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

生殖器官的同化物供应通过影响籽粒数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养分吸收的不同转移组织的建立有关。了解触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测序意外地发现大麦胚乳传递细胞(ETCs)分化的主要信号转导途径是双组分信号转导(TCS)磷酸转导途径。TCS元件的ETC特异性共表达模块和已证实的蛋白质相互作用表明信号元件参与了不同的磷传递。激素依赖的转录激活和相关数据表明，在ETC分化过程中，ABA/乙烯和TCS磷酸传递存在串扰。组氨酸激酶(HvHK1)转录量显著减少的RNAi品系在中央ETC区域显示低分化的细胞，缺少特征的细胞壁内长，且颗粒较小，淀粉积累显著减少。正在发展中的ETC区域的RNA-SEQ计划用于阐明HvHK1依赖的途径和调控网络。Talen诱导的C型反应调节因子HvRR15和/或基因拷贝的基因修饰诱导了强烈的胚乳特异性表型，中央胚乳显著破坏，翅区糊粉分化异常。进一步的组织学观察和分子分析将提炼出激动型。综合的组织特异性表达分析表明，进一步的候选TCS基因在穗状花序和籽粒的维管系统中优先表达。通过新开发的CRISPR/Cas9-技术击倒候选人将破译Planta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.