Detailed characterization of heat shock protein synthesis and induced thermotolerance in seedlings of Sorghum bicolor L.

Tolerance of both protein synthesis and seedling growth to apreviously lethal high temperature can be induced by prior exposureto a sub-lethal temperature during which the synthesis of heatshock proteins (HSPs) occurs. In this study, a thermal gradientbar was used to measure the physiological effects of temperatureon seedlings of sorghum (Sorghum bicolor L.) in conjunctionwith studies of gene expression. The duration of HSP synthesis,both during continued high temperature treatment or on returnto normal temperatures, was found to be very finely modulatedand was dependent on the severity of the initial heat shock.The synthesis of heat shock proteins and the induction of thermotolerancewere rapid, reversible and reinducible phenomena. Maximal thermotolerancewas obtained after treatments that induced the full complementof HSPs. Subsequent treatments that repressed HSP synthesis,also abolished thermotolerance. The presence of HSPs, however,was not sufficient for the tissue to be in a thermotolerantstate and the results suggest that either their de novo synthesis,or some other factor, is required for the induction of thermotolerance.Pre-existing HSPs did not inhibit the synthesis of new HSPs.Although the kinetics of the synthesis of HSPs and the developmentof thermotolerance show a tight correlation, the kinetics ofthe decay of thermotolerance and the degradation of HSPs werenot linked. The functional state or distribution of HSPs maywell change during the recovery process. Key words: Heat shock, thermotolerance, Sorghum bicolor, growth, protein synthesis     

Paclobutrazol- and Hardening-Induced Thermotolerance of Wheat: Are Heat Shock Proteins Involved?

The present report describes the effects of paclobutrazol andheat hardening treatments on the protein synthesis patternsin imbibing and germinating wheat seedlings (Triticum aestivumL. cv Frederick) during heat stress. A heat hardening treatmentgiven during the imbibition period induced the transient expressionof 118, 90, 70 and 18 kDa heat shock proteins (HSPs). However,the hardening and paclobutrazol treatments did not enhance thethermotolerance of imbibed seeds or etiolated seedlings. Bycontrast, the hardening and paclobutrazol treatments enhancedthe thermotolerance of light-grown seedlings. While, both hardenedand unhardened control seedlings synthesized several HSPs duringa high temperature stress period, these proteins were not synthesizedby the paclobutrazol-treated, light-grown seedlings. Thus, HSPsynthesis during heat shock may have been a manifestation ofstress perception by the seedlings and may not have mediatedthe thermotolerance induced by the triazole treatments. Sincedifferential thermotolerance was only apparent in light-grownseedlings, it is suggested that chloroplasts may be requiredfor the expression of paclobutrazol- and hardening-induced thermoprotection.Additional evidence indicating that chloroplasts are an importantsite of injury during high temperature stress was obtained fromchlorophyll fluorescence measurements. (Received July 11, 1994; Accepted October 26, 1994)     

Molecular responses of plants to an increased incidence of heat shock

Abstract. Climatic change as a result of the greenhouse effect is widely predicted to increase mean temperatures globally and, in turn, increase the frequency with which plants are exposed to heat shock conditions, particularly in the semi-arid tropics. The consequences of extreme high-temperature treatments on plants have been considered, particularly in relation to the synthesis of heat shock proteins (HSPs) and the capacity to acquire thermotolerance. The heat shock response is described using results obtained with seedlings of the tropical cereals, sorghum ( Sorghum bicolor ) and pearl millet ( Pennisetum glaucum ). A gradual temperature increase, as would occur in the field, is sufficient to induce thermotolerance. The synthesis of HSPs is a transient phenomenon and ceases once the stress is released. Despite the persistence of the HSPs themselves, de novo synthesis of HSPs is required for the induction of thermotolerance each time high temperatures are encountered. The effect of a repeated, diurnal heat shock was investigated and genotypic differences found in the ability to induce the heat shock response repeatedly.     

