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ARS Home » Plains Area » Lincoln, Nebraska » Wheat, Sorghum and Forage Research » Research » Publications at this Location » Publication #309930

Research Project: Genetic Improvement of Sorghum for Non-Grain Energy Uses

Location: Wheat, Sorghum and Forage Research

Title: Effect of waxy (low amylose) on fungal infection of sorghum grain

item Funnell-Harris, Deanna
item Sattler, Scott
item O`Neill, Patrick
item ESKRIDGE, KENT - University Of Nebraska
item Pedersen, Jeffrey

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/23/2015
Publication Date: 7/7/2015
Citation: Funnell-Harris, D.L., Sattler, S.E., O'neill, P.M., Eskridge, K.M., Pedersen, J.F. 2015. Effect of waxy (low amylose) on fungal infection of sorghum grain. Phytopathology 105: 786-796. DOI: 10.1094/PHYTO-09-14-0255-R.

Interpretive Summary: The waxy mutants alter starch composition of grain, which results in greater digestibility. Therefore, they are desirable for food, feed and grain-based bioethanol production. We previously characterized sorghum lines with this mutation. These waxy and normal sorghum lines were grown in the field and mold infection was assessed. The waxy lines were not more susceptible than normal lines to grain mold disease. We had previously developed waxy lines highly similar to normal lines except for the waxy trait. Grain from waxy lines and normal lines were infected with different grain molds and, again, the waxy lines were not more susceptible than normal lines. This information is valuable for developing waxy sorghum hybrids with resistance to grain molds.

Technical Abstract: Loss of function mutations in the Waxy (Wx) gene, encoding Granule Bound Starch Synthase (GBSS) that synthesizes amylose, results in starch granules containing mostly amylopectin. Grain with this trait has increased usability for feed, food and grain-based ethanol, due to altered starch properties. In sorghum, two classes of waxy (wx) alleles had been previously characterized for absence or presence of the GBSS protein, wxa (GBSS-) and wxb (GBSS+), respectively. Field-grown grain of Plant Introduction accessions with the phenotypes, wild-type; waxy, GBSS-; and waxy, GBSS+, were screened for fungal infection. Correlation analysis indicated that height was a factor: short wxb accessions were more susceptible than wild-type or tall waxy, GBSS+, accessions with an undescribed allele. Grain from GBSS- accessions had similar percent infection as wild-type. Grain from accessions, and near-isogenic wxa and wxb and lines, were inoculated with Alternaria sp., Fusarium thapsinum and Curvularia sorghina, and germination and seedling fitness were analyzed. As a group, waxy lines were not more susceptible than wild-type, supporting field evaluations. Amongst most lines, significantly reduced emergence, survival and seedling weights were observed following inoculations with C. sorghina and F. thapsinum. These results are valuable for developing waxy sorghum hybrids with resistance to grain-infecting fungi.