Molecular characterization of rice genes specifically expressed in the anther tapetum

In situ localization of mRNA was carried out on two cDNAs (Osc4 and Osc6) that had been isolated from rice anthers at the microspore stage. The mRNA corresponding to each cDNA was shown to be localized only in the tapetal cells of the rice immature anthers, but not in the microspores or the mature pollen. The corresponding genomic clone, Osg6B, was isolated, and its 5-upstream region was found to regulate -glucuronidase expression in the tapetum of transgenic tobacco. A set of 5 deletions was also generated and a 1095 bp 5 region was revealed to be necessary for activation of the Osg6B promoter in transgenic tobacco.     

An inhibitory effect of excess moisture on the early development of Sinapis alba L. seedlings

Abstract. Mustard seedlings in the early stages of growth are sensitive to the presence of excess moisture, growth of the radicle and anthocyanin synthesis being retarded by water at a suction of less than 3 cm water for seedlings growing on a plane surface. This inhibitory effect commences at about 12-15 h from wetting of the seed. It can be counteracted by increasing the partial pressure of oxygen in the atmosphere or by de-coating the seed, suggesting that the inhibition is caused by a restricted flow of oxygen through the mucilaginous seed coat. The positive effect of gravity on anthocyanin synthesis in the developing seedling can be wholly accounted for in terms of the removal of excess moisture. This explanation largely accounts for the improved growth of the root, but a tonic effect of gravity on root growth can also be discerned.     

Specificity of induction responses in Sinapis alba L.: Plant growth and development

Plant defenses are expected to be negatively correlated with plant growth, development and reproduction. In a recent study, we investigated the specificity of induction responses of chemical defenses in the Brassicaceae Sinapis alba.¹ It was shown that glucosinolate levels and myrosinase activities increased to different degrees after 24-hours-feeding by a specialist or generalist herbivore or mechanical wounding. Here, we present the specific influences of these treatments on organ biomasses which were recorded as a measure of growth. Directly after the treatments, organ biomasses were reduced locally and systemically by herbivore feeding, but not by mechanical wounding compared to control plants. Induction of glucosinolates, which increased in all treatments, is thus not necessarily expressed as cost in terms of reduced growth in S. alba. No significant long-term differences in plant development between herbivore treated and control plants were found. Thus, tissue loss and increased investments in chemical defenses could be compensated over time, but compensation patterns depended on the inducing agent. Furthermore, herbivore treatments resulted in an increased mechanical defense, measured as abaxial trichome densities. Plants respond highly dynamic with regard to defense and growth allocation and due to different inductors.Key words: Brassicaceae, organ biomass, plant development, specialist, generalist, herbivore, mechanical wounding, costs, trichome densityPlant defenses are generally thought to impose costs in relation to growth and fitness.² The ability to increase defense levels only after herbivory, i.e., induction, is one possible mechanism of lowering these allocation costs.³ In Brassicaceae, the glucosinolate-myrosinase system is known to hold a defensive function.⁴ The constitutive and induced production of glucosinolates and myrosinases is thought to be connected to allocation and ecological costs.^2,5In a recent study, we investigated the specificity of short-term induction patterns of chemical defenses in Sinapis alba L. var. Silenda damaged by a glucosinolate-sequestering specialist herbivore (turnip sawfly, Athalia rosae (L.), Hymenoptera), a generalist herbivore (fall armyworm, Spodoptera frugiperda J. E. Smith, Lepidoptera) or mechanical wounding (cork borer).¹ Feeding by the specialist as well as mechanical wounding led to 3-fold increases in both glucosinolate- and myrosinase-levels, whereas generalist feeding induced up to 2-fold increases in glucosinolates only.Different strengths of plant chemical responses might be mirrored in differences of subsequent fitness-related parameters of the plants.⁶ To assess short-term effects within 24 hours of induction on organ growth in S. alba, organ dry biomasses were calculated from the previous plant set.¹ Water content was determined of the organ halves which were freeze-dried and analyzed for glucosinolate content¹ and organ dry weights were calculated from water content and total organ fresh weight. The percentage of removed tissue area was determined by photo analysis and organ dry weights of treated leaves were corrected for the respective area. The percentage of lost area in damaged leaves was 7.9 ± 0.5 % after mechanical wounding, 15.1 ± 2.3 % after feeding by S. frugiperda and 15.6 ± 2.3 % after feeding by A. rosae (mean values ± SE, n = 7–8). The plants'' habits and total number of leaves did not vary between the tested plant groups (Fig. 1B; ANOVA: f = 2.36, df = 3, p = 0.095).Open in a separate windowFigure 1Organ dry biomasses of leaves and stems (A) and total numbers of leaves (B) of Sinapis alba cv. Silenda directly after induction. The second youngest leaves of three weeks old plants were treated with either mechanical wounding (cork borer), one Spodoptera frugiperda caterpillar (third instar) or one larva of Athalia rosae (third instar) enclosed in a muslin bag for 24 hours. Bagged leaves without any further treatment served as controls (mean values ± SE, n = 6–8 per treatment). Letters above bars indicate significant differences (ANOVA, Tukey-HSD tests: p < 0.05; n.s., not significant). DL, damaged leaf; OL, older leaf; YL, younger leaf; OS, older stem; YS, younger stem.The short-term growth responses were highly specific between treatments. Herbivore damage did not only result in reduced organ biomass growth of the damaged leaf (ANOVA: f = 11.29, df = 3, p < 0.001), but also of adjacent tissues compared to organs from bag treated and mechanically wounded plants after 24 hours of treatment (Fig. 1A; older leaf - ANOVA: f = 3.87, df = 3, p = 0.021; younger leaf - ANOVA: f = 6.02, df = 3, p = 0.003; younger stem - ANOVA: f = 4.12, df = 3, p = 0.017). Significant differences from bag treated control plants were found for damaged and systemic younger leaves of plants treated with A. rosae larvae. Differences of organ dry biomasses between mechanically wounded and herbivore treated plants were more pronounced, with reduced growth in the latter of 15 to 36 % in leaves and 23 to 48 % in stem parts. This specificity in growth response could be brought about by elicitors introduced to the wounded plant tissues from the herbivores'' saliva which can influence C-allocation to roots.⁷ The reduced growth of organ biomasses observed in herbivore treated leaves could be the result of specifically saliva elicited resource allocation away from leaf tissue,⁸ and might not represent costs of increased chemical defense.Long-term effects of herbivore feeding on development of S. alba were monitored in a second set of plants which were treated (as described previously in ref. ¹) for 24 hours with either the specialist or the generalist, enclosed in a bag. About three weeks later, on the day when the first flower opened, several parameters were recorded (9^,10 Thereby, thresholds for damage seem to exist, beyond which no compensation of tissue loss is possible.¹¹ The percentages of damage in S. alba were, however, below the threshold values reported for other Brassicaceae.¹¹ Influences on growth rates can be obviously transitory. In Arabidopsis thaliana (L.) Heynh., reduced growth rates were observed directly after treatment, but later growth increased so much, that these plants overcompensated and were even larger than control plants.⁹ Such plastic plant responses can be again modified by elicitors.^7,12

