In Vitro Synthesis of Chlorophyll A in the Dark Triggers Accumulation of Chlorophyll A Apoproteins in Barley Etioplasts”

An in vitro translation system using lysed etioplasts was developed to test if the accumulation of plastid-encoded chlorophyll a apoproteins is dependent on the de novo synthesis of chlorophyll a. The P700 apoproteins, CP47 and CP43, were not radiolabeled in pulsechase translation assays employing lysed etioplasts in the absence of added chlorophyll precursors. When chlorophyllide a plus phytylpyrophosphate were added to lysed etioplast translation assays in the dark, chlorophyll a was synthesized and radiolabeled P700 apoproteins, CP47 and CP43, and a protein which comigrates with D1 accumulated. Chlorophyllide a or phytylpyrophosphate added separately to the translation assay in darkness did not induce chlorophyll a formation or chlorophyll a apoprotein accumulation. Chlorophyll a formation and chlorophyll a apoprotein accumulation were also induced in the lysed etioplast translation system by the photoreduction of protochlorophyllide to chlorophyllide a in the presence of exogenous phytylpyrophosphate. Accumulation of radiolabeled CP47 was detectable when very low levels of chlorophyll a were synthesized de novo (less than 0.01 nmol/10(7) plastids), and radiolabel increased linearly with increasing de novo chlorophyll a formation. Higher levels of de novo synthesized chlorophyll a were required prior to detection of radiolabel incorporation into the P700 apoproteins and CP43 (greater than 0.01 nmol/10(7) plastids). Radiolabel incorporation into the P700 apoproteins, CP47 and CP43, saturated at a chlorophyll a concentration which corresponds to 50% of the etioplast protochlorophyllide content (0.06 nmol of chlorophyll a/10(7) plastids)

Relationship Between Physiological Characteristic and Bean Quality on Some Cocoa Clones (Theobroma Cacao L.)

Photosynthesis is one of the physiological process that influence the bean weight and this process related with the efectiveness of the stomata character and chlorophyll content in the leaves. The research was conducted at Kaliwining Research Station, Indonesian Coffee and Cocoa Research Institute. Design of experiment was randomized complete block design (RCBD) consisted of six clones as treatment were Sulawesi 1, Sulawesi 2, Sca 6, ICS 60, TSH 858, ICCRI 03, PA 300. Each treatment was replicated three times. Stomata resistance diffusion, tranpiration,the content of chlorophyll a, chlorophyll b, chlorophyll total (a+b), bean number and bean weight were observed. The resuts of experiment showed that difference in chlorophyll a, chlorophyll b, chlorophyll total (a+b), stomata resistance diffusion, bean number and bean weight existed within six clones tested. Transpiration rate did not show the significantly different between six clones tested. Sulawesi 1 showed the highest content of chlorophyll a and ICS 60 and ICCRI 03 showed higher content of chlorophyll b than the other clones. Chlorophyll a, b and total (a+b) showed positively influence on bean number and bean weight. Transpiration rate had negatively influence to bean number per pod, on the otherhand it showed positively influence to bean weight. Chlorophyll total (a+b) showed high genetic variance (σg2), high phenotypic variance (σf2) and high estimated value of heritability (H). The chlorophyll a,b had moderate genetic variance, moderate phenotypic variance and high of estimated value of heritability. Chlorophyll total (a+b) could be used a selection criteria based on the value of correlation, genetic variance, phenotypic variance and estimated value of heritability would give high opportunity in selection process

