CSN5A Subunit of COP9 Signalosome Temporally Buffers Response to Heat in Arabidopsis

Abstract

The COP9 (constitutive photomorphogenesis 9) signalosome (CSN) is an evolutionarily conserved protein complex which regulates various growth and developmental processes. However, the role of CSN during environmental stress is largely unknown. Using Arabidopsis as model organism, we used CSN hypomorphic mutants to study the role of the CSN in plant responses to environmental stress and found that heat stress specifically enhanced the growth of csn5a-1 but not the growth of other hypomorphic photomorphogenesis mutants tested. Following heat stress, csn5a-1 exhibits an increase in cell size, ploidy, photosynthetic activity, and number of lateral roots and an upregulation of genes connected to the auxin response. Immunoblot analysis revealed an increase in deneddylation of CUL1 but not CUL3 following heat stress in csn5a-1, implicating improved CUL1 activity as a basis for the improved growth of csn5a-1 following heat stress. Studies using DR5::N7-VENUS and DII-VENUS reporter constructs confirm that the heat-induced growth is due to an increase in auxin signaling. Our results indicate that CSN5A has a specific role in deneddylation of CUL1 and that CSN5A is required for the recovery of AUX/IAA repressor levels following recurrent heat stress to regulate auxin homeostasis in Arabidopsis.

Persistence of parental age effect on somatic mutation rates across generations in Arabidopsis

“…In the leaf epidermal cells of Arabidopsis, a strong correlation exists between the size of the cell and the amount of DNA (Melaragno et al, 1993). Plant cells frequently undergo endoreduplication, resulting in higher ploidy per nucleus which is correlated with increased cell size as well (Sugimoto- Shirasu and Roberts, 2003; Singh et al, 2019). As a result, the individual cell size and their numbers significantly contribute to the overall leaf size (Tsukaya, 2003).…”

SAV4 is required for ethylene‐induced root hair growth through stabilizing PIN2 auxin transporter in Arabidopsis

“…Transgenic plants were generated by the floral‐dipping method (Clough & Bent, 1998). SAV4pro::SAV4‐YFP , PIN2pro::PIN2‐Venus , PIN2pro::PIN2‐GFP , DR5::N7‐Venus and 35S::EIN3‐GFP were previously reported (He et al ., 2011; Leitner et al ., 2012; Ge et al ., 2017; Singh et al ., 2019; Wang et al ., 2019).…”

Regulatory Mechanism of the Constitutive Photomorphogenesis 9 Signalosome Complex in Response to Abiotic Stress in Plants

“…Recent studies have shown which CSN is triggered by heat stress that disrupts the redox balance of rice . However, in Arabidopsis, the underlying mechanism of CSN in response to high temperatures has been reported to target auxin signaling, which drives plant growth and morphogenesis . A large body of evidence on the function of CSN in response to auxin may support this view.…”

“…Plants exhibit limited growth and productivity under abiotic stresses, such as excess salt and alkali, extreme temperatures, drought, excessive ultraviolet (UV) light irradiation, and nutrient deprivation. − To respond and adapt to these adverse environmental conditions, plants adjust their physiology and activate the stress signaling pathway . Recently, a growing body of literature has reported the regulatory role of CSN in plants under abiotic stress. ,− The metabolic pathways of CSN in response to abiotic stress involve oxygen ion conduction, osmotic regulation, and signal transduction.…”