ayvaz et al

1Department of Agricultural Biotechnology, Faculty of Agriculture, Adnan Menderes University, Aydin, Turkey2Department of Biology, Faculty of Science and Letters, Gaziosmanpasa University, Tokat, Turkey3Department of Biology, Faculty of Science, Ege University, Izmir, Turkey4Department of Biosciences, Viikki Biocenter, University of Helsinki, Helsinki, Finland*Corresponding author: [email protected]

Does boron affect hormone levels of barleycultivars?

113

EurAsian Journal of BioSciences Eurasia J Biosci 6, 113-120 (2012)DOI:10.5053/ejobios.2012.6.0.14

Boron is an essential microelement for plant

growth and development (Warington 1923). On the

other hand toxicity and shortage range are very

narrow in plants (elik et al. 1998). Boron shortage

is widely known in soils around the world. On the

other hand toxicity is mostly seen on dry and semi-

dry regions thus limiting plant growth and causing

yield losses (Nable et al. 1997).

In Central Anatolia boron toxicity is a problem in

agricultural soils (Torun et al. 2002). Boron toxicity

has also been reported in South Australia, in

Mediterranean countries, in California and in Chile

(Aquea et al. 2012), causing yield losses in barley

(Cartwright et al. 1984). Boron functions as a cross-

linker for rhamnogalacturonan-II in the cell

membrane, and also as a component important for

structural cytoskeleton integrity in plants (O'Neill et

al. 2004). Plant species requiring higher boron are

also rich in the capacity to deposit it in their cell wall

(Marschner 1997). Since the detoxification

mechanism of excess boron is inadequate in plants,

metabolic disruptions evolve as boron binds to

ribose sugar of DNA and NAD+ (Loomis and Durst

1992). The boron tolerance capacity of some species

such as barley, wheat, Medicago sp. and peas (Pisum

sativum L.) differ from one another because of their

genetic traits (Nable and Paull 1991, Paull et al.

1992, Karabal et al. 2003). In a study with different

plant species, it has been showed that differences in

boron uptake mechanism are regulated by genetic

traits of the species (Paull et al. 1988, Nable and

Received: October 2012Accepted: November 2012

Printed: November 2012

INTRODUCTION

AbstractBackground: When mineral nutrients are present in excess or in inadequate amounts, their effectscan be severe in plants and can be considered as abiotic stress. In this study, we report howhormonal levels in barley cultivars respond to the toxic effect of boron, an essential plantmicronutrient.Materials and Methods: Two different barley (Hordeum vulgare) cultivars (Vamik Hoca and Efes 98)were used as a study material. Boron was applied in three different concentrations (0, 10, 20 ppm)to plants that had grown from seeds for four weeks. Plants were harvested, stem-root length andstem-root dry-fresh weight content were determined. For further analysis, chlorophyll, total protein,endogenic IAA and ABA content analyses were carried out.Results: According to the data obtained, plant growth and development decreased with increasingboron concentrations. With increasing boron concentrations, soluble total protein increased in bothcultivars. Boron application led to increased endogenic IAA content in both cultivars. 10 and 20 ppmboron application led to increased endogenic ABA content in Vamik Hoca cultivar whereasendogenic ABA content decreased in Efes 98. Absence of boron application led to increasedendogenic IAA and ABA content in both cultivars. Conclusions: As a result, the response to boron is different in the two cultivars and Efes 98 may bemore resistant to the toxicity than Vamik Hoca cultivar.Keywords: Abscisic acid, boron toxicity, Hordeum vulgare, indole acetic acid.

Abbreviations: IAA: Indole acetic acid; ABA: Abscisic acid; TLC: Thin Layer Chromatography; D: Absorbancevalues; cv: cultivated variety; B: Boron.

Ayvaz M, Koyuncu M, Guven A, Fagerstedt KV (2012) Does boron affect hormone levels of barleycultivars? Eurasia J Biosci 6: 113-120.

DOI:10.5053/ejobios.2012.6.0.14

Muavviz Ayvaz1*, Mesut Koyuncu2, Avni Guven3, Kurt V. Fagerstedt4

EurAsian Journal of BioSciences

Paull 1991, Bagheri et al. 1996, Jefferies et al. 1999).

