Assessment of aluminum sensitivity of maize cultivars using roots of intact plants and excised root tips

Maize cultivars (Zea mays L.) were evaluated for their aluminum (Al) sensitivity using intact plants and excised root tips exposed to 25 μM Al in nutrient solution of low ionic strength and pH 4.3. Aluminum supply increased callose formation and Al concentrations in root tips of intact plants as well as in excised root tips. Using intact plants, differences in Al sensitivity among cultivars could be characterized by Al‐induced callose formation, Al‐induced inhibition of root elongation, as well as Al contents in root tips as parameters. Significant correlations between Al‐induced callose formation and Al contents in root tips (r² = 0.64**) and inhibition of root elongation (r² = 0.80***) were found. Excised root tips did not show a significant Al‐induced inhibition of root elongation. While average Al‐induced callose formation was similar for root tips of intact plants and excised root tips, mean Al contents in excised root tips were up to 1.5‐fold higher than in root tips of intact plants after 24 h of Al treatment. Aluminum‐induced callose formation as found in excised root tips did neither correspond to Al‐induced callose formation nor to inhibition of root elongation of intact plants. The addition of 10 mM glucose to the incubation medium led to a significant increase in the elongation of excised root tips and a 2‐3‐fold increase in Al‐induced callose formation. Staining with triphenyl‐tetrazolium‐chloride (TTC) revealed increased viability of these root segments. However, these effects of glucose supply did not improve the characterization of the cultivars for Al resistance. The results presented suggest that Al exclusion mechanisms expressed in root tips of intact plants might be non‐operational in excised root tips. Therefore, the characterization of maize germplasm for Al resistance using excised root tips appears not to be reliable.     

Proton toxicity interferes with the screening of common bean (Phaseolus vulgaris L.) genotypes for aluminium resistance in nutrient solution

Common bean (Phaseolus vulgaris L.) proved to be very sensitive of low pH (4.3), with large genotypic differences in proton sensitivity. Therefore, proton toxicity did not allow the screening of common bean genotypes for aluminium (Al) resistance using the established protocol for maize (0.5 mM CaCl₂, 8 μM H₃BO₃, pH 4.3). Increasing the pH to 4.5, the Ca²⁺ concentration to 5 mM, and addition of 0.5 mM KCl fully prevented proton toxicity in 28 tested genotypes and allowed to identify differences in Al resistance using the inhibition of root elongation by 20 μM Al supply for 36 h as parameter of Al injury. As in maize, Al treatment induced callose formation in root apices of common bean. Aluminium‐induced callose formation well reflected the effect of Ca supply on Al sensitivity as revealed by root‐growth inhibition. Aluminum‐induced callose formation in root apices of 28 bean genotypes differing in Al resistance after 36 h Al treatment was positively correlated to Al‐induced inhibition of root elongation and Al contents in the root apices. However, the relationship was less close than previously reported for maize. Also, after 12 h Al treatment, callose formation and Al contents in root apices did not reflect differences in Al resistance between two contrasting genotypes, indicating a different mode of the expression of Al toxicity and regulation of Al resistance in common bean than in maize.     

Difference in response to aluminum among Japanese coniferous species

Seedlings of Chamaecyparis obtusa, Cryptomeria japonica D. Don, and Abies firma Sieb. et Zucco were grown hydroponically for 4 weeks in the presence or absence of aluminum (Al) and with or without reduced pH. Under exposure to AI, root and shoot growth of C. obtusa was enhanced. A. firma showed the same tendency as C. obtusa, though not significantly. Only in C. japonica, growth was reduced with Al, especially shoot growth. In all the species, callose production in the root tips was observed in the presence of Al. A positive correlation was observed between the relative root callose content and relative root growth (r = 0.83), and significant root elongation with AI treatment was observed in all the species. Therefore, it is considered that callose deposition in the root tips of these species may not indicate the Al-induced root cell injury causing root growth inhibition. The highest callose content in the root tip and strong callose fluorescence in the epidermis and zones of cell contact were observed in C. obtusa. Since the Al translocation rate from roots to leaves was the lowest in C. obtusa and since significant growth enhancement was observed in the presence of Al, it is possible that the accumulation of callose in the root epidermis and in the zones of cell contact is related to Al-resistance in C. obtusa.     

