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The use of biostimulants is associated with promoting plant growth by stimulating cell division and improving nutrient availability and uptake. A study was conducted at the University of Debrecen, Hungary, to examine the effect of biostimulants on alfalfa growth, chlorophyll content and fresh herbage yield. The experiment was arranged in a randomised complete block design with three biostimulant treatments plus control replicated three times. Data collected were subjected to analyses of variance using Genstat, where significantly different means were separated at a probability of 5% using the least significant difference. The findings show no different variation in plant height or chlorophyll content (SPAD) throughout the early stages of growth. Nonetheless, a notable impact was noted in the latter stages (28 days after biostimulant treatment application) on the growth of the alfalfa plant. Biostimulant treatments did not had effect on fresh yield for second through fourth cuts, but the fifth cut showed a significant effect, with T1 treatment recording the highest herbage yield of 19745 kg ha-1 followed by T2 (Tricho Immun plus Ino Green) and T3 (Tricho Immun), with yields of 19528 kg ha-1 and 17273 kg ha-1, respectively, while the T0 (control) recorded the lowest herbage yield of 12060 kg ha-1. However, the average mean yield indicated the application of biostimulants significantly increased fresh yield herbage by 20.5%. Correlation coefficient values suggested plant height at both 14 and 28 DAH (days after harvest) strongly correlated with fresh herbage yield (r = 0.7756 and 0.7455) which reflected in the increase in fresh herbage yield. Therefore, our results suggest that the use of biostimulants in alfalfa cultivation holds promise for improving growth and yield potential through their positive effects on chlorophyll content and the growth of alfalfa plant. [ABSTRACT FROM AUTHOR]

Plants are inevitably exposed to extreme climatic conditions that lead to a disturbed balance between the amount of absorbed energy and their ability to process it. Variegated leaves with photosynthetically active green leaf tissue (GL) and photosynthetically inactive white leaf tissue (WL) are an excellent model system to study source–sink interactions within the same leaf under the same microenvironmental conditions. We demonstrated that under excess excitation energy (EEE) conditions (high irradiance and lower temperature), regulated metabolic reprogramming in both leaf tissues allowed an increased consumption of reducing equivalents, as evidenced by preserved maximum efficiency of photosystem II (ФPSII) at the end of the experiment. GL of the EEE-treated plants employed two strategies: (i) the accumulation of flavonoid glycosides, especially cyanidin glycosides, as an alternative electron sink, and (ii) cell wall stiffening by cellulose, pectin, and lignin accumulation. On the other hand, WL increased the amount of free amino acids, mainly arginine, asparagine, branched-chain and aromatic amino acids, as well as kaempferol and quercetin glycosides. Thus, WL acts as an important energy escape valve that is required in order to maintain the successful performance of the GL sectors under EEE conditions. Finally, this role could be an adaptive value of variegation, as no consistent conclusions about its ecological benefits have been proposed so far. [ABSTRACT FROM AUTHOR]

Sweet pea (Lathyrus odoratus L.) is a major cut flower in Japan, generally grown in greenhouses in winter to spring. The wild-type sweet pea is a long-day summer-flowering plant. The day-neutral winter-flowering ability, which allows cut-flower production in Japan, is a recessive phenotype that emerged by spontaneous mutation. Although Japanese winter-flowering cultivars and additionally spring-flowering cultivars, which have semi-long-day flowering ability generated by crossing the winter- and summer-flowering cultivars, have superior phenotypes for cut flowers, they have limited variation in color and fragrance. In particular, variegated phenotypes do not appear in modern winter- and spring-flowering cultivars, only in summer-flowering cultivars. We try to expand the phenotypic diversity of Japanese cut flower cultivars. In the processes, we introduced the variegated phenotypes by crossing with summer-flowering cultivars, and succeeded in breeding some excellent cultivars. During breeding, we analyzed the segregation ratios and revealed the heredity of the phenotypes. Here we review the heredity of these variegated phenotypes and winter-flowering phenotypes and their related genes. We also describe how we introduced the trait into winter-flowering cultivars, tracing their pedigrees to show both phenotypes and genotypes of the progeny at each generation. This knowledge is useful for the efficient breeding of new variegated cultivars. [ABSTRACT FROM AUTHOR]

