AUTHOR=Mishra Laxmi S. , Mishra Sanatkumar , Caddell Daniel F. , Coleman-Derr Devin , Funk Christiane 

TITLE=The Plastid-Localized AtFtsHi3 Pseudo-Protease of Arabidopsis thaliana Has an Impact on Plant Growth and Drought Tolerance

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.694727

DOI=10.3389/fpls.2021.694727

ISSN=1664-462X

ABSTRACT=<p>While drought severely affects plant growth and crop production, the molecular mechanisms of the drought response of plants remain unclear. In this study, we demonstrated for the first time the effect of the pseudo-protease AtFtsHi3 of <italic>Arabidopsis thaliana</italic> on overall plant growth and in drought tolerance. An <italic>AtFTSHi3</italic> knock-down mutant [<italic>ftshi3-1(kd)</italic>] displayed a pale-green phenotype with lower photosynthetic efficiency and Darwinian fitness compared to wild type (Wt). An observed delay in seed germination of <italic>ftshi3-1(kd)</italic> was attributed to overaccumulation of abscisic acid (ABA); <italic>ftshi3-1(kd)</italic> seedlings showed partial sensitivity to exogenous ABA. Being exposed to similar severity of soil drying, <italic>ftshi3-1(kd)</italic> was drought-tolerant up to 20 days after the last irrigation, while wild type plants wilted after 12 days. Leaves of <italic>ftshi3-1(kd)</italic> contained reduced stomata size, density, and a smaller stomatic aperture. During drought stress, <italic>ftshi3-1(kd)</italic> showed lowered stomatal conductance, increased intrinsic water-use efficiency (WUEi), and slower stress acclimation. Expression levels of ABA-responsive genes were higher in leaves of <italic>ftshi3-1(kd)</italic> than Wt; <italic>DREB1A</italic>, but not <italic>DREB2A</italic>, was significantly upregulated during drought. However, although <italic>ftshi3-1(kd)</italic> displayed a drought-tolerant phenotype in aboveground tissue, the root-associated bacterial community responded to drought.</p>