Papers by Peter Gresshoff
Proceedings of the National Academy of Sciences of the United States of America, Mar 1, 1973
Specialized transducing phages (X and 480) have been used as vectors in the transfer of genes (wi... more Specialized transducing phages (X and 480) have been used as vectors in the transfer of genes (wild type and mutant) from the bacterium Escherichia coli to haploid cell lines of the plants Lycopersicon esculentum and Arabidopsis thaliana. The overall phenomenon of transfer, gene maintenance, transcription, translation, and function has been termed transgenosis. Transgenosis of galactose and lactose operon genes was detected by survival and growth of the plant cells on defined medium with galactose and lactose as sole sources of bulk carbon. Phages carrying a defective operon, unrelated bacterial genes, or no bacterial genes, do not affect the normal result of death on these media, nor do they prevent growth on optimal growth media. Transgenosis of the E. coli gene z (lac operon) was confirmed by a biochemicalimmunological test specific for E. coli j-galactosidase. Plant cells were unable to effectively suppress an E. coli nonsense mutation. The E. coli mutant suppressor gene,
Frontiers in Plant Science, Aug 8, 2018
Cytokinins are important regulators of cell proliferation and differentiation in plant developmen... more Cytokinins are important regulators of cell proliferation and differentiation in plant development. Here, a role for this phytohormone group in soybean nodulation is shown through the exogenous application of cytokinins (6-benzylaminopurine, N 6-(2isopentenyl)-adenine and trans-zeatin) via either root drenching or a petiole feeding technique. Overall, nodule numbers were reduced by treatment with high cytokinin concentrations, but increased with lower concentrations. This was especially evident when feeding the solutions directly into the vasculature via petiole feeding. These findings highlight the importance of cytokinin in nodule development. To further investigate the role of cytokinin in controlling nodule numbers, the IPT gene family involved in cytokinin biosynthesis was characterized in soybean. Bioinformatic analyses identified 17 IPT genes in the soybean genome and homeologous duplicate gene partners were subsequently identified including GmIPT5 and GmIPT6, the orthologs of LjIPT3. Expression of GmIPT5 was upregulated in the shoot in response to nodulation, but this was independent of a functional copy of the autoregulation of nodulation (AON) receptor, GmNARK, which suggests it is unlikely to have a role in the negative feedback system called AON. Legumes also control nodule numbers in the presence of soil nitrogen through nitrate-dependent regulation of nodulation, a locally acting pathway in soybean. Upon nitrate treatment to the root, the tandem duplicates GmIPT3 and GmIPT15 were upregulated in expression indicating a role for these genes in the plant's response to soil nitrogen, potentially including the nitrate-dependent regulation of legume nodulation pathway. Additional roles for cytokinin and their IPT biosynthetic genes in nodulation and the control of nodule numbers are discussed.
Journal of Experimental Botany, Jul 17, 2015
CLE peptides are key regulators of cell proliferation and differentiation in plant shoots, roots,... more CLE peptides are key regulators of cell proliferation and differentiation in plant shoots, roots, vasculature, and legume nodules. They are C-terminally encoded peptides that are post-translationally cleaved and modified from their corresponding pre-propeptides to produce a final ligand that is 12-13 amino acids in length. In this study, an array of bionformatic and comparative genomic approaches was used to identify and characterize the complete family of CLE peptide-encoding genes in two of the world's most important crop species, soybean and common bean. In total, there are 84 CLE peptide-encoding genes in soybean (considerably more than the 32 present in Arabidopsis), including three pseudogenes and two multi-CLE domain genes having six putative CLE domains each. In addition, 44 CLE peptideencoding genes were identified in common bean. In silico characterization was used to establish all soybean homeologous pairs, and to identify corresponding gene orthologues present in common bean and Arabidopsis. The soybean CLE pre-propeptide family was further analysed and separated into seven distinct groups based on structure, with groupings strongly associated with the CLE domain sequence and function. These groups provide evolutionary insight into the CLE peptide families of soybean, common bean, and Arabidopsis, and represent a novel tool that can aid in the functional characterization of the peptides. Transcriptional evidence was also used to provide further insight into the location and function of all CLE peptide-encoding members currently available in gene atlases for the three species. Taken together, this in-depth analysis helped to identify and categorize the complete CLE peptide families of soybean and common bean, established gene orthologues within the two legume species, and Arabidopsis, and provided a platform to help compare, contrast, and identify the function of critical CLE peptide hormones in plant development.