Aucuba japonica ‘Variegata’ is a widely used ornamental shrub with green-yellow variegated leaves. In this study, the formation of leaf variegation and photosynthetic characteristics in green and yellow sectors were investigated. There were no marked anatomical differences in tissue organization between the green and yellow sectors. At the cellular level, it was observed that the chloroplasts in the yellow leaf tissue were vacuolated. Besides, the pigment contents of the yellow leaf tissue were obviously lower than those in the green areas, and a very low intensity of chlorophyll auto-fluorescence was generated from the yellow areas. Furthermore, significantly lower values of F 0 , F m , F v /F m , Ф PSII and non-photochemical quenching (NPQ) were noticed in yellow sectors compared to the green ones, indicating that the yellow leaf tissue was less photoprotected than the green area. In addition, the yellow sectors showed lower net photosynthesis and dark respiration rates compared to the green leaf tissue. Immunofluorescence showed large amounts of ribulose-1, 5-bisphosphate carboxylase/oxygenase (Rubisco) in green leaf tissue, while only faint fluorescence was detected in the yellow sectors. As a whole, the results of this study suggest that the leaf variegation of A. japonica ‘Variegata’ is “pigment type” and that this pigment-related leaf variegation affects photosynthetic light use in the variegated leaves. These findings also shed light on the coloration mechanism of ornamental plant foliage. [ABSTRACT FROM AUTHOR]

In this study we exposed variegated leaves of Pelargonium zonale to strong sunlight (>1100 μmol m −2 s −1 of photosynthetically active radiation) with and without paraquat (Pq), with the aim to elucidate the mechanisms of H 2 O 2 regulation in green and white tissues with respect to the photosynthetically-dependent generation of reactive oxygen species (ROS). Sunlight induced marked accumulation of H 2 O 2 in the apoplast of vascular and (peri)vascular tissues only in green sectors. This effect was enhanced by the addition of Pq. In the presence of diphenyl iodide, an NADPH oxidase inhibitor, H 2 O 2 accumulation was abolished. Distinct light-induced responses were observed: in photosynthetic cells, sunlight rapidly provoked ascorbate (Asc) biosynthesis and an increase of glutathione reductase (GR) and catalase activities, while in non-photosynthetic cells, early up-regulation of soluble ascorbate peroxidase, dehydroascorbate reductase (DHAR) and GR activities was observed. Paraquat addition stimulated DHAR and GR activities in green sectors, while in white sectors activities of monodehydroascorbate reductase, DHAR and class III peroxidases, as well as Asc content rapidly increased. Differential antioxidative responses in the two tissues in the frame of their contrasting metabolisms, and the possible role of (peri)vascular H 2 O 2 in signaling were discussed. [ABSTRACT FROM AUTHOR]

Green-white variegated leaves of Pelargonium zonale were studied using the photoacoustic method. Our aim was to characterize photosynthetically active green tissue and nonphotosynthetically active white tissue by the photoacoustic amplitude signals. We observed lower stomatal conductance and higher leaf temperature in white tissue than in green tissue. Besides these thermal differences, significantly higher absorbance in green tissue was based on chlorophyll and carotenoids which were absent in white tissue. However, optical properties of epidermal layers of both tissues were equal. The photoacoustic amplitude of white tissue was over four times higher compared to green tissue, which was correlated with lower stomatal conductance. In addition, at frequencies >700 Hz, the significant differences between the photoacoustic signals of green and white tissue were obtained. We identified the photoacoustic signal deriving from photosynthetic oxygen evolution in green tissue, using high intensity of red light modulated at 10 Hz. Moreover, the photoacoustic amplitude of green tissue increased progressively with time which corresponded to the period of induction of photosynthetic oxygen evolution. For the first time, very high frequencies (1 kHz to 5 kHz) were applied on leaf material. [ABSTRACT FROM AUTHOR]

