Purification and Identification of a Plasma Membrane Associated Electron Transport Protein from Maize (Zea mays L.) Roots

Plasma membranes isolated from three-day-old maize (Zea mays L.) roots by aqueous two-phase partitioning were used as starting material for the purification of a novel electron transport enzyme. The detergent-solubilized enzyme was purified by dyeligand affinity chromatography on Cibacron blue 3G-A-agarose. Elution was achieved with a gradient of 0 to 30 micromolar NADH. The purified protein fraction exhibited a single 27 kilodalton silver nitrate-stained band on sodium dodecyl sulfate polyacrylamide gel electrophoretograms. Staining intensity correlated with the enzyme activity profile when analyzed in affinity chromatography column fractions. The enzyme was capable of accepting electrons from NADPH or NADH to reduce either ferricyanide, juglone, duroquinone, or cytochrome c, but did not transfer electrons to ascorbate free-radical or nitrate. The high degree of purity of plasma membranes used as starting material as well as the demonstrated insensitivity to mitochondrial electron transport inhibitors confirmed the plasma membrane origin of this enzyme. The purified reductase was stimulated upon prolonged incubation with flavin mononucleotide suggesting that the enzyme may be a flavoprotein. Established effectors of plasma membrane electron transport systems had little effect on the purified enzyme, with the exception of the sulfhydryl inhibitor p-chloromercuriphenyl-sulfonate, which was a strong inhibitor of ferricyanide reducing activity.     

Electrotropism of Maize (Zea mays L.) Roots (Facts and Artifacts)

Intact and decapped primary roots of maize (Zea mays L.) were exposed to DC electric fields of 0.5 to 8.0 V/cm in low-salinity media to resolve conflicting results about the direction of electrotropism. In DC fields of 0.5 V/cm or 1.0 V/cm, intact roots always curved toward the cathode. In a field of 8.0 V/cm, intact roots curved toward the anode and stopped growth. Decapped roots also curved toward the anode both in weak and strong fields. The results indicate that growth toward the cathode is the true response of healthy roots.     

Light-dependent Proton Excretion of Wheat (Triticum aestivum L.) and Maize (Zea mays L.) Roots

We investigated the change of root net proton excretion of seedlings of Triticum aestivum L. and Zea mays L. with daily variation of illumination using a multi-channel pH-stat system. We found an increase of net proton excretion during darkness and a drop after the beginning of illumination. Inhibition of carotenoid biosynthesis by norflurazone and photooxidation of chlorophylls did not change the periodicity or its induction. The induction of diurnal periodicity was possible with blue, green and red light. After induction the oscillation of net proton excretion continued for at least two cycles under constant light. We conclude that net H⁺ excretion of wheat and maize roots may be regulated by an endogenous clock or by a signal from the leaves. The nature of such a hypothetical signal remains unknown.     

Effects of Salinity on Water Transport of Excised Maize (Zea mays L.) Roots

The root pressure probe was used to determine the effects of salinity on the hydraulic properties of primary roots of maize (Zea mays L. cv Halamish). Maize seedlings were grown in nutrient solutions modified by additions of NaCl and/or extra CaCl₂ so that the seedlings received one of four treatments: Control, plus 100 millimolar NaCl, plus 10 millimolar CaCl₂, plus 100 millimolar NaCl plus 10 millimolar CaCl₂. The hydraulic conductivities (Lp_r) of primary root segments were determined by applying gradients of hydrostatic and osmotic pressure across the root cylinder. Exosmotic hydrostatic Lp_r for the different treatments were 2.8, 1.7, 2.8, and 3.4·10⁻⁷ meters per second per megapascals and the endosmotic hydrostatic Lp_r were 2.4, 1.5, 2.7, and 2.3·10⁻⁷ meters per second per megapascals, respectively. Exosmotic Lp_r of the osmotic experiments were 0.55, 0.38, 0.68, and 0.60·10⁻⁷ meters per second per megapascals and the endosmotic Lp_r were 0.53, 0.21, 0.56, and 0.54·10⁻⁷ meters per second per megapascals, respectively. The osmotic Lp_r was significantly smaller (4-5 times) than hydrostatic Lp_r. However, both hydrostatic and osmotic Lp_r experiments showed that salinization of the growth media at regular (0.5 millimolar) calcium levels decreased the Lp_r significantly (30-60%). Addition of extra calcium (10 millimolar) to the salinized media caused ameliorative effects on Lp_r. The low Lp_r values may partially explain the reduction in root growth rates caused by salinity. High calcium levels in the salinized media increased the relative availability of water needed for growth. The mean reflection coefficients of the roots using NaCl were between 0.64 and 0.73 and were not significantly different for the different treatments. The mean values of the root permeability coefficients to NaCl of the different treatments were between 2.2 and 3.5·10⁻⁹ meters per second and were significantly different only in one of four treatments. Cutting the roots successively from the tip and measuring the changes in the hydraulic resistance of the root as well as staining of root cross-sections obtained at various distances from the root tip revealed that salinized roots had mature xylem elements closer to the tip (5-10 millimeters) compared with the controls (30 millimeters). Our results demonstrate that salinity has adverse effects on water transport and that extra calcium can, in part, compensate for these effects.     