Arabidopsis thaliana BOR1 was the first gene shown

to play a role in boron tolerance (Takano et al. 2002).

Parr and Loughman (1983) postulated many

functions for boron in plants in cell wall synthesis

and in cell wall structure, in membranes, in

lignification, in sugar transport, and in carbohydrate

and RNA metabolism. The effect may be through

boron involving in metabolic pathways directly or

through a cascade that is triggered similarly as is

known for the phytohormones. Although a possible

role of boron in auxin or indole-3-acetic acid (IAA)

metabolism was suggested as early as in 1940, the

interaction between boron and auxin has not been

clarified (Coke and Whittington 1968, Hirsch et al.

1982). Lambert et al. (1980) have suggested that in

plant roots boron fertilization leads to decreased

IAA oxidase activity and therefore increased IAA

content. According to Dugger (1983) IAA and IAA

oxidase levels changed in boron deficient

conditions: IAA oxidase activity decreased and IAA

increased (Bryant and Lane 1979, Paull et al. 1992).

On the other hand, abscisic acid (ABA) depresses

plant growth under many stress conditions such as

water deficiency, salt stress, and mineral nutrition

stress (Sharp and LeNoble 2002).

Mineral toxicity is a problem for some parts of

the Turkish soils, and therefore to find out the

physiological responses of plants to toxic mineral

stress is an important issue. In this paper we have

examined whether excess boron leads to a

significant change in IAA and ABA contents of two

different barley cultivars. Our aim is to shed light on

the physiological responses of barley cultivars under

excess boron stress.

In this study two different barley cultivars

(Hordeum vulgare L. cv. Efes 98 and Hordeum vulgare

L. cv. Vamik Hoca) were used as a material. Barley

seeds were soaked with distilled water and placed

on a rolled filter paper in vertical position and then

transferred to plastic pots.

The plants were divided into four groups, each

containing 5 replicate pots. Each group was irrigated

with a Hoagland solution containing 0, 10 and 20

ppm Boron (B) (boron treatments) for 4 w. The

experiment was performed in a controlled climate

room under the conditions of 24C and photoperiod

of 18/8 h (day/night). Position of the pots was

rotated at random every 4 days during the

experiment to standardize the environmental

conditions. Plants were harvested and leaves were

used for determinations.

Fresh and dry weight, root length and shoot

height of the barley seedling were recorded. For dry

weight seedlings were oven dried at 80C for 96 h.

Hormone (IAA and ABA) determination

Hormone (IAA and ABA) extraction method was

conducted as described by Scott and Jacobs (1964)

with modifications.

Barley leaves (5 g) was ground in 50 mL of cooled

methanol. After grinding, 5 mL distilled water and

BHT added and left at 0C for 2 h. Extract was

filtered and evaporated under low pressure at 35C.

25 mL distilled water added and pH was adjusted to

2.5-3 with 0.1N HCl. the acidic water phase hormone

extract was filtered again and anhydride sodium

sulfate was added and left in a cool, dark place for

overnight. Water-free ethyl acetate phase was

evaporated at 35C. The residue was dissolved with

1 mL of methanol and was used for TLC.

Thin layer chromatography (TLC)

Extraction and purification of plant hormones

(IAA and ABA) in 1 mL of methanol acid phase was

conducted by Thin Layer Chromatography (TLC).

1 mL of methanol acid phase was applied on

2020 cm, 0.5 mm Silica Gel 60254 covered TLC

plates with Hamilton micro syringe. Methanol

dissolved IAA and ABA were applied as reference.

TLC plates were run in isopropyl alcohol: ammonia:

distilled water (80:10:10 v/v/v) solution in the dark at

25C and dried in cool air after the run.

Quantitative determination of IAA and ABA

extracts

IAA and ABA reference Rf value were detected

under 254 nm UV light. Silica gel on the TLC plate

were scraped and transferred into tubes according

to Rf values for the quantitative determination of

IAA and ABA. 5mL of methanol was added to the

tubes and left at for 1 h. After 1 h, extracts were

Ayvaz et al.

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EurAsian Journal of BioSciences 6: 113-120 (2012)

MATERIALS AND METHODS

filtered and filled with methanol to 5 mL volume.

