Arabidopsis MORE AXILLARY GROWTH2 (MAX2) is a key component in the strigolactone (SL) and karrikin (KAR) signaling pathways and regulates the degradation of SUPPRESSOR OF MAX2 1/ SMAX1-like (SMAX1/SMXL) proteins, which are transcriptional co-repressors that regulate plant architecture, as well as abiotic and biotic stress responses. The max2 mutation reduces resistance against Pseudomonas syringae pv. tomato (Pst). To uncover the mechanism of MAX2-mediated resistance, we evaluated the resistance of various SL and KAR signaling pathway mutants. The resistance of SL-deficient mutants and of dwarf 14 (d14) was similar to that of the wild-type, whereas the resistance of the karrikin insensitive 2 (kai2) mutant was compromised, demonstrating that the KAR signaling pathway, not the SL signaling

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Arabidopsis Casparian strip membrane domain proteins (CASPs) form a transmembrane scaffold to recruit lignin biosynthetic enzymes for Casparian strip (CS) formation. Compared with Arabidopsis, rice root is more complex with a CS of the exodermis and sclerenchyma and a CS that does not block propidium iodide entry into the stele. Rice CASP1 is highly similar to AtCASPs, but it is not required for CS formation. Its mutation results in early leaf senescence and fewer tillers and does not change the CS structure and permeability. OsCASP1 is mainly located in the nuclear membrane. Its expression is concentrated in the root stele and at small lateral root tips and can be induced by salt stress. OsCASP1 mutation causes ectopic suberin deposition in small lateral roots and ion imbalances in the plant. Homeostatic disorder induces nutrient recycling and accelerate leaf senescence. To our knowledge, OsCASP1 is the first CASP to be described in the nuclear membrane; it modulates suberin deposition and does not involve CS formation, representing a novel regulatory mode of CASPs.Rice CASP1 regulates suberin deposition in small lateral roots and plays crucial role in metal homeostasis in plant