Scientific Reports, Nov 13, 2017
This Article contains an error in the legend of Figure 5. "Multiple sequence alignment of the pre... more This Article contains an error in the legend of Figure 5. "Multiple sequence alignment of the prepropeptides of AtCLE18 and LjCLE34. CLE domains are highlighted with a red box and the CLEL domain is underlined in blue. Conservation between amino acid residues of the two sequences is represented by grey (partial) and black (100%) shading". should read: "Sequence alignment of LjCLE5 and MtCLE12. The LjCLE5 translation start site corresponding to that of MtCLE12 results in a truncated prepropeptide (denoted by the asterisk shaded in black). The blue box represents an alternative start codon that results in the CLE domain region of LjCLE5 (underlined in red) being translated in frame. Black highlighted nucleic acid bases are 100% conserved".
Journal of Experimental Botany, Feb 5, 2013
Legumes control the nitrogen-fixing root nodule symbiosis in response to external and internal st... more Legumes control the nitrogen-fixing root nodule symbiosis in response to external and internal stimuli, such as nitrate, and via systemic autoregulation of nodulation (AON). Overexpression of the CLV3/ESR-related (CLE) pre-propeptideencoding genes GmNIC1 (nitrate-induced and acting locally) and GmRIC1 (Bradyrhizobium-induced and acting systemically) suppresses soybean nodulation dependent on the activity of the nodulation autoregulation receptor kinase (GmNARK). This nodule inhibition response was used to assess the relative importance of key structural components within and around the CLE domain sequences of these genes. Using a site-directed mutagenesis approach, mutants were produced at each amino acid within the CLE domain (RLAPEGPDPHHN) of GmRIC1. This approach identified the Arg1, Ala3, Pro4, Gly6, Pro7, Asp8, His11, and Asn12 residues as critical to GmRIC1 nodulation suppression activity (NSA). In contrast, none of the mutations in conserved residues outside of the CLE domain showed compromised NSA. Chimeric genes derived from combinations of GmRIC1 and GmNIC1 domains were used to determine the role of each pre-propeptide domain in NSA differences that exist between the two peptides. It was found that the transit peptide and CLE peptide regions of GmRIC1 significantly enhanced activity of GmNIC1. In contrast, the comparable GmNIC1 domains reduced the NSA of GmRIC1. Identification of these critical residues and domains provides a better understanding of how these hormone-like peptides function in plant development and regulation.
Predominant mRNAs from ANU289-Induced Nodules of Siratro and Parasponia
The slow-growing Parasponia rhizobium strain ANU289 forms effective nodules on the tropical legum... more The slow-growing Parasponia rhizobium strain ANU289 forms effective nodules on the tropical legume Siratro and the non-legume Parasponia. We are examining the plant-specified mRNAs and proteins (nodulins) synthesized in nodules from these two different types of plants.
pGFPGUSPlus, a new binary vector for gene expression studies and optimising transformation systems in plants
Biotechnology Letters, Aug 9, 2007
Molecular Mapping of Soybean Nodulation Genes
Molecular Genetic Analysis of Nodulation Genes in Soybean
John Wiley & Sons, Inc. eBooks, Jun 22, 2010
... genuine but not nitrogen-fixing nodules formed in the absence of Rhizobium on specific ... Si... more ... genuine but not nitrogen-fixing nodules formed in the absence of Rhizobium on specific ... Since short-term nitrate effects on nitrogenase activity are mediated through regulation of the ... Such nodules harbored the original bacterial inoculum and not a superinfected strain added at ...
Genetic analysis and complementation studies on a number of mutant supernodulating soybean lines
Journal of Genetics, Apr 1, 1988
Genetic analysis was done on a number of nitrate tolerant supernodulating (nts) mutant soybean li... more Genetic analysis was done on a number of nitrate tolerant supernodulating (nts) mutant soybean lines. These lines are altered in the autoregulation response, and each was isolated as a separate mutational event following chemical mutagenesis. Crosses were made betweennts lines on a diallel pattern, and each was also crossed usingnts lines as female parent, to wild-type nodulation cultivars. F1 and F2 data were analysed from each cross for nodulation type and number. No complementation was noted wherents lines were intercrossed, suggesting that in each line the same gene was affected. Wherents lines were crossed with wild-type cultivars all the F1 progeny were wild-type, confirming that thenls gene is recessive and, with one exception,nts 1116, all of the F2 progeny segregated into a 3:1 wild-type to supernodulating phenotype, indicating that a single gene is involved. The hypernodulating linents 1116 gave a 1:1 ratio in its F2 progeny when crossed with othernts lines. This line behaved as a dominant in the latter crosses. No wild-type segregants were recovered, therefore again no complementation look place. This line may be a leaky mutant with partial autoregulation as its segregation ratios do not fall into any of the obvious patterns.
