GATA转录因子成员调控杨树抗旱生长的分子机制

Four GATA transcription factor genes, which have been cloned from fast-growing Populus genotype NE19，including PdGATA19 (PdGNC) and PdGATA14 from leaves, PdGATA31 from stems, and PdGATA6 from roots, will be focused on for functional investigation. Previously, we have successfully employed CRISPR/Cas9 editing system and overexpression transgenic technology to achieve PdGNC knock-out mutant events (crispr-GNC) and overexpressing transgenic poplar lines (oxPdGNC). The crispr-GATAs and oxPdGATAs poplars for the other three GATA genes will continue to be developed. We will analyze performance differences of growth and structure, nitrogen utilization, photosynthesis between crispr-GATAx、oxPGATAx and WT Poplars under long-term drought stress. Transcriptomic sequencing (RNA-seq) and Chromatin Immunoprecipitation Sequencing（ChIP-Seq）technology will be employed for screening candidate downstream target genes of GATAx genes. We will continue to identify the function of candidate gene by transgenic technology. Molecular physiological basis of 4 GATA family members in regulating the growth and biomass accumulation of poplar under normal and long-term drought stress will be explored. Our research will try to reveal the transcriptional regulatory pathways mediated by GATA members and provide theoretical basis for the improvement and breeding of drought resistance traits for woody plant.

本项目拟在前期从欧美杨NE19中克隆了GATA家族4个成员：PdGATA19(GNC)(叶中诱导表达)与PdGATA14(叶中诱导表达)、PdGATA31(茎中诱导表达)和PdGATA6（根中诱导表达），采用CRISPR/Cas9编辑和转化技术获得了杨树GNC基因敲除突变体(crispr-GNC)和超表达GNC株系(oxPdGNC)的基础上，继续培育3个GATA基因crispr-GATAx与oxPdGATAx株系。通过比较长期干旱胁迫下crispr-GATAx、oxPGATAx和WT杨在生长表型特征、光合和氮素利用等生理响应差异；利用RNA-seq与ChIP-seq技术联合分析筛选GATAx下游调控候选基因；鉴定候选靶基因功能；深入探讨GATA家族4个成员在干旱胁迫下调节杨树生长与生物量积累的分子生理机理，解析GATA成员介导杨树生长的转录调控途径，为树木抗旱生长性状选育与改良提供基础。

提高干旱条件下生产力是作物性状改良的重要目标，深入研究植物调控抗逆生长发育的分子机理有重要的理论意义与应用价值。本项目通过培育GATAx过量表达和CRISPR突变体转基因杨树，GATAx靶基因及GATAx途径下游调控基因功能研究，GATAx启动子特征分析，项目解析了GATA转录因子PdGATA19 和PdGATA13调控杨树抗旱生长的分子生理途径。发现PdGATA19通过直接调控PdHXK1在杨树中的表达，通过促进保卫细胞中NO和H2O2的产生，进一步减小气孔开度和提高水分利用效率来增强杨树的耐旱能力；发现PdGATA19直接激活了硝酸盐转运体PdNRT2.4b基因的启动子，显著增加了杨树在低硝酸盐供应水平下硝酸盐的吸收，PdGATA19-NRT2.4b模块在调节氮素利用效率和生长方面发挥了重要作用。PdGATA13可促进气孔关闭，提高植株的水分利用效率(WUE)，进一步提高抗旱性。另外，克隆与鉴定了杨树转录因子PdNF-YB21、PeSHN1、PeSTZ1、ABF3等、受体类激酶ERECTA等对抗旱生长性状表达有重要功能的基因。总之，本研究为通过生物育种提高杨树干旱条件生产力提供了重要的理论和技术依据。