Knock-Down of Arabidopsis PLC5 Reduces Primary Root Growth and Secondary Root Formation While Overexpression Improves Drought Tolerance and Causes Stunted Root Hair Growth

The study explored the effects of altering the expression of Phospholipase C (PLC5) in Arabidopsis thaliana. Knock-down of PLC5 led to slower primary root growth and fewer lateral roots, while overexpression of PLC5 resulted in improved drought tolerance but stunted root hair growth. Overexpression lines showed a 100- to 300-fold increase in PLC5 expression and exhibited altered lipid signaling, with decreased levels of PIP and PIP₂ and increased phosphatidic acid. The stunted root hair growth in overexpression lines could be reversed by overexpressing PIP5K3, which is involved in PIP₂ synthesis. The study, which included sample sizes greater than 200 for seedling measurements and three replicates for biochemical assays, concluded that PLC5 is crucial for root development and drought response, with PIP₂ playing a key role in root hair growth.