Effect of aluminum on soybean nodulation and nodule activity in a vertical split‐root system

Soybean plants (Glycine max L. cv Santa Rosa) grown hydroponically in nutrient solutions had reduced nodule mass and numbers in the presence of aluminum (Al). Reduced nodule number was attributed mainly to hydrogen (H) ion toxicity, whereas Al had a stronger effect on nodule growth. Using a vertical split‐root system with Al exclusively in the lower (hydroponic) layer also resulted in a significant reduction of nodulation and nodule growth in the surface compartment (vermiculite). This indirect effect could be attributed mainly to Al rather than H. Subsurface Al had no apparent effect on shoot growth or root growth of the upper compartment, but significantly limited root growth in the lower compartment where it was applied. The indirect effect of Al on nodulation could be a reflection of the abnormal root growth in the lower compartment. Split‐root experiments with a high Al soil, however, produced different effects. High Al in soil used exclusively in the lower compartment did not reduce nodule numbers or mass in the upper compartment despite being more harmful than the Al solutions to nodulation and growth of plants when used in a single compartment. Growth of roots in the subsurface compartment was also much less affected by the high soil Al compared with the Al‐containing nutrient solutions. Nodule activity, as estimated by xylem sap ureide levels, was only reduced after direct exposure of nodules to Al. A pronounced increase in the ratio of asparagine/glutamine occurred in all Al treatments where nodulation was reduced, and in some cases, there was an increase in total amino acid concentration of the xylem sap.     

Decline in leaf growth under salt stress is due to an inhibition of H+‐pumping activity and increase in apoplastic pH of maize leaves

In this study, salt‐induced changes in the growth rate of maize (Zea mays L.) were investigated during the first phase of salt stress. Leaf growth was reduced in the presence of 100 mM NaCl, and effects were more pronounced for the salt‐sensitive cv. Pioneer 3906 in comparison to the hybrid SR03. While hydrolytic activity of plasma membrane remained unaffected, H⁺‐pumping activity was reduced by 47% in Pioneer 3906, but was unchanged in SR03. Changes in apoplastic pH were detected by ratiometric fluorescence microscopy using the fluorescent dye fluorescein isothiocyanate‐dextran (50 mM). Pioneer 3906 responded with an increase of 0.2 pH units in contrast to SR03 for which no apoplastic alkalization was found. With respect to the hypothesis that the apoplastic pH is influenced by salinity, it is suggested that salt resistance is partly achieved due to efficient H⁺‐ATPase proton pumping, which results in cell‐wall acidification and loosening.     

The significance of organic‐anion exudation for the aluminum resistance of primary triticale derived from wheat and rye parents differing in aluminum resistance

Eight primary octoploid triticale genotypes (xTriticosecale Wittmack) derived from four wheat cultivars (Triticum aestivum L.) and two rye inbred lines (Secale cereale L.) differing in aluminum (Al) resistance were investigated with respect to their response to Al supply. Aluminum‐induced inhibition of root elongation (48 h, 25 µM Al supply), callose formation, and the accumulation of Al in root tips (4 h, 25 µM Al supply) were used as parameters to assess Al resistance. Using these parameters, the existing information on Al resistance of the wheat and rye cultivars was generally confirmed. The triticale cultivars showed a wide range of Al resistance amongst the Al‐sensitive wheat and the Al‐resistant rye cultivars. The rye parents and the Al‐resistant wheat parent Carazinho were characterized by Al‐induced exudation particularly of citrate but also of malate from whole root systems of 14 d old seedlings (8 h, 50 µM Al supply). Regression analysis revealed that the degree of Al resistance of the triticale genotypes was closely related to the Al‐induced citrate exudation, which was mainly controlled by the Al resistance of the wheat parent.     

Aluminium-induced callose formation in root tips of Norway spruce (Picea abies (L.) Karst.)

The objective of this study was to examine whether aluminium (Al) induces callose formation in roots of Norway spruce as it does in soybean. Spruce seedlings were grown in Al-free nutrient solution under controlled conditions in a growth chamber at pH 3.8. After 21 days 170 μM Al was added or not (controls) to the complete nutrient solution (molar Ca/Al ratio: 0.75). Callose could be detected in outer root-tip cells of Al-treated plants within 3 h, using fluorescence microscopy after staining with aniline blue. Prolonged Al treatment up to 24 h increased both the density of the callose deposits and the number of affected cell layers. Control plants showed no comparable callose deposits. Ultrastructural examinations showed cell-wall appositions in Al-treated root cells but not in controls. The possible implications of Al-induced callose formation for nutrient and water uptake by roots are discussed.     