Sugar Efflux from Maize (Zea mays L.) Pedicel Tissue

Sugar release from the pedicel tissue of maize (Zea mays L.) kernels was studied by removing the distal portion of the kernel and the lower endosperm, followed by replacement of the endosperm with an agar solute trap. Sugars were unloaded into the apoplast of the pedicel and accumulated in the agar trap while the ear remained attached to the maize plant. The kinetics of ¹⁴C-assimilate movement into treated versus intact kernels were comparable. The rate of unloading declined with time, but sugar efflux from the pedicel continued for at least 6 hours and in most experiments the unloading rates approximated those necessary to support normal kernel growth rates. The unloading process was challenged with a variety of buffers, inhibitors, and solutes in order to characterize sugar unloading from this tissue.

Unloading was not affected by apoplastic pH or a variety of metabolic inhibitors. Although p-chloromercuribenzene sulfonic acid (PCMBS), a nonpenetrating sulfhydryl group reagent, did not affect sugar unloading, it effectively inhibited extracellular acid invertase. When the pedicel cups were pretreated with PCMBS, at least 60% of sugars unloaded from the pedicel could be identified as sucrose. Unloading was inhibited up to 70% by 10 millimolar CaCl₂. Unloading was stimulated by 15 millimolar ethyleneglycol-bis(β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid which partially reversed the inhibitory effects of Ca²⁺. Based on these results, we suggest that passive efflux of sucrose occurs from the maize pedicel symplast followed by extracellular hydrolysis to hexoses.

     

Biochemical composition of maize (Zea mays L.) pollen

Summary Mean percentages of sugars, water-soluble polysaccharides, starch, total carbohydrates and lipids were 40.1, 7.4, 28.6, 76.1, and 1.8 respectively. Differences among the mutants were found only for water-soluble polysaccharides with both wx and sh₂ decreasing the percentage a small but significant amount. In terms of the various carbohydrates measured, no correlation was found between the expression of these mutants in the pollen and the kernel.

---

Zusammenfassung Die Untersuchung des Kohlenhydrat- und Lipid-Gehaltes im Pollen der Endosperm-Mutanten waxy, shrunken und sugary vom Mais ergab einen gemittelten Gehalt an Zucker von 40,1%, wasserlöslichen Polysacchariden 7,4%, Stärke 28,6, Gesamtkohlenhydraten 76,1% und Lipiden 1,8%.Unterschiede zwischen den Mutanten wurden lediglich hinsichtlich der wasserlöslichen Polysaccharide gefunden, und zwar bei wx und sh₂, die einen signifikant niedrigeren Gehalt aufwiesen.Hinsichtlich der verschiedenen analysierten Kohlenhydrate wurde keine Korrelation zwischen der Expression der Mutanten im Pollen und in den Karyopsen gefunden.

---

---

Herrn Professor Dr. J. Straub (Köln-Vogelsang) zu seinem 60. Geburtstag gewidmet.

---

Journal Series Paper No. 3621, Florida Agricultural Experiment Station.     