Hydrogen peroxide is an important signalling molecule, involved in regulation of numerous metabolic processes in plants. The most important sources of H2O2 in photosynthetically active cells are chloroplasts and peroxisomes. Here we employed variegated Pelargonium zonale to characterise and compare enzymatic and non-enzymatic components of the antioxidative system in autotrophic and heterotrophic leaf tissues at (sub)cellular level under optimal growth conditions. The results revealed that both leaf tissues had specific strategies to regulate H2O2 levels. In photosynthetic cells, the redox regulatory system was based on ascorbate, and on the activities of thylakoid-bound ascorbate peroxidase ( tAPX) and catalase. In this leaf tissue, ascorbate was predominantly localised in the nucleus, peroxisomes, plastids and mitochondria. On the other hand, non-photosynthetic cells contained higher glutathione content, mostly located in mitochondria. The enzymatic antioxidative system in non-photosynthetic cells relied on the ascorbate-glutathione cycle and both Mn and Cu/Zn superoxide dismutase. Interestingly, higher content of ascorbate and glutathione, and higher activities of APX in the cytosol of non-photosynthetic leaf cells compared to the photosynthetic ones, suggest the importance of this compartment in H2O2 regulation. Together, these results imply different regulation of processes linked with H2O2 signalling at subcellular level. Thus, we propose green-white variegated leaves as an excellent system for examination of redox signal transduction and redox communication between two cell types, autotrophic and heterotrophic, within the same organ. [ABSTRACT FROM AUTHOR]

The photosynthetic performance of variegated leaves can be very important in the cultivation and management of variegated plants. Actinidia kolomikta (Rupr. & Maxim.) Maxim. leaves have striking color variation. To clarify the variegated leaf type and photosynthetic cost, we measured leaf structure and ultrastructure, spectral properties, chlorophyll fluorescence and net photosynthetic rate (Pn). The study was conducted in Jilin during spring, summer, and fall in 2013. Leaf anatomy and ultrastructure were observed with light and electron microscopy. Leaf reflectance and pigment content were measured with a Unispec spectrometer and high performance liquid chromatography. Photosynthetic characterization was performed with a photosynthesis system and plant efficiency analyzer. In the palisade tissue of variegated areas, intercellular spaces were found, and cells contained fewer and abnormally developed chloroplasts. Normal chloroplasts were distributed mostly in spongy tissue. The reflectance of the adaxial surface was higher in variegated leaves than in green leaves. The Pn of variegated leaves was 80 to 94% of green leaves, the maximum photosystem II efficiency of the adaxial and abaxial surfaces in variegated leaves was similar to green leaves, and the quantum use efficiency of the abaxial surface was higher than the adaxial surface in variegated leaves. These results show that the photosynthetic performance of variegated leaves was retained well. Th us, variegated leaves are not a limiting factor for cultivation and application in A. kolomikta, and do not need to be removed as parasitic leaves during cultivation and management. [ABSTRACT FROM AUTHOR]

We used variegated P lectranthus coleoides as a model plant with the aim of clarifying whether the effects of realistic ultraviolet-B ( UV- B) doses on phenolic metabolism in leaves are mediated by photosynthesis. Plants were exposed to UV- B radiation (0.90 W m−2) combined with two photosynthetically active radiation ( PAR) intensities [395 and 1350 μmol m−2 s−1, low light ( LL) and high light ( HL)] for 9 d in sun simulators. Our study indicates that UV- B component of sunlight stimulates CO2 assimilation and stomatal conductance, depending on background light. UV- B-specific induction of apigenin and cyanidin glycosides was observed in both green and white tissues. However, all the other phenolic subclasses were up to four times more abundant in green leaf tissue. Caffeic and rosmarinic acids, catechin and epicatechin, which are endogenous peroxidase substrates, were depleted at HL in green tissue. This was correlated with increased peroxidase and ascorbate peroxidase activities and increased ascorbate content. The UV- B supplement to HL attenuated antioxidative metabolism and partly recovered the phenolic pool indicating stimulation of the phenylpropanoid pathway. In summary, we propose that ortho-dihydroxy phenolics are involved in antioxidative defence in chlorophyllous tissue upon light excess, while apigenin and cyanidin in white tissue have preferentially UV-screening function. [ABSTRACT FROM AUTHOR]