Gene Discovery in Legume Nodulation: From Soybean to Lotus japonicus
Springer eBooks, 1998
The ability of legumes to respond to bacterial signals to form nitrogen-fixing nodules has long b... more The ability of legumes to respond to bacterial signals to form nitrogen-fixing nodules has long been the focus of biologists. Recognition of (a) distinct nodule types, (b) plant genes that are expressed in nodules (nodulins), and (c) plant mutants altered the symbiotic phenotype shifted emphasis towards the genetic analysis of legumes. Nature provides sufficient variation to allow the recognition of the plant’s importance in the symbiotic processes. For example, naturally occurring symbiosis mutants exist in several legumes (Caetano-Anolles, Gresshoff, 1991). In parallel, genetic variation can be induced.
Molecular Plant-microbe Interactions, 1998
A synthetic xylanase as a novel reporter in plants
Plant Cell Reports, Sep 1, 2003
Transient gene expression assays are often used to screen promoters before stable transformation.... more Transient gene expression assays are often used to screen promoters before stable transformation. Current transient quantification methods have several problems, including a lack of reporter gene stability and expense. Here we report a synthetic, codon-optimised xylanase gene ( sXynA) as a reporter gene for quantitative transient analyses in plants. Azurine-crosslinked xylan (AZCL-xylan) was used as a substrate for assaying xylanase activity. The enzymatic nature of the protein allows for sensitive assays at the low levels of transgene protein found in transiently transformed tissue extracts. The xylanase (XYN) protein is stable, activity slopes are linear over long time periods and assays are cost-effective. Coupled with the GUS Plus reporter gene, the XYN reporter allows sensitive and accurate quantification of gene control sequences in transient expression systems.
Identification of AFLP and SSR markers linked closely to nodulation genes in Soybean
Functional & Integrative Genomics, Jul 4, 2009
DNA binding with One Finger (Dof) protein is a plant-specific transcription factor implicated in ... more DNA binding with One Finger (Dof) protein is a plant-specific transcription factor implicated in the regulation of many important plant-specific processes, including photosynthesis and carbohydrate metabolism. This study has identified 31 Dof genes (TaDof) in bread wheat through extensive analysis of current nucleotide databases. Phylogenetic analysis suggests that the TaDof family can be divided into four clades. Expression analysis of the TaDof family across all major organs using quantitative RT-PCR and searches of the wheat genome array database revealed that the majority of TaDof members were predominately expressed in vegetative organs. A large number of TaDof members were down-regulated by drought and/or were responsive to the light and dark cycle. Further expression analysis revealed that light up-regulated TaDof members were highly correlated in expression with a number of genes that are involved in photosynthesis or sucrose transport. These data suggest that the TaDof family may have an important role in light-mediated gene regulation, including involvement in the photosynthetic process.
Plant Science, Dec 1, 2007
RING zinc finger proteins are known for their role predominantly in targeted protein degradation ... more RING zinc finger proteins are known for their role predominantly in targeted protein degradation and participate in gene regulation through interaction with other regulatory proteins. In this study seven RING zinc finger genes from Triticum aestivum (bread wheat) were analysed for expression profiles in various organs (leaf, root, stem, spike, endosperm and embryo) and during leaf development and aging as well as in their responses to water deficit. Expression levels of six of these seven genes varied markedly among the six organs examined. All seven genes changed their expression levels in the leaf from the growing to senescing stage. Four genes were responsive to water deficit. A RING-H2 zinc finger gene, TaRZF70 showed differential response to water deprivation, namely up-regulation in the leaf and down-regulation in the root. This differential response was also observed in abscisic acid (ABA)-treated plants. Sequence analysis revealed that TaRZF70 contained four RING-H2 domains, the largest number of RING-H2 domains in any RING-H2 zinc finger proteins reported to date. These results indicate that these RING zinc finger genes are involved in diverse physiological processes in wheat, including response to drought.
Long distance signalling in nodulation directed by a Clavata1-like receptor kinase
24th Conference on Organisation & Expression of the Gene, 2003
Nodulation genes in soybean and Lotus Japonicus
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Papers by Peter Gresshoff