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• Overexpression TaMBF1c improved thermotolerance of perennial ryegrass. • Thermotolerance of transgenic perennial ryegrass associated with elevated antioxidative capacity. • MBF1c offers a strategy to develop cool-season turfgrass/forage plants to cope with the challenges of higher temperature. High temperature is one of the major threats to global crop production, especially the C 3 plant species, such as a widely used forage/turfgrass, perennial ryegrass. MBF1c gene belongs to group II of the highly conserved multiprotein bridging factor1 (MBF1) family, and it has been reported to be involved in various plant abiotic stresses, in particular, heat stress. In the study, a wheat MBF1c (TaMBF1c) was overexpressed in perennial ryegrass, and physiological parameters including antioxidant enzyme activities were investigated under both control (16/22 °C, n/d) and high temperature (42 °C) treatments for 24 and 48 h. The results found that the ectopic expression of TaMBF1c improved thermotolerance of perennial ryegrass, demonstrated by lower leaf electrolyte leakage and lipid peroxidation, better water status, higher chlorophyll content (SPAD index), and net photosynthetic rate under high temperature, while there was no difference between wild type and transgenic perennial ryegrass plants under control condition. The enhanced stress tolerance of transgenic perennial ryegrass was, at least partially associated with its elevated antioxidative capacity under stress. The findings confirmed that MBF1c could confer thermotolerance in C 3 perennial grass species, which offers an additional strategy to develop cool-season turfgrass/forage plants to cope with the challenges of higher temperature and more frequent heat waves due to global warming. [ABSTRACT FROM AUTHOR]

Perennial ryegrass (Lolium perenne L.) is considered a premier turfgrass and forage grass worldwide yet susceptibility to freezing damage limits its use. C-repeat binding factor (CBF) dehydration-responsive element-binding protein (DREB) related genes are considered important for the regulation of abiotic stress in plants. In this study, CBF DREB-related genes in perennial ryegrass, also known as LpCBF genes, were resequenced from cultivated and landrace plants from a worldwide collection. A total of 109 plants survived clonal propagation and were tested for freezing tolerance. The resulting data was subjected to mixed model analysis to determine whether the freezing tolerance is related to single nucleotide polymorphism (SNP) and indel markers within two genes, LpCBFIIIb and LpCBFIIIc. One major quantitative trait locus (QTL) was discovered in LpCBFIIIc for freezing tolerance, with the majority of the plants possessing the superior allele. Several minor loci were also discovered in this gene, but no significant loci were discovered in LpCBFIIIb. [ABSTRACT FROM AUTHOR]

Overseeding warm-season perennial grasses with annual ryegrass (Lolium multiflorum Lam.) is a common practice throughout the southeastern United States to extend the grazing season with high quality forage. 'Coastal' bermudagrass [Cynodon dactylon (L.) Pers.] competition to overseeded annual ryegrass was determined by light reaching the soil surface, ryegrass seedling density, and ryegrass herbage production. Treatments were 0, 56, and 112 kg ha-1 N 6 to 8 wk before planting ryegrass and sod management practices (SMPs) of a shallow disking (2.5 to 5.0 cm), applying a desiccant, and a control before planting in combination with mowing to a 2.5 or 10.0-cm sod height (SH) for 3 yr. Applying N 6 to 8 wk before planting did not influence any of the plant parameters measured. The shallow disking SMP and 2.5-cm SH allowed the most light to reach the soil surface and had the greatest ryegrass seedling density. At the 10-cm SH the shallow disking SMP had a greater seedling density than the desiccant and control SMP. None of the SMP-SH combinations consistently improved first harvest or annual herbage mass yields over the control at the 2.5-cm SH. Significant differences may have occurred if the first harvest was taken earlier. Spring bermudagrass recovery was reduced by the shallow disking SMP and 2.5-cm SH. At a bermudagrass SH of 10 cm or less there was little advantage to disking or using a desiccant to enhance ryegrass production. [ABSTRACT FROM AUTHOR]

Accumulated temperature may provide an indicator of the phenology of cool-season grass to assist in the timing of management operations but its value is highly dependent on a reliable measure of phyllochron, i.e. time between the elongation of successive leaves. Field and controlled environment studies with Italian ryegrass (IRG, Lolium multiflorum Lam.) and tall fescue (TF, Festuca arundinacea Schreb.) measured leaf-appearance responses to accumulated temperature with varying conditions of exposure to low temperatures, soil moisture content and nitrogen application. In a controlled environment, soil volumetric water contents below 20% (equivalent to moisture potentials greater than −0·1 MPa) or more frequent exposure to below-freezing air temperatures increased the phyllochron values on the main tiller of IRG and TF. There was no evidence of an interaction between soil moisture content and cold exposure on phyllochron values. Nitrogen application resulted in only small reduction in phyllochron values. In field studies over 4 years the phyllochron values in IRG during the months of January to March were 184, 180, 180 and 167 accumulated °C above 0°C leaf−1, more than double the mean value measured in a controlled environment. A greater understanding of the impact of variable low temperatures and of soil moisture potential on the phyllochron is necessary before accumulated temperature can be used to indicate changes in development stages in grasses in different environments. [ABSTRACT FROM AUTHOR]

Seven kinds of heavy metal accumulation of rubbish compost in turfgrass by EDTA chelating were investigated. With EDTA application, heavy metal accumulation by two species of turfgrass was increased significantly. The enrichment coefficients of Lolium perenne L(L) and Festuca arundinacea L(F) to Cr reached 9.45 and 6.15 respectively. In the range of EDTA dosages given, heavy metal accumulation in turfgrass increased with increasing EDTA level. There were significant differences in remediation of different metals by applying EDTA. L had high ability to accumulate Cr, Cd, Ni and Zn, showing better remediation to heavy metals of rubbish compost. In contrast, F showed high ability to accumulate Cr, Ni, Cu and Zn. Low EDTA level increased aboveground net primary production (ANP) of turfgrass, but EDTA would considerably inhibit it when EDTA was higher than 20 mmol/kg. The results demonstrated that the optimum dosage of EDTA for remediating heavy metals in rubbish compost by turfgrass was between 10 mmol/kg and 20 mmol/kg. [ABSTRACT FROM AUTHOR]

The suitability of different protocols was compared for entire plant regeneration by somatic embryo-genesis, of the forage plants Lolium multiflorum Lam. (Italian ryegrass) and Festuca arundinacea Schreb. (tall fescue). In the first protocol, immature embryos were used as starting material, while mature seeds were retained in the other two. Whichever the considered protocol, undifferentiated calli were produced on MURASHIGE and SKOOG MS medium supplemented with 2,4-D. The calli were subcultured in the dark on solid MS agar medium, containing 5 mg/l 2,4-D (protocol 2) or on solid MS medium followed by transfer to a rotated liquid MS medium with 2 mg/I 2,4-D (protocol 1). In these conditions, induction of somatic embryogenesis occurred, and whole plants were regenerated during a limited lapse of time, upon transfer in the light, to MS medium supplemented with BAP but devoid of 2,4-D. The simultaneous elimination of 2,4-D and transfer to light appeared essential for full regeneration of the plants. Using this characteristic, an additional step was added to a new protocol (protocol 3) in which microcalli, cultured on liquid MS medium containing 5 mg/l 2,4-D, were transferred to the same medium with 2 mg/l 2,4-D, in the dark. In these conditions, the suspensions kept their embryogenic potential for months. In all cases, plantlets were successfully transferred into the soil. An evaluation of the somaclonal variation potential of the plants issued from each protocol is now underway. [ABSTRACT FROM AUTHOR]