Dehydrin-Like Proteins in Soybean Seeds in Response to Drought Stress during Seed Filling

There is no information on accumulation of dehydrin proteins during seed development and maturation of soybean [Glycine max (L.) Merr.] in response to drought stress. Our objective was to study accumulation of dehydrin-like proteins in developing soybean seeds in response to drought stress. A greenhouse experiment and a field experiment were conducted. In the greenhouse experiment, three treatments were imposed on soybean plants after beginning of linear seed filling (R5): well-watered (WW), gradual stress (GS) imposed before severe stress, and sudden severe stress (SS). In the field treatments were irrigation (I) and nonirrigation (NI) (rainfed) conditions imposed from R5 to R8 (mature seeds). Greenhouse results indicated dehydrin-like proteins (28 and 32 kDa) were detected 18 d after R5 (R5.8) in developing seeds from drought-stressed plants but not in seeds from the well-watered plants. In the mature seeds, dehydrin-like proteins (28, 32, and 34 kDa) were detected in seeds from drought-stressed plants as well as the well-watered plants. In the field, dehydrin-like proteins accumulated similarly under irrigation and nonirrigation conditions, with the first detection for dehydrins (28 and 32 kDa) at 22 d after R5 (R6). Accumulation of dehydrin-like proteins was maximal in seeds harvested at 43 d after R5 (seed physiological maturity)

Lanthanide ions are agonists of transient gene expression in rice protoplasts and act in synergy with ABA to increase Em gene expression

Previous work has shown that in rice suspension cells, NaCl at 0.4 M can induce Em gene expression and act synergistically with ABA, possibly by potentiating the ABA response pathway through a rate-limiting intermediate (R.M. Bostock and R.S. Quatrano (1992) Plant Physiol., 98, 1356-1363). Since calcium is an intermediate in ABA regulation of stomatal closure, we tested the effect of calcium changes on ABA-inducible Em gene expression in transiently transformed rice protoplasts. We show that calcium is required for ABA-inducible Em-GUS expression and can act in synergy with ABA. The trivalent ions lanthanum, gadolinium, and aluminum, which are known to interact with calcium- and other signaling pathways, can act at sub-millimolar concentrations to increase GUS reporter gene expression driven by several promoters in transiently transformed rice protoplasts. This effect is not specific for the ABA-inducible Em promoter, but is synergistic with ABA. The lanthanum synergy with ABA does not require calcium. In rice suspension cells, lanthanum alone does not induce Em gene expression, in contrast to transiently transformed protoplasts, yet can act synergistically with ABA to effectively increase the sensitivity to ABA greater than tenfold. Trivalent ions may be a useful tool to study the regulation of gene expression. The possible effects of trivalent ions on ABA signal transduction and gene expression are discussed

FASEB summer research conference on signal transduction in plants. Final report, June 16, 1996--June 21, 1996

This is the program from the second FASEB conference on Signal Transduction in Plants. Topic areas included the following: environmental signaling; perception and transduction of light signals; signaling in plant microbe interactions; signaling in plant pathogen interactions; cell, cell communication; cytoskeleton, plasma membrane, and cellwall continuum; signaling molecules in plant growth and development I and II. A list of participants is included

Genetic analysis of DEK1 loop function in three-dimensional body patterning in physcomitrella patens.

DEK1 of higher plants plays an essential role in position dependent signaling and consists of a large transmembrane domain (MEM) linked to a protease catalytic domain (CysPc) and a regulatory domain (C2L). Here we show that the postulated sensory Loop of the MEM domain plays an important role in the developmental regulation of DEK1 activity in the moss Physcomitrella patens. Compared with P. patens lacking DEK1 (∆dek1), the dek1∆loop mutant correctly positions the division plane in the bud apical cell. In contrast to an early developmental arrest of ∆dek1 buds, dek1∆loop develops aberrant gametophores lacking expanded phyllids resulting from mis-regulation of mitotic activity. In contrast to the highly conserved sequence of the catalytic CysPc domain, the Loop is highly variable in land plants. Functionally, the sequence from Marchantia polymorpha fully complements the dek1∆loop phenotype, whereas sequences from Zea mays and Arabidopsis thaliana give phenotypes with retarded growth and affected phyllid development. New bioinformatic analysis identifies MEM as a member of the Major Facilitator Superfamily, membrane transporters reacting to stimuli from the external environment. Transcriptome analysis comparing WT and ∆dek1 tissues identifies an effect of two groups of transcripts connected to dek1 mutant phenotypes, i.e. transcripts related to cell wall remodeling and regulation of the APB2 and APB3 transcription factors known to regulate bud initiation. Finally, new sequence data support the hypothesis that the advanced charophyte algae that evolved into ancestral land plants lost cytosolic calpains, retaining DEK1 as the sole calpain in the evolving land plant lineage

The wheat Em promoter drives reporter gene expression in embryo and aleurone tissue of transgenic barley and rice

The early methionine (Em) proteins are members of the late embryogenesis abundant (LEA) group of proteins that have been considered to be embryo specific. The ability of a 646-bp wheat Em promoter to control green fluorescent protein (gfp) expression was investigated in transgenic barley and rice. Seeds of transgenic plants expressed gfp in the developing embryo but also in the aleurone layer. The 646-bp Em promoter also directed strong gfp expression in cells comprising the junction between the endosperm transfer cells and cells of the aleurone layer. Em-gfp expression in transgenic barley showed differences in spatial and temporal control when compared with that observed in transgenic rice. Em-gfp expression was also detected in mature aleurone cells of transgenic barley and rice with and without abscisic acid (ABA) treatment. Reverse transcriptase-polymerase chain reaction (RT-PCR) results indicated the presence of Em and Em-homologous transcript in embryo, aleurone and endosperm tissues of wheat and of barley and rice, respectively. These results suggest that Em proteins may be expressed in both the embryo and aleurone during seed development, possibly providing protection against desiccation in these two tissues that survive seed drying. They may also have a similar role in these tissues during germination. The Em promoter from wheat may be useful in the expression of novel genes in cereal grains, as an embryo- and aleurone-specific promoter complementing other available endosperm- and pericarp-specific promoters to collectively increase the expression of transgenes in seeds