Biochemical composition of maize (Zea mays L.) pollen

Summary Pollen grains containing either the Wx, wx, Su ₁, su ₁, Sh ₂ or sh ₂ alleles were stored at 0, 1, 2, 3, 4 and 5 days at 2 °C. After each storage period, a portion of pollen from each genotype was analyzed for free amino acid content. Over all genotypes, storage significantly altered the content of all 16 amino acids measured. With increasing storage, a relatively consistent increase in aspartic acid, isoleucine, leucine, phenylalanine, ethanolanine, aminobutyric acid, NH₃ and lysine was found. A relatively consistent decrease in glutamic acid, proline, glycine and alanine occurred with increasing storage. No consistent response to storage was obtained with threonine-serine, valine, histidine and the unknown. Apparently, storage or stage of viability loss has a pronounced effect on amino acid metabolism in maize pollen grains. The experiment was designed so that comparisons free of genetic background effects could be made between alleles at each locus. Significant allele X storage interactions at each locus were found as follows: at the waxy locus, aspartic acid, glycine, alanine and ethanolanine; at the sugary locus, aspartic acid, alanine, ethanolanine and aminobutyric acid; and at the shrunken locus, aspartic acid, alanine, valine, leucine and ethanolanine. Amino acid metabolism is apparently influenced by the action of the alleles at these loci. The differences between the loci in the amino acids affected indicate the different areas of amino acid metabolism are influenced by each locus.Journal Series Paper No. 4425, Florida Agricultural Experiment Station.     

Proliferation of Maize (Zea mays L.) Roots in Response to Localized Supply of Nitrate

Maize (Zea mays L.) plants with two primary nodal root axeswere grown for 8 d in flowing nutrient culture with each axisindependently supplied with . Dry matter accumulation by roots was similar whether 1.0 mol m^–3 was supplied to on( or both axes. When was supplied to only one axis, however, accumulationof dry matter within the root system was significantly greaterin the axis supplied with . The increased dry matter accumulation by the +N-treated axis was attributableentirely to increased density and growth of lateral branchesand not to a difference in growth of the primary axis. Proliferation of lateral branches for the + N axis was associatedwith the capacity for in situ reduction and utilization of aportion of the absorbed , especially in the apical region where lateral primordia are initiated. Althoughreduced nitrogen was translocated to the –N axis, concentrationsin the –N axis remained significantly lower than in the+N axis. The concentratio of reduced nitrogen, as well as invitro reductase activity, was greater in apical than in more basal regions of the +N axis. The enhancedproliferation of lateral branches in the + N axis was accompaniedby an increase in total respiration rate of the axis. Part ofthe increased respiration was attributable to increased massof roots. The specific respiration rate (umol CO₂ exolved perhour per gram root dry weight) was also greater for the +N thanfor the –N axis. If respiration rate is taken as representativeof sink demand, stimulation of initiation and growth of lateralsby in situ utilization of a localized exogenous supply of establishes an increased sink demand through enhancedmetabolic activity and the increased partitioning of assimilatesto the + N axis responds to the difference in sink demand between+N and –N axes. Key words: NO₃^- reduction, NO₃^- uptake nitrogen partitioning, root respiration, sink demand     

Ethylene Evolution from Maize (Zea mays L.) Seedling Roots and Shoots in Response to Mechanical Impedance

The effect of mechanical impedance on ethylene evolution and growth of preemergent maize (Zea mays L.) seedlings was investigated by pressurizing the growth medium in triaxial cells in a controlled environment. Pressure increased the bulk density of the medium and thus the resistance to growth. The elongation of maize primary roots and preemergent shoots was severely hindered by applied pressures as low as 10 kilopascals. Following a steep decline in elongation at low pressures, both shoots and roots responded to additional pressure in a linear manner, but shoots were more severely affected than roots at higher pressures. Radial expansion was promoted in both organs by mechanical impedance. Primary roots typically became thinner during the experimental period when grown unimpeded. In contrast, pressures as low as 25 kilopascals caused a 25% increase in root tip diameter. Shoots showed a slight enhancement of radial expansion; however, in contrast to roots, the shoots increased in diameter even when growing unimpeded. Such morphological changes were not evident until at least 3 hours after initiation of treatment. All levels of applied pressure promoted ethylene evolution as early as 1 hour after application of pressure. After 1 hour, ethylene evolution rates had increased 10, 32, 70, and 255% at 25, 50, 75, and 100 kilopascals respectively, and continued to increase linearly for at least 10 hours. When intact corn seedlings were subjected to a series of hourly cycles of pressure, followed by relaxation, ethylene production rates increased or decreased rapidly, illustrating tight coupling between mechanical impedance and tissue response. Seedlings exposed to 1 microliter of ethylene per liter showed symptoms similar to those shown by plants grown under mechanical impedance. Root diameter increased 5 times as much as the shoot diameter. Pretreatment with 10 micromolar aminoethoxyvinyl glycine plus 1 micromolar silver thiosulfate maintained ethylene production rates of impeded seedlings at basal levels and restored shoot and root extension to 84 and 90% of unimpeded values, respectively. Our results support the hypothesis that ethylene plays a pivotal role in the regulation of plant tissue response to mechanical impedance.     