REACTIVITY OF CHLOROPHYLL a/b-PROTEINS AND MICELLAR TRITON X-100 COMPLEXES OF CHLOROPHYLLS a OR b WITH BOROHYDRIDE

The reaction of several plant chlorophyll-protein complexes with NaBH4 has been studied by absorption spectroscopy. In all the complexes studied, chlorophyll b is more reactive than Chi a, due to preferential reaction of its formyl substituent at C-7. The complexes also show large variations in reactivity towards NaBH4 and the order of reactivity is: LHCI > PSII complex > LHCII > PSI > P700 (investigated as a component of PSI). Differential pools of the same type of chlorophyll have been observed in several complexes. Parallel work was undertaken on the reactivity of micellar complexes of chlorophyll a and of chlorophyll b with NaBH4 to study the effect of aggregation state on this reactivity. In these complexes, both chlorophyll a and b show large variations in reactivity in the order monomer > oligomer > polymer with chlorophyll b generally being more reactive than chlorophyll a. It is concluded that aggregation decreases the reactivity of chlorophylls towards NaBH4 in vitro, and may similarly decrease reactivity in naturally-occurring chlorophyll-protein complexes

Underwater optical wireless communications : depth dependent variations in attenuation

Depth variations in the attenuation coefficient for light in the ocean were calculated using a one-parameter model based on the chlorophyll-a concentration Cc and experimentally-determined Gaussian chlorophyll-depth profiles. The depth profiles were related to surface chlorophyll levels for the range 0–4  mg/m2, representing clear, open ocean. The depth where Cc became negligible was calculated to be shallower for places of high surface chlorophyll; 111.5 m for surface chlorophyll 0.8<Cc<2.2  mg/m3 compared with 415.5 m for surface Cc<0.04  mg/m3. Below this depth is the absolute minimum attenuation for underwater ocean communication links, calculated to be 0.0092  m−1 at a wavelength of 430 nm. By combining this with satellite surface-chlorophyll data, it is possible to quantify the attenuation between any two locations in the ocean, with applications for low-noise or secure underwater communications and vertical links from the ocean surface

The derivation of the formyl-group oxygen of chlorophyll b in higher plants from molecular oxygen.

The mechanism of formation of the formyl group of chlorophyll b has long been obscure but, in this paper, the origin of the 7-formyl-group oxygen of chlorophyll b in higher plants was determined by greening etiolated maize leaves, excised from dark-grown plants, by illumination under white light in the presence of either H218O or 18O2 and examining the newly synthesized chlorophylls by mass spectroscopy. To minimize the possible loss of 18O label from the 7-formyl substituent by reversible formation of chlorophyll b-71-gem-diol (hydrate) with unlabelled water in the cell, the formyl group was reduced to a hydroxymethyl group during extraction with methanol containing NaBH4: chlorophyll a remained unchanged during this rapid reductive extraction process. Mass spectra of chlorophyll a and [7-hydroxymethyl]-chlorophyll b extracted from leaves greened in the presence of either H218O or 18O2 revealed that 18O was incorporated only from molecular oxygen but into both chlorophylls: the mass spectra were consistent with molecular oxygen providing an oxygen atom not only for incorporation into the 7-formyl group of chlorophyll b but also for the well-documented incorporation into the 131-oxo group of both chlorophylls a and b [see Walker, C. J., Mansfield, K. E., Smith, K. M. & Castelfranco, P. A. (1989) Biochem. J. 257, 599–602]. The incorporation of isotope led to as much as 77% enrichment of the 131-oxo group of chlorophyll a: assuming identical incorporation into the 131 oxygen of chlorophyll b, then enrichment of the 7-formyl oxygen was as much as 93%. Isotope dilution by re-incorporation of photosynthetically produced oxygen from unlabelled water was negligible as shown by a greening experiment in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea. The high enrichment using 18O2, and the absence of labelling by H218O, unequivocally demonstrates that molecular oxygen is the sole precursor of the 7-formyl oxygen of chlorophyll b in higher plants and strongly suggests a single pathway for the formation of the chlorophyll b formyl group involving the participation of an oxygenase-type enzyme

