A small heat shock protein (sHSP) gene from sunflower, Ha hsp17.6 G1, showed expression patterns that differ from what is known for members of this gene family. The mRNAs of this gene accumulated in seeds during late desiccation stages of zygotic embryogenesis but not in response to heat shock in vegetative tissues. The failure to respond to heat shock was independent of the developmental stage after germination and shock temperature. Nuclear run-on analyses demonstrated that transcription from the Ha hsp17.6 G1 promoter is not induced by heat shock. This agrees with the presence, in this promoter, of sequences with little similarity to heat shock elements. Our results show an evolutionary divergence, in the regulation of plant sHSP genes, which has originated stress-responsive genes and nonresponsive members within this gene family. We discuss implications for mechanisms controlling the developmental regulation of sHSP genes in plants. A small heat shock protein (sHSP) gene from sunflower, Ha hsp17.6 G1, showed expression patterns that differ from what is known for members of this gene family. The mRNAs of this gene accumulated in seeds during late desiccation stages of zygotic embryogenesis but not in response to heat shock in vegetative tissues. The failure to respond to heat shock was independent of the developmental stage after germination and shock temperature. Nuclear run-on analyses demonstrated that transcription from the Ha hsp17.6 G1 promoter is not induced by heat shock. This agrees with the presence, in this promoter, of sequences with little similarity to heat shock elements. Our results show an evolutionary divergence, in the regulation of plant sHSP genes, which has originated stress-responsive genes and nonresponsive members within this gene family. We discuss implications for mechanisms controlling the developmental regulation of sHSP genes in plants. One of the characteristics of the plant heat shock response is the synthesis of a large number of different, but evolutionarily related, polypeptides of 17–30 kDa (the sHSPs). 1The abbreviations used are: sHSP(s), small heat shock protein(s); HSE, heat shock element; HSF, heat shock factor; hHSF1, human heat shock factor 1; bp, base pair(s); dpi, days postimbibition; dpa, days postanthesis. 1The abbreviations used are: sHSP(s), small heat shock protein(s); HSE, heat shock element; HSF, heat shock factor; hHSF1, human heat shock factor 1; bp, base pair(s); dpi, days postimbibition; dpa, days postanthesis. In contrast, animals express only one to four sHSPs upon heat shock. The diversification in plants of heat-inducible sHSP genes could be a consequence of sesility; because plants cannot move away from heat, they would have evolved a battery of specialized 舠stress genes,舡 the sHSPs. These are expressed in response to heat in all subcellular compartments and could allow plants to cope better with the stress conditions on site (for review, see Ref. 1Waters E.R. Lee G.J. Vierling E. J. Exp. Bot. 1996; 47: 325-338Crossref Scopus (575) Google Scholar). In animal and plant systems, heat shock genes encoding proteins of higher molecular weight, for example the HSP70s, have been shown to contain heat-inducible and noninducible members (2DeRocher A. Vierling E. Plant Mol. Biol. 1995; 27: 441-456Crossref PubMed Scopus (64) Google Scholar,3Gurley W.B. Key J.L. Biochemistry. 