Biology subjects

Schmulling, T.

Publications and source records attributed to Schmulling, T..

5 recordsLinked to original sources

bioRxiv2022

CEP peptide and cytokinin pathways converge on CEPD glutaredoxins to inhibit root growth

C-TERMINALLY ENCODED PEPTIDE (CEP) and cytokinin hormones act over short and long distances to control plant responses to environmental cues. CEP and cytokinin pathway mutants share phenotypes, however, it is not known if these pathways intersect. We show that CEP and cytokinin signalling converge on CEP DOWNSTREAM (CEPD) glutaredoxins to inhibit primary root growth. CEP inhibition of root growth was impaired in mutants defective in trans-zeatin (tZ)-type cytokinin biosynthesis, transport, perception, and output. Concordantly, mutants affected in CEP RECEPTOR 1 showed reduced root growth inhibition in response to tZ, and altered levels of tZ-type cytokinins. Grafting and organ-specific hormone treatments showed that tZ-mediated root growth inhibition required CEPD activity in roots. By contrast, root growth inhibition by CEP depended on shoot CEPD function. The results demonstrate that CEP and cytokinin pathways intersect, and utilise signalling circuits in separate organs involving common glutaredoxin genes to coordinate root growth.

plant biology↗

bioRxiv2020

Photoperiod stress alters the cellular redox status and is associated with an increased peroxidase and decreased catalase activity

Periodic changes of light and dark regulate numerous processes in plants. Recently, a novel type of stress caused by an extended light period has been discovered in Arabidopsis and was named photoperiod stress. Photoperiod stress causes the induction of numerous stress response genes during the night following the extended light period of which many are indicators of oxidative stress. The next day, stress-sensitive genotypes display reduced photosynthetic efficiency and programmed cell death in leaves. Here, we have analysed further the consequences of photoperiod stress and report that it causes changes of the cellular redox status. A prolonged light period caused a strong reduction of the AsA redox during the following night indicating that it induces an oxidizing cellular environment. Further, photoperiod stress was associated with an increased activity of peroxidases and a decreased activity of catalases. Increased peroxidase activity was localized to the apoplast and might be causal for the oxidative stress induced by photoperiod stress.

plant biology↗

bioRxiv2020

Root-derived trans-zeatin cytokinin protects Arabidopsis plants against photoperiod stress

Recently, a novel type of abiotic stress caused by a prolongation of the light period - coined photoperiod stress - has been described in Arabidopsis. During the night after the prolongation of the light period, stress and cell death marker genes are induced. The next day, strongly stressed plants display a reduced photosynthetic efficiency and leaf cells eventually enter programmed cell death. The phytohormone cytokinin (CK) acts as a negative regulator of this photoperiod stress syndrome. In this study, we show that Arabidopsis wild-type plants increase the CK concentration in response to photoperiod stress. Analysis of cytokinin synthesis and transport mutants revealed that root-derived trans-zeatin (tZ)-type CKs protect against photoperiod stress. The CK signaling proteins ARABIDOPSIS HISTIDINE PHOSPHOTRANSFER PROTEIN 2 (AHP2), AHP3 and AHP5 and transcription factors ARABIDOPSIS RESPONSE REGULATOR 2 (ARR2), ARR10 and ARR12 are required for the protective activity of CK. Analysis of higher order B-type arr mutants suggested that a complex regulatory circuit exists in which the loss of ARR10 or ARR12 can rescue the arr2 phenotype. Together the results revealed the role of root-derived CK acting in the shoot through the two-component signaling system to protect from the negative consequences of strong photoperiod stress.

plant biology↗

bioRxiv2019

Acclimation, priming and memory in the response of Arabidopsis thaliana seedlings to cold stress

Because stress experiences are often recurrent plants have developed strategies to remember a first so-called priming stress to eventually respond more effectively to a second triggering stress. Here, we have studied the impact of discontinuous or sustained cold stress (4 {degrees}C) on in vitro grown Arabidopsis thaliana seedlings of different age and their ability to get primed and respond differently to a later triggering stress. Cold treatment of 7-d-old seedlings induced the expression of cold response genes but did not cause a significantly enhanced freezing resistance. The competence to increase the freezing resistance in response to cold was associated with the formation of true leaves. Discontinuous exposure to cold only during the night led to a stepwise modest increase in freezing tolerance provided that the intermittent phase at ambient temperature was less than 32 h. Seedlings exposed to sustained cold treatment developed a higher freezing tolerance which was further increased in response to a triggering stress during three days after the priming treatment had ended indicating cold memory. Interestingly, in all scenarios the primed state was lost as soon as the freezing tolerance had reached the level of naive plants indicating that an effective memory was associated with an altered physiological state. Known mutants of the cold stress response (cbfs, erf105) and heat stress memory (fgt1) did not show an altered behaviour indicating that their roles do not extend to memory of cold stress.

plant biology↗

bioRxiv2019

Characterisation of the ERF102 to ERF105 genes of Arabidopsis thaliana and their role in the response to cold stress

The ETHYLENE RESPONSE FACTOR (ERF) genes of Arabidopsis thaliana form a large family encoding plant-specific transcription factors. Here, we characterise the four phylogenetically closely related ERF102/ERF5, ERF103/ERF6, ERF104 and ERF105 genes. Expression analyses revealed that these four genes are similarly regulated by different hormones and abiotic stresses. Analyses of tissue-specific expression using promoter:GUS reporter lines revealed their predominant expression in root tissues including the root meristem (ERF103), the quiescent center (ERF104) and the root vasculature (all). All GFP-ERF fusion proteins were nuclear-localised. The analysis of insertional mutants, amiRNA lines and 35S:ERF overexpressing transgenic lines indicated that ERF102 to ERF105 have only a limited impact on regulating shoot and root growth. Previous work had shown a role for ERF105 in the cold stress response. Here, measurement of electrolyte leakage to determine leaf freezing tolerance and expression analyses of cold-responsive genes revealed that the combined activity of ERF102 and ERF103 is also required for a full cold acclimation response likely involving the CBF regulon. Together, these results suggest a common function of these ERF genes in regulating root architecture and the response to cold stress.

plant biology↗