Table 1

Developmental responses of 3-week-old Sinapis alba plants treated for 24 hours with either one larva of the specialist Athalia rosae or one caterpillar of the generalist Spodoptera frugiperda

Molecular characterization of two Brassica napus genes related to oleosins which are highly expressed in the tapetum

Two highly homologous Brassica napus flower cDNA clones, Sta 41-2 and Sta 41-9, were isolated and characterized. These clones were shown to correspond to genes expressed in the tapetum from the early uninucleate microspore stage to the dinucleate stage. The predicted Sta 41-2 and Sta 41-9 proteins possessed characteristics similar to oleosins such as a polar N-terminal domain, a large relatively conserved hydrophobic domain and a long C-terminal domain which consisted of four different groups of repeats. In addition, like oleosins, the Sta 41-2 and Sta 41-9 proteins have a basic pl, lack a signal peptide and are found in a tissue which accumulates lipids in small lipid bodies.     

The development of protein and oil bodies in the seed of Sinapis alba L.

Summary The cotyledons of Sinapis alba L. seed are the storage organs and first photosynthetic organs. The development of the cotyledon cell contents was studied using electron and light microscopy. From the heart shaped embryo (11 days from petal fall) to the mature seed, nine stages were examined.Both types of protein grains (designated aleurone grains and myrosin grains) were found to form within vacuoles, but the mode of protein accumulation differed with each type of grain.Oil bodies were apparent with the EM from 18 days onwards, but could not be seen to arise from the ER. They were granular in appearance at early stages, but later became electron transparent.     

Nucleotide sequences encoding two different chalcone synthases expressed in cotyledons of SAN 9789 treated mustard (Sinapis alba L.)

Supported by the Deutsche Forschungsgemeinschaft (SFB 206).     

New evidence from Sinapis alba L. for ancestral triplication in a crucifer genome.