Distribution of Accumulated Aluminum and Changes in Cell Wall Polysaccharides in Eucalyptus camaldulensis and Melaleuca cajuputi under Aluminum Stress

Distribution of aluminum (Al) within plant components and Al-induced changes in cell wall polysaccharides in root tips of Eucalyptus camaldulensis Dehnh. seedlings were compared with those of Melaleuca cajuputi Powell. In E. camaldulensis , 0.5 mM Al (pH 4.2 for 40 d) reduced plant dry weight by 50%, increased callose concentration in the root tips and induced leaf necrosis. In comparison with M. cajuputi , Al concentrations were higher in roots and leaves of E. camaldulensis on both a fresh weight basis and in the cell sap, but were lower in the cell wall. Al increased pectin, hemicellulose and cellulose concentration in the cell walls of E. camaldulensis root tips. Al-induced leaf necrosis and growth reduction in E. camaldulensis is discussed in the context of potentially toxic concentrations of Al in plant tissue and changes in polysaccharide content which could reduce water and nutrient uptake and cell wall extensibility in roots.     

Short‐term effects of pH and aluminium on mineral nutrition in maize varieties differing in proton and aluminium tolerance

In short‐term (24 h) nutrient solution experiments, the influence of different proton (pH 6.0 and pH 4.3) and aluminium (Al) (0, 20, and 50 μM) concentrations on root and coleoptile elongation, dry weight, and the uptake of selected mineral nutrients was studied in maize (Zea mays L.) varieties that differ in acid soil tolerance under field conditions. The acid‐soil‐tolerant maize varieties, Adour 250 and C525M, proved to be hydrogen (H⁺) ion sensitive, but Al tolerant, while the acid soil tolerant variety BR201F was H⁺ tolerant but Al sensitive. The acid soil sensitive variety HS 7777 was affected by both H⁺ and Al toxicity. The proton‐induced inhibition of root elongation was closely related to the proton‐induced decrease of the specific absorption rates (SAR) of boron (B), iron (Fe), magnesium (Mg), calcium (Ca), and phosphorus (P). In contrast, only the specific absorption rate of B (SARB) was significantly correlated to the Al‐induced inhibition of root elongation. It is concluded, that alterations of nutrient uptake may play an important role in H⁺ toxicity, while at least after short‐term exposure to Al, alterations of Ca, Fe, Mg, or P uptake do not seem to be responsible for Al‐induced inhibition of root elongation. Further attention deserves the Al‐B interaction, moreover taking into account that a highly significant correlation between Al‐induced increase of callose concentration in root tips and Al‐induced decrease of SAR_B could be established.     

Differential Responses of Anti-Oxidative Enzymes to Aluminum Stress in Tolerant and Sensitive Soybean Genotypes

Seedlings of two soybean genotypes, BX10 [aluminum (Al)-tolerant] and BD2 (Al-sensitive), were treated with Al to evaluate the relative root growth (RRG), callose content, Al-sensitive zone, lipid peroxidation, and the anti-oxidative enzyme activities by histochemical and biochemical assays. Under Al toxicity, the RRG reduction of BD2 was more significant than that of BX10, while callose content displayed a contrary trend. The 2–5 mm zone of root apex was the main Al-sensitive zone for soybeans. The activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) were found to be higher in the two genotypes under Al toxicity than that of the controls. The SOD, POD, and CAT activities of BX10; however, were significantly lower than those of BD2. These results implied that producing low quantity of ROS may be one aspect of the Al-tolerant mechanism for soybeans, which in turn helps them adapt to Al stress.     

The role of root border cells in aluminum resistance of pea (Pisum sativum) grown in mist culture

Root border cells are considered to contribute to aluminum (Al) resistance by protecting the root apex from Al toxicity. In the present study, the responses of root apices of pea (Pisum sativum) to Al exposure in mist culture with border cells stripped off or not were compared. Inhibition of root elongation, induction of callose synthesis, and accumulation of Al were more pronounced in root apices stripped from border cells. Aluminum application led to higher Al concentrations in border cells than in root apices. The same trend was found for Al contents in cell walls of border cells compared to root apices. The analysis of cell‐wall pectin indicated that the concentrations of total sugars, uronic acids, and 2‐keto‐3‐deoxyoctonic acid (KDO) were higher in border cells than in root apices, especially when exposed to Al. Together, these results suggest that root border cells enhance the Al resistance of root apices by immobilizing Al in their cell‐wall pectin, thus protecting the root apex.     