Absorbance at 224 nm for IAA and 263 nm for

ABA was recorded with spectrophotometer.

Quantitative IAA and ABA in g for 1 g of leaf weight

was calculated according to Yrekli et al. (1974).

Chlorophyll determination

Chlorophyll was extracted by homogenizing of

0.1 g fresh leaves in 10 mL of 80% acetone. After

filtering, extract fill up to 10 mL in volume, the

chlorophyll content was determined via a

spectrophotometer from the acetone extract at 654

nm and 663 nm, as described by Witham et al. (1971).

Absorbance values (D) at 654 nm and 663 nm

were placed in the equation below. Chlorophyll a, b

and total Chlorophyll content as mg in 1 gram of

plant tissue were calculated.

mg Chlorophyll a/g tissue= [12.7 (D663)2.69

(D645)].(V/1000.Weight)

mg Chlorophyll b/g tissue= [22.9 (D645)4.68

(D 663)].(V/1000. Weight)

mg total Chlorophyll/g tissue= [20.2 (D645)+8.02

(D663)].(V/1000. Weight)

Carotenoid determination

Carotenoid content was determined from the

acetone extract at 450 nm as described by Witham

et al. (1971) via a spectrophotometer. Absorbance

value (D) at 450 nm was placed in the below

equation. Carotenoid contents as mg in 1 g of plant

tissue were calculated.

mg Total carotenoid/g tissue= 4.07 (D645)

[(0.0435 Kla amount)+(0.367 Klb amount)]

Protein determination

Protein concentration was evaluated by the

method of Bradford (1976) using bovine serum

albumin as a standard.

Hordeum vulgare cv. Vamik Hoca and cv. Efes 98

cultivated in 0, 10 and 20 ppm boron concentration

were harvested after 4 w. According to our results;

root length and shoot height of excess boron

applied to Efes 98 and Vamik Hoca cultivars

decreased with increasing boron (Table 1).

Increasing boron conditions led to decreased fresh

weight in both cultivars compared to control plants.

In both cultivars under boron deficient conditions,

fresh weight did not change compared to control. In

both cultivars dry weight did not change

significantly among different groups except at 20

ppm group (Table 2).

Endogenous ABA content of the cv. Vamik Hoca

leaves increased with increasing boron

concentrations. However, Vamik Hoca cultivar plants

grown in boron deficient conditions had 69% more

IAA and 93% more ABA compared to control. On the

other hand, boron-deficient plants had 54% more

IAA and 72% more ABA when compared with 10 ppm

boron application, whereas Efes 98 cultivar grown in

the absence of boron had a 64% increase in the

content of IAA and 72% in ABA compared to the

control group. When both boron deficient plants

were compared, Efes 98 had 17% more IAA and 17%

less ABA. Control group of Efes 98 had 17% more

IAA and 71% more ABA than Vamik Hoca cultivar. 10

ppm boron applied to Efes 98 resulted in 33% more

IAA and %59 less ABA than in Vamik Hoca cultivar. In

20 ppm boron application groups, there seems no

difference in the amount of IAA, while Efes 98

cultivar contained 66% less ABA than Vamik Hoca

cultivar.

In the boron deficient application group of both

cultivars, endogenic IAA levels were higher than in

the boron applied groups. Also in ABA, boron

deficient application groups had more hormone

than in the excess boron applied groups (Table 3).

Plants grown in boron deficient conditions had

higher chlorophyll a, chlorophyll b and total

chlorophyll content than plants grown in control and

excess boron conditions. On the other hand, in both

cultivars increasing boron concentration gave rise to

significant reduction in chlorophyll pigment levels.

In boron deficient conditions, Efes 98 cultivar

contained 14% more chlorophyll a, 20% more

chlorophyll b and 16% more total chlorophyll

pigment than Vamik Hoca cultivar.

