Showing papers by "Dong Liu published in 1994"

Plant Defense Genes Are Synergistically Induced by Ethylene and Methyl Jasmonate.

Abstract: Combinations of ethylene and methyl jasmonate (E/MeJA) synergistically induced members of both groups 1 and 5 of the pathogenesis-related (PR) superfamily of defense genes. E/MeJA caused a synergistic induction of PR-1b and osmotin (PR-5) mRNA accumulation in tobacco seedlings. E/MeJA also synergistically activated the osmotin promoter fused to a [beta]-glucuronidase marker gene in a tissue-specific manner. The E/MeJA responsiveness of the osmotin promoter was localized on a -248 to +45 fragment that exhibited responsiveness to several other inducers. E/MeJA induction also resulted in osmotin protein accumulation to levels similar to those induced by osmotic stress. Of the several known inducers of the osmotin gene, including salicylic acid (SA), fungal infection is the only other condition known to cause substantial osmotin protein accumulation in Wisconsin 38, a tobacco cultivar that does not respond hypersensitively to tobacco mosaic virus. Based on the ability of the protein kinase C inhibitor 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine to block ethylene induction of PR-1b mRNA accumulation and its inability to block osmotin mRNA induction by ethylene, these two PR gene groups appeared to have at least partially separate signal transduction pathways. Stimulation of osmotin mRNA accumulation by okadaic acid indicated that another protein kinase system is involved in regulation of the osmotin gene. SA, which is known to induce pathogen resistance in tobacco, could not induce the osmotin gene as much as E/MeJA and neither could it induce PR-1b as much as SA and MeJA combined.

Osmotin overexpression in potato delays development of disease symptoms.

Abstract: Transgenic potato and tobacco plants carrying the osmotin gene under the control of the cauliflower mosaic virus 35S promoter constitutively overexpressed osmotin to a level of approximately 2% of total cellular protein. Leaves of transgenic potato plants exhibited delayed development of disease symptoms after inoculation with spore suspensions of Phytophthora infestans, which is the cause of late blight disease of potato. In contrast, transgenic tobacco plants did not display any change in the development of disease symptoms when challenged with either spore suspensions or fungal mycelia of Phytophthora parasitica var. nicotianae. Using in vitro assays, purified osmotin was found to be more effective against P. infestans. Some inhibition of P. parasitica also was observed in vitro even though no in vivo effect could be established.

A NaCl‐regulated plant gene encoding a brain protein homolog that activates ADP ribosyltransferase and inhibits protein kinase C

Abstract: Summary A cDNA clone pCZ1, with a 1.1 kb insert, was isolated from a NaCI-adapted tobacco cell cDNA library that encodes an apparently full-length 29 kDa protein (251 amino acids) with a calculated pl of 5.7. The encoded peptide had a high amino acid sequence identity with bovine 14-3-3 protein which was originally found as an abundant protein in the animal central nervous system. Recently, proteins with sequence identity to 14-3-3 protein have also been found in plants, insects and yeast, and appear to have diverse physiological functions. Similar to the bovine brain 14-3-3 protein, the recombinant pCZ1 protein stimulated ADP-ribosylation of protein substrate by ADP-ribosyl-transferase from the plant and animal pathogenic bacterium Pseudomonas aeruginosa. This recombinant protein also inhibited protein kinase C activity in vitro. Southern blot analyses indicated that most likely five genes encoding 14-3-3-like proteins are present in tobacco. The pCZ1 cDNA insert hybridized to a single mRNA of 1.1 kb from cultured tobacco cells. The level of this mRNA transcript in tobacco cells was downregulated upon adaptation to NaCl but was unaffected by short-term treatment with NaCl, ABA or ethylene. In tobacco plants, expression of transcript that hybridized to pCZ1 was tissue specific, and was most abundant in roots and flower parts. Monoclonal antibody raised against GF14 protein, a maize protein with substantial sequence identity with 14-3-3 protein detected two bands on SDS-PAGE of total proteins from unadapted tobacco cells and only a single band from cells adapted to NaCl. The GF14 antibody was also used to illustrate that the G-box element of a salt-induced gene is associated with a 14-3-3-type protein.

Structure, Regulation and Function of the Osmotin Gene

Abstract: Over the past years several genes have been reported to be osmotically regulated (Storey and Storey, 1981; Holtum and Winter, 1982; Singh et al, 1985; Singh et al, 1987a;Bedford et al, 1987; Close et al, 1989; Cushman et al, 1989; Singh et al, 1989a; 1989b; Delauney and Verma, 1990; Perez-Prat et al, 1990; Skriver and Mundy, 1990; Bartels et al, 1991; Dhindsa, 1991, Estragarcia et al, 1991; Narasimhan et al, 1991; Perez-Prat et al, 1992; Kononowicz et al, 1992; Nelson et al, 1992; Niu et al, 1993; Zhu et al, 1993b) These studies have been rationalized on the assumption that amongst these genes are molecular determinants of osmotic tolerance Although the products of many of these genes still remain unidentified there are a number that have been well characterized and are of interest of several laboratories One of these genes is osmotin (Singh et al, 1987a; LaRosa et al, 1989, Meeks-Wagner et al, 1989; Grosset et al, 1990; Roberts and Selitrennikoff, 1990; Stintzi et al, 1991; Woloshuk et al, 1991; Casas et al, 1992; LaRosa et al, 1992, Kononowicz et al, 1993)