Transcriptome Analysis of Lolium temulentum Exposed to a Combination of Drought and Heat Stress

Drought and heat are two major stresses predicted to increase in the future due to climate change. Plants exposed to multiple stressors elicit unique responses from those observed under individual stresses. A comparative transcriptome analysis of Lolium temulentum exposed to drought plus heat and non-stressed control plants revealed 20,221 unique up-regulated and 17,034 unique down-regulated differentially regulated transcripts. Gene ontology analysis revealed a strong emphasis on transcriptional regulation, protein folding, cell cycle/parts, organelles, binding, transport, signaling, oxidoreductase, and antioxidant activity. Differentially expressed genes (DEGs) encoding for transcriptional control proteins such as basic leucine zipper, APETALA2/Ethylene Responsive Factor, NAC, and WRKY transcription factors, and Zinc Finger (CCCH type and others) proteins were more often up-regulated, while DEGs encoding Basic Helix-Loop-Helix, MYB and GATA transcription factors, and C2H2 type Zinc Finger proteins were more often down-regulated. The DEGs encoding heat shock transcription factors were only up-regulated. Of the hormones, auxin-related DEGs were the most prevalent, encoding for auxin response factors, binding proteins, and efflux/influx carriers. Gibberellin-, cytokinin- and ABA-related DEGs were also prevalent, with fewer DEGs related to jasmonates and brassinosteroids. Knowledge of genes/pathways that grasses use to respond to the combination of heat/drought will be useful in developing multi-stress resistant grasses.

Caracterización de la comunidad de malezas y su diversidad en una modelación estadística en un cultivo de duraznero (Prunus persica (L.) Batsch.)

En los frutales, incluido el duraznero, las malezas son uno de los principales problemas que afectan la productividad y la calidad y se considera necesario conocer aspectos de la biología y la ecología de estas especies, para realizar un correcto manejo integral. El objetivo de este estudio fue realizar la caracterización de las especies de malezas presentes en el cultivo de duraznero (Prunus persica (L.) Batsch), determinando los índices de diversidad y el uso de un modelo geoespacial, para observar su distribución en campo. Se seleccionó un cultivo comercial de 4,5ha de duraznero variedad Robidoux, se muestrearon 15 puntos aleatoriamente, mediante un cuadro de 0,25m2; con las especies de malezas presentes en cada cuadro, se determinaron los índices de valor de importancia (IVI), de dominancia (1-D), Shannon-Wiener (H´) y Pielou (E). A estos índices, se les realizó modelación de la variabilidad espacial, mediante interpolación polinomial local. La representatividad relativa con los estimadores Chao 2 y Jacknife 1 confirmó que se documentó el 79 y 72% de las especies presentes, respectivamente. Se identificaron 12 especies, de las cuales, Oxalis corniculata, Modiola caroliniana, Lolium temulentum y Fuertesimalva limensis presentaron el mayor IVI y estas especies, se consideran como las de mayor interferencia en el cultivo. Se encontró que la diversidad fue baja, no es equitativa y presenta dominancia de O. corniculata y M. caroliniana. La modelación geoespacial de los índices de diversidad reportó una variación importante en todo el cultivo. Esta información, se convierte en una herramienta útil para el manejo integral de malezas en el cultivo de duraznero.

The wild plants of Scotia Illustrata (1684)

Scotia Illustrata was published in 1684 and contains a section (II:1) describing 662 ‘naturally occurring plants of Scotland’. This paper sets out to identify and discuss the species in the text. It was possible to identify 652 species from the text and 396 could be securely identified. Most of these are species which are widespread today, but there are some important exceptions. Three arable weeds are mentioned which now seem to be extinct in Scotland: Lolium temulentum, Scandix pecten-veneris and Euphorbia exigua. There are also references to one possibly-extinct river species (Sium latifolium), and one coastal species (Centaurea calcitrapa). Two species, now rare in Scotland, are described in the text as species widespread on roads: Cynoglossum officinale and Hyoscyamus niger.

Structural analysis of oligomeric fructans from excised leaves of Lolium temulentum

Individual fructan tri-, tetra- and pentasaccharide isomers in neutral, water-soluble extracts from Lolium temulentum were purified and the linkages present in these isomeric oligosaccharides were analysed by combined GC-mass spectrometry of partially methylated alditol acetates. 1-Kestose and neokestose were the most abundant trisaccharides with 6-kestose present in much lower amounts. Analysis of isomers of DP 4 and 5 showed that multiple linkage types were present with structures based on all three trisaccharides. Oligosaccharides based on neokestose but with 2,6 linkages between adjacent fructose residues have not been previously detected in higher plants. © 1992.

Structural analysis of oligomeric fructans from excised leaves of Lolium temulentum

Individual fructan tri-, tetra- and pentasaccharide isomers in neutral, water-soluble extracts from Lolium temulentum were purified and the linkages present in these isomeric oligosaccharides were analysed by combined GC-mass spectrometry of partially methylated alditol acetates. 1-Kestose and neokestose were the most abundant trisaccharides with 6-kestose present in much lower amounts. Analysis of isomers of DP 4 and 5 showed that multiple linkage types were present with structures based on all three trisaccharides. Oligosaccharides based on neokestose but with 2,6 linkages between adjacent fructose residues have not been previously detected in higher plants. © 1992.