1991; 30: 1-12Crossref PubMed Scopus (68) Google Scholar). In the case of plant sHSPs the evidence for the existence of genes that are not induced by heat shock is weak and indirect, as it is based on the detection in seeds of sHSP isoforms that are different from the heat shock-induced polypeptides (4Coca M.A. Almoguera C. Jordano J. Plant Mol. Biol. 1994; 25: 479-492Crossref PubMed Scopus (124) Google Scholar, 5Zur Nieden U. Neumann D. Bucka A. Nover L. Planta. 1995; 196: 530-538Crossref Scopus (42) Google Scholar). In addition to being part of the heat shock response, some plant sHSP genes have been shown to be expressed at normal growth temperatures during zygotic embryogenesis (4Coca M.A. Almoguera C. Jordano J. Plant Mol. Biol. 1994; 25: 479-492Crossref PubMed Scopus (124) Google Scholar, 5Zur Nieden U. Neumann D. Bucka A. Nover L. Planta. 1995; 196: 530-538Crossref Scopus (42) Google Scholar, 6Almoguera C. Jordano J. Plant Mol. Biol. 1992; 19: 781-792Crossref PubMed Scopus (132) Google Scholar, 7DeRocher A.E. Vierling E. Plant J. 1994; 5: 93-102Crossref Scopus (107) Google Scholar). Developmental regulation studies of plant sHSP genes are scarce. So far, only two plant sHSP promoters and 5′-flanking sequences have been reported to confer regulation to chimeric genes in maturing seeds: those from soybean Gm hsp17.3B (8Prändl R. Kloske E. Schöffl F. Plant Mol. Biol. 1995; 28: 73-82Crossref PubMed Scopus (55) Google Scholar) and sunflower Ha hsp17.7 G4 (9Coca M.A. Almoguera C. Thomas T.L. Jordano J. Plant Mol. Biol. 1996; 31: 863-876Crossref PubMed Scopus (85) Google Scholar). Initial studies have pointed to common control elements between the heat shock response and activation during embryogenesis. For example, the functional implication of HSEs in both processes is supported by results of deletion analysis (8Prändl R. Kloske E. Schöffl F. Plant Mol. Biol. 1995; 28: 73-82Crossref PubMed Scopus (55) Google Scholar, 9Coca M.A. Almoguera C. Thomas T.L. Jordano J. Plant Mol. Biol. 1996; 31: 863-876Crossref PubMed Scopus (85) Google Scholar). Other observations point to the involvement in embryos of distinct control elements, for example, the effect of abi3 mutations on sHSP accumulation inArabidopsis seeds (10Wehmeyer N. Hernandez L.D. Finkelstein R.R. Vierling E. Plant Physiol. 1996; 112: 747-757Crossref PubMed Scopus (210) Google Scholar). It is also clear that not all plant sHSP genes are developmentally regulated during embryogenesis, at least for the most systematically analyzed sunflower (9Coca M.A. Almoguera C. Thomas T.L. Jordano J. Plant Mol. Biol. 1996; 31: 863-876Crossref PubMed Scopus (85) Google Scholar) andArabidopsis genes (10Wehmeyer N. Hernandez L.D. Finkelstein R.R. Vierling E. Plant Physiol. 1996; 112: 747-757Crossref PubMed Scopus (210) Google Scholar). Thus, there is no obvious explanation for the differential regulation of a subset of sHSP genes during embryogenesis, and such regulation might involve control elements that are common and/or distinct from those involved in the heat shock response. In this work, we describe and analyze the genomic sequences of Ha hsp17.6 G1, a sunflower sHSP gene expressed during zygotic embryogenesis (6Almoguera C. Jordano J. Plant Mol. Biol. 1992; 19: 781-792Crossref PubMed Scopus (132) Google Scholar). By detailed analyses of gene-specific mRNA accumulation and transcription, we demonstrate that transcription from the Ha hsp17.6 G1 promoter is not induced in response to heat shock. Interestingly, such a unique expression pattern has been described in other animal genes that are structurally related (11Caspers G.J. Leunissen J.A.M. de Jong W.W. Mol. Biol. Evol. 1995; 40: 238-248Crossref Scopus (308) Google Scholar) to the sHSPs, as for the eye lens-specific αA-crystallins (12Overbeek P.A. Chepelinsky A.B. Khillan J.S. Piatigorsky