In control group plants, Efes 98 contained nearly

15% more chlorophyll pigment than Vamik Hoca

cultivar. With 10 ppm boron application, 10% more

chlorophyll a, chlorophyll b and total chlorophyll was

detected in Efes 98 than in Vamik Hoca cultivar. On

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Ayvaz et al.EurAsian Journal of BioSciences 6: 113-120 (2012)

RESULTS

the other hand, with 20 ppm boron application,

there was no difference in the amount of chlorophyll

b among cultivars, whereas 24% more chlorophyll a

and 17% more total chlorophyll was observed in

Vamik Hoca than in Efes 98 cultivar (Table 4 and 5).

When carotenoid pigment values were examined,

in both barley cultivars boron deficient plants had

higher carotenoid compared to excess boron applied

groups. In general, increasing boron led to a

reduction in the amount of carotenoid pigment

(Table 5).

Total protein levels were elevated in excess and

in deficient groups of both cultivars when compared

to control group. Accordingly, 10 and 20 ppm boron

application led to increase in total protein levels in

both Efes 98 and Vamik Hoca cultivar. In addition,

Efes 98 cultivar was found to have higher total

protein content than Vamik Hoca cultivar (Table 6).

One of the symptoms of boron toxicity is

inhibition of root growth (Nable 1988, Reid et al.

2004, Choi et al. 2007). Toxicity also causes yield

losses in barley (Cartwright et al. 1984). In a study of

optimizing growth conditions for Brassica oleracea, 1

ppm boron applied plants had the maximum fresh

weight (Shelp and Shattuck 1987). On the other

hand, plants grown in boron deficient conditions did

not show any negative effect on vegetative growth,

whereas plants faced problems in reproductive parts

(Mozafar 1993). According to our results, root length

and shoot height of excess boron applied Efes 98

and Vamik Hoca cultivars decreased with increasing

boron. In both cultivars under boron deficient

conditions, fresh weight did not change compared to

control. Therefore, our results are in line with the

above literature showing increasing boron

concentration led to decreased fresh weight in both

116


Table 1. Root length and shoot height of barley cultivars grown under different boron concentrations.

standart error, values are in centimeter (cm), cv: cultivated variety, B: boron

Table 2. Fresh and dry weight of barley cultivars grown under different boron concentrations.

standart error, values are in grams (g), cv: cultivated variety, B: boron

Table 3. Indole acetic acid and abscisic acid content of different barley cultivars grown under different boronconcentrations.

values are in (g/g) tissue, cv: cultivated variety, B: boron

DISCUSSION

cultivars.

Triticum durum Desf. grown under boron

deficiency led to increased IAA content and it

tended to decrease with increasing boron

concentrations (Gemici et al. 2002). In sunflower

(Helianthus annuus L.) IAA content decreased under

boron stress in comparison to the control plants

(Akam-Oluk and Demiray 2004). According to

Dugger (1983) IAA and IAA oxidase levels changed in

boron deficient conditions: IAA oxidase activity

decreased and IAA contrarily increased (Paull et al.

1992, Bryant and Lane 1979). Under boron deficient

conditions, chlorogenic and caffeic acids accumulate

and this inhibits IAA oxidase activity, leading to auxin

accumulation in the plant tissue (Gupta 2006). In our

study, both cultivars of boron deficient group had

higher endogenic IAA levels than boron applied

groups. Our results are consistent with previous

studies indicating that in excess boron conditions,

IAA oxidase activity may be decreased and IAA

contrarily increased.

ABA is a hormone that regulates stomatal closure

in plants, and hence, reduces water loss via

transpiration (Harris and Outlaw 1991). ABA also

limits shoot growth (Creelman et al. 1990) and leaf

area expansion (Van Volkenburgh and Davies 1983).

In contrast, ABA stimulates root growth (Sharp et al.

1994). In a study with carrot (Daucus carota L.) root

callus under boron stress, ABA content increased

(Demiray and Dereboylu 2006). Our results showed

that boron deficient application groups had higher

hormone content than excess boron applied groups.

When the cultivars were compared for their

endogenic hormone levels, Efes 98 was slightly

higher in quantity which may be a hereditary trait. In

accordance with earlier investigations, boron stress

led to increased endogenous ABA content in our

study.

In a study with barley cultivars under excess

boron, protein content increased, and some toxicity

related proteins were identified (Mahboobi et al.

2000). In our study total protein levels increased in

excess and deficient groups of both cultivars when

compared to control. Our results were in line with

the previous studies.

