Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 31, 2005
Publication Date: April 1, 2006
Citation: Funnell, D., Pedersen, J.F. 2006. Association of plant color and pericarp color with colonization of grain by members of Fusarium and Alternaria in near isogenic sorghum lines. Plant Disease. 90:411-418. Interpretive Summary: Sorghum pigments in grain or leaves have been reported to provide protection to plants against insects and diseases. However, sorghum that lacks such pigments is preferred for food or food products consumed by humans and livestock. Field and greenhouse studies were conducted on sorghum lines that lack red pigments in the grain (called “white”) and purple pigments in the leaves (called “tan”) to test for resistance to two groups of potentially pathogenic fungi, Fusarium and Alternaria. Greenhouse tests to compare purple plants with red seed, purple plants with white seed, tan plants with red seed and tan plants with white seed suggested that there were no significant differences between the four types of sorghum when inoculated with either Alternaria or Fusarium moniliforme. Field tests suggested that plants with white grain were as resistant as plants with red grain to Alternaria and several Fusarium species. However, when plants were grown in a field in which there was increased moisture, grain (red or white) grown on tan plants could be infected more frequently by some Fusarium species than grain grown on purple plants.
Technical Abstract: White sorghum grain from tan plants is more desirable for human or animal consumption. Colonization by Fusarium and Alternaria spp. was assessed for near isogenic lines differing in wound response (purple or tan) and pericarp color (red or white) in field-grown grain and in greenhouse grown plants. Seeds were screened on a semi-selective medium for Alternaria and Fusarium. Significantly fewer fungal colonies were obtained from tan plants with white seed, and fewer numbers of Alternaria colonies were obtained from white seed, regardless of plant color, from an irrigated field, while there were no differences in fungal composition of seeds grown at a non-irrigated field. Screening of seed from the non-irrigated field on Fusarium semi-selective medium, yielded fewer Fusarium isolations from seed grown on purple plants as compared with seed from tan plants. When inoculated with Alternaria sp. and F. moniliforme, there were no differences in lesion lengths on tan/white plants when compared with purple/red plants in most assays; in one assay, tan/white plants had smaller lesion lengths following inoculation with F. moniliforme. These results suggest that plants with white seeds were as resistant as plants with the red pericarp trait to colonization by Alternaria and Fusarium spp., However, the results also suggest that under appropriate environmental conditions seed from tan plants may be more susceptible to Fusarium spp. than seed from purple plants