We present clear evidence of ancestral genome triplication in Sinapis alba, a close relative of the cultivated Brassica species. Exceptionally high levels of heterozygosity in the parents of an F1 intercross permitted the mapping of an estimated 87% of all detected restriction fragment length polymorphism (RFLP) loci, with each RFLP probe typically detecting 2 or 3 loci. These duplicated loci were arranged in 8 triplicated homologous linkage blocks and 2 small, duplicated, homologous linkage blocks covering the majority of the S. alba genome. Several large-scale inversions and translocations appear to have rearranged the order of loci within homologous blocks. The role of successive polyploidization events on the evolution of crucifer species is discussed.     

Effects of temperature on the development of Sinapis alba L. phytochrome-control of nitrate reductase activity at 10°C

Abstract. An analysis of three biochemical parameters during growth of white mustard in continuous white light (WL) has been undertaken at 10°, 15° and 20°C. The time required for anthocyanin and chlorophyll content and nitrate reductase [E.C. 1661 NAD(P)H: nitrate oxidoreductase] activity (NRA) to reach a peak in the cotyledons is shown to be temperature dependent, the rise in chlorophyll content being delayed to a much greater extent than anthocyanin content. In addition, with NRA, there is a significant increase in the level of the peaks with a lowering of temperature.
The NRA in dark-grown plants has been investigated in detail at 10°C. The pre-competence time for this response is increased to 20–24 h, compared with 14 h in seeds grown at 25°C. Other responses are affected far more by the lower temperature; for example, time for 50% loss of photoreversibility of a red (R) pulse in 48-h-old seeds is approximately 13 h, compared with 8 min in seeds grown at 25°C. At 25°C, light treatments during precompetence have been found to increase significantly the effectiveness of a subsequent R pulse on NRA; at 10°C, this effect appears to be almost entirely absent.     

Bee visits and the nectar of Echium vulgare L. and Sinapis alba L.

Abstract. 1. The time-course of anthesis of Echium vulgare is described.
2. Diel changes in the sugar concentration of the nectar, the quantity of nectar and the quantity of sugar per flower are illustrated for E.vulgare and for Sinapis alba.
3. These changes are interpreted in terms of (a) the periodicity of secretion and (b) the influence of microclimate and insect visits on post-secretory changes in the composition and volume of nectar.
4. There was hour-to-hour and day-to-day variation in the species composition and the proportion of workers taking nectar rather than nectar plus pollen among the social bees visiting E.vulgare.
5. Honeybee visits to E.vulgare were more numerous in humid weather, when there was enough nectar per flower for their relatively short tongues to reach, and in an area where the corollas grew shorter than they did elsewhere.
6. The significance of changes in the caloric content, volume, concentration, viscosity and sugar composition is discussed from the points of view of insects and ecologists.     

Biosynthesis of wax esters in tissues of Sinapis alba L. seeds

The biosynthesis of wax esters has been investigated in maturing seeds of Sinapis alba. Exogenous long-chain alcohols are incorporated exclusively into alkyl moieties of wax esters. Oxidation of the long-chain alcohols is not detected. Exogenous fatty acids are incorporated into acyl moieties of wax esters to a low extent. A reduction of fatty acids to alcohols is not observed. Synthesis of wax esters is localized exclusively in the testa; both outer and inner integument are equally active in wax ester biosynthesis. The biosynthesis of wax esters is specific with regard to both chain length and degree of unsaturation of long-chain alcohols. Exogenous and endogenous sterols are not esterified.     

Molecular characterization of glutathione reductase cDNAs from pea (Pisum sativum L.)

A cDNA for pea glutathione reductase has been cloned and sequenced. The derived amino acid sequence of 562 residues shows a high degree of homology to the previously published GR sequences from human erythrocytes and from two prokaryotes: Escherichia coli and Pseudomonas aeruginosa. The pea enzyme differs from other GRs in having an N-terminal leader sequence of about 60-70 residues which may be a chloroplast transit peptide and a 20 amino acid C-terminal extension of unknown function.     

Molecular characterization of cDNAs corresponding to genes expressed during almond (Prunus amygdalus Batsch) seed development

A number of different cDNA clones corresponding to the most abundant mRNAs present in immature seeds have been isolated from an almond (Prunus amygdalus cv. Texas) immature seed cDNA library. Those corresponding to proteins involved in storage processes have been further characterized. Two of these cDNAs (PA3BF1 and PA3BE12) code for the almond globulins (prunins), the main family of storage proteins synthesized in seeds during embryogenesis, and another cDNA (PA3BA1) codes for the 15.7 kDa almond oleosin, a protein located on the surface of oil bodies in plant seeds. These cDNAs have been sequenced and their expression during almond fruit development has been studied. Their expression is seed-specific and localized in cotyledons around 100 days after flowering. Both prunin and oleosin genes are present in one or two copies in the almond genome.