As a result, barley plants cultivated for 4 w under

boron toxic and deficient conditions showed that

117


Table 4. Chlorophyll a, chlorophyll b content of barley cultivar leaves grown under different boron concentrations.

Values are in (mg/g) Fresh Weight, cv: cultivated variety, B: boron

Table 5. Carotenoid and total chlorophyll content of barley cultivar leaves grown under different boron concentrations.

Values are in (mg/g) Fresh Weight, cv: cultivated variety, B: boron

Table 6. Total protein content of barley cultivars grownunder different boron concentrations.

Values are in (mg/mL), cv: cultivated variety, B: boron

boron concentrations led to severe damage, yield

losses and changes in hormone and chlorophyll

contents in both cultivars. We concluded that the

cultivar Vamik Hoca had more toxicity symptoms

with elevating boron concentrations than Efes 98

cultivar.

118


Akam-Oluk E, Demiray H (2004) The Effects of Boron on the Growth of sambro no.3 Sunflower (Helianthus annuusL.). Ege niversitesi Ziraat Fakltesi Dergisi 41(1): 181-190.

Aquea F, Federici F, Moscoso C, Vega A, Jullian P, Haseloff J, Arce-Johnson P (2012) A molecular framework for theinhibition of Arabidopsis root growth in response to boron toxicity. Plant Cell and Environment 35: 719-734. doi:10.1111/j.1365-3040.2011.02446.x

Bagheri A, Paull JG, Rathjen A J (1996) Genetics of tolerance to high concentrations of soil boron in peas (Pisum sativumL.). Euphytica 87: 69-75. doi:10.1007/BF00022967

Bradford M (1976) A Rapid and Sensitive method for the quantitation of Microgram Quantities of Protein Utilizing thePrinciple of Protein Dye Binding. Analytical Biochemistry 72: 248-254. doi:10.1016/0003-2697(76)90527-3

Bryant SD, Lane FE (1979) Indole-3-acetic acid oxidase from peas. Plant Physiology 63: 696-699. doi:10.1104/pp.63.4.696

Cartwright B, Zarcinas BA, Mayfield AH (1984) Toxic Concentration of Boron in a Red-Brown Earth at Gladstone SouthAustralia. Australian Journal of Soil Research 22: 261-272. doi:10.1071/SR9840261

elik H, Aaolu SY, Fidan Y, Marasal B, Sylemezolu G (1998) Genel Baclk. Mesleki Kitaplar Serisi:1, Sunfidan A.,Ankara.

Choi EY, Kolesil P, Mcneill A, Collins H, Zhang QS, Huynh BL, Graham R, Stangoulis JCR (2007) The mechanism of borontolerance for maintenance of root growth in barley (Hordeum vulgare L.). Plant Cell and Environment 30: 984-993.doi:10.1111/j.1365-3040.2007.01693.x

Coke L, Whittington WJ (1968) The Role of Boron in Plant Growth: IV. Interrelationships between Boron and Indol-3ly-acetic acid in the Metabolism of Bean Radicles. Journal of Experimental Botany 19(2): 295-308.doi:10.1093/jxb/19.2.295

Creelman RA, Mason HS, Bensen RJ, Boyer JS, Mullet JE (1990) Water deficit and abscisic acid cause differentialinhibition of shoot versus root growth in soybean seedlings: Analysis of growth, sugar accumulation and geneexpression. Plant Physiology 92: 205-214.

Demiray H, Dereboylu AE (2006) The effects of excess boron with niacin on Daucus corata L. (carrot) root callus. ActaBiologica Hungarica 57(1): 105-114. doi:10.1556/ABiol.57.2006.1.10

Dugger WM (1983) Boron in Plant Metabolism. In: Lauchli A, Bieleski RL (eds) Encylopedia of Plant Physiology, NewSeries, Vol. 15B, Springer Verlag, Berlin, 626-650.

Gemici M, Akta LY, Trkylmaz B, Gven A (2002) The Effects of the Excessive Boron Applications on Indole-3-AceticAcid levels in Triticum durum Desf cv. Gediz Seedlings. Cumhuriyet niversitesi Fen Bilimleri Dergisi 23(2): 17-24.