Solubilization of a Proline Dehydrogenase from Maize (Zea mays L.) Mitochondria

L-Proline is oxidized to pyrroline-5-carboxylic acid in intact plant mitochondria by a proline dehydrogenase (EC 1.4.3) that is bound to the matrix side of the inner mitochondrial membrane (TE Elthon, CR Stewart [1981] Plant Physiol 67: 780-784). This investigation reports the first solubilization of the L-proline dehydrogenase (PDH) from plant mitochondria. The supernatant from NP-40-treated etiolated shoot mitochondria of maize, Zea mays L., reduced iodonitrotetrazolium violet in a proline dependent manner. The pH optimum for this activity was 8. The apparent K_m for proline was 6.6 millimolar. When supplied with proline, this solubilized PDH activity also synthesized pyrroline-5-carboxylic acid. The PDH activity was inhibited in vitro by 300 millimolar potassium chloride but not by 300 millimolar potassium acetate. The PDH activity had a molecular mass that was greater than 150 kilodaltons. Mitochondria were prepared from etiolated shoots grown in 100% water-saturated vermiculite (control) and 16% water-saturated vermiculite (stress). The specific activity of solubilized PDH from the stress treatment was 11% of the same activity from the control treatment. Oxygen uptake in the presence of proline and ADP (state 3 proline oxidation) by mitochondria from the stress treatment was 25% of the same rate by mitochondria from the control treatment. Mitochondria were also prepared 16 hours after rewatering the seedlings growing in the stress treatment. Both the solubilized PDH specific activity and state 3 proline oxidation returned to the control levels. The specific activities of the NAD⁺-dependent pyrroline-5-carboxylic acid dehydrogenase and cytochrome c oxidase in the solubilized preparations were unaffected by these stress and recovery treatments. Oxygen uptake rates by intact mitochondria in the presence of ADP and NADH, succinate or malate-pyruvate were also unaffected by these treatments.     

Structural Analysis of Secreted Root Slime from Maize (Zea mays L.)

Secreted slime isolated from the incubation medium of Zea mays roots maintained axenically contains fucose, arabinose, xylose, galactose, and glucose as the major monosaccharides. The slime preparation contains low levels (3% weight/weight [w/w]) of uronic acids. Methylation analysis reveals an extraordinarily diverse range of glycosyl residues. The fucosyl residues are primarily terminal (60%) and 3-linked (33%) with a relatively small proportion being 2-linked (6%). The methylation data are consistent with, but not proof of, the presence of a range of polymers including arabinogalactan-proteins (AGPs), xyloglucans, arabinoxylans, and glucans in the slime. The specific binding of the β-glucosyl Yariv reagent, a dye which binds and precipitates AGPs, to the slime preparation and to the outer periclinal epidermal cell wall surface in root sections, is further evidence for the presence of AGPs. Low levels of phenolic acids (approximately 0.17% w/w), in particular trans-ferulic acid, and protein (approximately 6% w/w) were also detected.     

Anatomy of Seedling Roots of Tropical Maize (Zea mays L.) Cultivars at Low Water Supply

Establishment of maize seedlings can be difficult at low soilmoisture content. Anatomy of root metaxylem vessels may influencethe capacity for water transport and respective genotypic differencesmight be useful for selection purposes. To test this, six tropicalmaize (Zea mays L.) cultivars were grown in large PVC tubescontaining a sandy substrate at 5% (M5) and 10% (M10) moisturecontents for 2 weeks. The percentage changes in root diametersdue to M5 was similar for most cultivars but differed for mainroot types. Root diameters were not consistently related tometaxylem structure, but in a few cases, thin roots had smallerdiameter metaxylem vessels. The M5 treatment reduced the numberof late metaxylem vessels of primary roots by about 0 to 20%,while effects on nodal roots were slight. Generally, the ratioof cross-sectional areas between late and early metaxylem vesselsincreased from primary to seminal and nodal roots. Within thecultivar Tuxpefio this ratio was much reduced by M5. A few cultivarsmaintained the combined cross-sectional areas of metaxylem vesselsat M5 in some main root types, but only one cultivar could achievethis for the total of cross-sectional areas of metaxylem vessels,calculated over all root axes, by increasing the number of seminaland nodal roots. These anatomical traits seemed to be mostlyconstitutive with limited response to an actual environment,but they could be decisive for the suitability of a cultivarto an environment with frequent water shortages during seedlingestablishment. Key words: Metaxylem vessels, water stress, tropical maize     

Endopolyploidy in Diploid and Tetraploid Maize (Zea mays L.)