J. Westphal H. Proc. Natl. Acad. Sci. U. S. A. 1985; 82: 7815-7819Crossref PubMed Scopus (150) Google Scholar) and, more recently, for some αB-crystallins (13Wistow G. Graham C. Biochim. Biophys. Acta. 1995; 1263: 105-113Crossref PubMed Scopus (11) Google Scholar). Thus, our observation provides strong evidence for a similar evolution of the regulation of a member of the sHSP superfamily in the plant kingdom. In addition, the structural and functional characteristics of the Ha hsp17.6 G1 promoter would support developmental control mechanisms, during plant embryogenesis, which are different from those involved in the heat shock response. Two restriction fragments containing the HSE sequences of Ha hsp17.7 G4 and Ha hsp17.6 G1 were purified from 1.67 agarose gels and end labeled with Klenow and dATP33 (14Sambrook J. Fritsch E.F. Maniatis T. Molecular Cloning: A Laboratory Manual. 2nd Ed. Cold Spring Harbor Laboratory, Cold Spring Harbor, NY1989Google Scholar). TheHa hsp17.6 G1 probe is a 175-nucleotide fragment between theHindIII sites at −126 and +50, and the Ha hsp17.7 G4 probe is a 287-nucleotide fragment that contains promoter sequences between −188 (EcoRV) and +80 (9Coca M.A. Almoguera C. Thomas T.L. Jordano J. Plant Mol. Biol. 1996; 31: 863-876Crossref PubMed Scopus (85) Google Scholar). This fragment was labeled at an EcoRI site from vector polylinker sequences. Binding reactions were performed for 15 min, at 20 °C, in 10 mm Hepes, pH 7.9; 1.5 mm MgCl2; 0.05 mm EDTA; 120 mm NaCl; and 67 glycerol. Reactions included 1 ng of each labeled fragment, 1.8 ॖg of poly(dI-dC) (Pharmacia Biotech Inc.) and 2 ॖg of a protein extract, obtained from Escherichia coli BL21 cells expressing human HSF1 from plasmid pHu HSFM1 (15Rabindran S.K. Giorgi G. Clos J. Wu C. Proc. Natl. Acad. Sci. U. S. A. 1991; 88: 6906-6910Crossref PubMed Scopus (376) Google Scholar). For competition experiments the binding reactions also included a 50-fold molar excess of the unlabeled fragments or of a synthetic, double-stranded, HSE oligonucleotide described by Hübel and Schöffl (16Hübel A. Schöffl F. Plant Mol. Biol. 1994; 26: 353-362Crossref PubMed Scopus (92) Google Scholar). The same molar excess of the 445-bp PvuII fragment from pBluescript SK+ was used as negative control. Subsequent to binding of protein extracts, samples with labeled DNA were subjected to gel shift assays (17Zimarino V. Wu C. Nature. 1987; 327: 727-730Crossref PubMed Scopus (249) Google Scholar). Conditions for growth and heat shock treatments of whole sunflower plants and seedlings (Helianthus annuus L., cv Sunweed, Rhône Poulenc) have been described elsewhere in detail (4Coca M.A. Almoguera C. Jordano J. Plant Mol. Biol. 1994; 25: 479-492Crossref PubMed Scopus (124) Google Scholar, 6Almoguera C. Jordano J. Plant Mol. Biol. 1992; 19: 781-792Crossref PubMed Scopus (132) Google Scholar, 18Almoguera C. Coca M.A. Jordano J. Plant J. 1993; 4: 947-958Crossref Scopus (62) Google Scholar). Embryos were collected at different stages of zygotic embryogenesis under controlled growth conditions and analyzed as reported (6Almoguera C. Jordano J. Plant Mol. Biol. 1992; 19: 781-792Crossref PubMed Scopus (132) Google Scholar). Four days postimbibition (dpi) seedlings were treated with 100 ॖm abscisic acid for 24 h (6Almoguera C. Jordano J. Plant Mol. Biol. 1992; 19: 781-792Crossref PubMed Scopus (132) Google Scholar). RNase A protection assays were performed as described (19Almoguera C. Coca M.A. Jordano J. Plant Physiol. 1995; 107: 765-773Crossref PubMed Scopus (32) Google Scholar). The RNA probes (riboprobes) were prepared by in vitrotranscription with T3 RNA polymerase (19Almoguera C. Coca M.A. Jordano J. Plant Physiol. 