植物细胞(THE PLANT CELL)2013-09-05 2:57 AM

Deletion of a Tandem Gene Family in Arabidopsis: Increased MEKK2 Abundance Triggers Autoimmunity when the MEKK1-MKK1/2-MPK4 Signaling Cascade Is Disrupted

An Arabidopsis thaliana mitogen-activated protein (MAP) kinase cascade composed of MEKK1, MKK1/MKK2, and MPK4 was previously described as a negative regulator of defense response. MEKK1 encodes a MAP kinase kinase kinase and is a member of a tandemly duplicated gene family with MEKK2 and MEKK3. Using T-DNA insertion lines, we isolated a novel deletion mutant disrupting this gene family and found it to be phenotypically wild-type, in contrast with the mekk1 dwarf phenotype. Follow-up genetic analyses indicated that MEKK2 is required for the mekk1, mkk1 mkk2, and mpk4 autoimmune phenotypes. We next analyzed a T-DNA insertion in the MEKK2 promoter region and found that although it does not reduce the basal expression of MEKK2, it does prevent the upregulation of MEKK2 that is observed in mpk4 plants. This mekk2 allele can rescue the mpk4 autoimmune phenotype in a dosage-dependent manner. We also found that expression of constitutively active MPK4 restored MEKK2 abundance to wild-type levels in mekk1 mutant plants. Finally, using mass spectrometry, we showed that MEKK2 protein levels mirror MEKK2 mRNA levels. Taken together, our results indicate that activated MPK4 is responsible for regulating MEKK2 RNA abundance. In turn, the abundance of MEKK2 appears to be under cellular surveillance such that a modest increase can trigger defense response activation.

KEYWORDS

SHARE & LIKE

COMMENTS

ABOUT THE AUTHOR

植物细胞(THE PLANT CELL)

0 Following 1 Fans 0 Projects 47 Articles

SIMILAR ARTICLES

BINDING PROTEIN (BiP) is a major chaperone in the endoplasmic reticulum (ER) lumen, and this study shows that BiP binds to the C-terminal tail of the s

Read More

Vesicle trafficking plays an important role in cell division, establishment of cell polarity, and translation of environmental cues to developmental re

Read More

The genus Brassica includes several important agricultural and horticultural crops. Their current genome structures were shaped by whole-genome triplic

Read More

Trans-acting small interfering RNAs (tasiRNAs) are a major class of small RNAs performing essential biological functions in plants. The first reported

Read More

RK5 is a member of the Arabidopsis thaliana Ca2+/calmodulin-dependent kinase-related kinase family. Here, we show that inactivation of CRK5 inhibits pr

Read More

The waxy plant cuticle protects cells from dehydration, repels pathogen attack, and prevents organ fusion during development. The transcription factor

Read More

Constrained to develop within the seed, the plant embryo must adapt its shape and size to fit the space available. Here, we demonstrate how this adjust

Read More

N-myristoylation is a crucial irreversible eukaryotic lipid modification allowing a key subset of proteins to be targeted at the periphery of specific

Read More

Exocysts are highly conserved octameric complexes that play an essential role in the tethering of Golgi-derived vesicles to target membranes in eukaryo

Read More

Apical actin filaments are crucial for pollen tube tip growth. However, the specific dynamic changes and regulatory mechanisms associated with actin fi

Read More