Root hair lifespan is antagonistically controlled by autophagy and programmed cell death

Abstract

Root hairs are tubular tip-growing extensions of root epidermal cells that enhance root surface area for water and nutrient uptake. While mechanisms governing root hair fate, polarity, and tip growth are well understood, the regulation of root hair longevity remains largely unknown. Here, we show that root hair cells employ high levels of autophagy to promote their lifespan. Loss-of-function mutations in the autophagy regulators ATG2, ATG5, or ATG7 induce a premature, cell-autonomous cell death program. This cell death is activated via a gene regulatory network downstream of the NAC transcription factors ANAC046 and ANAC087. Our findings uncover an antagonistic relationship between autophagy and developmentally controlled cell death in root hair lifespan regulation, with potential implications for optimizing plant nutrient and water uptake in crop breeding. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=193 SRC="FIGDIR/small/643910v1_ufig1.gif" ALT="Figure 1"> View larger version (80K): org.highwire.dtl.DTLVardef@1bd570borg.highwire.dtl.DTLVardef@19db5eborg.highwire.dtl.DTLVardef@11279fborg.highwire.dtl.DTLVardef@661c7_HPS_FORMAT_FIGEXP M_FIG C_FIG