Relationships Between Oleic and Linoleic Acid Content and Seed Colonization by Cercospora kikuchii and Diaporthe phaseolorum

Abstract

Compared with standard cultivars, seed of mid-oleic soybean genotypes sometimes have shown increased colonization by Cercospora kikuchii in the field as judged by increased levels of purple-stained seed. To examine relationships between oleic and linoleic acid levels in soybean seed and postharvest seed colonization by two fungal seed pathogens, we inoculated seed with differing oleic:linoleic acid (O/L) ratios. Seed with defined O/L ratios were produced by allowing seed development of two isogenic soybean lines to occur in three different air temperature environments. Seed produced in these environments were harvested, individually analyzed for fatty acid composition, and inoculated with mycelium preparations of the fungal seed pathogens C. kikuchii or Diaporthe phaseolorum var. sojae. Fungal biomass of infected seed was quantified by measuring in vitro ergosterol content. For both soybean lines, colonization by C. kikuchii was positively correlated with the O/L ratio (r = 0.55, P < 0.03) and oleic acid content (r = 0.61, P < 0.02), and negatively correlated with linoleic (r = –0.60, P < 0.02) and linolenic (r = –0.58, P < 0.03) acid content. No association was found between the extent of seed colonization by D. phaseolorum and the seed O/L ratio. Our data suggest that the O/L ratio may be related to soybean seed colonization by C. kikuchii, but there is no evidence of a relationship with D. phaseolorum var. sojae colonization.

Screening of early maturing soybean genotypes for production of high quality edible oil

“…According to Bellaloui et al (2015), cooler temperatures favour synthesis of linolenic acid, while at the same time the synthesis of oleic acid is negatively affected as a result of inverse relationship between them. The same was true in research done by Xue et al (2008), where increasing air temperature during pod fill significantly increased oleic acid, while significantly decereasing linoleic and linolenic acid concentrations. The inverse relationship of these fatty acids was clearly confirmed in this research where oleic acid was at its highest in hot and dry 2012, while linoleic and linolenic acids had their highest amounts recorded in 2010, which had more modest temperatures and high humidity (Figs 1 and 2, Table 1).…”

Glufosinate Effects on Nitrogen Nutrition, Growth, Yield, and Seed Composition in Glufosinate-Resistant and Glufosinate-Sensitive Soybean

“…The increase of seed protein after glufosinate application could be due to a stress response of soybean to the herbicide. For example, it was found that seed protein increased due to environmental stresses such as drought [30], diseases [31,32], and glyphosate [19]. The increase in oleic acid and decrease in linolenic acids could be due to indirect physiological disturbances that affect fatty acid desaturases, as suggested by Bennett et al [33], or as a result of carbon metabolism alteration as suggested by Bellaloui et al [19].…”

Effects of temperature during soybean seed development on defense-related gene expression and fungal pathogen accumulation

“…Increased seed infection by Phomopsis was positively correlated with linoleate and linolenate, and negatively correlated with palmitate and oleate levels. Results from infection studies with detached soybean seeds that differed in oleate/linoleate content ratios has shown that seed colonization by the fungus Cercospora kikuchii (Matsumoto and Tomoy) Gardner was greater in seeds with higher oleate and less in seeds with higher linoleate content (Xue et al 2008).…”