Biology subjects

Motyka, V.

Publications and source records attributed to Motyka, V..

4 recordsLinked to original sources

bioRxiv2024

Physiological and Molecular Responses of Projected Future Temperatures on Potato Tuberization

Potato (Solanum tuberosum L.) is one of the most important food crops globally and is especially vulnerable to heat stress. Significant knowledge gaps remain however, in our understanding of the developmental mechanisms associated with tuber responses to heat stress. This study uses whole-plant physiology, transcriptomics, and hormone profiling to gain insights into the mechanisms associated with heat stress impacts on potato tuber development. When plants were grown in projected future temperature conditions, levels of abscisic acid (ABA) were significantly decreased in leaf and tuber tissues while rates of leaf carbon assimilation and stomatal conductance were not significantly affected. While plants grown in elevated temperature conditions initiated more tubers on average per plant, there was a significant decrease (66%) in mature tubers at final harvest. We hypothesize that reduced tuber yields at elevated temperatures are not due to reductions in tuber initiation, but due to impaired tuber filling. Transcriptomic analysis found significant changes in transcript expression for genes related to response to ABA, heat and auxin biosynthetic process. The known tuberization repressor genes SELF PRUNING 5G (StSP5G) and CONSTANS-LIKE1 (StCOL1) were found to be differentially expressed in tubers grown in elevated temperatures. IDENTITY OF TUBER 1 (StIT1) and TIMING OF CAB EXPRESSION 1 (StTOC1) are other known tuberization genes that displayed distinct expression patterns in elevated versus ambient temperatures but were not differentially expressed. This work highlights potential gene targets and key developmental stages associated with tuberization to development more heat tolerant potatoes.

plant biology↗

bioRxiv2024

Comprehensive Model of Cell-to-Cell Cytokinin Transport Reveals A Specific Mode of Cytokinin Riboside Influx

1Ribosylated forms of plant hormones cytokinins (CKs) are the dominant CK species translocated at long distances. Their particular roles in plant physiology imply the existence of a yet uncharacterized CK riboside-specific membrane transport system. In this work, we report significant differences in the kinetics of the membrane transport of CK nucleobases and ribosides and the overall affinity of membrane-bound carriers towards the two CK forms. We show that CK ribosides can inhibit the uptake of CK nucleobases in tobacco Bright Yellow 2 cell suspensions but not vice versa, confirming the existence of a membrane transport system that strictly recognizes CK ribosides. We further characterize the membrane transport of CK nucleobases and ribosides mediated by AtENT3 (EQULIBRATIVE NUCLEOSIDE TRANSPORTER 3), showing its preference towards trans-zeatin riboside (tZR) over isopentenyl adenosine (iPR). With the molecular docking and molecular dynamics, we assess the interactions among the side chain of tZR and AtENT3 residues Tyr61 and Asp129, which are conserved in all AtENTs but not in the ENTs from non-plant species. Lastly, we show that atent3 mutation affects shoot phenotype, demonstrating the impact of CK riboside membrane transport on shoot development.

plant biology↗

bioRxiv2023

Cytokinin Dehydrogenase in Xylem Sap Reveals A Direct Link Between Cytokinin Metabolism and Long-Distance Transport

Metabolic degradation of plant hormones cytokinins (CKs) co-regulates their homeostasis and signalling. In this work, we employed a large-scale bioinformatical analysis to address a diversity of cytokinin oxidase/dehydrogenase (CKX) substrate specificities previously described in several case studies. We present a three-way correlation of the entire CKX amino acid sequences, a variable motif involved in substrate binding, and subcellular localizations predicted by a deep learning model. This correlation is conserved in monocotyledonous plants, suggesting that the CKX diversity in a single species allows a precise tuning of the CK homeostasis. Following these findings, we detected CKX activity in xylem sap for the first time, using the oat (Avena sativa) as a model plant. Further investigation of the substrate specificity and glycosylation of this xylem-located CKX suggested that it originates in roots. We have identified 27 putative CKXs in oats and attributed the xylem-located activity to the extracellular isoforms AsCKX1a,c,d. Finally, we show that the xylem-located CKX activity responds to the nitrate supply, highlighting its physiological relevance. Taken together, we show that CKX directly modulates root-to-shoot CK translocation through metabolic degradation of the transported CKs.

plant biology↗

bioRxiv2023

Phytohormone profiling in an evolutionary framework

Multiple phytohormones act as conserved developmental regulators in land plants. Although the closely related streptophyte green algae typically lack full complements of molecular pathways underlying these responses, scattered reports of endogenous phytohormone production in these organisms exist. In this study, we performed a detailed LC/MS-based analysis of several phytohormones, their precursors and metabolites in all lineages of streptophyte algae. We also included chlorophyte algae and early-diverging land plants as outgroups. Free auxin, tRNA-derived cytokinins and certain phenolics including salicylic acid were found ubiquitously. However, land plants differed from green algae by the consistent detection of abscisic acid and the presence of auxin and cytokinin conjugates and trans-zeatin, supporting the hypotheses that these three phytohormones likely came to regulate development in the ancestral land plant. By contrast, we observed a patchy distribution of jasmonates among streptophytes. We additionaly analyzed the corresponding culture and empty media to account for phytohormone excretion and environmental contamination. Extracellular auxins and cytokinins were frequently detected, while agar constituted a major external source of phenolic compounds. We provide a highly comprehensive evolution-directed screen of phytohormone compound occurrence and thoroughly discuss our data in the context of current plant hormonomics and phylogenomics. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=143 SRC="FIGDIR/small/534998v1_ufig1.gif" ALT="Figure 1"> View larger version (52K): org.highwire.dtl.DTLVardef@1532f4org.highwire.dtl.DTLVardef@1c4396borg.highwire.dtl.DTLVardef@195d0eborg.highwire.dtl.DTLVardef@c71b11_HPS_FORMAT_FIGEXP M_FIG C_FIG

plant biology↗