Characterization of oxalic acid tolerance in sunflower basal stalk rot resistance.

Authors: Underwood, William

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 8/9/2022
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The cosmopolitan necrotrophic fungal pathogen Sclerotinia sclerotiorum causes three distinct diseases on sunflower: head rot, mid-stalk rot, and basal stalk rot. Basal stalk rot is unique among crop diseases caused by S. sclerotiorum as this disease is incited by infection of sunflower roots by S. sclerotiorum mycelia. Oxalic acid (OA) is an important virulence factor for S. sclerotiorum, causing plant cell death and contributing to disease development. Treatment of sunflower roots with OA mimics the symptoms of basal stalk rot disease including wilting, leaf necrosis, stem streaking, and development of basal stem lesions. Additionally, some sunflower lines with moderate to high levels of resistance to basal stalk rot exhibit tolerance to OA, suggesting that OA tolerance may contribute to stalk rot disease resistance. The goal of this project is to examine the physiological and molecular nature of sunflower tolerance to OA. Project objectives are to: 1) Determine if sunflower tolerance to OA is associated with reduced OA accumulation in aerial tissues; 2) Determine if OA tolerance is conferred by the sunflower rootstock or shoot by performing grafting experiments; 3) Define transcriptional changes associated with OA tolerance by RNAseq comparison of tolerant and sensitive sunflower lines. Initial results indicate that OA tolerance appears to be conferred by the shoot tissues rather than roots (which are directly exposed to OA). The results of this project will complement ongoing efforts to dissect the genetic basis of sunflower quantitative resistance to basal stalk rot.