A novel extensin gene encoding a hydroxyproline-rich glycoprotein requires sucrose for its wound-inducible expression in transgenic plants.

Vegetative reproduction relies on the initiation of new plant organs in response to environmental changes. The rapid formation of roots, and ultimately whole plants, from stem cuttings of grape ( Vitis vinifera L.) provides a useful system to investigate the physiological and molecular basis of organ initiation during vegetative reproduction. In the present study the differential RNA display technique was employed to identify two genes, VvPRP1 and VvPRP2 , that are induced in stem cuttings of grape during rooting. Each of these genes encodes a distinct type of proline-rich protein that is related to different groups of putative cell wall proteins, and their expression is rapidly induced in stem segments within 6 h after severing. Further, each gene's transcript becomes most concentrated in the basal portion of the stem segment in the region of new root formation. Induction of these genes is not significantly enhanced by indole-3-acetic acid (IAA) treatment, and the expression of the VvPRP1 gene, but not the VvPRP2 gene, is wound-inducible. These results suggest that these VvPRP genes play an important role in the initiation of new roots on grape stem cuttings, perhaps by altering the cell wall mechanical properties to enable root emergence.

Section: Discussionmentioning

confidence: 99%

Molecular identification of proline‐rich protein genes induced during root formation in grape (Vitis vinifera L.) stem cuttings

Thomas

Lee

Schiefelbein

2003

“…This indicates that carbohydrate-depleted plants restrict sugar import and growth to a small number of sites in the plant, and that growth is stimulated at further sites when the levels of sugars increase (Koch 1996). Sugars also induce genes involved in pigment synthesis and defence (Koch 1996;Ahn et al 1996;Herbers et al 1996).…”

Section: Introductionmentioning

confidence: 99%

The sugar‐mediated regulation of genes encoding the small subunit of Rubisco and the regulatory subunit of ADP glucose pyrophosphorylase is modified by phosphate and nitrogen

Nielsen

Krapp

Röper‐Schwarz

et al. 1998

126

Tobacco seedlings were grown in nutrient agar at a range of ammonium nitrate concentrations either without added sucrose, or with 100 mol m -3 sucrose. In the absence of added sucrose, nitrogen-limited plants had increased levels of glucose, fructose and sucrose, decreased chlorophyll, decreased protein, and decreased Rubisco activity, but the level of the transcript for the small subunit of Rubisco (RbcS) did not decrease compared with nitrogen-sufficient plants. When sucrose was added to nitrogen-sufficient seedlings, there was an increase of sucrose, glucose and fructose in the leaves, growth was increased, and the chlorophyll and protein content, Rubisco activity, and the RbcS transcript level did not change. When sucrose was added to nitrogen-limited seedlings, there was a further increase of sucrose, glucose and fructose, growth was not increased, and there was a further decrease of chlorophyll, protein and Rubisco activity, and a marked decrease of the RbcS transcript level. To check that the decrease of the RbcS transcript level was not an indirect effect due to changes of nitrogen metabolites after adding sugars, glucose was added to Chenopodium cells in the presence and absence of glutamine or azaserine. Changes of glutamine that suffice to increase and decrease the level of the transcript for nitrate reductase (Nia) do not affect the RbcS transcript concentration, and glucose addition still led to a decrease of the RbcS transcript level when the internal glutamine concentration was high. Tobacco seedlings were also grown in nutrient agar at a range of phosphate concentrations either without added sucrose, or with 100 mol m -3 sucrose. Phosphate-limited seedlings did not show a decrease of chlorophyll, protein, Rubisco activity, or the level of the RbcS transcript, compared with phosphate-sufficient seedlings. The addition of sucrose to phosphate-limited plants led to a similar increase of sugars to that seen after adding sucrose to nitrogen-limited seedlings, but did not alter chlorophyll, protein, Rubisco activity, or the level of the RbcS transcript. The addition of sucrose to phosphate-limited plants led to a slight increase of the level of the transcript for nitrate reductase (Nia), increased nitrate reductase activity, and a marked increase of the amino acid content. Phosphate limitation led to an increased level of the transcript for the regulatory subunit of ADP glucose pyrophosphorylase (AgpS2), and this response was strengthened when sucrose was added. The regulation of AgpS2 expression by phosphate and sucrose was further investigated by feeding sucrose and phosphate to detached source leaves via the transpiration stream. The level of the AgpS2 transcript decreased after feeding phosphate and increased after feeding sucrose, and the effect of sucrose was antagonised by phosphate. It is concluded that the response to sugar signalling is modulated by nitrogen and phosphate in a gene-specific manner. The significance of these results for understanding the visual phenotype of nitrogen-and phospha...

“…HRGPs are structural components of the cell wall important for plant development, and are involved in stress responses in tobacco (Raggi 2000), Arabidopsis (Merkouropoulos, Barnett & Shirsat 1999), potato (Dey et al 1997), tomato (Zhou et al 1992) and other species (Showalter et al 1985;Ahn et al 1996;Shailasree et al 2004;Deepak et al 2007). It is interesting that the stress activation of bean HRGP4.1 is superimposed on its tissue-specific expression in stem nodes and root tips (Wycoff et al 1995).…”

Section: Ntprorp1 Is An Important Protein In Osmotic Stress Response mentioning

confidence: 99%

“…HRGPs are distributed widely and may function in the stress response in different plants (Zhou, Rumeau & Showalter 1992;Ahn et al 1996;Raggi 2000Raggi , 2007Ahn & Lee 2003;Pearce & Ryan 2003;Narváez-Vásquez, Pearce & Ryan 2005;Deepak et al 2007;Pearce et al 2007). New knowledge on plant response to stress during reproductive development is especially valuable for the improvement of crop yield (Barnabas, Jager & Feher 2008).…”

Section: Introductionmentioning

confidence: 99%

NtProRP1, a novel proline‐rich protein, is an osmotic stress‐responsive factor and specifically functions in pollen tube growth and early embryogenesis in Nicotiana tabacum

Chen

Zhao

Ning

et al. 2013

Proline-rich proteins (PRPs) are known to play important roles in sexual plant reproduction. Most of the known proteins in the family were found in styles or pollen and modulate pollen tube growth. Here, we identified a novel member of the gene family, NtProRP1, which is preferentially expressed in tobacco pollen grains, pollen tubes and zygotes. NtProRP1 could be secreted into the extracellular space including the cell wall, and the predicted N-terminal signal peptide is crucial for its secretion. In NtProRP1-RNAi plants, pollen germination and pollen tube growth were significantly slower and showed zigzag or swell morphology in vitro. Early embryogenesis also exhibited aberrant development, indicative of its critical role in both pollen tube growth and early embryogenesis. Further investigation revealed that NtProRP1 plays a crucial role in osmotic stress response during pollen tube growth and is likely regulated by Tsi, a stress-responsive gene, suggesting that the regulatory mechanism is also involved in the stress response during sexual plant reproduction. These data provide evidence that NtProRP1 functions as a downstream factor of Tsi1 in the stress response and converges the stress signal into the modulation of pollen tube growth and early embryogenesis.