The variegated flower colors of many plant species have been shown to result from the insertion or excision of transposable elements into genes that encode enzymes involved in anthocyanin synthesis. To date, however, it has not been established whether this phenomenon is responsible for the variegation produced by other pigments such as betalains. During betalain synthesis in red beet, the enzyme CYP76AD1 catalyzes the conversion of l -dihydroxyphenylalanine (DOPA) to cyclo -DOPA. RNA sequencing (RNA-seq) analysis indicated that the homologous gene in four o’clock ( Mirabilis jalapa ) is CYP76AD3 . Here, we show that in four o’clock with red perianths, the CYP76AD3 gene consists of one intron and two exons; however, in a mutant with a perianth showing red variegation on a yellow background, a transposable element, dTmj1 , had been excised from the intron. This is the first report that a transposition event affecting a gene encoding an enzyme for betalain synthesis can result in a variegated flower phenotype. [ABSTRACT FROM AUTHOR]

Abstract: The incidence and severity of citrus variegated chlorosis (CVC) caused by Xylella fastidiosa are higher in the northern region of Sao Paulo, Brazil than in the southern region. This phenomenon is partly due to differences in the climate, especially rainfall, as the northern region tends to be drier than the southern region. The progress of CVC under three levels of irrigation was assessed in a grove located in the northern region of Sao Paulo. Trees (10-year-old Natal sweet orange) were arranged in a randomized complete block in a 3 × 2 factorial scheme with three levels of irrigation and two methods of infection with X. fastidiosa. The disease incidence in branches and the number of symptomatic fruits per tree were evaluated for three years. A monomolecular model was used to describe the progress of CVC incidence for all treatments. Irrigation reduced CVC symptoms in trees, especially the number of symptomatic fruits per tree. Based on this significant reduction, citrus irrigation can be used to reduce the main negative effect of CVC: reduced fruit size. Our results also explain the higher incidence of CVC in the northern region of Sao Paulo, where a dry season occurs. [Copyright &y& Elsevier]

Copyright of Revista Colombiana de Biotecnología is the property of Universidad Nacional de Colombia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Citrus Variegated Chlorosis (CVC) is currently present in approximately 40% of citrus plants in Brazil and causes an annual loss of around 120 million US dollars to the Brazilian citrus industry. Despite the fact that CVC has been present in Brazil for over 20 years, a relationship between disease intensity and yield loss has not been established. In order to achieve this, an experiment was carried out in a randomized block design in a 3 × 2 factorial scheme with 10-year-old Natal sweet orange. The following treatments were applied: irrigation with 0, 50 or 100% of the evapotranspiration of the crop, combined with natural infection or artificial inoculation with Xylella fastidiosa, the causal agent of CVC. The experiment was evaluated during three seasons. A negative exponential model was fitted to the relationships between yield versus CVC severity and yield versus Area Under Disease Progress Curve (AUDPC). In addition, the relationship between yield versus CVC severity and canopy volume was fitted by a multivariate exponential model. The use of the AUDPC variable showed practical limitations when compared with the variable CVC severity. The parameter values in the relationship of yield-CVC severity were similar for all treatments unlike in the multivariate model. Consequently, the yield-CVC intensity relationship (with 432 data points) could be described by one single model: y = 114·07 exp(−0·017 x), where y is yield (symptomless fruit weight in kg) and x is disease severity ( R2 = 0·45; P < 0·01). [ABSTRACT FROM AUTHOR]

Abstract: The main objective of this work was to compare activity of chlorophyllase (chlase) in green and non-green sectors of leaves. Our results show that various plants exhibited different abilities and specificities with regard to chlases. Large variations in chlase activity existed in seven all-green plants, and Pachira macrocarpa contained significantly higher chlase activity compared to the other plants. The chlase activity was detected in both non-green and green sectors of the leaves; however, non-green parts had significantly higher chlase activity than did green parts in most of the variegated plants. Most of the chlases in all-green and variegated plants exhibited higher substrate preference toward the chl b than chl a. The activity and localization of chlase in P. macrocarpa were higher in chloroplast envelope membrane fractions than thylakoid fractions. [Copyright &y& Elsevier]

