芍药茎纤维素特征及其生长素调节机制

芍药是我国传统名花，也是国际市场的新切花，我国有丰富的资源，但切花品种较少，主要问题是茎直立性不够。直立性是切花作物的重要农艺性状，目前影响芍药花茎直立性的因素不完全清楚，给切花栽培和育种带来困惑。本课题组前期研究发现，直立性明显不同的芍药品种在发育过程中，除了木质素的差异，茎中纤维素含量、生长素和纤维素合成相关基因的表达也有明显差异。该研究以前期研究使用的直立‘大富贵’和弯茎‘垂头红’为对象，测定不同品种直立性出现差异时期的纤维素合成底物及其关键酶活性、纤维素含量、生长素含量；采用原子力显微镜和X-射线衍射仪研究纤维素结构及排列；明确直立性不同品种上述特征的关键差异。在此基础上，施用外源生长素和纤维素合成抑制剂，观测其对关键差异因子的影响；利用转录组和蛋白组测序方法，探究生长素对芍药茎纤维素合成及调控的影响。目的是探究纤维素对芍药直立性的影响及其作用机制，为芍药切花品种选育提供理论依据。

Paeonia lactiflora, a traditional famous flower in China, also is an important cut flower in the international market. There are many cultivars in China, but a few are suitable for cut flowers due to poor inflorescence stem straightness. Stem straightness is an essential agronomic characteristic of cut flowers. Currently, the factors that affect the inflorescence stem straightness of P. lactiflora are not clear, which hinder its cultivation and breeding. Our previous studies found several significant differences beyond lignin, including cellulose content and genes related to auxin and cellulose biosynthesis in cultivars with distinctly different straightness during their stem development. The objective of this study is to investigate the key differences (KDs) in cellulose characteristics, auxin content ,both relationship with stem straightness of P. lactiflora ‘Da Fugui’ and ‘Chui Touhong’, two cultivars with significantly different inflorescence stem straightness used previously. At the end of stem elongation, enzyme activity of cellulose synthesis substrate, cellulose and auxin content will be measured. The structure and arrangement of cellulose in stems will be explored by atomic force microscope and X-ray diffractometer. Then we will investigate the effect of auxin on cellulose biosynthesis and regulation with exogenous auxin and cellulose synthesis inhibitor using, respectively, and explore its effect on KDs. Next, the transcriptome and iTRAQ proteome sequencing are used to study the molecular mechanisms of interaction. Combining with the above results, we hope to reveal the role of cellulose on straightness of inflorescence stems in P. lactiflora and the mechanism of IAA on it ,so as to provide a theoretical basis for the selection and breeding of cut herbaceous peonies.