Interaction of hormonal and two component signaling pathways - regulatory modules determining differentiation of transfer tissues in barley

同化物对生殖器官的供应通过影响籽粒数量和籽粒大小对大麦等谷类作物的产量产生重大影响。小穗/小花和籽粒的发育与穗和籽粒中维管束的分化以及子代籽粒器官特别是胚乳中营养吸收的不同转移组织的建立有关。了解引发转移组织分化的分子基础和调控网络是提高产量潜力的先决条件。组织特异性454和Illumina测序出乎意料地鉴定出双组分信号（TCS）磷酸传递是大麦胚乳转移细胞（ETC）分化的主要信号转导途径。TCS元件的ETC特异性共表达模块和确认的蛋白质相互作用精确定位于不同磷酸化继电器中信号传导元件的参与。激素依赖的转录激活和相关数据显示，在ETC分化过程中阿坝/乙烯和TCS磷传递的串扰。组氨酸激酶（HvHK 1）转录量大幅减少的RNAi系显示，ETC中心区域的细胞分化较差，缺少特征性的细胞壁向内生长和淀粉积累大幅减少的较小籽粒。正在开发的ETC区域的RNA-seq计划阐明HvHK 1依赖性途径和调控网络。TALEN诱导的C型反应调节因子HvRR 15和/或基因拷贝的基因修饰诱导了强烈的胚乳特异性表型，具有中央胚乳的显著破坏和翅区的异常糊粉层分化。进一步的组织学观察和分子生物学分析将进一步完善令人兴奋的表型。全面的组织特异性表达分析揭示了进一步的候选TCS基因优先在穗和谷粒的脉管系统中表达。通过新开发的CRISPR/CAS9技术敲除候选人将破译植物中的功能。

Assimilate supply to reproductive organs has a major impact on yield in cereal crops like barley by affecting grain number and grain size. The development of spikelets/florets and grains is associated with differentiation of vascular bundles in spikes and grains and establishment of distinct transfer tissues for nutrient uptake in filial grain organs, particularly the endosperm. Understanding the molecular basis and regulatory networks triggering differentiation of transfer tissues is a prerequisite for improvement of yield potential. Tissue-specific 454 and Illumina sequencing unexpectedly identified two-component signaling (TCS) phosphorelays as major signal transduction pathway in differentiating endosperm transfer cells (ETCs) of barley. ETC-specific co-expression modules of TCS elements and confirmed protein interactions pinpoint to a participation of signaling elements in distinct phosphorelays. Hormone-dependent transcriptional activation and correlative data revealed a crosstalk of ABA/ethylene and TCS phosphorelays during ETC differentiation. RNAi-lines with strongly reduced histidine kinase (HvHK1) transcript amounts showed poorly differentiated cells in the central ETC region, missing characteristic cell wall ingrowths and smaller grains with strongly reduced starch accumulation. RNA-seq of the developing ETC region is planned to elucidate HvHK1-dependent pathways and regulatory networks. TALEN-induced gene modification of the type-C response regulator HvRR15 and/or gene copies induced a strong endosperm-specific phenotype with a prominent disruption of the central endosperm and abnormal aleurone differentiation in the wing region. Further histological observation and molecular analysis will refine the exciting phenotype. Comprehensive tissue-specific expression analysis revealed further candidate TCS genes preferentially expressed in the vasculature of spikes and grains. Knock-out of candidates by the newly developed CRISPR/CAS9-technology will decipher the function in planta.