Characterization of the heat shock response in cultured sugarcane cells : I. Physiology of the heat shock response and heat shock protein synthesis

Effect of heat shock on the growth of cultured sugarcane cells (Saccharum officinarum L.) was measured. Heat shock (HS) treatment at 36 to 38°C (2 hours) induced the development of maximum thermotolerance to otherwise nonpermissive heat stress at 54°C (7 minutes). Optimum thermotolerance was observed 8 hours after heat shock. Development of thermotolerance was initiated by treatments as short as 30 minutes at 36°C. Temperatures below 36°C or above 40°C failed to induce maximum thermotolerance. In vivo labeling revealed that HS at 32 to 34°C induced several high molecular mass heat shock proteins (HSPs). A complex of 18 kilodalton HSPs required at least 36°C treatment for induction. The majority of the HSPs began to accumulate within 10 minutes, whereas the synthesis of low molecular mass peptides in the 18 kilodalton range became evident 30 minutes after initiation of HS. HS above 38°C resulted in progressively decreased HSP synthesis with inhibition first observed for HSPs larger than 50 kilodaltons. Analysis of two-dimensional gels revealed a complex pattern of label incorporation including the synthesis of four major HSPs in the 18 kilodalton range and continued synthesis of constitutive proteins during HS.     

Effect of cycloheximide or puromycin on induction of thermotolerance by sodium arsenite in Chinese hamster ovary cells: involvement of heat shock proteins

After sodium arsenite (100 microM) treatment, the synthesis of three major heat shock protein families (HSPs; Mr = 110,000, 87,000, and 70,000), as studied with one-dimensional gels, was enhanced twofold relative to that of unheated cells. The increase of unique HSPs, if studied with two-dimensional gels, would probably be much greater. In parallel, thermotolerance was observed as a 100,000-fold increase in survival from 10(-6) to 10(-1) after 4 hr at 43 degrees C, and as a thermotolerance ratio (TTR) of 2-3 at 10(-3) isosurvival for heating at 45.5 degrees C. Cycloheximide (CHM: 10 micrograms/ml) or puromycin (PUR: 100 micrograms/ml), which inhibited total protein synthesis and HSP synthesis by 95%, completely suppressed the development of thermotolerance when either drug was added after sodium arsenite treatment and removed prior to the subsequent heat treatment. Therefore, thermotolerance induced by arsenite treatment correlated with an increase in newly synthesized HSPs. However, with or without arsenite treatment, CHM or PUR added 2-6 hr before heating and left on during heating caused a 10,000-100,000-fold enhancement of survival when cells were heated at 43 degrees C for 4 hr, even though very little synthesis of heat shock proteins occurred. Moreover, these cells manifesting resistance to heating at 43 degrees C after CHM treatment were much different than those manifesting resistance to 43 degrees C after arsenite treatment. Arsenite-treated cells showed a great deal of thermotolerance (TTR of about 10) when they were heated at 45 degrees C after 5 hr of heating at 43 degrees C, compared with less thermotolerance (TTR of about 2) for the CHM-treated cells heated at 45 degrees C after 5 hr of heating at 43 degrees C. Therefore, there are two different phenomena. The first is thermotolerance after arsenite treatment (observed at 43 degrees C or 45.5 degrees C) that apparently requires synthesis of HSPs. The second is resistance to heat after CHM or PUR treatment before and during heating (observed at 43 degrees C with little resistance at 45.5 degrees C) that apparently does not require synthesis of HSPs. This phenomenon not requiring the synthesis of HSPs also was observed by the large increase in thermotolerance to 45 degrees C caused by heating at 43 degrees C, with or without CHM, after cells were incubated for 6 hr following arsenite pretreatment. For both phenomena, a model based on synthesis and redistribution of HSPs is presented.     

Ethanol treatment triggers a heat shock-like response but no thermotolerance in soybean (Glycine max cv. Kaohsiung No.8) seedlings

Non‐lethal heat‐shock (HS) treatment has previously been shown to induce thermotolerance in soybean (Glycine max cv. Kaohsiung No.8) seedlings. This acquired thermotolerance correlates with the de novo synthesis of heat‐shock proteins (HSPs). Interestingly, we found that ethanol treatments also elicited HS‐like responses in aetiolated soybean seedlings at their normal growth temperature of 28 °C. Northern blot analyses revealed that the expression of HS genes hsp17.5, hsp70 and hsc 70 was induced by ethanol. Radioactive amino acids were preferentially incorporated into high molecular weight (HMW) HSPs rather than class I low molecular weight (LMW) HSPs during non‐lethal ethanol treatments. Immunoblot analysis confirmed that no accumulation of class I LMW HSPs occurred after non‐lethal ethanol treatment. Pre‐treatment with a non‐lethal dose of ethanol did not provide thermotolerance, as the aetiolated soybean seedlings could not survive a subsequent heat shock of 45 °C for 2 h. In contrast, non‐lethal HS pre‐treatment, 40 °C for 2 h, conferred tolerance on aetiolated soybean seedlings to otherwise lethal treatments of 7·5% ethanol for 8 h or 10% ethanol for 4 h. These results suggest that plant class I LMW HSPs may play important roles in providing both thermotolerance and ethanol tolerance.     

