IFEVA   02662
INSTITUTO DE INVESTIGACIONES FISIOLOGICAS Y ECOLOGICAS VINCULADAS A LA AGRICULTURA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Ecological consequences of fungal endophytes on host plant invasion and plant community structure.
Autor/es:
CASAS, C; GUNDEL, PE; SEMMARTIN,M; OMACINI M
Lugar:
Rosario, Aregentina
Reunión:
Congreso; IX International Rangeland Congress; 2011
Resumen:
&lt;!-- /* Font Definitions */ @font-face {font-family:"DejaVu Sans"; mso-font-alt:"Arial Unicode MS"; mso-font-charset:128; mso-generic-font-family:auto; mso-font-pitch:variable; mso-font-signature:0 0 0 0 0 0;} @font-face {font-family:"@DejaVu Sans"; mso-font-charset:128; mso-generic-font-family:auto; mso-font-pitch:variable; mso-font-signature:0 0 0 0 0 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:none; mso-hyphenate:none; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"DejaVu Sans"; mso-font-kerning:.5pt; mso-ansi-language:ES-AR; mso-fareast-language:AR-SA;} p.MsoCommentText, li.MsoCommentText, div.MsoCommentText {mso-style-noshow:yes; margin:0cm; margin-bottom:.0001pt; mso-pagination:none; mso-hyphenate:none; font-size:10.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"DejaVu Sans"; mso-font-kerning:.5pt; mso-ansi-language:ES-AR; mso-fareast-language:#00FF;} span.apple-style-span {mso-style-name:apple-style-span;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --&gt; Cattle grazing promotes the invasion of exotic plants in temperate grasslands (Chaneton et al., 2002), while invasive plants can have substantial consequences at the community and ecosystem levels (Walker and Smith, 1997). Lolium multiflorum is an annual grass promoted in pampean grasslands of Argentina due to its high quality and production during winter. Naturalized populations of this species are usually highly infected (~90%) with the fungal endophyte Neotyphodium occultans (Gundel et al., 2009). Our aim was to evaluate the impact of this endophyte-grass symbiosis on the invasive ability of L. multiflorum in grasslands of the Flooding Pampa and in turns, its effect on the cover of different functional plant groups. &lt;!-- /* Font Definitions */ @font-face {font-family:"DejaVu Sans"; mso-font-alt:"Arial Unicode MS"; mso-font-charset:128; mso-generic-font-family:auto; mso-font-pitch:variable; mso-font-signature:0 0 0 0 0 0;} @font-face {font-family:"@DejaVu Sans"; mso-font-charset:128; mso-generic-font-family:auto; mso-font-pitch:variable; mso-font-signature:0 0 0 0 0 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:none; mso-hyphenate:none; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"DejaVu Sans"; mso-font-kerning:.5pt; mso-ansi-language:ES-AR; mso-fareast-language:AR-SA;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --&gt; We performed a field experiment that consisted in the addition of L. multiflorum (Lm) seeds with high and low level of endophyte infection (+E: 79% and -E: 4%, respectively) in grasslands of the Flooding Pampa (36°30′ S, 58°30′ W) covered by humid mesophytic meadows with different grazing history: Grazed (n=12) and Ungrazed (n=7, ten year-old exclosures). In a split-plot design, three treatments of sowing (+E, -E and C (without seeds)) were assigned to 0.6m x 0.9m plots after removing all the Lm plants emerged from the soil bank. Plant cover per species was estimated in spring and summer. Species were sorted as: warm- and cool-season grasses (excluding Lm) and forbs. The endophyte infection level of Lm was checked at the end of the growing season. The cover of Lm and each species group were analyzed separately using mixed models (lme function, nlme package, (R Development Core Team, 2007) &lt;!-- /* Font Definitions */ @font-face {font-family:"DejaVu Sans"; mso-font-alt:"Arial Unicode MS"; mso-font-charset:128; mso-generic-font-family:auto; mso-font-pitch:variable; mso-font-signature:0 0 0 0 0 0;} @font-face {font-family:"@DejaVu Sans"; mso-font-charset:128; mso-generic-font-family:auto; mso-font-pitch:variable; mso-font-signature:0 0 0 0 0 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:none; mso-hyphenate:none; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"DejaVu Sans"; mso-font-kerning:.5pt; mso-ansi-language:ES-AR; mso-fareast-language:AR-SA;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --&gt; The association with endophytes increased the ability of Lm to invade ungrazed stands (P<0.0001). During the spring, symbiosis presence reduced the relative cover of other cool season grasses (P=0.008). The effect on cool grasses persisted regardless of Lm cover, suggesting that other mechanisms different from competition may be involved. Conclusions Fungal endophytes are often overlooked in studies of plant community. However, their presence in exotic grass species such as Lm may explain host success as invader in natural communities. In spite of this symbiosis is not toxic for cattle, it can modify the structure and dynamic of plant communities which, in turn, may affect forage availability and quality.