Isolation and Mobilization of Storage Proteins from Apple Shoot Bark

117

Bark storage proteins (BSPs) accumulate in the inner bark parenchyma of many woody plants during autumn and winter. We investigated the effect of a short-day (SD) photoperiod on the accumulation of the 32-kilodalton bark storage protein of poplar (Populus deltoides Bart. ex Marsh.) under controlled environmental and natural growing conditions. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and protein gel blot analysis revealed that 10 days of SD exposure (8 hours of light) resulted in a 20% increase in the relative abundance of the 32-kilodalton bark storage protein of poplar. After 17 days of SD exposure, the 32-kilodalton bark storage protein accounted for nearly one-half of the soluble bark proteins. In natural field conditions, accumulation of the 32-kilodalton bark storage protein was observed to start by August 18 (daylength 14.1 hours). Immunoprecipitation of in vitro translation products with anti-BSP serum revealed that the SD protein accumulation was correlated with changes in the pool of translatable mRNA. A survey of poplar clones from different geographic origins revealed the presence of the 32-kilodalton BSP in the dormant bark of all the clones tested. These results demonstrate that a SD photoperiod induces, whether directly or indirectly, rapid changes in woody plant gene expression, leading to the accumulation of BSP.

Section: Discussionmentioning

confidence: 99%

Photoperiod Control of Poplar Bark Storage Protein Accumulation

Coleman¹,

Chen²,

Ernst³

et al. 1991

117

“…Recently, a group ofproteins termed BSPs2 has been shown to accumulate in the bark tissue of a number of temperate woody plants during autumn and winter and decline during spring shoot growth (14,15,32). These proteins are sequestered in protein storage vacuoles ofthe inner bark parenchyma during autumn and winter (7,8,32).…”

mentioning

confidence: 99%

Complementary DNA Cloning of Poplar Bark Storage Protein and Control of Its Expression by Photoperiod

Coleman¹,

Chen²,

Fuchigami³

1992

Bark storage proteins accumulate in the bark of many woody plants during autumn and winter. In poplar (Populus de/toides Bartr. ex Marsh), the accumulation of the 32-kilodalton bark storage protein is controlled by photoperiod. We have isolated a full-length cDNA encoding for the poplar 32-kilodalton bark storage protein and determined its nucleotide sequence. The derived amino acid sequence shows that poplar bark storage protein is rich in serine, leucine, phenylalanine, and lysine. Poplar bark storage protein is similar to the poplar wound-induced cDNA clone 4 and clone 16 (TJ Parsons, HD Bradshaw, MP Gordon [1989] Proc NatI Acad Sci USA 86: 7895-7899). DNA gel blot analysis suggests that poplar bark storage protein is encoded by a multigene family of about five genes. Poplar plants grown in long days contained low levels of mRNA for the bark storage protein. Exposure to short days resulted in an increase in bark storage protein mRNA within 7 days. After 21 days of short day exposure, high levels of mRNA were detected. The accumulation of bark storage protein mRNA in response to short days was also observed in plants exposed to natural shortening daylengths. Our results indicate that the accumulation of poplar bark storage protein mRNA is controlled by photoperiod. This finding will provide a useful system for investigating photoperiodism in woody plants.

“…proteins have been identified in the bark of Malus (8,16), Sambucus (14), Robinia (14), Acer (18,25), Salix (25), and Populus (4,20,25). These proteins accumulate during late summer or early autumn and are highly abundant throughout the winter.…”

mentioning

confidence: 99%

Vegetative Storage Proteins in Poplar

Langheinrich

Tischner²

1991

Bark, wood, and root tissues of several Populus species contain a 32-and a 36-kilodalton polypeptide which undergo seasonal fluctuations and are considered to be storage proteins. These two proteins are abundant in winter and not detectable in summer as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunodetection. An antibody raised against the 32-kilodalton storage protein of Populus trichocarpa (T. & G.) cross-reacts with the 36-kilodalton protein of this species. The synthesis of the 32-and 36-kilodalton proteins can be induced in micropropagated plants by short-day conditions in the growth chamber. These proteins are highly abundant in structural roots, bark, and wood and combined represent >25% of the total soluble proteins in these tissues. Nitrate concentration in the leaves and nitrate uptake rate decreased dramatically when LD plants were transferred to short-day conditions; the protein content in leaves was unaffected. A decrease of the 32-and 36-kilodalton polypeptides occurs after transferring induced plants back to LD conditions. Both polypeptides are glycosylated and can be efficiently purified by affinity chromatography using concanavalin A-Sepharose 4B. The 32-and the 36-kilodalton polypeptides have identical basic isoelectric points and both consist of at least three isoforms. The storage proteins show a loss in apparent molecular mass after deglycosylation with trifluoromethanesulfonic acid. It is concluded that the 32-and 36-kilodalton polypeptides are glycoforms differing only in the extent of glycosylation. The relative molecular mass of the native storage protein was estimated to be 58 kilodalton, using gel filtration. From the molecular mass and the elution pattern it is supposed that the storage protein occurs as a heterodimer composed of one 32-and one 36-kilodalton subunit. Preliminary data suggest the involvement of the phytochrome system in the induction process of the 32-and 36-kilodalton polypeptides.Most deciduous, woody perennials exhibit a seasonal variation in the nitrogen levels in many of their tissues. The seasonal fluctuation of nitrogen reserves has been reported in several earlier studies (6,8,22 (17) showed that poplar is extremely efficient at nitrogen conservation. More than 80% of the whole-tree nitrogen content is conserved during dormancy, and the majority of stored nitrogen can be found in the roots. It might be possible to increase biomass production of poplar through clonal selection for a minimal loss of nitrogen during the winter.In this paper, we characterize a 32-and a 36-kD storage protein in vegetative tissues of poplar which show seasonal fluctuations and are supposed to occur as glycoforms. We also demonstrate the induction of these two proteins in micropropagated plants under SDs and their disappearance under LDs using a 32-kD antibody. Involvement of the phytochrome system in the induction process is discussed. MATERIALS AND METHODS Plant MaterialBark and wood from first-order twigs and bark of structural roots were...