A class of soybean low molecular weight heat shock proteins : immunological study and quantitation

Two major polypeptides of the 15- to 18-kilodalton class of soybean (Glycine max) heat shock proteins (HSPs), obtained from an HSP-enriched (NH₄)₂SO₄ fraction separated by two-dimensional polyacrylamide gel electrophoresis, were used individually as antigens to prepare antibodies. Each of these antibody preparations reacted with its antigen and cross-reacted with 12 other 15- to 18-kilodalton HSPs. With these antibodies, the accumulation of the 15- to 18-kilodalton HSPs under various heat shock (HS) conditions was quantified. The 15- to 18-kilodalton HSPs began to be detectable at 35° C, and after 4 hours at 40° C they had accumulated to a maximum level of 1.54 micrograms per 100 micrograms of total protein in soybean seedlings and remained almost unchanged up to 24 hours after HS. Accumulation of the HSPs was reduced at temperatures higher than 40° C. At 42.5° C the HSPs were reduced to 1.02 micrograms per 100 micrograms, and at 45° C they were hardly detectable. A brief HS at 45° C (10 minutes), followed by incubation at 28° C, which also induced HSP synthesis, resulted in synthesis of this class of HSPs at levels up to 1.06 micrograms per 100 micrograms of total protein. Taking into consideration the previous data concerning the acquisition of thermotolerance in soybean seedlings, our estimation indicates that the accumulation of the 15- to 18-kilodalton HSPs to 0.76 to 0.98% of total protein correlated well with the establishment of thermotolerance. Of course, other HSPs, in addition to this group of proteins, may be required for the development of thermotolerance.     

Differences in preferential synthesis and redistribution of HSP70 and HSP28 families by heat or sodium arsenite in Chinese hamster ovary cells

Since both heat and sodium arsenite induce thermotolerance, we investigated the differences in synthesis and redistribution of stress proteins induced by these agents in Chinese hamster ovary cells. Five major heat shock proteins (HSPs; Mr 110, 87, 70, 28, and 8.5 kDa) were preferentially synthesized after heat for 10 min at 45.5 degrees C, whereas four major HSPs (Mr 110, 87, 70, and 28 kDa) and one stress protein (33.3 kDa) were preferentially synthesized after treatment with 100 microM sodium arsenite (ARS) for 1 hr. Two HSP families (HSP70a,b,c, and HSP28a,b,c) preferentially relocalized in the nucleus after heat shock. In contrast, only HSP70b redistributed into the nucleus after ARS treatment. Furthermore, the kinetics of synthesis of each member of HSP70 and HSP28 families and their redistribution were different after these treatments. The maximum rates of synthesis of HSP70 and HSP28 families, except HSP28c, were 6-9 hr after heat shock, whereas those of HSP70b and HSP28b,c were 0-2 hr after ARS treatment. In addition, the maximum rates of redistribution of HSP70 and HSP28 families occurred 3-6 hr after heat shock, whereas that of HSP70b occurred immediately after ARS treatment. The degree of redistribution of HSP70b after ARS treatment was significantly less than that after heat treatment. These results suggest that heat treatment but not sodium arsenite treatment stimulates the entry of HSP70 and HSP28 families into the nucleus.     

Heat shock proteins and heat adaptation of the whole organism

Moseley, Pope L. Heat shock proteins andheat adaptation of the whole organism. J. Appl.Physiol. 83(5): 1413-1417, 1997.Adaptation toheat may occur through acclimatization or thermotolerance; however, thelinkage of these phenomena is poorly understood. The importance of heatshock proteins (HSPs) in thermotolerance and differences in theiraccumulation in organisms adapted to the heat suggest a role for HSPsin acclimatization as well. The role of HSPs in heat adaptation of thewhole organism and the interrelationships among heat adaptation,endotoxin tolerance, and cytokine resistance through HSPs are reviewed.