Enhancement of callose production by a combination of aluminum and iron in suspension-cultured tobacco (Nicotiana tabacum) cells

In nutrient medium, aluminum (A1) enhances ferrous ion [Fe(II)] -mediated per oxidation of lipids, which results in the loss of the plasma membrane integrity and the accumulation of A1 in tobacco cells. Under these conditions, the mechanism of callose production and possible involvement of callose in the accumulation of Al were investigated. Callose production was enhanced by both Al and Fe(II), but not by A1 or Fe(II) alone, and the enhancement was inhibited by a lipophilic antioxidant, suggesting that the enhancement of callose production is caused by the A1-enhanced, Fe(II)-mediated peroxidation of lipids. The enhancement of callose production depended on the presence of external Ca²⁺ in the treatment medium. The activity of β-l,3-glucan synthase in the microsomes was increased several times by the addition of Ca²⁺ in the assay medium, although the activity in the microsomes was reduced by the treatment of cells with Al and Fe(II) together. Therefore, it is likely that callose production is enhanced by exogenous Ca²⁺ via the AI-enhanced, Fe(II)-mediated peroxidation of lipids. During the exposure of the cells to Al and Fe(II), callose production started and increased simultaneously with Al accumulation. However, the digestion of callose in the cell wall materials prepared from the A1-treated cells by laminarinase did not release A1, suggesting that callose is not involved in the binding or trapping of A1.     

The role of the apoplast in aluminium toxicity and resistance of higher plants: A review

In acid mineral soils excess of aluminium ions (AI) is one of the most important factors determining plant species and ecotype distribution, and limiting growth and yield of crops. Aluminium preferentially accumulates in the root tips as sites of cell division and cell elongation. Whether inhibition of cell-division rate is due to direct interaction of Al with the chromatin in the nuclei is rather questionable because of the low radial mobility of Al in the root and the rapidity of cessation of root elongation after Al addition to the growth medium. Externally applied Al instantaneously binds to binding sites in the apoplast. Cross binding of pectates by Al may affect extensibility and water permeability of the cell wall. Interaction of Al with other cell-wall constituents is most likely but needs clarification. Aluminium also affects plasma-membrane characteristics. Ca²⁺ influx and K⁺ efflux are inhibited, and synthesis of callose is induced. Induction of callose suggests an increase rather than a decrease in cytosolic Ca²⁺ as initial response to Al. There is little evidence suggesting major disruption of plasma membrane and cytoplasmic functions by AI. K⁺ uptake, H⁺ extrusion, Fe(III) reducing capacity and lipid peroxidation are hardly affected even in roots severely inhibited in elongation by Al. Al uptake and physiological/biochemical effects of Al on intact plant roots can be mimicked even more sensitively using cell suspension cultures which, therefore, represent a powerful tool for the study of Al toxicity. Large differences in Al resistance exist between plant species and cultivars of a species. Root elongation-rate and callose formation can be used as indicators for Al injury. Since short term Al injury is mainly expressed in the apoplast. Al resistance requires exclusion of Al from or/and inactivation of Al in the apoplast. Generally, Al-resistant genotypes are characterized by lower Al accumulation of the root apical meristems. This is achieved by a lower cation-exchange capacity/surface negativity or complexation of Al through root exudates (mucilage, organic acids). Long term exposure of plants to Al also inhibits shoot growth via induction of nutrient (Mg, Ca, P) deficiencies, drought stress and phytohormone imbalances. Such longer term effects have to be taken into consideration when selecting genotypes for high yielding capacity on acid soils high in available Al.     

Effect of aluminum on callose synthesis in root tips of tea (Camellia sinensis L.) plants

Aluminum (Al) toxicity is a major factor limiting yield production on acid soils (Foy 1983). The initial symptom of Al toxicity in many plants is manifested by the inhibition of root elongation (Ownby and Popham 1990; Llugany et al. 1994; Sasaki et al. 1994; Horst et al. 1997), which occurs during a very short period of time after exposure to Al (Llugany et al. 1994; Staß and Horst 1995). In a large number of recent reports, it was shown that the root apex plays a major role in the Al-sensitivity and response mechanisms (Zhang et al. 1994; Sasaki et al. 1997; Sivaguru and Horst 1998). However, it is interesting to note that stimulatory effects of Al on the growth of plants have also been reported in some studies (Chenery 1955; Konishi et al. 1985; Huang and Bachelard 1993; Osaki et al. 1997). In tea plant (Camellia sinensis L.) a stimulatory effect of Al on the growth was also demonstrated in some experiments, using intact plant (Chenery 1955; Konishi et al. 1985), cultured roots (Tsuji et al. 1994), and pollen tubes (Yokota et al. 1997). The growth of tea roots was typically more stimulated than that of shoots by Al (Konishi et al. 1985). It was assumed that Al effects might be due to the amelioration of phosphorus absorption (Konishi et al. 1985), secretion of malic acid from roots to dissolve aluminum phosphate in the rhizosphere (Jayman and Sivasubramaniam 1975), stimulation of growth of microorganisms on the root surface (Konishi 1990) or replacement of some functions of boron (Konishi 1992; Yokota et al. 1997). However, the stimulatory effects of Al on tea plant growth have not yet been el ucidated.