Nuclei from different tissues such as stem, mesocotyl, nodalroot and root tip of diploid and tetraploid maize were isolated,stained with propidium iodide and passed through an EPICS-751flow-cytometer cell sorter. Variations in flow histograms wereobserved in different tissues. Stem tissues of both the diploidand tetraploid had two peaks representing G1 and G2 somaticnuclei. The remaining tissues in both the diploids and tetraploidsexhibited three peaks. The first peak observed in these tissuesrepresents G1 somatic nuclei of the lowest ploidy level. Thesecond peak represent G2 somatic nuclei of the lowest ploidylevel+G1 somatic nuclei of the next ploidy level. The thirdpeak represents G2 of the higher ploidy level+G1 somatic nucleiof the next higher ploidy level. Statistically significant differenceswere observed between the diploid and tetraploid maize tissueswith respect to nuclei distribution in the higher ploidy levelpeaks implying variation in the degree of endopolyploidy inthe diploid and tetraploid maize. The results of this studysuggest that the amount of endopolyploid observed in maize genotypeshas an effect on their overall agronomic performance under thefield conditions.Copyright 1993, 1999 Academic Press Zea mays L., maize, endopolyploidy, diploid, tetraploid, flow cytometry     

Purification and Partial Characterization of Maize (Zea mays L.) beta-Glucosidase

Maize (Zea mays L.) β-glucosidase (β-d-glucoside glucohydrolase, EC 3.2.1.21) was extracted from the coleoptiles of 5- to 6-day-old maize seedlings with 50 millimolar sodium acetate, pH 5.0. The pH of the extract was adjusted to 4.6, and most of the contaminating proteins were cryoprecipitated at 0°C for 24 hours. The pH 4.6 supernatant from cryoprecipitation was further fractionated by chromatography on an Accell CM column using a 4.8 to 6.8 pH gradient of 50 millimolar sodium acetate, which yielded the enzyme in two homogeneous, chromatographically different fractions. Purified enzyme was characterized with respect to subunit molecular weight, isoelectric point, amino acid composition, NH₂-terminal amino acid sequence, pH and temperature optima, thermostability, and activity and stability in the presence of selected reducing agents, metal ions, and alkylating agents. The purified enzyme has an estimated subunit molecular mass of 60 kilodaltons, isoelectric point at pH 5.2, and pH and temperature optima at 5.8 and 50°C, respectively. The amino acid composition data indicate that the enzyme is rich in Glx and Asx, the sum of which approaches 25%. The sequence of the first 20 amino acids in the N-terminal region was H₂N-Ser-Ala-Arg-Val-Gly-Ser-Gln-Asn-Gly-Val-Gln-Met-Leu-Ser-Pro-(Ser?) -Glu-Ile-Pro-Gln, and it shows no significant similarity to other proteins with known sequence. The enzyme is extremely stable at 0 to 4°C up to 1 year but loses activity completely at and above 55°C in 10 minutes. Likewise, the enzyme is stable in the presence of or after treatment with 500 millimolar 2-mercaptoethanol, and it is totally inactivated at 2000 millimolar 2-mercaptoethanol. Such metal ions as Hg²⁺ and Ag⁺ reversibly inhibit the enzyme at micromolar concentrations, and inhibition could be completely overcome by adding 2-mercaptoethanol at molar excess of the inhibitory metal ion. The alkylating agents iodoacetic acid and iodoacetamide irreversibly inactivate the enzyme and such inactivation is accelerated in the presence of urea.     

Chlorophyll Synthesis from Protochlorophyll(ide) in Chill-Stressed Maize (Zea mays L.)

