AUTHOR=Lian Conglong , Li Qing , Yao Kun , Zhang Ying , Meng Sen , Yin Weilun , Xia Xinli 

TITLE=Populus trichocarpa PtNF-YA9, A Multifunctional Transcription Factor, Regulates Seed Germination, Abiotic Stress, Plant Growth and Development in Arabidopsis

JOURNAL=Frontiers in Plant Science

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2018.00954

DOI=10.3389/fpls.2018.00954

ISSN=1664-462X

ABSTRACT=<p><italic>NF-YAs</italic> play important roles in abiotic stress. However, their characteristics and functions in abiotic stress of <italic>poplar</italic>, a model woody plant, have not been fully investigated. Here, the biological functions of <italic>PtNF-YA9</italic> (Potri.011G101000), an <italic>NF-YA</italic> gene from <italic>Populus trichocarpa</italic>, were first fully investigated. PtNF-YA9 is located in the nucleus. The expression of <italic>PtNF-YA9</italic> was reduced by mannitol, NaCl, and abscisic acid (ABA). The GUS staining of ProNF-YA9::GUS transgenic lines was also reduced by mannitol treatments. In the <italic>PtNF-YA9</italic>-overexpressed <italic>Arabidopsis</italic> (OxPtNA9), OxPtNA9 lines exhibited sensitivity to simulated drought, ABA, and salinity stress during germination stage, and growth arrest emerged at post-germination stage. These phenomena might involve the ABA signaling pathway via the regulation of <italic>ABI3</italic>, <italic>ABI4</italic>, and <italic>ABI5</italic>. At vegetative stages, OxPtNA9 lines decreased in water loss via promoting stomatal closure and displayed high instantaneous water-use efficiency (WUE) of the leaf to exhibit enhanced drought tolerance. Furthermore, OxPtNA9 lines exhibited long primary root in the half-strength Murashige–Skoog agar medium supplemented with NaCl and conferred strong tolerance in the soil under salt stress. Additionally, <italic>PtNF-YA9</italic> exhibited dwarf phenotype, short hypocotyl, small leaf area and biomass, delayed flowering, and increased chlorophyll content. Above all, our research proposes a model in which <italic>PtNF-YA9</italic> not only plays a key role in reducing plant growth but also can play a primary role in the mechanism of an acclimatization strategy in response to adverse environmental conditions.</p>