The formation of callose (1,3-β-glucan) has been reported as a common plant response to a variety of stresses, as well as mechanical, biophysical, chemical, and biological injury (Jaffe and Leopold 1984; Zhang et al. 1994). Increased synthesis of callose has been observed upon exposure to excess amounts of some elements, such as boron (McNairn and Currier 1965), cobalt, nickel, zinc (Peterson and Rauser 1979), and manganese (Wissemeier and Horst} 1987, 1992). Callose synthesis was also induced by Al in the roots of Triticum aestivum (Zhang et al. 1994) and Zea mays (Horst et al. 1997; Sivaguru and Horst 1998), suspension-cultured cells of Glycine max (Staß and Horst 1995), and protoplasts of Avena sativa (Schaeffer and Walton 1990) and Zea mays (Wagatsuma et al. 1995). Induction of callose synthesis in roots seems to be a very rapid physiological indicator of Al-induced injury or genotypical differences in Al sensitivity (Wissemeier and Horst 1992; Zhang et al. 1994; Horst et al. 1997). Nevertheless, Al-induced callose synthesis in tea plant, whose growth is stimulated by suitable Al concentrations, has not been described yet. Therefore, to elucidate the physiological basic effects of Al on tea plant, callose synthesis affected by Al in the root tips of intact plants was analyzed in the present study.     

Distribution of Accumulated Aluminum and Changes in Cell Wall Polysaccharides in Eucalyptus camaldulensis and Melaleuca cajuputi under Aluminum Stress

Distribution of aluminum (Al) within plant components and Al-induced changes in cell wall polysaccharides in root tips of Eucalyptus camaldulensis Dehnh. seedlings were compared with those of Melaleuca cajuputi Powell. In E. camaldulensis, 0.5 mM Al (pH 4.2 for 40 d) reduced plant dry weight by 50%, increased callose concentration in the root tips and induced leaf necrosis. In comparison with M. cajuputi, Al concentrations were higher in roots and leaves of E. camaldulensis on both a fresh weight basis and in the cell sap, but were lower in the cell wall. Al increased pectin, hemicellulose and cellulose concentration in the cell walls of E. camaldulensis root tips. Al-induced leaf necrosis and growth reduction in E. camaldulensis is discussed in the context of potentially toxic concentrations of Al in plant tissue and changes in polysaccharide content which could reduce water and nutrient uptake and cell wall extensibility in roots.     

Aluminium Tolerance of Maize Cultivars as Assessed by Callose Production and Root Elongation

The differences in Al tolerance between 12 maize cultivars were investigated using early stress indicators such as relative root elongation rate, induction of callose formation and Al concentrations in 5 mm root tips. Plants were grown in nutrient solution (pH 4.3) and exposed to 0 (control), 20 or 50 μM Al for 24 h. According to the relative root elongation rates, Regent, C 525 M and Adour 250 were the most Al-tolerant cultivars, while BR 201 F, Teosinte, Alarik, Burras and HS 7777 were Al-sensitive. Cultivars Brummi, HS 1230, Lixis and Aladin showed an intermediate behaviour. A significant inverse correlation between relative root-elongation rates and both Al concentration in root tips and callose concentrations could be established. The usefulness of callose as an early indicator of Al stress and the importance of Al exclusion from root tips as an Al tolerance mechanism are discussed.     

