Integrated Dual-Channel Retrograde Signaling Directs Stress Responses by Degrading the HAT1/TPL/IMPα-9 Suppressor Complex and Activating CAMTA3.

Unlabelled: The intricate communication between plastids and the nucleus, shaping stress-responsive gene expression, has long intrigued researchers. This study combines genetics, biochemical analysis, cellular biology, and protein modeling to uncover how the plastidial metabolite MEcPP activates the stress-response regulatory hub known as the Rapid Stress Response Element (RSRE). Specifically, we identify the HAT1/TPL/IMPα- 9 suppressor complex, where HAT1 directly binds to RSRE and its activator, CAMTA3, masking RSRE and sequestering the activator.

Activation of stress-response genes by retrograde signaling-mediated destabilization of nuclear importin IMPα-9 and its interactor TPR2.

Stress-induced retrograde signal transmission from the plastids to the nucleus has long puzzled plant biologists. To address this, we performed a suppressor screen of the ceh1 mutant, which contains elevated 2-C-methyl-d-erythritol-2,4-cyclopyrophosphate (MEcPP) levels, and identified the gain-of-function mutant impα-9, which shows reversed dwarfism and suppressed expression of stress-response genes in the ceh1 background despite heightened MEcPP. Subsequent genetic and biochemical analyses established that the accumulation of MEcPP initiates an upsurge in Arabidopsis SKP1-like 1 (ASK1) abundance, a pivotal component in the proteasome degradation pathway.

Ice plant root plasma membrane aquaporins are regulated by clathrin-coated vesicles in response to salt stress.

The regulation of root Plasma membrane (PM) Intrinsic Protein (PIP)-type aquaporins (AQPs) is potentially important for salinity tolerance. However, the molecular and cellular details underlying this process in halophytes remain unclear. Using free-flow electrophoresis and label-free proteomics, we report that the increased abundance of PIPs at the PM of the halophyte ice plant (Mesembryanthemum crystallinum L.

A differential subcellular localization of two copper transporters from the COPT family suggests distinct roles in copper homeostasis in Physcomitrium patens.

The moss Physcomitrium (Physcomitrella) patens is a bryophyte that provides genetic information about the adaptation to the life on land by early Embryophytes and is a reference organism for comparative evolutionary studies in plants. Copper is an essential micronutrient for every living organism, its transport across the plasma membrane is achieved by the copper transport protein family COPT/CTR. Two genes related to the COPT family were identified in Physcomitrella patens, PpaCOPT1 and PpaCOPT2.