Gupta UC (2006) Boron. In: Barker AV, Pilbean DJ (eds.) Handbook of Plant Nutrition, Taylor and Francis Publications,Boca Raton, 241-277.

Harris MJ, Outlaw WH Jr (1991) Rapid adjustment of guardcell abscisic acid levels to current leaf-water status. PlantPhysiology 95: 171-173. doi:10.1104/pp.95.1.171

Hirsch AM, Pengelly WL, Torrey JG (1982) Endogenous IAA levels in boron-deficient and Control Root Tips of Sunflower.Botanical Gazette 143(1): 15-19.

Jefferies SP, Barr AR, Karakousis A, Kretschmer JM, Manning S, Chalmers KJ, Nelson JC, Islam AKMR, Langride P (1999)Mapping of Choromosome Regions Conferring to Boron Toxicity Tolerance in Barley (Hordeum vulgare L.).Theoretical and Applied Genetics 98: 1293-1303. doi:10.1007/s001220051195

Karabal E, Yucel M, Oktem HA (2003) Antioxidant responses of tolerant and sensitive barley cultivars to boron toxicity.Plant Science 164: 925-933. doi:10.1016/S0168-9452(03)00067-0

Lambert DH, Cole HC, Baker DE (1980) The role of boron in plant response to mycorrhizal infection. Plant and Soil 57:431-438. doi:10.1007/BF02211700

Loomis WD, Durst RW (1992) Chemistry and Biology of Boron. BioFactors 3: 229-239.

REFERENCES

Mahboobi H, Yucel M, ktem HA (2000) Changes in Total Protein Profiles of Barley Cultivars in Responce to Toxic BoronConcentration. Journal of Plant Nutrition 23(3): 391-399. doi:10.1080/01904160009382025

Marschner H (1995) Mineral Nutrition of Higher Plants. Academic Press, New York.Mozafar A (1993) Role of Boron in seed production. In: Gupta UC (ed), Boron and its Role in Crop Production, CRC

Press, Boca Raton, 186-206.Nable ON, Banuelous SG, Paull GJ (1997) Boron Toxicty. Plant and Soil 198: 181-198. doi:10.1023/A:1004272227886Nable RO (1988) Resistance to boron toxicity amongst several barley and wheat cultivars: a preliminary examination

of the resistance mechanism. Plant and Soil 112: 45-52. doi:10.1007/BF02181751Nable RO, Paull JG (1991) Mechanism of Genetics of Tolerance to Boron Toxicty in Plants. Current Topics in Plant

Biochemistry and Physiology 10: 257-273.O'Neill MA, Ishii T, Albersheim P, Darvill AG (2004) Rhamnogalacturonan II: Structure and function of a borate

crosslinked cell wall pectic polysaccharide. Annual Review of Plant Biology 55: 109-139.doi:10.1146/annurev.arplant.55.031903.141750

Parr A J, Loughman BC (1983) Boron and Membrane Function in Plants. In: Robb DA, Pierpoint WS (eds), Metals andMicronutrients: Uptake and Utilization, Plants Academic Press, London, 87-107.

Paull JG, Cartwright B, Rathjen A J (1988) Responses of wheat and Barley Genotypes Toxic Concentrations of Soil Boron.Euphytica 39: 137-144. doi:10.1007/BF00039866

Paull JG, Nable RO, Lake AWH, Materne MA, Rathjen A J (1992) Response of Annual Medics (Medicago spp.) and FieldPeas (Pisum sativum) to High Concentration of Boron: Genetic Variation and The Mechanism of Tolerance.Australian Journal of Agricultural Research 43: 203-213. doi:10.1071/AR9920203

Reid RJ, Hayes JE, Post A, Stangoulis JCR, Graham RD (2004) A critical analysis of the causes of boron toxicity in plants.Plant Cell and Environment 27: 1405-1414. doi:10.1111/j.1365-3040.2004.01243.x

Scott TK, Jacobs WP (1964) Critical assessment of techniques for identifying the physiologically significant auxins inplants. In: Nitsch JP (ed), Rgulateurs Naturels de la Croissance Vgtale, Centre National de la RechercheScientifique (CNRS), Paris, 457-474.