     

Induction of thermotolerance and enhanced heat shock protein synthesis in chinese hamster fibroblasts by sodium arsenite and by ethanol

Synthesis of a family of proteins called “heat shock” proteins is enhanced in cells in response to a wide variety of environmental stresses. This suggests that these proteins may have functions essential to cell survival under stressful conditions. A causative relationship between heat shock protein synthesis and development of thermotolerance would imply that agents known to induce heat shock protein synthesis, such as sodium arsenite, also induce thermotolerance. Conversely, agents known to induce thermotolerance, such as ethanol, would also enhance heat shock protein synthesis. To test this hypothesis, I have examined the effect of sodium arsenite or ethanol treatment on protein synthesis and cell survival in Chinese hamster ovary HA-1 cells. After either sodium arsenite or ethanol treatment, the synthesis of heat shock proteins was greatly enhanced over that of untreated cells. In parallel, cell survival was increased as much as 10⁴-fold when cells exposed to either agent were challenged by a subsequent heat treatment. The synthesis of heat shock proteins correlated well with the development of thermotolerance. A qualitative analysis of individual proteins suggests that the synthesis of 70,000 and 87,000 molecular weight proteins most closely mirrored the development of thermotolerance. The results, therefore, strongly reinforce the hypothesis that a causal relationship exists between the enhanced synthesis of heat shock protein and cell survival under specific stresses.     

Treatment with 24-epibrassinolide,a brassinosteroid,increases the basic thermotolerance of Brassica napus and tomato seedlings

Brassinosteroids are plant growth-promoting compounds that exhibit structural similarities to animal steroid hormones. Recent studies have indicated that brassinosteroids are essential for proper plant development. In addition to a role in development, several lines of evidence suggest that brassinosteroids exert anti-stress effects on plants. However, the mechanism by which they modulate plant stress responses is not understood. We show here that Brassica napus and tomato seedlings grown in the presence of 24-epibrassinolide (EBR) are significantly more tolerant to a lethal heat treatment than are control seedlings grown in the absence of the compound. Since a preconditioning treatment of seedlings was not required to observe this effect, we conclude that EBR treatment increases the basic thermotolerance of seedlings. An analysis of heat shock proteins (HSPs) in B. napus seedlings by western blot analysis indicated that the HSPs did not preferentially accumulate in EBR-treated seedlings at the control temperature. However, after heat stress, HSP accumulation was higher in EBR-treated than in untreated seedlings. The results of the present study provide the first direct evidence for EBR-induced expression of HSPs. The higher accumulation of HSPs in EBR-treated seedlings raises the possibility that HSPs contribute, at least in part, to thermotolerance in EBR-treated seedlings. A search for factors other than HSPs, which may directly or indirectly contribute to brassinosteroid-mediated increase in thermotolerance, is underway.     

Gene Activity during Germination of Spores of the Fern, Onoclea sensibilis: RNA and Protein Synthesis and the Role of Stored mRNA

Pattern of ³H-uridine incorporation into RNA of spores of Onocleasensibilis imbibed in complete darkness (non-germinating conditions)and induced to germinate in red light was followed by oligo-dTcellulose chromatography, gel electrophoresis coupled with fluorographyand autoradiography. In dark-imbibed spores, RNA synthesis wasinitiated about 24 h after sowing, with most of the label accumulatingin the high mol. wt. poly(A)^–RNA fraction. There was noincorporation of the label into poly(A) ⁺ RNA until 48 h aftersowing. In contrast, photo-induced spores began to synthesizeall fractions of RNA within 12 h after sowing and by 24 h, incorporationof ³H-uridine into RNA of irradiated spores was nearly 70-foldhigher than that into dark-imbibed spores. Protein synthesis,as monitored by ³H-arginine incorporation into the acid-insolublefraction and by autoradiography, was initiated in spores within1–2 h after sowing under both conditions. Autoradiographicexperiments also showed that the onset of protein synthesisin the cytoplasm of the germinating spore is independent ofthe transport of newly synthesized nuclear RNA. One-dimensionalsodium dodecyl sulphate-polyacrylamide gel electrophoresis of³⁵S-methionine-labelled proteins revealed a good correspondencebetween proteins synthesized in a cell-free translation systemdirected by poly(A) ⁺RNA of dormant spores and those synthesizedin vivo by dark-imbibed and photo-induced spores. These resultsindicate that stored mRNAs of O. sensibilis spores are functionallycompetent and provide templates for the synthesis of proteinsduring dark-imbibition and germination. Key words: Onoclea sensibilis, fern spore germination, gene expression, protein synthesis, sensitive fern, stored mRNA     

