Fluctuation of Vegetative Storage Proteins in the Seedlings of Swietenia macrophylla, Analogous to the Seasonal Changes of Those in the Shoot of the Adult Tree

In order to Identify appropriate plant materials for studying the gene expression and biological function of vegetative storage proteins （VSPs） in woody plants, the VSPs in the seedlings of Swietenla rnacrophylla King were investigated by using light microscopy, sodium dodecyl sulfate-polyacrylamide gel electrophoresis （SDS-PAGE） and Western.blotting. The seed of S. macrophylla was rich in storage proteins that accumulated In the vacuoles of cotyledon parenchyma cells in appearance of compact spherical grains. The growth and development of S. macrophylla seedlings were characterized by an obvious growth rhythm. The storage proteins In seeds disappeared during seedling growth while VSPs appeared in the stem 2 weeks after seedling leaves matured. Thereafter, the VSPs In the seedling stem almost exhausted during new shoot growth, and when the leaves of new shoot Just matured, both the stem beneath the new shoot of seedlings and the stem of new shoot started to accumulate VSPs. Nitrogen application dramatically Increased the level of VSPs, but had little influence on the dynamics of VSP consumption and accumulation in seedling stem. Together with these data, the fluctuation of VSPs in seedlings was very similar to that in the branches of the adult trees. In addition, seedlings are easy to be treated due to their small size. Our results suggested that S. rnacrophylla seedlings were suitable for Investigating the biological roles of VSPs and the mechanism of nitrogen storage in trees.     

Vegetative Storage Protein with Trypsin Inhibitor Activity Occurs in Sapindus mukorassi,a Sapindaceae Deciduous Tree

A vegetative storage protein （VSP） with trypsin inhibitor activity in a deciduous tree, Sapindus mukorassi, was characterized by means of sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western-blot, immuno-histochemical localization, light- and electro-microscopy, together with analysis of proteinase inhibitor activity of the purified VSP in vitro. There were two proteins with molecular masses of about 23 and 27 kDa in a relatively high content in the bark tissues of terminal branches of S. mukorassi in leafless periods. The proteins decreased markedly during young shoot development, indicating their role in seasonal nitrogen storage. Immuno-histochemical localization with the polyclonal antibodies raised against the 23 kDa protein demonstrated that the 23 kDa protein was the major component of protein inclusions in protein-storing cells. The protein inclusions were identified by protein-specific staining and should correspond to the electron-dense materials in different forms in the vacuoles of phloem parenchyma cells and phloem ray parenchyma cells under an electron microscope. So, the 23 kDa protein was a typical VSP in S. mukorassi. The 23 and 27 kDa proteins shared no immuno-relatedness, whereas the 23 kDa protein was immuno-related with the 22 kDa VSP in lychee and possessed trypsin inhibitor activity. The 23 kDa protein may confer dual functions： nitrogen storage and defense.     

Annual uptake and distribution of N15-labelled ammonia and nitrate in young Jonathan/MM104 apple trees grown in solution cultures

Summary By using N¹⁵-labelled calcium nitrate and ammonium sulphate, the uptake of ammonia and nitrate by young Jonathan/MM104 apple trees grown in a glasshouse in water culture was determined. A batch of 4 trees was exposed to the appropriate tracer for seven days and then sampled. This procedure was repeated at 4 weekly intervals during a 12-month period. The results show that the uptake by apple trees of either ammonia or nitrate is continuous throughout the year with a relative high peak (expressed in μg N/100 mg dry weight) in December (summer period) and low values during August-September (winter period). The total uptake in the whole tree was steady for December to June inclusive and decreased from July, with the lowest uptake during August-September period. The young trees, previously receiving nitrogen as ammonium plus nitrate (1: 7), absorbed both ions in nearly equivalent amounts, except for the winter period when the uptake of ammonia was in excess of that for nitrate. This difference in uptake of both ions probably results from a lower activity of the enzymic nitrate reducing system during the time of low temperature. Low activity of the nitrate reductase enzyme results also in a restricted uptake of nitrate by apple trees previously receiving only ammonia nitrogen. A detailed analysis of total nitrogen content showed the lowest nitrogen values (0.77%) in February, near the end of the second growth period of the first year. From then on, the total nitrogen percentage of the apple trees steadily increased to reach a peak of 1.57% N during the flush of early spring growth of the second year. Leaves, fruit, soft twig growth, blossoms and roots had the highest N levels at this time. The total nitrogen percentage of the whole tree then gradually decreased. The established distribution pattern of absorbed nitrogen from both N¹⁵-labelled compounds showed that the relatively highest incorporation of absorbed nitrogen from both sources was in newly grown tissues during early spring growth flush of the second year, indicating the importance of currently absorbed nitrogen for early spring growth. With the increase in rate of growth in the later period, the value of the nitrogen stored within the apple trees became evident.     