1995; 107: 765-773Crossref PubMed Scopus (32) Google Scholar). In the case of Ha hsp17.6 G1, the 813 nucleotide riboprobe contains, in addition to 55 nucleotides from the vector (from the T3 promoter to SmaI in the SK+ polylinker), the noncoding strand sequences of Ha hsp17.6 G1 between −533 and +225. In the case of Ha hsp17.7 G4, we used a 651-nucleotide riboprobe described before (9Coca M.A. Almoguera C. Thomas T.L. Jordano J. Plant Mol. Biol. 1996; 31: 863-876Crossref PubMed Scopus (85) Google Scholar). Intact nuclei were extracted from samples of control (at 14 dpi) and heat-stressed seedlings (40 min at 40 °C) as well as from zygotic embryos (at 20–24 days postanthesis (dpa)) dissected from plants grown under control conditions. The nuclear purification protocol was a of one of the described by and Plant Physiol. PubMed Google Scholar). the of nuclei the was and was in by at for min at The purified nuclear was in of nuclear and at for min at were in of nuclear and at The of nuclear DNA in the was the of and Plant 1991; PubMed Scopus Google Scholar). transcription containing 100 ॖg of nuclear DNA in a of 100 were performed for 20 min at The reactions mm pH 10 mm MgCl2; mm mm 1 mm 1 mm of mm each of and glycerol. Reactions were and the in RNA purified as described by and R. A. Plant J. 1994; 5: PubMed Scopus Google Scholar). in RNA was of nuclear of were used for with labeled run-on were in DNA with containing ॖg of different DNA These fragments were shown to patterns in sunflower the Ha hsp17.6 G1 sequences and the Ha sequences between and and the Ha hsp17.7 G4 sequences and to with to transcription The also included ॖg of a DNA fragment This fragment contains sequences between and (19Almoguera C. Coca M.A. Jordano J. Plant Physiol. 1995; 107: 765-773Crossref PubMed Scopus (32) Google Scholar). were performed at for h in of and under the described conditions (4Coca M.A. Almoguera C. Jordano J. Plant Mol. Biol. 1994; 25: 479-492Crossref PubMed Scopus (124) Google Scholar, 6Almoguera C. Jordano J. Plant Mol. Biol. 1992; 19: 781-792Crossref PubMed Scopus (132) Google were for The genomic described in Coca (9Coca M.A. Almoguera C. Thomas T.L. Jordano J. Plant Mol. Biol. 1996; 31: 863-876Crossref PubMed Scopus (85) Google Scholar) was as a probe the Ha hsp17.6 (6Almoguera C. Jordano J. Plant Mol. Biol. 1992; 19: 781-792Crossref PubMed Scopus (132) Google Scholar). A genomic that to the sequences in the was and Ha hsp17.6 This gene a sHSP as well as the during zygotic embryogenesis in the of stress (4Coca M.A. Almoguera C. Jordano J. Plant Mol. Biol. 1994; 25: 479-492Crossref PubMed Scopus (124) Google Scholar, 6Almoguera C. Jordano J. Plant Mol. Biol. 1992; 19: 781-792Crossref PubMed Scopus (132) Google Scholar). A fragment that the was in pBluescript and the nucleotide of this as well as of 5′-flanking and of was on both of DNA 1 A and not of transcription in mRNAs from embryos was by a from to in Ha hsp17.6 G1 and by RNase A protection assays other in higher not These two two transcription sites at and nucleotides from the by in 1 The of two sites better to the sequences for of plant genes 1987; PubMed Scopus Google Scholar) and is at a normal from the Thus, site 1 was to nucleotide 1 patterns of Ha hsp17.6 G1 mRNAs during zygotic embryogenesis and RNA samples were hsp17.6 G1 RNA were with RNase A and the analyzed by gel The RNA samples were from embryos at different developmental stages to in and from seedlings (at under control conditions or after with