Synthesis of soluble heat shock proteins in seminal root tissues of some cultivated and wild wheat genotypes

Effect of heat stress on the synthesis of soluble heat shock proteins (HSPs) and the regrowth in seminal roots of three cultivated and three wild wheat genotypes was examined. In regrowth experiments, 2-d-old etiolated seedlings were exposed to 23 (control), 32, 35, 37 and 38 degrees C for 24 h, and 35 and 37 degrees C (24 h) followed by 50 degrees C (1 h). The lengths of the seminal roots generally decreased significantly at the end of 48 and 72 h recovery growth periods at 35, 37 and 38 degrees C temperature treatments compared with control. Genotypic variability was significant level at all temperature treatments for the seminal root length. Also, genotypic differences for the number of seminal roots were determined among the wheat cultivars and between the wild wheat species and the wheat cultivars at all temperature treatments; but genotypic differences among wild wheat species were only detected at 37-->50 degrees C treatment. Acquired thermotolerance for the seminal root length is over 50% at 37-->50 degrees C treatment. The genotypic variability of soluble heat shock proteins in seminal root tissues were analyzed by two-dimensional electrophoresis (2-DE). Total number of low molecular weight (LMW) HSPs was more than intermediate-(IMW) and high- (HMW) HSPs at high temperature treatments. The most of LMW HSPs which were generally of acidic character ranged between 14.2-30.7 kDa. The genotypes had both common (43 HSP spots between at least two genotypes and 23 HSP spots between 37 and 37-->50 degrees C) and genotype-specific (72 HSP spots) LMW HSPs.     

Heat shock proteins in Sorghum bicolor and Pennisetum americanum I. genotypic and developmental variation during seed germination

Abstract The capacity to synthesize heat shock proteins (HSPs) during seed germination of sorghum (Sorghum bicolor) and pearl millet (Pennisetum americanum) has been examined. HSP synthesis is detectable in a thermotolerant genotype of sorghum during the first hour of imbibition of the seed under high temperature stress. A non-coordinate control of HSP synthesis during germination was revealed. Genotypic differences were manifest in the stage of germination at which the ability to synthesize HSPs was first apparent and this related to the thermosensitivity of that genotype.     

Induction of Heat Shock Proteins and Acquisition of Thermotolerance in Germinating Pigeonpea Seeds

Heat shock proteins (HSPs) ranging in molecular masses from 14 to 110 kDa were induced in embryonic axes of germinating Cajanus cajan (L.) Millspaugh seeds after exposure to 40 °C for 1 or 2 h. At 45 °C, there was a marked decline in synthesis of HSPs. A close relationship was observed between HSPs induced and the growth of the germinating seeds. Pretreatment of germinating seeds at 40 °C for 1 h or 45 °C for 10 min followed by incubation at 28 °C for 3 h led to considerable thermotolerance (45 °C, 2 h) and the recovery of protein synthesis. This revised version was published online in July 2006 with corrections to the Cover Date.     

Heat shock protein synthesis is induced by diethyl phthalate but not by di(2-ethylhexyl) phthalate in radish (Raphanus sativus)

The toxicity and effects on protein synthesis of the phthalate esters diethyl phthalate (DEP) and di(2-ethylhexyl) phthalate (DEHP) was studied in radish seedlings (Raphanus sativus cv. Kööpenhaminan tori). Phthalate esters are a class of commercially important compounds used mainly as plasticizers in high molecular-weight polymers such as many plastics. They can enter soil through various routes and can affect plant growth and development. First the effect of DEP and DEHP on the growth of radish seedlings was determined in an aqueous medium. It was found that DEP, but not DEHP, caused retardation of growth in radish. A further investigation on protein synthesis during DEP-stress was executed by in vivo protein labeling combined with two-dimensional gel electrophoresis (2D-PAGE). For comparisons with known stress-induced proteins a similar experiment was done with heat shock, and the induced heat shock proteins (HSPs) were compared with those of DEP-stress. The results showed that certain HSPs can be used as an indicator of DEP-stress, although the synthesis of most HSPs was not affected by DEP. DEP also elicited the synthesis of numerous proteins found only in DEP-treated roots. The toxic effect of phthalate esters and the roles of the induced proteins are discussed.     

