Endophyte Survival During Seed Storage: Endophyte/Host Interactions and Heritability.

Incorporation of novel, non-toxic, endophytes into forage tall fescue is the preferred plant strategy used to overcome fescue toxicosis.  Endophytes are transmitted maternally through the seed but suffer mortality preferentially to the embryo during seed storage.  Loss of viable endophyte reduces the value of the seed.  Thus increasing storage life of the endophyte in seed would be of benefit to the seed industry.  The objectives of this study were to examine 1) viability of a common novel endophytes in different tall fescue cultivars, and different novel endophytes in a common tall fescue cultivar when seed were stored for extended periods of time, and 2) whether selection for persistence of endophyte viability during seed storage was a heritable trait.  Three diverse tall fescue cultivars with endophye AR542, and ‘Jesup’ tall fescue with endophytes AR542 and AR584were stored at room temperatures for 18 months.  Seedling plants were tested for viable endophyte monthly.  Plants grown from each Jesup population following  18 months of seed storage were selected and placed into polycross blocks.  Seed from the selected and parent populations were stored at 30^oC for 22 months.  Viable endophyte was tested in the seed monthly.  Heritability of endophyte viability during seed storage was calculated.  One cycle of selection for endophyte survival increased endophyte viability in stored seed and had heritabilities of 38 and 63% for endophytes AR542 and AR584, respectively. A second cycle of selection increased endophyte viabilty to germination rates fell before endophyte death.