Differential gene expression in salt-tolerant rice mutant and its parental variety

The differential expressions of three genes rbcL, salT and rab!6 in response to ABA, NaCl, PEG and heat shock were investigated in seedlings of a salt-tolerant rice mutant 20 (mutant 20) and its parental variety Oryza sativa var. japonica 77-170(170). By Northern blot analysis it was found that ABA induced the expression of all three genes of rbcL, salT and rab16 in shoots and roots of both 170 and mutant 20 with the exceptions of rab16 in shoots of mutant 20 and rbcL in roots of 170. Lower concentrations of NaCl induced rbcL expression in shoots of mutant 20 but not 170. Higher concentrations of NaCl decreased rbcL expression but induced expressions of salT and rab16 in shoots of both 170 and mutant 20. PEG(15%) and 37℃ heat shock showed almost no effects on the expression of the three genes in mutant 20. However, they caused a decrease in rbcL expression and slight induction of the rab16 gene in 170, with salT expression unaffected. These results indicated that mutant 20 was relatively less responsiv     

Ringing induces the accumulation of vegetative storage proteins in poplar bark

Poplar branches were ringed in late spring to determine whether the interruption of the phloem flow could induce the accumulation of vegetative storage proteins (VSPs) in the bark of adult trees. Eight days after ringing, an increased deposition of starch as well as a premature rise in the soluble-protein level occurred in the bark tissues located 1 cm above the ring. Changes in the SDS-PAGE pattern of bark proteins were characterized by the accumulation of three polypeptides (32, 36 and 38 kDa), which exhibited the same molecular weight as VSPs described in poplar bark during winter, cross-reacted to antibodies raised against a poplar VSP, and bound to several lectins in the same way as poplar bark VSPs. These results indicate that during the vegetative period, ringing induces the accumulation of VSPs in the bark of poplar.     

Clonal variation in apical growth and content in vegetative storage proteins in Populus

Summary Apical shoot growth and storage protein content in various poplar species and clones were followed in trees growing in the field and in micropropagated plants cultivated in the growth chamber under a controlled environment. In autumn a 32 kD and a 36 kD vegetative storage protein accumulate in wood, bark and roots of poplar and comprise together about 25% of the soluble proteins. In spring, at the time of dormancy break, the storage proteins are degraded and 3 weeks after budburst these proteins are no longer immunologically detectable. As in autumn, short day exposure of black cottonwood plants (Populus trichocarpa Torr. and Gray) induces cessation of apical growth and accumulation of the 32 kD and 36 kD vegetative storage proteins in all clones studied. In order to simulate spring conditions, short day induced plants were transferred back to long days. Like the situation in spring, budburst and storage protein degradation occurred considerably earlier in clone 9/60 than in clone Muhle Larsen. The latter clone accumulates both in winter and after short day exposure more storage proteins than the former. Furthermore two P. trichocarpa clones differ qualitatively in storage protein content: they possess an additional 34 kD polypeptide which cross-reacts with the anti-32 kD antibody. In conclusion, apical shoot growth and the capacity to synthesize storage proteins can be easily followed in micropropagated poplar cultivated in the growth chamber under inducing photoperiods. This offers the major advantage of independence from the annual growth cycle. Within one species considerable clonal variance in storage protein content and in the induction times needed for dormancy and dormancy break were observed. The suitability of storage protein content and apical growth as early selection traits in breeding programs focusing on nitrogen efficient poplar and clones adapted to specific latitudes will be discussed.     