Acquisition of thermotolerance in bay scallops, Argopecten irradians irradians, via differential induction of heat shock proteins

Many cells and organisms are rendered transiently resistant to lethal heat shock by short exposure to sublethal temperatures. This induced thermotolerance is thought to be related to increased amounts of heat shock proteins (HSPs) which, as molecular chaperones, protect cells from stress-induced damage. As part of a study on bivalve stress and thermotolerance, work was undertaken to examine the effects of sublethal heat shock on stress tolerance of juveniles of the northern bay scallop, Argopecten irradians irradians, in association with changes in the levels of cytoplasmic HSP70 and 40. Juvenile bay scallops heat-shocked at a sublethal temperature of 32 °C survived an otherwise lethal heat treatment at 35 °C for at least 7 days. As determined by ELISA, acquisition of induced thermotolerance closely paralleled HSP70 accumulation, whereas HSP40 accrual appeared less closely associated with thermotolerance. Quantification of scallop HSPs following lethal heat treatment, with or without conditioning, suggested a causal role for HSP70 in stress tolerance, with HSP40 contributing to a lesser, but significant extent. Overall, this study demonstrated that sublethal heat shock promotes survival of A. irradians irradians juveniles upon thermal stress and the results support the hypothesis that HSPs have a role in this induced thermotolerance. Exploitation of the induced thermotolerance response shows promise as a means to improve survival of bay scallops in commercial culture.     

Wild and cultivated Triticum species differ in thermotolerant habit and HSP gene expression

High temperature (HT) stress is one of the most important environmental stimuli, negatively affecting plant survival and crop yield. Basal and acquired thermotolerance (ATT) are two components of plant response to HT, the mechanisms controlling them are not completely known yet. Basal thermotolerance was evaluated in a collection of 47 Triticum turgidum and Triticum durum genotypes, by the cell membrane stability (CMS) test, observing high variability. T. turgidum accessions exhibited the highest CMS values corresponding to higher thermotolerance, while T. durum cultivars (cvs) exhibited lower CMS values. The heat shock response is characterized by the synthesis of heat shock proteins (HSPs), and variation in HSPs production may be related to variation in ATT. The expression of HSP genes (coding cytoplasmic and plastidial small HSPs and two members of HSP70 family), previously hypothesized to be correlated with thermotolerance, was evaluated in thermotolerant and thermosensitive genotypes grown in the field, in control and HT conditions. The results obtained suggest that the genes coding for the two members of HSP70 family, may be responsible for basal thermotolerance. The overall results suggest that wild genotypes may possess a yet undisclosed variability for alleles involved in thermotolerance.     

Heat shock of cultivated and wild wheats during early seedling stage: growth, cell viability and heat shock proteins

Growth, cell viability and heat shock proteins (HSPs) in Bezostaya-1, Cukurova-86 and Diyarbakir-81 cultivated wheat cultivars and three Aegilops species were investigated. Etiolated seedlings were exposed to 23 degrees C, 32 degrees C, 35 degrees C, 37 degrees C and 38 degrees C for 24 h, and 35 degrees C (24 h) --> 50 degrees C (1 h) and 37 degrees C (24 h) --> (50 degrees C (1 h). At the end of recovery growth periods, the shoot lengths of the genotypes generally decreased significantly at 35, 37 and 38 degrees C. The acquired thermal tolerance (ATT) in intact seedlings was over 50% at 35 degrees C --> 50 degrees C and 37 degrees C --> 50 degrees C, but in cell viability test it ranged from 2.75% (Ae. triuncialis) to 32.87 (Bezostaya-1) at 35 degrees C, and from 2.82% (Ae. triuncialis) to 37.82 (Bezostaya-1) at 37 degrees C. Ae. triuncialis was most sensitive genotype in both ATT determination. In electrophoretic profiles of proteins, while some HSPs were newly synthesized, some normal cellular proteins disappeared at 37 degrees C and 37 degrees C -->50 degrees C compared to 23 degrees C. The number of low molecular weight (LMW) HSPs were more than intermediate- (IMW) and high- (HMW) HSPs. The genotypes had both common (12 HSPs between at least two genotypes) and genotype-specific (33 HSPs) LMW HSPs. The common HSP of 19.8 kDa (pI 6.5) was synthesized in Bezostaya-1, Cukurova-86, Diyarbakir-81, Ae. biuncialis and Ae. umbellulata. Bezostaya-1 is the only genotype that synthesized 12 IMW and 2 HMW HSPs at 37 degrees C --> 50 degrees C. Ae. triuncialis had only two common LMW HSPs [22.1 (pI 7.1) and 24.2 kDa (pI 6.5)].