Molecular and Physiological Analysis of a Heat-Shock Response in Wheat

Abstract

We have isolated two cDNA clones from wheat (Triticum aestivum L. var Stephens), designated WHSP16.8 and WHSP16.9, that are highly similar in sequence to the low molecular weight heatshock protein genes previously isolated from soybean. RNA blot analysis confirms that these sequences are present in heat-shocked wheat seedlings, but not in control tissues. The WHSP16.8 and WHSP16.9 cDNAs were isolated by screening a lambda gt1l expression library with antibodies to HMGc (a chromosomal protein of wheat). Immunoblot analysis has demonstrated that the antibodies raised against HMGc also recognize a group of proteins that are induced by heat shock and have molecular weights (estimated by sodium dodecyl sulfate electrophoresis) consistent with the molecular weights of the proteins deduced from the sequences of the cDNAs.Heat-shock proteins are a set of proteins whose synthesis is induced upon heat stress. The induction of heat-shock proteins is a highly conserved response that has been observed in every species studied thus far. The heat-shock proteins are also induced by other environmental stresses, and in some organisms, certain heat-shock proteins are induced during the course of normal development. The function of the heat-shock proteins is as yet unknown. However, evidence suggests that these proteins may provide organisms with a mechanism for thermotolerance (10).The low mol wt heat-shock proteins are the predominant heat-shock-induced proteins in plants. These been documented (1,2,6,8,12,30), and the number of low mol wt heat-shock proteins induced in several monocot species has been determined (12). These studies reveal that in wheat, 11 low mol wt proteins are induced and 1 enhanced by heat shock. We have isolated two wheat (Triticum aestivum L. var Stephens) cDNA clones that are highly similar to the soybean 17-kD heat-shock protein genes described by Nagao et al. (17). The work presented in this article shows that these cDNA clones represent heat-shock-inducible transcripts in wheat. Because the wheat heat-shock cDNA clones were isolated through screening an expression library with the antibodies to the HMGc3 chromosomal protein of wheat (25), it seemed likely that the HMGc antibodies would cross-react with low mol wt heat-shock proteins of wheat. Immunoblot analysis of protein extracts from heat-stressed tissues has confirmed this conjecture. Use of the HMGc antibodies has revealed a set of immunologically related proteins that are induced upon heat shock in wheat and have mol wts consistent with those deduced from the cDNA sequences. MATERIALS AND METHODS Plant MaterialWheat (Triticum aestivum L. var. Stephens) seeds were surface sterilized with 0.5% sodium hypochlorite and allowed to imbibe for 3 h. Seedings were grown in the dark at 200C for 5 d and were then transferred to 400C for heat-shock treatments. The etiolated coleoptiles and first leaves were harvested into liquid nitrogen and stored frozen at -700C.Preparation and Screening of a Wheat cDNA Library Total RNA was isolated from the c...

Stress and Stress Coping in Cultivated Plants

“…HSP also appear during the course of normal plant development and tissue differentiation and may be induced by other environmental stresses, such as salt stress (McElwain and Spiker 1992;Kuznetsov et al 1993). Furthermore, under the complete absence of hyperthermia, HSP have been found in generative organs of clover flowers, seed pods and seeds; this leads to the speculation that besides their function in heat tolerance some HSP may play a role in the reproductive process (Hernandez and Vierling 1993).…”

Differential display-mediated rapid identification of different members of a multigene family, HSP16.9 in wheat

“…4A). Another pair of cDNAs is HSP 16.9d [14] and 17LC1 (Genbank accession no. L37069) which are highly similar but HSP 16.9d will belong to the Tt2VC group and 17LCI belongs to TI2VT mRNA population due to a poly(A) site 20 bp downstream as compared to HSP 16.9d (Fig.…”

“…Previously, we have isolated and characterized several members of these families in wheat including two members of HSP 16.9 family (for review see [ 15]). Two other members of HSP 16.9 family in wheat have been reported by McElwain and Spiker [ 13,14]. In vitro hybrid selection/translation and 2-D gel electrophoresis using the HSP16.9 cDNA probe indicated that this family consists of at least 12 members with differing pI values [22].…”

“…1). We decided first to apply [14]. Note the high level of amino acid sequence conservation in this family.…”

Physicochemical and Sensory Properties of Tofu Prepared With Heat‐treated Soybeans

“…Heat‐shock proteins are a set of proteins whose synthesis is induced by heat stress (McElwain and Spiker 1992). The induction of heat‐shock protein synthesis in response to thermal stress occurs in all organisms, ranging from bacteria to humans (Vierling 1991).…”