Vegetative storage protein with trypsin inhibitor activity occurs in Sapindus mukorassi, a sapindaceae deciduous tree

A vegetative storage protein (VSP) with trypsin inhibitor activity in a deciduous tree,Sapindus mukorassi,was characterized by means of sodium dodecyl sulfate-polyacrylamide gel electrophoresis,Western-blot,immuno-histochemical localization,light- and electro-microscopy,together with analysis of proteinase inhibitor activity of the purified VSP in vitro.There were two proteins with molecular masses of about 23 and 27 kDa in a relatively high content in the bark tissues of terminal branches of S.mukorassi in leafless periods.The proteins decreased markedly during young shoot development,indicating their role in seasonal nitrogen storage.Immuno-histochemical localization with the polyclonal antibodies raised against the 23 kDa protein demonstrated that the 23 kDa protein was the major component of protein inclusions in protein-storing cells.The protein inclusions were identified by protein-specific staining and should correspond to the electron-dense materials in different forms in the vacuoles of phloem parenchyma cells and phloem ray parenchyma cells under an electron microscope.So,the 23 kDa protein was a typical VSP in S.mukorassi.The 23 and 27 kDa proteins shared no immuno-relatedness,whereas the 23 kDa protein was immuno-related with the 22 kDa VSP in lychee and possessed trypsin inhibitor activity.The 23 kDa protein may confer dual functions:nitrogen storage and defense.     

Within-tree and among-tree variation in growth of Epirrita autumnata on mountain birch leaves

Abstract.

• 1 We studied among-tree and within-tree variation in the growth of larvae of a geometrid, Epirrita autumnata, on mountain birch (Betula pubescens ssp. tortuosa) leaves at different hierarchical levels: among trees (genets), among ramets within trees, among branches within ramets, among shoots within branches and among leaves within shoots. We used only short shoot leaves, which burst simultaneously in spring.
• 2 Trees accounted for most of the variation in larval growth rate, but there was substantial variation also among ramets within trees, among branches within ramets, and among short shoots within branches. Variation among leaves within short shoots was negligible. When the probabilities from different experiments were combined, the differences were statistically significant at the tree, ramet and branch levels, and approached significance at the shoot level.
• 3 In different experiments, larval growth was from 9% to 54% lower on the worst tree than on the best tree of the experiment. On average, larval growth rate was in different experiments from 11% to 32% lower on the worst ramet than on the best ramet within tree, from 8% to 18% lower on the worst than on the best branch within ramet, and from 12% to 30% lower on the worst than on the best shoot within branch.
• 4 The amount of among-and within-tree variation shown by our results may have ecological and evolutionary implications: among-tree variation should select for discrimination by ovipositing females and dispersing larvae, within-tree variation should select also for optimal foraging behaviour of larvae.

     

Gene expression associated with N-induced shifts in resource allocation in poplar

Surprisingly little is known about molecular mechanisms by which nitrogen (N) availability acts to modulate the growth of forest trees. To address this issue, differential display was used in conjunction with filter‐based arrays to identify 52 partial cDNA clones that were significantly regulated within days in response to limiting or luxuriant levels of NH₄NO₃ fertilization in Populus trichocarpa Torr. & Gray × deltoides Bartr. ex Marsh. A subset of these cDNAs also demonstrated shifts in expression patterns in stem‐girdled trees, a manipulative physiology technique that disrupts phloem transport. Stem girdling also induced changes in glutamine and asparagine pools which were correlated with the observed changes in expression profiles for these genes. The identity of these genes provides insight into biochemical processes that are altered by N availability in poplar. Carbon–nitrogen interactions appear to figure prominently in the N‐response. The gene expression data suggest that N availability modulates the partitioning of C and N resources into metabolic fates that have the potential to alter both wood quality and quantity, including synthesis of vegetative storage proteins, cell wall components, and terpenoids.     

Relationship between reproductive behavior and new shoot development in 5-year-old branches of olive trees (Olea europaea L.)

The development of new shoots plays a central role in the complex interactions determining vegetative and reproductive growth in woody plants. To explore this role we evaluated the new shoots in the olive tree, Olea europaea L., and the effect of fruiting on new shoot growth and subsequent flowering. Five-year-old branches served as canopy subunits in order to obtain a global, whole-tree view of new shoot number, size and morphological origin. The non-bearing trees had many more shoots than the fruit-bearing trees, and a greater number of longer shoots. In both bearing conditions, however, the majority of shoots were less than 4 cm long, with shoots of progressively longer lengths present in successively decreasing frequencies. Six major shoot types were defined on the basis of apical or lateral bud origin and of parent shoot age. On fruit-bearing trees, the new shoots originated predominantly from the shoot apex, while on non-fruiting trees, they formed mainly from axillary buds, but in both cases, they tended to develop on younger parent shoots. The previous bearing condition of the tree was the main determinant for subsequent inflorescence development, which was independent of both shoot type and length. Thus, reproductive behavior strongly affected both the amount and type of new branching, but subsequent flowering level was more influenced by previous bearing than by the potential flowering sites on new shoots.