The Effect of Endophyte on Salinity Tolerance in Perennial Ryegrass Eric Koch and Stacy A. Bonos, Joshua Honig, and Jennifer Vaiciunas Rutgers, The State University of New Jersey
Endophytic Fungi Neotyphodium spp. Grows intercellularly in leaf, sheath, and stem Survives off of cell leakage Conveys tolerance to biotic and abiotic stresses (Van Zijll de Jong et al., 2008) Drought, disease, above-ground feeding insects Perennial ryegrass (Lolium perenne L.) Tall fescue (Festuca arundinacea) Fine fescue Strong Creeping Red Fescue (Festuca rubra ssp. rubra) Chewings Fescue (Festuca rubra ssp. fallax) Hard Fescue (Festuca brevipila)
Endophyte growing between cells Chinch bug damage in creeping red fescue E- E+ www.aps.net.org Courtesy Dr. William Meyer E- E+ Drought tolerance in tall fescue due to endophyte presence Oregon State University Online Tall Fescue Monograph
Prior Research Research studying endophytes and salinity have been minimal thus far; other abiotic stresses have been studied extensively Malinowski and Belesky, 2000 Tall fescue E+ have better drought tolerance, drought recovery Fine fescue E+ have better Al tolerance Zaurov et al., 2001 found that there was an endophytehost interaction for Al tolerance N increases alkaloid production while P and K decrease alkaloid production Cheplick, 2004 Perennial ryegrass drought study: E- plants had greater tiller numbers, greater leaf area, and greater mass when compared to E+
Perennial Ryegrass Moderately salt tolerant - 6-10 ds m -1 Used for overseeding dormant warm season turfgrass sites in southern United States Selection for salt tolerant perennial ryegrass genotypes Objective: Determine the role of endophytes in salinity tolerance of four different genotypes of perennial ryegrass
Materials and Methods Four genotypes (All contained endophytic fungi) Salt susceptible Paragon GLR clone 4 (PG 4) and Brightstar SLT clone 5 (BS 5) Salt tolerant - S12 4540-9, and S12 4501-7 Banner MAXX II (Propiconazole) Rate- 1g / 2.69m 2 Sprayed 5 times on 1-week interval Checked for presence of endophyte using Agrinostics Phytotoscreen Immunoblot Kit (Agronostics Ltd. Co)
Materials and Methods Clones brought down to 1 tiller and grown for 2 months All plants were washed free of Pro-mix Shoots were cut at 3.8 cm above crown Roots were cut directly below crown Three replicates of each E+ and E- clone per treatment were arranged in a completely random design within each plastic tray containing topdressing sand Ten week study : 2 Runs Conducted in greenhouse Supplemental lighting April- Run 1 24.9 C December- Run 2 18.2 C
Irrigation Method Treatments applied using overhead irrigation chambers (Koch et al. 2011)
Irrigation Method Two treatments- Control 0.5 ds m -1 and treated 15.0 ds m -1 Plants were established for 1 week before initiation of salinity treatment Irrigation applied every other day 2 ds m -1 each irrigation day until reaching final concentration Avoid Shock Irrigation quantity : 4.98 cm Nutrients supplemented with half-strength Hoaglands Solution (Hoagland and Arnon, 1950) Salt solution were made using Instant Ocean (Spectrum Brands Inc.)
Data Collection Individual plants visually rated weekly for percent green which indicated leaf senescence Quantified with digital image analysis Correlation r=0.88 p<0.001 Vegetative growth cut back weekly to 3.8 cm Clippings were collected, dried 48 hours at 65 C, and weighed every 2 weeks After 10 weeks, all plants were removed and separated into roots and shoots Dried at same conditions as clippings Data presented as a percentage of control
Results Significant treatment differences for all measurements Measurements taken Visual percent green Digital images Clipping weights Root/Shoot weight Root Length Run x cultivar interaction for visual percent green ratings Separate runs SAS v9.3 -ANOVA, Contrast between E+ and E-
Salinity Damage After 8 Weeks of Salinity Stress Control Salt Treated
Percent Green Visual Ratings
** Percent Green Visual Ratings Endophyte Contrast PG 4 E- PG 4 E+ **
Dried Root/Shoot Weights Measured After 10 Weeks of Salinity Stress *** ** Contrast E+ vs. E-=NS *** ** ** ** Contrast E+ vs. E-=**
Conclusions The role of endophyte is minimal for percent green and shoot weight Clone 4 Paragon GLR E- performed better than E+ consistently Variable for other genotypes Zaurov et al., 2001: Endophyte host interaction Increased root formation is influenced by endophyte absence Presence of the endophyte had a negative impact on 3 of 4 tested clones Cheplick, 2004 Perennial ryegrass drought study: E- plants had greater tiller numbers, greater leaf area, and greater mass when compared to E+ Endophyte utilizing important nutrients needed for root formation
Additional Research Breeding for salinity has been slow and the mechanism is not fully understood Identify sequence variation in RNA transcripts between tolerant and susceptible plants Can use this information to develop SNP markers for marker assisted selection Compare transcriptomes of E+ and E- perennial ryegrass plants Identify the genes being expressed with and without the endophyte
Acknowledgements Rutgers Center for Turfgrass Science United States Golf Association Committee Members: Dr. Bingru Huang Dr. William A. Meyer Dr. Richard Hurley Dr. Stacy Bonos
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