Average seasonal changes in chlorophyll a in Icelandic waters

The standard algorithms used to derive sea surface chlorophyll a concentration from remotely sensed ocean colour data are based almost entirely on the measurements of surface water samples collected in open sea (case 1) waters which cover ~60% of the worlds oceans, where strong correlations between reflectance and chlorophyll concentration have been found. However, satellite chlorophyll data for waters outside the defined case 1 areas, but derived using standard calibrations, are frequently used without reference to local in situ measurements and despite well-known factors likely to lead to inaccuracy. In Icelandic waters, multiannual averages of 8-d composites of SeaWiFS chlorophyll concentration accounted for just 20% of the variance in a multiannual dataset of in situ chlorophyll a measurements. Nevertheless, applying penalized regression spline methodology to model the spatial and temporal patterns of in situ measurements, using satellite chlorophyll as one of the predictor variables, improved the correlation considerably. Day number, representing seasonal variation, accounted for substantial deviation between SeaWiFS and in situ estimates of surface chlorophyll. The final model, using bottom depth and bearing to the sampling location as well as the two variables mentioned above, explained 49% of the variance in the fitting dataset

SPAD-502 and atLEAF CHL PLUS values provide good estimation of the chlorophyll content for Hevea brasiliensis Müll. Arg. Leaves

Measurement of chlorophyll content using destructive methods is not efficient due to a large number of samples, cost, and time needed. Estimationof chlorophyll content by nondestructive methods using handheld chlorophyll meter may be considered to improve efficiency. This research aimed to determine the formula to convert SPAD-502 and atLEAF CHL PLUS values (relative indicator of chlorophyll content) to estimated (absolute) rubber leaves chlorophyll content. Twenty leaves of rubber plant were measured using SPAD-502 and atLEAF CHL PLUS at the same time to determine SPAD-502 and atLEAF CHL PLUS values. The measured leaves were then collected to determine the chlorophyll content using a standard laboratory procedure. Regression and correlation analyses (among 3 methods) were conducted using SAS v.9 software. The results showed that between SPAD-502 and atLEAF CHL PLUS values were closely correlated, hence both of the devices can substitute each other to estimate rubber leaf chlorophyll content. In addition, the relationship between atLEAF CHL PLUS and SPAD-502 values with actual chlorophyll content of rubber clone SP 217, PB 260, GT1, and all clones (general) were significant with high coefficient of determination (R2) as well as low Root Mean Square Error (RMSE) and Coefficient of Variation (CV). Therefore, by using formula determined in this study, both atLEAF CHL PLUS and SPAD-502 can be suggested for accurate, fast, and non-destructive estimation of chlorophyll content of rubber plant leaf

Interplay between carotenoids, abscisic acid and jasmonate guides the compatible rice-Meloidogyne graminicola interaction

In this study, we have characterized the role of carotenoids and chlorophyll in the compatible interaction between the sedentary root knot nematode (RKN) Meloidogyne graminicola and the monocot model plant rice (Oryza sativa). Previous transcriptome data showed a differential expression of carotenoid and chlorophyll biosynthesis genes in nematode-induced giant cells and gall tissue. Metabolite measurement showed that galls indeed accumulate chlorophyll a, b and carotenoids, as well as the hormone abscisic acid (ABA). When ABA was externally applied on rice plants, or when ABA-biosynthesis was inhibited, a significant increase in gall formation and nematode development was found, showing the complex role of ABA in this interaction. ABA application suppressed jasmonic acid (JA) levels in the plants, while ABA-biosynthesis inhibition lead to increased JA levels confirming an antagonism between ABA and JA in rice roots. In addition, combined applications of ABA and JA showed that the ABA-effect can overcome JA-induced defense. Based on these observations, we hypothesized that the accumulation of chlorophyll and carotenoid precursors would be beneficial to nematode infection. Indeed, when chemically blocking the carotenoid biosynthesis pathway at different steps, which leads to differential accumulation of carotenoids and chlorophyll in the plants, a positive and clear link between accumulation of carotenoids and chlorophyll and rice susceptibility to RKN was detected