Effect of Temperature and BASF 13 338 on the Lipid Composition and Respiration of Wheat Roots

Abstract

The fatty acid composition of wheat seedling roots changed in response to temperature. As temperature declined, the level of linolenic acid increased and the level of linoleic acid decreased. The distribution of phospholipid classes was not influenced by temperature. Phosphatidyl choline and phosphatidyl ethanolamine were the predominant phospholipids isolated and comprised 85% of the total lipid phosphorus. Smaller quantities of phosphatidyl glycerol, phosphatidyl inositol, phosphatidic acid, and phosphatidyl serine were isolated. The fatty acid composition of phosphatidyl choline and phosphatidyl ethanolamine were the same and temperature affected the fatty acid composition of both phospholipids in the same manner.Growth in the presence of the substituted pyridazinone, BASF 13 338 (4-chloro-5-dimethylamino-2-phenyl-3(2H)pyridazinone), reduced the level of linolenic acid and increased the level of linoleic acid in the phosphatidyl choline, phosphatidyl ethanolamine, and total polar lipid fractions. BASF 13 338 did not affect the levels of palmitate, stearate, and oleate or the distribution of phospholipid classes.Respiration rates of wheat root tips were measured over a range of temperatures. The respiration rate declined as the temperature decreased. Neither the temperature at which the tissue was grown nor BASF 13 338 treatment influenced the ability of root tips to respire at any temperature from 4 to 30 C. The results indicated that the relative proportion of linolenic acid to linoleic acid did not influence the plants ability to grow and respire over the range of temperatures tested.As the temperature declines in the fall of the year, winter wheat undergoes physiological changes which lead to increased freezing resistance. Considerable research has focused on changes in membrane lipid composition during temperature acclimation. When wheat plants are exposed to cold temperatures, the level of linolenic acid increases and the level of linoleic acid decreases (4,9,27). Fatty acid unsaturation increases to the same extent in cultivars varying widely in resistance to freezing (6,27).Recent studies demonstrated that the substituted pyridazinone BASF 13 338 simultaneously inhibits the accumulation of linolenic acid and the acquisition of winter hardiness (22,23,26 was proposed that an increase in linolenic acid would increase the fluidity of membranes at low temperatures. This should enable wheat to function normally at low temperatures and perform the necessary steps involved in the acquisition of freezing resistance.Our objectives were to characterize the effect of temperature and pyridazinone treatment on the phospholipid and fatty acid composition of wheat roots and to determine the relation between lipid composition and the ability of wheat plants to grow and respire at low temperatures. MATERIALS AND METHODSGrowth of Wheat Seedlings. Winter wheat (Triticum aestivum L. 'Arthur') seeds were germinated in paper seed towels moistened with either distilled H20 or 100 /SM BASF 13 338 (4-chloro-5-dimethyla...

Fluridone and norflurazon, carotenoid‐biosynthesis inhibitors, promote seed conditioning and germination of the holoparasite Orobanche minor

“…Substituted pyridazinones including norflurazon were reported to affect lipid synthesis through inhibition of fatty acid desaturases (St John 1976, St John et al 1979, Ashworth et al 1981, Wang et al 1987) and therefore these compounds may have profound effects that are independent of effects on carotenoid or ABA synthesis. This might explain some of their effects observed in the present study.…”

The Effect of Cold Stress on the Root-Specific Lipidome of Two Wheat Varieties with Contrasting Cold Tolerance

“…Several studies have reported on the lipid profiling of a particular lipid class or more complicated lipidome analyses upon cold stress in wheat [ 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 ]. In [ 36 ], Roche et al studied the phospholipid content of seedlings grown at 2 °C and reported that the content was higher than that of seedlings grown at 24 °C.…”

“…In [ 36 ], Roche et al studied the phospholipid content of seedlings grown at 2 °C and reported that the content was higher than that of seedlings grown at 24 °C. Ashworth et al [ 37 ] reported the decrease of linoleic acid but increase in linolenic acid in wheat seedling roots in response to declined temperature, while phospholipid was not influenced by temperature. Vigh et al [ 38 ] studied the correlation of glycolipids and fatty acids of chloroplast thylakoid membranes in two wheat varieties of contrasting hardiness.…”

“…Li et al [ 41 ] reported that cerebroside C increased tolerance to chilling injury and altered lipid composition in the roots of wheat seedlings. In all these studies, the tissues used for the analyses were either shoots, seedlings, or whole seedling roots [ 36 , 37 , 38 , 39 , 40 , 41 ]. However, a thorough investigation of the effect of cold stress in roots or more specifically in the different developmental root zones of the young roots has not been conducted.…”

PPARα-Mediated Positive-Feedback Loop Contributes to Cold Exposure Memory

“…Environmental stimuli such as cold exposure or chronic dietary changes influence cellular responses, for instance, altered energy balance, gene expression, and composition or fluidity of lipid membranes 1 – 6 . It has previously been shown in various organisms that exposure to cold stimulates an increase in fat utilization 7 , 8 and causes alterations in membrane fluidity through incorporation of unsaturated fatty acids into lipid membranes 9 , 10 . In addition, cold exposure also causes activation of the desaturase system 11 .…”