Cytoplasmic HSP70 homologues of pea: differential expression in vegetative and embryonic organs

Abstract

Eukaryotes express several cytoplasmic HSP70 genes, and their encoded proteins participate in diverse cellular processes. Three cDNAs encoding highly expressed cytoplasmic HSP70 homologues from Pisum sativum were cloned and characterized. They were designated PsHSP71.2, PsHSC71.0, and PsHSP70b. These HSP70 genes have different expression profiles in leaves: PsHSP71.2 is observed only in response to heat stress, PsHSC71.0 is present constitutively, and PsHSP70b is weakly constitutively expressed, but induced strongly in response to heat stress. In addition to being heat induced, the PsHSP71.2 mRNA is also expressed in zygotic, but not maternal organs of developing pea seeds, while PsHSC71.0 and PsHSP70b mRNAs are present in maternal and zygotic organs throughout seed development. Immunoblot analysis of parallel protein samples detects a 70 kDa polypeptide in all samples, and a 72 kDa polypeptide that corresponds to the PsHSP71.2 gene product is observed in cotyledons beginning at mid-maturation and in axes beginning between late maturation and desiccation. This polypeptide is not detected in the seed coat. The 72 kDa polypeptide remains abundant in both cotyledons and axes through germination, but declines substantially between 48 and 72 h after the onset of inbibition. Differential control of HSP70 expression during heat stress, seed maturation, and germination is consistent with the hypothesis that there are functional distinctions between cytoplasmic HSP70s.

Cellular Response of Pea Plants to Cadmium Toxicity: Cross Talk between Reactive Oxygen Species, Nitric Oxide, and Calcium

“…These discrepancies could be explained by the differential distribution of PRs in biotic and abiotic stress conditions. The third gene induced by Cd corresponds to the cytosolic heat shock protein, HSP71.2, which is known to be up-regulated under heat stress; its function is to act as a molecular chaperone facilitating protein transport into organelles (DeRocher and Vierling, 1995) or preventing protein agregation (Ma et al, 2006). The induction of HSPs in pea plants under Cd treatment is apparently regulated by H 2 O 2 overproduction, since ascorbate reversed the up-regulation induced by Cd; in addition to that, transcription factors involved in HSP regulation can act as H 2 O 2 sensors (Miller and Mittler, 2006).…”

Functional analysis of Hsp70 superfamily proteins of rice (Oryza sativa)

“…In tomato, Hsc70 transcripts were detected in mature anthers (Duck and Folk 1994). Several plant cytosolic Hsp70 genes are expressed during seed development, maturation, and/or germination (DeRocher and Vierling 1995;Sung et al 2001). While levels of Hsp70 proteins are noted to be abundant in dry seeds, their levels drastically decline within 72 h after the onset of imbibitions (Sung et al 2001).…”

Protein expression upon desiccation and imbibition of Magnolia ovata A. St.-Hil seeds

“…Some Lea proteins and HSPs may provide this protective function not only in the dry state but also throughout the germination. This pattern was observed by Gallardo et al (2001) and DeRocher and Vierling (1995) in the seeds of Arabidopsis thaliana and Pisum sativum, respectively. Proteins from the group 3 (Fig.5) presented the most intriguing expression pattern that seemed related to final germination of M. ovata seeds (Fig.1).…”