Sharp RE, LeNoble ME (2002) ABA, ethylene and the control of shoot and root growth under water stress. Journal ofExperimental Botany 53 (366): 33-37. doi:10.1093/jexbot/53.366.33

Sharp RE, Wu Y, Voetberg GS, Saab IN, LeNoble ME (1994) Confirmation that abscisic acid accumulation is required formaize primary root elongation at low water potentials. Journal of Experimental Botany 45: 1743-1751.

Shelp BJ, Shattuck VI (1987) Boron nutrition and mobility and its relation to hollow stem and the elementalcomposition of greenhouse grown cauliflower. Journal of Plant Nutrition 10(2): 143-162.doi:10.1080/01904168709363564

Takano J, Noguchi K, Yasumori M, Kobayashi M, Gajdos Z, Miwa K, Hayashi H, Yoneyama T, Fujiwara T (2002) Arabidopsisboron transporter for xylem loading. Nature 420: 337-340. doi:10.1038/nature01139

Torun B, Kalayci, Ozturk L, Torun A, Aydin M, Cakmak I (2002) Differences in Shoot Boron Concentrations, LeafSymptoms, and Yield of Turkish Barley Cultivars Grown on Boron-Toxic Soil in Field. Journal of Plant Nutrition 26(9):1735-1747. doi:10.1081/PLN-120023279

Van Volkenburgh E, Davies WJ (1983) Inhibition of light-stimulated leaf expansion by abscisic acid. Journal ofExperimental Botany 34(7): 835-845. doi:10.1093/jxb/34.7.835

Warington K (1923) The Effect of Boric Acid and Borax on the broad bean and certain other plants. Annals of Botany37: 457-466.

Witham FH, Blayles DF, Levlin RM (1971) Experiments in Plant Physiology. Van Nostrand Reinhold Company, New York.Yrekli K, Gven A, Grk G (1974) Spektrofotometre ile Hormonlarn Kantitatif Tayinleri zerinde almalar. Bitki 1:

60-68.

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Bor, Arpa eitlerinde Hormon Miktarlarn Etkiler mi?

zet:Giri: Mineral besleme elementlerinin fazla yada yetersiz olmas bitkilerde ciddi sonulara neden olabilen abiyotikstres olarak tanmlanr. Bu almada bitkiler iin gerekli bir element olan borun fazlal ve yokluunda, arpaeitlerindeki hormonal deiim yantlar allmtr.Materyal ve Metot: ki farkl arpa (Hordeum vulgare) eidi (Vamk Hoca ve Efes 98) alma materyali olarakkullanlmtr. Bor farkl konsantrasyonda (0, 10, 20 ppm) tohumdan 4 hafta boyunca yetitilen bitkilereuygulanmtr. Bitkiler hasat edilerek, gvde-kk boyu, gvde-kk ya-kuru arlklar tespit edilmitir. Daha sonraklorofil, toplam protein, endogen AA ve ABA miktar analizleri gerekletirilmitir. Bulgular: Elde edilen sonulara gore, bitki byme ve gelimesi artan bor konsantrasyonlarnda azalmtr. Artan borkonsantrasyonunda zlebilen toplam protein miktar her iki eitte artmtr. Bor uygulamas endogen AAmiktarnn artna neden olmutur. 10 ve 20 ppm bor uygulamas Vamk Hoca eitinde ABA miktar artna, dieryandan Efes 98 eitinde ise endogen ABA miktar azalna neden olmutur Bor yokluundaki uygulamada ise her ikieittede endogen AA ve ABA miktarlar art gstermitir.Sonu: Bora olan tepki her iki eitte farkldr. Toksisite ynnden Efes 98 eiti, Vamk Hoca eitinden daha dayanklolabilir.

Anahtar Kelimeler: Absisik asit, bor toksistesi, Hordeum vulgare, indol asetik asit.

Does boron affect hormone levels of barleycultivars?INTRODUCTIONMATERIALS AND METHODSHormone (IAA and ABA) determinationThin layer chromatography (TLC)Quantitative determination of IAA and ABAextractsChlorophyll determinationCarotenoid determinationProtein determination

RESULTSDISCUSSIONREFERENCES

ayvaz et al

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