abscisic acid In the case of the same RNA samples of 1 and also to the Ha hsp17.7 G4 riboprobe to control by abscisic acid on the the RNA fragments with 1 and 2 to the two sites of Ha hsp17.6 1 DNA is Ha hsp17.6 G1 RNase A protection assays with RNA samples from embryos the accumulation patterns of during normal zygotic embryogenesis, with and from dpa, with desiccation during late embryogenesis. from the two transcription sites accumulated to similar during late embryogenesis, functional and 20 The mRNAs that accumulated during during germination by abscisic acid treatments of seedlings at this stage to the accumulation of the same 1 and such induced accumulation of mRNAs from the gene Ha hsp17.7 G4 of the sequences in the promoter of Ha hsp17.6 G1 characteristics with the same of two sHSP genes from sunflower, Ha hsp17.7 G4 and Ha was the in the promoter of of HSEs as those described for Ha hsp17.7 G4, Ha 1 and Ref. 9Coca M.A. Almoguera C. Thomas T.L. Jordano J. Plant Mol. Biol. 1996; 31: 863-876Crossref PubMed Scopus (85) Google and for most plant sHSP genes (for review, see Ref. W.B. Key J.L. Biochemistry. 1991; 30: 1-12Crossref PubMed Scopus (68) Google Scholar). These in which the or nucleotides at 1 or of the have been shown to be for binding and activation E. W.B. Plant Mol. Biol. 1992; 19: PubMed Scopus Google H. 1994; PubMed Scopus Google Scholar). A functional HSE is to at least of in a promoter T. A. C. The of and Molecular Cold Spring Harbor Laboratory, Cold Spring Harbor, Scholar). The nucleotide of Ha hsp17.6 G1 showed only 1 of which the one in the not to the for the at the A that the at the is of the other 1 This is a as functional HSEs a between J. J. R. Mol. Biol. PubMed Scopus Google Scholar). The four that the HSE of Ha hsp17.6 G1 are at from the This would better to that of the most of the two HSE in the promoter of other plant sHSP genes, the Ha hsp17.7 G4 and Ha promoters and W.B. Key J.L. Biochemistry. 1991; 30: 1-12Crossref PubMed Scopus (68) Google and 9Coca M.A. Almoguera C. Thomas T.L. Jordano J. Plant Mol. Biol. 1996; 31: 863-876Crossref PubMed Scopus (85) Google Scholar). the binding of the HSE hsp17.6 G1, we shift assays (15Rabindran S.K. Giorgi G. Clos J. Wu C. Proc. Natl. Acad. Sci. U. S. A. 1991; 88: 6906-6910Crossref PubMed Scopus (376) Google Scholar) and two DNA fragments containing the HSE of Ha hsp17.7 G4 or Ha hsp17.6 Binding of to each fragment was by competition experiments the same molar of unlabeled a control (the same fragment used as labeled and a negative control DNA fragment from plasmid vector We binding of to a fragment containing the HSE in Ha hsp17.6 G1 The of binding was demonstrated by competition of vector DNA fragment not the the same excess of unlabeled Ha hsp17.6 G1 or Ha hsp17.7 G4 fragments detection of the The Ha hsp17.7 G4 fragment was the most This was by other experiments molar of the same and other DNA one oligonucleotide with a HSE We also similar the hsp17.7 G4 and could be by a 50-fold molar excess of the unlabeled Ha hsp17.7 G4 fragment and but in contrast, the same excess of the unlabeled Ha hsp17.6 was as an as the vector DNA fragment and Thus, competition experiments that to the Ha hsp17.6 G1 sequences a for this factor the HSEs of Ha hsp17.7 In the promoter of Ha hsp17.6 a and HSE with other similar sHSP This the heat of this In we by the accumulation of sHSP as probe the Ha hsp17.6 (6Almoguera C. Jordano J. Plant Mol. Biol. 1992; 19: 781-792Crossref PubMed Scopus (132) Google Scholar, 18Almoguera C. Coca M.A. Jordano J. Plant J. 1993; 4: 947-958Crossref Scopus (62) Google Scholar). this probe is not we to the heat stress expression patterns of the Ha hsp17.6 G1 mRNAs the more of which has been used to gene-specific expression patterns of plant sHSP genes (9Coca M.A. Almoguera C. Thomas T.L. Jordano J. Plant Mol. Biol. 1996; 31: 863-876Crossref PubMed Scopus (85) Google Scholar, A. Plant Physiol. 