meristem and a modification of expression of branching-related genes. Our study indicates that the expression of genes in the // and pathways, along with that of their target genes, is altered from the unbranched stage of development. This suggests that differences in panicle complexity between the two African rice species result from early alterations to gene expression during reproductive development.
非洲栽培稻大约在3000年前从其野生近缘种驯化而来。在驯化过程中，圆锥花序的复杂性从野生稻中低复杂性的圆锥花序，转变为栽培稻中携带更多种子的高度分支的圆锥花序。为了了解这两个物种之间圆锥花序发育差异的基础，我们对圆锥花序早期发育进行了形态学和分子分析。
利用X射线断层扫描技术，我们分析了圆锥花序发育早期阶段的形态学基础。我们发现栽培稻的穗轴分生组织比野生稻的更宽。在分子水平上，利用原位杂交和qRT-PCR获得了与分生组织活性和分生组织命运控制相关基因直系同源物的时空表达谱。尽管栽培稻和野生稻之间的空间表达模式高度保守，但这些早期作用基因的表达水平存在差异。
与野生近缘种相比，栽培稻圆锥花序更高的复杂性与更宽的穗轴分生组织以及分支相关基因表达的改变有关。我们的研究表明，在生殖发育过程中，从无分支阶段开始，//和途径中的基因及其靶基因的表达就发生了改变。这表明两个非洲稻种之间圆锥花序复杂性的差异是生殖发育过程中基因表达早期改变的结果。
