Poplar GATA transcription factor PdGNC is capable of regulating chloroplast ultrastructure, photosynthesis, and vegetative growth in Arabidopsis under varying nitrogen levels

Photosynthesis and nitrogen availability are crucial to the accumulation of biomass. The GATA transcription factor family plays important roles in chloroplast development and nitrogen metabolism. Here, we cloned, for the first time, the GATA transcription factor PdGNC from the fast-growing poplar clone NE-19. The overexpression results from Arabidopsis under high nitrate, sufficient nitrate, and low nitrate (LN) support that PdGNC increased the chloroplast number and size per cell in leaf and stem, improved the chlorophyll level by 26.12 % and exhibited the highest starch content in LN. Overexpression of PdGNC also had pronounced effects on chloroplast ultrastructure by increasing the number of grana and thylakoids. The photosynthetic rate in transgenic LN lines was 42.17 % higher than in the wild type through modification of the chlorophyll fluorescence parameters F-v/F-0, F-v/F-m, qP, NPQ, and I broken vertical bar(PSII). Morphologically, PdGNC promoted longer primary roots and larger leaf areas, and exhibited a higher relative growth rate in LN. Altogether, PdGNC improved photosynthetic capacity and plant growth under low nitrate levels; thus, it could potentially be used in transgenic breeding to improve nitrate utilization and plant growth rates under limited nitrogen conditions.