1992; PubMed Scopus Google Scholar). accumulation of the Ha hsp17.6 G1 mRNAs was RNA samples from seedlings and plants results in The same RNA samples were to Ha hsp17.7 G4 or to Ha hsp17.6 Ha hsp17.7 G4 was used as a control for heat in sunflower (9Coca M.A. Almoguera C. Thomas T.L. Jordano J. Plant Mol. Biol. 1996; 31: 863-876Crossref PubMed Scopus (85) Google Scholar). from the Ha hsp17.6 G1 gene were only in a control from seeds but not in control or heat-stressed samples from seedlings and or from plants an was in the heat-stressed In contrast, the analysis of the same RNA samples with the Ha hsp17.7 G4 probe showed that from this gene accumulated in all after heat shock which was after those used for detection of Ha hsp17.6 A and of on Ha hsp17.6 G1 mRNA RNA samples from seedlings dpi) at control growth 20 °C) or after heat shock treatments for 2 h min at different temperatures °C) were analyzed by RNase A protection the The the of the fragment from the Ha hsp17.7 G4 The two the for the two fragments from protection of Ha hsp17.6 G1 The used for are Ha hsp17.6 G1 and Ha hsp17.7 G4 The to an after a The of are as in the of The of heat shock response of Ha hsp17.6 be on as not all plant heat shock genes would respond at the same temperature. We this by different heat shock treatments at temperatures within growth conditions for accumulation of Ha hsp17.6 G1 and Ha hsp17.7 G4 was by RNase A protection as described The accumulation of Ha hsp17.7 G4 was from °C, at 40 and at The same RNA samples analyzed with the Ha hsp17.6 G1 riboprobe not show heat shock-induced accumulation of Ha hsp17.6 in of the stress conditions The experiments described that the mRNAs of Ha hsp17.6 G1 not in response to heat in different and developmental after germination of Our observation could be by a regulation of Ha hsp17.6 G1 in response to heat shock. this we run-on transcription analyses with nuclei from embryos at normal growth and from control and heat-stressed a control of the by RNA polymerase we used the detection of of sunflower genes expressed in all of conditions (19Almoguera C. Coca M.A. Jordano J. Plant Physiol. 1995; 107: 765-773Crossref PubMed Scopus (32) Google Scholar). The of two heat-inducible genes, Ha and Ha hsp17.7 G4 (9Coca M.A. Almoguera C. Thomas T.L. Jordano J. Plant Mol. Biol. 1996; 31: 863-876Crossref PubMed Scopus (85) Google were used as a control for activation by heat and those of Ha hsp17.7 G4 also as a control for activation in The hsp17.6 G1, Ha hsp17.7 G4, and Ha were by with gene-specific The of probe was with analysis and sunflower genomic DNA run-on analysis the heat of Ha hsp17.7 G4 and Ha control and heat but to heat shock-induced transcription from the Ha hsp17.6 G1 promoter control and heat In this analysis hsp17.6 G1 and Ha hsp17.7 G4 2 and it to transcription from the Ha promoter In all the probe the of RNA polymerase in the nuclei The of a developmentally regulated plant sHSP gene during zygotic embryogenesis, but which is not to heat shock in vegetative the evolution of the regulation in members of the sHSP gene superfamily in the plant kingdom. known to contain genes noninducible by heat shock only those encoding large for example, the of genes are developmentally show expression of A. Vierling E. Plant Mol. Biol. 1995; 27: 441-456Crossref PubMed Scopus (64) Google Scholar). evolutionary for the of genes is from heat-inducible as is as an and well It is that this involved in for the heat shock response the The of HSEs is a of plant genes (for review, see Ref. W.B. Key J.L. Biochemistry. 