Total Non‐Structural Carbohydrates in Winter Wheat Populations Segregating for Snow Mold Tolerance

Abstract

Evaluation of wheat (Triticum aestivum L.) for tolerance to snow mold (caused by Typhula idahoensis Remsberg) is difficult because of the irregular occurrence and distribution of the disease in the field. Some wheat genotypes tolerant to snow mold are known to accumulate high levels of total non-structural carbohydrates (TNC), a trait that could be utilized for rapid screening of snow mold tolerance. The objective was to determine the heritability of TNC and the correlation of TNC with survival under disease pressure in two hard red winter wheat populations segregating for snow mold tolerance. Whole-plant TNC content (excluding roots), grain yield, and survival were measured in experiments planted near Tetonia, ED, an area prone to snow mold in wheat. Two experiments consisted of BCiFe and BCiF? lines derived from two crosses, < Manning'*2/'Survivor' and "Blizzard^/'Sumner'. The third (mixed) experiment consisted of selected lines from each cross. In 1992-1993, conditions were excellent for the occurrence of snow mold infection, but no obvious snow mold damage occurred in 1993-1994. Heritability estimates of TNC measured before snowfall were 64.7% for the Manning population, 82.6% for the Blizzard population, and 87.0% for the Mixed population. Heritability estimates for winter survival were nonsignificant because of differences in snow mold infection between the 2 yr. Correlation of fall TNC levels with spring 1993 survival was r = 0.55 (P < 0.01) in the Manning backcross population, nonsignificant for the Blizzard population, and r = 0.48 (P < 0.01) in the Mixed population, suggesting that accumulation of TNC is moderately correlated to snow mold tolerance. Levels of TNC in the fall had no significant line x year interaction. Selection based upon TNC would advance a population toward higher TNC levels and may indirectly increase tolerance to snow mold in some populations. I N THE RAINFED wheat production areas of southern Idaho, snow mold damage is attributed mainly to Ty

Sources of Variation in the Solvent Retention Capacity Test of Wheat Flour

“…Sums of squares due to the random effects models were calculated using PROC GLM in SAS (SAS Institute, 1991). Population sizes for this experiment were similar to those used in a previous study to estimate variances among inbreds for complex traits (Mohammad et al, 1997). Each population was analyzed independently.…”

Graminan breakdown by fructan exohydrolase induced in winter wheat inoculated with snow mold

“…Most overwintering cereals and temperate grasses accumulate large amounts of water-soluble carbohydrates instead of starch throughout the cold hardening period. Accumulation of water-soluble carbohydrates in winter cereals during cold hardening is associated with winter survival (Mohammad et al, 1997;Yoshida et al, 1998). Most of the water-soluble polysaccharides accumulated in wheat (Triticum aestivum) during cold hardening are fructans, polymers of fructose based on sucrose, and the contents reach 10% or more of the fresh weight at the end of the cold hardening period (Yoshida et al, 1998).…”

Fructan:fructan 1-fructosyltransferase, a key enzyme for biosynthesis of graminan oligomers in hardened wheat

“…In addition to being a carbohydrate reserve, fructans are thought to play roles in protection against environmental stresses such as low temperature and drought (Hendry 1993;Pilon-Smits et al 1995;Konstantinova et al 2002). Accumulation of water-soluble carbohydrates including fructans in winter cereals during cold hardening has been shown to be associated with winter survival (Olien 1984;Pontis 1989;Tognetti et al 1990; Mohammad et al 1997;Yoshida et al 1998). In order to improve the survival of plants that encounter environmental stresses, it is essential to understand the mechanisms of fructan accumulation in plants.…”