In Vitro Oxidative Stress Threatening Maize Pollen Germination and Cytosolic Ca(2+) Can Be Mitigated by Extracts of Emmer Wheatgrass Biofortified with Selenium

In this work, we studied the effects of in vitro oxidative stress applied by H(2)O(2) to maize pollen germination and cytosolic Ca(2+), taken as an experimental model to test the biological activity of extracts of emmer (Triticum turgidum L. spp. dicoccum (Schrank ex Shubler) Thell.) wheatgrass obtained from grains sprouted with distilled water, or salinity (50 mM) or selenium (45 mg L(−1) of Na(2)SeO(3)). Wheatgrass extracts were obtained in two ways: by direct extraction in methanol, which represented the free phenolic fraction of extracts (Ef), and by residual content after alkaline digestion, which made it possible to obtain extracts with the bound fraction (Eb). Comparative tests on maize pollen were carried out by differently combining H(2)O(2) and either wheatgrass extracts or pure phenolic acids (4-HO benzoic, caffeic, p-coumaric and salicylic). The cytosolic Ca(2+) of maize pollen was influenced by either H(2)O(2) or pure phenolic acids or Ef, but not by Eb. The negative effect of H(2)O(2) on maize pollen germination and cytosolic Ca(2+) was mitigated by Ef and, slightly, by Eb. The extent of the biological response of Ef depended on the sprouting conditions (i.e., distilled water, salinity or selenium). The extracts of Se-biofortified wheatgrass were the most effective in counteracting the oxidative stress.