Nitric oxide reduces the stress effects of aluminum on the process of germination and early root growth of rice

The present study examined the action of nitric oxide (NO) on the germination process of rice seeds and early root growth under aluminum (Al) stress. Seeds and seedlings of two rice genotypes, with different levels of sensitivity to aluminum stress, were examined after treatment with Al and NO or only with Al. Further, the histochemical localization of Al and NO was performed on the root tissues. In both genotypes, NO was able to neutralize the inhibitory Al effects on germination. In the roots of seedlings, a reduction of Al toxicity as mediated by NO was indicated by an increased root elongation and a reduction of Al accumulation on the root surface in the Al hematoxylin complexation, irrespective of the genotype. The histolocalization of NO in roots using diaminofluorescein diacetate (DAF‐2DA) and confocal microscopy revealed endogenous Al‐induced levels of NO. It is concluded that NO can alleviate Al stress in the seedlings of the studied rice genotypes by improving germination and early root growth and is likely to play a role in a specific stress‐signaling pathway.     

Effects of calcium deficiency on nutrient concentration of xylem sap of excised tomato plants

The effects of calcium (Ca) deficiency on cation uptake and concentration of xylem sap from tomato roots after excision of the aerial parts, were studied. The measurements were made on tomato plants grown on nutrient solutions with +Ca or without‐Ca, over a period of 48 hours. Calcium deficiency entailed a significant increase of the flux of xylem sap between the 6th and 14th hour on the first day after excision. In spite of the lack of Ca in the nutrient solution, the Ca concentration in xylem sap was unaffected in regard to that of excised roots with +Ca. The maintenance of the Ca concentration in xylem sap of plants grown on a Ca deficient solution was related to a reuse of the Ca from the apoplastic root stores. So, this regulation indicates a possible translocation of the Ca available in the root supply and a mobility of this element out of the roots only during the early stages of exposure to a Ca deficiency. The presence of NH₄ ⁺ in xylem sap with both +Ca and‐Ca treatments confirms the nitrogenous reduction activity of tomato roots. The accumulation of free ammonium 24 h after excision in both xylem saps (+Ca and‐Ca) is likely to be evidence of an alteration process of protein synthesis which is related to the depletion of the root water soluble carbohydrate supply.     

Soil base saturation affects root growth of European beech seedlings§

To assess the potential effects of Al toxicity on the roots of young European beech (Fagus sylvatica L.), seeds were sown in soil monoliths taken from the Ah and B horizons of forest soils with very low base saturation (BS) and placed in the greenhouse. The Ah horizons offered a larger supply of exchangeable cation nutrients than the B horizons. After 8 weeks of growth under optimal moisture conditions, the seedlings were further grown for 14 d under drought conditions. Root‐growth dynamics were observed in rhizoboxes containing soils from the Ah and B horizons. The concentrations of Al³⁺, base cations, and nitrate in the soil solution and element concentrations in the root tissue were compared with above‐ and belowground growth parameters and root physiological parameters. There was no strong evidence that seedling roots suffered from high soil‐solution Al³⁺ concentrations. Within the tested range of BS (1.2%–6.5%) our results indicated that root physiological parameters such as O₂ consumption decreased and callose concentration increased in soils with a BS < 3%. In contrast to the B horizons, seedlings in the Ah horizons had higher relative shoot‐growth rates, specific root lengths, and lengths and branching increments, but a lower root‐to‐shoot ratio and root‐branching frequency. In conclusion, these differences in growth patterns were most likely due to differences in nutrient availability and to the drought application and not attributable to differences in Al³⁺ concentrations in the soil solution.     

Policosanol Contents and Composition of Grain Sorghum Kernels and Dried Distillers Grains

Grain sorghum can be a major source of policosanols, long‐chained alcohols, that have beneficial physiological activities. Sorghum dried distillers grains (DDG), a by‐product of ethanol production from grain sorghum, contain a large amount of policosanols. Content and composition of policosanols in long‐chained lipids extracted from grain sorghum kernels and DDG were determined. Long‐chained lipids were extracted using hot hexane or hot ethanol. The major components of the long‐chained lipids extracted from grain sorghum kernels, as determined using HPLC, were policosanols (37–44%), aldehydes (44–55%), and acids (4–5%). Long‐chained lipids from DDG contained 52% policosanols, 23% aldehydes, 6.4% acids, and 17% wax esters/steryl esters. Composition of policosanols in DDG matched the composition in grain sorghum kernels, as determined by gas chromatography, even though the content of policosanols in DDG was greater than the content in grain sorghum kernels. Policosonal composition ranges were 0–1% C22:0, 0–3% C24:0, 6–8% C26:0, 1% C27:0, 43–47% C28:0, 1–2% C29:0, 40–43% C30:0, and 1–4% C32:0.