@article{EbrahimianMotlaghRiboneThirumalaikumaretal.2017, author = {Ebrahimian-Motlagh, Saghar and Ribone, Pamela A. and Thirumalaikumar, Venkatesh P. and Allu, Annapurna Devi and Chan, Raquel L. and Mueller-Roeber, Bernd and Balazadeh, Salma}, title = {JUNGBRUNNEN1 Confers Drought Tolerance Downstream of the HD-Zip I Transcription Factor AtHB13}, series = {Frontiers in plant science}, volume = {8}, journal = {Frontiers in plant science}, publisher = {Frontiers Research Foundation}, address = {Lausanne}, issn = {1664-462X}, doi = {10.3389/fpls.2017.02118}, pages = {12}, year = {2017}, abstract = {Low water availability is the major environmental factor limiting growth and productivity of plants and crops and is therefore considered of high importance for agriculture affected by climate change. Identifying regulatory components controlling the response and tolerance to drought stress is thus of major importance. The NAC transcription factor (TF) JUNGBRUNNEN1 (JUB1) from Arabidopsis thaliana extends leaf longevity under non-stress growth conditions, lowers cellular hydrogen peroxide (H2O2) level, and enhances tolerance against heat stress and salinity. Here, we additionally find that JUB1 strongly increases tolerance to drought stress in Arabidopsis when expressed from both, a constitutive (CaMV 35S) and an abiotic stress-induced (RD29A) promoter. Employing a yeast one-hybrid screen we identified HD-Zip class I TF AtHB13 as an upstream regulator of JUB1. AtHB13 has previously been reported to act as a positive regulator of drought tolerance. AtHB13 and JUB1 thereby establish a joint drought stress control module.}, language = {en} } @article{ShahnejatBushehriAlluMehterovetal.2017, author = {Shahnejat-Bushehri, Sara and Allu, Annapurna Devi and Mehterov, Nikolay and Thirumalaikumar, Venkatesh P. and Alseekh, Saleh and Fernie, Alisdair R. and Mueller-Roeber, Bernd and Balazadeh, Salma}, title = {Arabidopsis NAC Transcription Factor JUNGBRUNNEN1 Exerts Conserved Control Over Gibberellin and Brassinosteroid Metabolism and Signaling Genes in Tomato}, series = {Frontiers in plant science}, volume = {8}, journal = {Frontiers in plant science}, publisher = {Frontiers Research Foundation}, address = {Lausanne}, issn = {1664-462X}, doi = {10.3389/fpls.2017.00214}, pages = {13}, year = {2017}, abstract = {The Arabidopsis thaliana NAC transcription factor JUNGBRUNNEN1 (AtJUB1) regulates growth by directly repressing GA3ox1 and DWF4, two key genes involved in gibberellin (GA) and brassinosteroid (BR) biosynthesis, respectively, leading to GA and BR deficiency phenotypes. AtJUB1 also reduces the expression of PIF4, a bHLH transcription factor that positively controls cell elongation, while it stimulates the expression of DELLA genes, which are important repressors of growth. Here, we extend our previous findings by demonstrating that AtJUB1 induces similar GA and BR deficiency phenotypes and changes in gene expression when overexpressed in tomato (Solanum lycopersicum). Importantly, and in accordance with the growth phenotypes observed, AtJUB1 inhibits the expression of growth-supporting genes, namely the tomato orthologs of GA3ox1, DWF4 and PIF4, but activates the expression of DELLA orthologs, by directly binding to their promoters. Overexpression of AtJUB1 in tomato delays fruit ripening, which is accompanied by reduced expression of several ripeningrelated genes, and leads to an increase in the levels of various amino acids (mostly proline, beta-alanine, and phenylalanine), gamma-aminobutyric acid (GABA), and major organic acids including glutamic acid and aspartic acid. The fact that AtJUB1 exerts an inhibitory effect on the GA/BR biosynthesis and PIF4 genes but acts as a direct activator of DELLA genes in both, Arabidopsis and tomato, strongly supports the model that the molecular constituents of the JUNGBRUNNEN1 growth control module are considerably conserved across species.}, language = {en} } @article{SedaghatmehrThirumalaikumarKamranfaretal.2019, author = {Sedaghatmehr, Mastoureh and Thirumalaikumar, Venkatesh P. and Kamranfar, Iman and Marmagne, Anne and Masclaux-Daubresse, Celine and Balazadeh, Salma}, title = {A regulatory role of autophagy for resetting the memory of heat stress in plants}, series = {Plant, cell \& environment : cell physiology, whole-plant physiology, community physiology}, volume = {42}, journal = {Plant, cell \& environment : cell physiology, whole-plant physiology, community physiology}, number = {3}, publisher = {Wiley}, address = {Hoboken}, issn = {0140-7791}, doi = {10.1111/pce.13426}, pages = {1054 -- 1064}, year = {2019}, abstract = {As sessile life forms, plants are repeatedly confronted with adverse environmental conditions, which can impair development, growth, and reproduction. During evolution, plants have established mechanisms to orchestrate the delicate balance between growth and stress tolerance, to reset cellular biochemistry once stress vanishes, or to keep a molecular memory, which enables survival of a harsher stress that may arise later. Although there are several examples of memory in diverse plants species, the molecular machinery underlying the formation, duration, and resetting of stress memories is largely unknown so far. We report here that autophagy, a central self-degradative process, assists in resetting cellular memory of heat stress (HS) in Arabidopsis thaliana. Autophagy is induced by thermopriming (moderate HS) and, intriguingly, remains high long after stress termination. We demonstrate that autophagy mediates the specific degradation of heat shock proteins at later stages of the thermorecovery phase leading to the accumulation of protein aggregates after the second HS and a compromised heat tolerance. Autophagy mutants retain heat shock proteins longer than wild type and concomitantly display improved thermomemory. Our findings reveal a novel regulatory mechanism for HS memory in plants.}, language = {en} }