Submitted to: American Society of Agronomy Meetings
Publication Type: Abstract Only
Publication Acceptance Date: 8/11/2004
Publication Date: 10/5/2004
Citation: Hodnett, G.L., Burson, B.L., Rooney, W.L., Dillon, S.L., Price, H.J. 2004. Pollen-pistil interactions in interspecific sorghum crosses [abstract]. American Society of Agronomy. 2004 CDROM. Interpretive Summary:
Technical Abstract: Wild Sorghum species are considered to be important sources for the genetic improvement of grain sorghum (Sorghum bicolor [L.] Moench). Unfortunately, crosses between grain sorghum and most wild species have not produced hybrids. This study was undertaken to determine why hybrids have not been produced. A cytoplasmic male sterile sorghum line (ATx623) was pollinated with 14 wild Sorghum species. At different time intervals following pollination, female florets were fixed in a 3:1 solution of ethyl alcohol and glacial acetic acid. Pollinated pistils were excised from the florets, stained with aniline blue, and examined with fluorescent microscopy to quantify pollen germination and tube growth. At 24-hrs after pollination, pollen tubes of: 1) eight species had not grown beyond the stigmas; 2) three species had grown into the styles; and 3) the remaining three species (S. ecarinatum, S. macrospermum, and S. matarankense) were in the ovary. Sorghum florets pollinated with these species were examined 15 days after pollination and the number with immature embryos was 10/1119, 1/1237, and 13/533 for S. ecarinatum, S. macrospermum, and S. matarankense, respectively. However, the endosperm in these immature seed aborted and no viable seed were produced. Thus, cross-incompatibility and post-fertilization events are the reasons why hybrids can not be produced.