Submitted to: Planta
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/17/2005
Publication Date: 5/10/2006
Citation: Sarath, G., Bethke, P.C., Jones, R., Baird, L.M., Guichuan, H., Mitchell, R. 2006. Nitric oxide accelerates seed germination in warm-season grasses. Planta (2006) 223:1154-1164
Interpretive Summary: Seeds of many warm-season grasses exhibit dormancy. Breaking of dormancy and stimulation of seed germination can improve establishment and productivity of species such as switchgrass and big bluestem. In this study we have documented for the first time the ability of several chemicals to promote seed germination in these species. All of these chemicals are thought to generate nitric oxide in-situ, and suggests that NO could be an endogenous trigger for release from dormancy in these species.
Technical Abstract: The nitric oxide (NO) donor sodium nitroprusside (SNP) significantly promoted germination of switchgrass (Panicum virgatum L. cv Kanlow) in the light and in the dark at 25°C. The dose response curve for SNP indicated that it was effective across a broad range of concentration, and concentrations as high as 500 µM, did not significantly inhibit germination. SNP also promoted seed germination in two other warm-season grasses. A chemical scavenger of NO inhibited germination and blocked SNP stimulation of seed germination. (+)-Catechin acted synergistically with SNP and nitrite in promoting seed germination. Acidified nitrite, sodium cyanide, potassium ferricyanide and potassium ferrocyanide at 200 µM significantly stimulated seed germination. Ferrocyanide and cyanide stimulation of seed germination was blocked by an NO scavenger. ABA at 10 µM depressed germination, inhibited root elongation and almost abolished coleoptile emergence. SNP did not overcome the effects of ABA. Light microscopy indicated extension of the radicle and coleoptiles in seeds maintained on water or on SNP after 2 days. In contrast, there was minimal growth of the radicle and coleoptile in ABA treated seeds even after 4 days. These data indicate that seed germination of warm-season grasses is significantly stimulated by conditions that are known to generate NO and suggests that NO could be an endogenous trigger for release from dormancy in these species.