Search

The root system of a plant provides vital functions including resource uptake, storage, and anchorage in soil. The uptake of macro-nutrients like nitrogen (N), phosphorus (P), potassium (K), and sulphur (S) from the soil is critical for plant growth and development. Small signaling peptide (SSP) hormones are best known as potent regulators of plant growth and development with a few also known to have specialized roles in macronutrient utilization. Here we describe a high throughput phenotyping platform for testing SSP effects on root uptake of multiple nutrients. The SSP, CEP1 (C-TERMINALLY ENCODED PEPTIDE) enhanced nitrate uptake rate per unit root length in Medicago truncatula plants deprived of N in the high-affinity transport range. Single structural variants of M. truncatula and Arabidopsis thaliana specific CEP1 peptides, MtCEP1D1:hyp4,11 and AtCEP1:hyp4,11, enhanced uptake not only of nitrate, but also phosphate and sulfate in both model plant species. Transcriptome analysis of Medicago roots treated with different MtCEP1 encoded peptide domains revealed that hundreds of genes respond to these peptides, including several nitrate transporters and a sulfate transporter that may mediate the uptake of these macronutrients downstream of CEP1 signaling. Likewise, several putative signaling pathway genes including LEUCINE-RICH REPEAT RECPTOR-LIKE KINASES and Myb domain containing transcription factors, were induced in roots by CEP1 treatment. Thus, a scalable method has been developed for screening synthetic peptides of potential use in agriculture, with CEP1 shown to be one such peptide.

The root system of a plant provides vital functions including resource uptake, storage, and anchorage in soil. The uptake of macro-nutrients like nitrogen (N), phosphorus (P), potassium (K), and sulphur (S) from the soil is critical for plant growth and development. Small signaling peptide (SSP) hormones are best known as potent regulators of plant growth and development with a few also known to have specialized roles in macronutrient utilization. Here we describe a high throughput phenotyping platform for testing SSP effects on root uptake of multiple nutrients. The SSP, CEP1 (C-TERMINALLY ENCODED PEPTIDE) enhanced nitrate uptake rate per unit root length in Medicago truncatula plants deprived of N in the high-affinity transport range. Single structural variants of M. truncatula and Arabidopsis thaliana specific CEP1 peptides, MtCEP1D1:hyp4,11 and AtCEP1:hyp4,11, enhanced uptake not only of nitrate, but also phosphate and sulfate in both model plant species. Transcriptome analysis of Medicago roots treated with different MtCEP1 encoded peptide domains revealed that hundreds of genes respond to these peptides, including several nitrate transporters and a sulfate transporter that may mediate the uptake of these macronutrients downstream of CEP1 signaling. Likewise, several putative signaling pathway genes including LEUCINE-RICH REPEAT RECPTOR-LIKE KINASES and Myb domain containing transcription factors, were induced in roots by CEP1 treatment. Thus, a scalable method has been developed for screening synthetic peptides of potential use in agriculture, with CEP1 shown to be one such peptide. [ABSTRACT FROM AUTHOR]

C5-epimerases are promising tools for the production of rare l-hexoses from their more common d-counterparts. On that account, UDP-glucuronate 5-epimerase (UGA5E) attracts attention as this enzyme could prove to be useful for the synthesis of UDP-l-iduronate. Interestingly, l-iduronate is known as a precursor for the production of heparin, an effective anticoagulant. To date, the UGA5E specificity has only been detected in rabbit skin extract, and the respective enzyme has not been characterized in detail or even identified at the molecular level. Accordingly, the current work aimed to shed more light on the properties of UGA5E. Therefore, the pool of putative UGA5Es present in the UniProt database was scrutinized and their sequences were clustered in a phylogenetic tree. However, the examination of two of these enzymes revealed that they actually epimerize UDP-glucuronate at the 4- rather than 5-position. Furthermore, in silico analysis indicated that this should be the case for all sequences that are currently annotated as UGA5E and, hence, that such activity has not yet been discovered in nature. The detected l-iduronate synthesis in rabbit skin extract can probably be assigned to the enzyme chondroitin-glucuronate C5-epimerase, which catalyzes the conversion of d-glucuronate to l-iduronate on a polysaccharide level. [ABSTRACT FROM AUTHOR]