Illumination of aetiolated maize at temperatures lower than20 °C results in negligible accumulation of chlorophyll.Illumination of leaf tissue, previously incubated in 10 molm^–3 ALA in darkness, shows only a slight conversion ofprotochlorophyll(ide) to chlorophyll a and b at temperaturesless than 20 °C. A refined procedure for measuring photosynthesisby photo-acoustic spectroscopy in leaves that differ in chlorophyllcontent is presented. Studies of photosynthesis in aetiolatedseedlings illuminated at different temperatures by photo-acousticspectroscopy suggests that impairment of the chlorophyll pathwayis paralleled by an aberrant development of the thylakoid membrane. Key words: Protochlorophyll(ide), temperature, photo-acoustic spectroscopy, membrane biogenesis     

Effects of Moniliformin on Mitosis in Maize (Zea mays L.)

Maize (Zea mays L. ‘Norfolk White’) roots were treatedwith solutions of moniliformin (a metabolite of Fusarium moniliformeSheldon) at 0.0001 M and 0.001 M for 8, 24, and 48 h. Only aslight inhibition of division was noted in root tips treatedwith the lower concentration. The higher concentration causeda disruption of the spindle apparatus and consequent C-mitosis,and metaphase accumulation. (Received February 14, 1984; Accepted May 18, 1984)     

Further Studies on Mosaic Disease of Maize (Zea mays L.)

Schizaphis graminum (Rondani) is proved to be an additional vector of maize mosaic virus (MMV). The pH range for the infectivity of the virus in extracted juice is found to be from 4.4 to 9.0, the optimum being 5.6 to 7.2. Effect of certain chemicals on the virusin vitro has also been studied. Cross protection between MMV and Sugar-cane mosaic virus (SMV) indicated positive results. It has been concluded on the basis of similar physical properties, tolerance towards certain chemicals, host range, symptomatology, aphid vectors and positive immunological tests, that MMV and SMV are related viruses.     

Characterization of Paraquat Transport in Protoplasts from Maize (Zea mays L.) Suspension Cells

Protoplasts isolated from maize (Zea mays L.) suspension cells were used to study transport of paraquat. [14C]Paraquat uptake was measured in 400-[mu]L centrifuge tubes using silicon oil centrifugation techniques. Approximately 50% of accumulation from a 100 [mu]M paraquat solution occurred in the first 10 s, and net accumulation reached a maximum after about 10 min. Membrane binding accounted for about 30% of apparent accumulation. Concentration-dependent uptake kinetics were characterized by a non-saturating curve, which was resolved into a linear and a saturable component. The Km of the saturable component was 132 [mu]M, and the Vmax was 0.512 nmol [mu]L of protoplasts-1 min-1. In the absence of sucrose, the Vmax of the saturable component was reduced by 52%, suggesting that paraquat uptake across the plasmalemma is energy dependent. Measurement of concentration-dependent binding of paraquat to burst protoplasts showed a linear response. This suggests that the linear component from intact protoplast concentration kinetics represented paraquat binding to the plasmalemma surface. Calcium inhibited the saturable component, and this inhibition was shown by Lineweaver-Burk analysis to be noncompetitive. Putrescine, a divalent cationic polyamine with a charge distribution similar to that of paraquat, competitively inhibited paraquat uptake. These results show that paraquat transport characteristics at the plasmalemma of maize protoplasts are similar to those reported earlier for paraquat transport in roots of intact maize seedlings.     

玉米中与DRE元件结合的转录因子的克隆和结构分析

DREB类的转录因子特异性地与DRE 元件（脱水应答元件）结合,在植物感受干旱、高盐及低温等逆境条件时,激活一系列下游逆境应答基因的表达。进一步的研究发现,拟南芥DREB蛋白的DNA结合域（AP2区）中14位的缬氨酸和19位的谷氨酸对该类转录因子与DNA结合起着关键性的作用。利用酵母单杂交的方法,我们从玉米 (Zea mays L.) 的cDNA文库中分离到一个编码与DRE元件结合的蛋白的基因,命名为maDREB1。酵母体内的反式激活实验表明,该基因编码的蛋白能特异地与DRE元件结合并能激活下游报告基因的表达。对maDREB1蛋白14位和19位的氨基酸进行单点突变和双点突变实验,发现14位的缬氨酸突变为丙氨酸后maDREB1几乎丧失了其转录激活能力,而19位的谷氨酸突变为天门冬氨酸后maDREB1的转录激活能力也受到较大影响.