1991; 30: 1-12Crossref PubMed Scopus (68) Google and This with the and in binding characteristics of the HSE in Ha hsp17.6 G1 with those of other plant sHSP genes, two from sunflower 1 The HSE in Ha hsp17.6 G1 would not support HSF1 binding in or heat shock-induced activation heat shock The HSEs in Ha hsp17.7 G4 show characteristics and support heat shock 1 and and Ref. 9Coca M.A. Almoguera C. Thomas T.L. Jordano J. Plant Mol. Biol. 1996; 31: 863-876Crossref PubMed Scopus (85) Google Scholar). This is of from the in Ha 1 and in other plant sHSP promoters (for review, see Ref. W.B. Key J.L. Biochemistry. 1991; 30: 1-12Crossref PubMed Scopus (68) Google Scholar). Interestingly, there are for a similar evolution of the regulation of genes in These genes proteins (the A and of expressed in the eye The are structurally related to the sHSPs and might have evolved from a common (11Caspers G.J. Leunissen J.A.M. de Jong W.W. Mol. Biol. Evol. 1995; 40: 238-248Crossref Scopus (308) Google Scholar). most of the promoters HSEs and heat and some promoters not contain HSEs and are not heat-inducible (12Overbeek P.A. Chepelinsky A.B. Khillan J.S. Piatigorsky J. Westphal H. Proc. Natl. Acad. Sci. U. S. A. 1985; 82: 7815-7819Crossref PubMed Scopus (150) Google Scholar, G. Graham C. Biochim. Biophys. Acta. 1995; 1263: 105-113Crossref PubMed Scopus (11) Google Scholar). Other has that a sHSP gene from is not in response to heat shock in cells Mol. Biol. PubMed Scopus Google Scholar). Our results show that an evolution has in plants for other members of the sHSP on the of the regulated The observation of transcription from different plant sHSP promoters in of the presence, or of HSEs some to the developmental regulation of genes (9Coca M.A. Almoguera C. Thomas T.L. Jordano J. Plant Mol. Biol. 1996; 31: 863-876Crossref PubMed Scopus (85) Google Scholar, R. Schöffl F. Plant Mol. Biol. 1996; 31: PubMed Google Scholar). A involvement of HSEs and of similar to HSF1 not the for the sunflower Thus, transcription from the Ha promoter is not in zygotic heat in vegetative with the of HSEs at a 1 and In addition, Ha hsp17.6 G1 and Ha hsp17.7 G4 of activation in embryos and with HSEs and In the case of Ha hsp17.7 G4, analyses of HSEs that heat of this gene in vegetative be on developmental regulation during mutations expression of Ha hsp17.7 G4 during desiccation and J. for In the case hsp17.6 G1, evolution more HSEs in of the Ha hsp17.7 G4 and Ha hsp17.6 G1, not to heat is expressed during late embryogenesis. involvement of HSEs in the developmental regulation of Ha hsp17.6 G1 during desiccation elements would different with different from that of The and of plant for DNA binding and functional (for review, see Ref. L. D. E. W.B. 1996; PubMed Google could allow the of some in developmental as in animal S.K. A. A. C. The of and Molecular Cold Spring Harbor Laboratory, Cold Spring Harbor, Scholar). Ha hsp17.6 G1 and Ha hsp17.7 G4 unique to the molecular of developmental regulation of plant sHSP genes during zygotic embryogenesis. a unique of genes, expressed with similar patterns in the same for which and are analysis and expression that developmental expression in seeds might be by distinct control We are to Wu of for the of plasmid pHu We and of of for of this
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