Fructosyl transfer from sucrose and oligosaccharides during fructan synthesis in excised leaves of Lolium temulentum L.

Fructan biosynthesis begins with the transfer of a fructosyl moiety from one sucrose molecule to another to yield a trisaccharide. Trisaccharides may also arise by the reversible transfer of a fructosyl moiety from higher oligomers to sucrose but in this case there is no net fructan synthesis. Short‐term and long‐term exposure of detached illuminated leaf blades of Lolium temulentum (L.I to 14CO2 was used to examine the mechanism of transfer of fructosyl residues to sucrose. Two trisaccharides, 1‐kestose and neokestose, were found to be radioactive when leaves excised and illuminated for 15 h ‐were exposed to NCO2 for 30 min. The label increased in neokestose during the chase period, while that in 1‐kestose increased for the first 2 h of the chase period then declined for the remaining 4h. With a longer exposure to 14CO2 during the first 6 h of the induction period, three trisaccharides, neokestose, 1‐kestose and 6‐kestose were radiolabelled. The label turned over in neokestose and 1‐kestose, but continued to accumulate in 6‐kestose during a subsequent 18 h chase period. The specific activities of glucose and fructose of the sucrosyl portion and the terminal fructosyl moiety of the various trisaccharides were compared. In the rapid pulse‐chase experiment the specific activity of the1 terminal fructosyl moiety was consistently less than that of the sucrosyl moiety. During the chase period, the specific activity of the terminal and internal fructose moieties became similar. These results indicate that in addition to trisaccharide formed by transfer of fructosyl units from sucrose, substantial amounts of both neokestose and 1‐kestose are made by transfer of fructosyl units from higher oligomers onto sucrose in reactions probably localized in the vacuole. Copyright © 1991, Wiley Blackwell. All rights reserved

Fructosyl transfer from sucrose and oligosaccharides during fructan synthesis in excised leaves of Lolium temulentum L.

Fructan biosynthesis begins with the transfer of a fructosyl moiety from one sucrose molecule to another to yield a trisaccharide. Trisaccharides may also arise by the reversible transfer of a fructosyl moiety from higher oligomers to sucrose but in this case there is no net fructan synthesis. Short‐term and long‐term exposure of detached illuminated leaf blades of Lolium temulentum (L.I to 14CO2 was used to examine the mechanism of transfer of fructosyl residues to sucrose. Two trisaccharides, 1‐kestose and neokestose, were found to be radioactive when leaves excised and illuminated for 15 h ‐were exposed to NCO2 for 30 min. The label increased in neokestose during the chase period, while that in 1‐kestose increased for the first 2 h of the chase period then declined for the remaining 4h. With a longer exposure to 14CO2 during the first 6 h of the induction period, three trisaccharides, neokestose, 1‐kestose and 6‐kestose were radiolabelled. The label turned over in neokestose and 1‐kestose, but continued to accumulate in 6‐kestose during a subsequent 18 h chase period. The specific activities of glucose and fructose of the sucrosyl portion and the terminal fructosyl moiety of the various trisaccharides were compared. In the rapid pulse‐chase experiment the specific activity of the1 terminal fructosyl moiety was consistently less than that of the sucrosyl moiety. During the chase period, the specific activity of the terminal and internal fructose moieties became similar. These results indicate that in addition to trisaccharide formed by transfer of fructosyl units from sucrose, substantial amounts of both neokestose and 1‐kestose are made by transfer of fructosyl units from higher oligomers onto sucrose in reactions probably localized in the vacuole. Copyright © 1991, Wiley Blackwell. All rights reserved

Transcriptome Analysis of Wounding in the Model Grass Lolium temulentum

For forage and turf grasses, wounding is a predominant stress that often results in extensive loss of vegetative tissues followed by rapid regrowth. Currently, little is known concerning the perception, signaling, or molecular responses associated with wound stress in forage- and turf-related grasses. A transcriptome analysis of Lolium temulentum plants subjected to severe wounding revealed 9413 upregulated and 7704 downregulated, distinct, differentially expressed genes (DEGs). Categories related to signaling, transcription, and response to stimuli were enriched in the upregulated DEGs. Specifically, sequences annotated as enzymes involved in hormone biosynthesis/action and cell wall modifications, mitogen-activated protein kinases, WRKY transcription factors, proteinase inhibitors, and pathogen defense-related DEGs were identified. Surprisingly, DEGs related to heat shock and chaperones were more prevalent in the downregulated DEGs when compared with the upregulated DEGs. This wound transcriptome analysis is the first step in identifying the molecular components and pathways used by grasses in response to wounding. The information gained from the analysis will provide a valuable molecular resource that will be used to develop approaches that can improve the recovery, regrowth, and long-term fitness of forage and turf grasses before/after cutting or grazing.