Residual chlorophyll in chlorophyll-deficient (albino) areas of variegated leaves of Ficus benjamina originates from guard cell chloroplasts. Photosynthetic features of green and albino sectors of F. benjamina were studied by imaging the distribution of the fluorescence decrease ratio Rfd within a leaf calculated from maximum (Fm) and steady-state leaf chlorophyll fluorescence (Fs) at 690 and 740 nm. Local areas of albino sectors demonstrated an abnormally high Rfd/Rfd ratio. Fluorescence transients excited in albino sectors at red (640 and 690 nm) wavelengths showed an abrupt decrease of the Rfd values (0.4 and 0.1, correspondingly) as compared with those excited at blue wavelengths (1.7-2.4). This 'Red Drop' was not observed for green sectors. Normal and chlorophyll-deficient leaf sectors of F. benjamina were also tested for linear and cyclic electron transport in thylakoids. The tests have been performed studying fluorescence at a steady-state phase with CO-excess impulse feeding, photoacoustic signal generated by pulse light source at wavelengths selectively exciting PSI, fluorescence kinetics under anaerobiosis and fluorescence changes observed by dual-wavelength excitation method. The data obtained for albino sectors strongly suggest the possibility of a cyclic electron transport simultaneously occurring in guard cell thylakoids around photosystems I and II under blue light, whereas linear electron transport is absent or insufficient. [ABSTRACT FROM AUTHOR]

The article presents the author's insights the problem associated with two Vriesea (V. bituminosa x saundersii), a variegated vrieseas, imported to Australia under parentage formula from the U.S. The author states that the plant was named by Peter Huddy, and mentions the use of the names Shiraz, Highway Beauty, Highway (non-variegated Highway Beauty) and RoRo for the plant. He adds that Huddy acquired the plants for Queensland in 1990.

VAR2 is an integral thylakoid membrane protein and a member of the versatile FtsH class of metalloproteases in prokaryotes and eukaryotes. Recessive mutations in the VAR2 locus give rise to variegated plants (var2) that contain white sectors with abnormal plastids and green sectors with normal-appearing chloroplasts. In a continuing effort to isolate second-site suppressors of var2 variegation, we characterize in this report ems2505, a suppressor strain that has a virescent phenotype due to a missense mutation in At4g28590, the gene for a pioneer protein. We designated this gene SVR4 (for SUPPRESSOR OF VARIEGATION4) and the mutant allele in ems2505 as svr4-1. We demonstrate that SVR4 is located in chloroplasts and that svr4-1 single mutants are normal with respect to chloroplast anatomy and thylakoid membrane protein accumulation. However, they are modestly impaired in several aspects of photochemistry and have enhanced non-photochemical quenching (NPQ) capacity. A T-DNA insertion allele of SVR4, svr4-2, is seedling-lethal due to an early blockage of chloroplast development. We conclude that SVR4 is essential for chloroplast biogenesis, and hypothesize that SVR4 mediates some aspect of thylakoid structure or function that controls NPQ. We propose that in the suppressor strain, photoinhibitory pressure caused by a lack of VAR2 is ameliorated early in chloroplast development by enhanced NPQ capacity caused by reduced SVR4 activity. This would result in an increase in the number of chloroplasts that are able to surmount a threshold necessary to avoid photo-damage and thereby develop into functional chloroplasts. [ABSTRACT FROM PUBLISHER]

The landscape modification model proposed by was used to assess the modification of Tasmania's native vegetation and its potential implications for biodiversity conservation. The inclusion of new 'substates' in the model allowed the varying degrees of landscape variegation and fragmentation observed in Tasmania to be quantified. The mapped extent of Tasmania's native vegetation is approximately 5.06 million ha or 74% of the land area. The extent of native vegetation varies across bioregions from a low of around 36% in the Tasmanian Northern Midlands bioregion to a high of 94% in the Tasmanian West bioregion. Overall, the Tasmanian landscape can be described as medium variegated as the State retains 76% cover of native vegetation, by area. Two of Tasmania's nine bioregions are in an intact state, four are variegated, and three are fragmented. Seven of the State's 48 catchments are in an intact state, 24 catchments are variegated, and 17 are fragmented. Tasmania was estimated to support 33 760 patches of native vegetation. Fewer than 3% of these patches exceed 50 ha in area. Small and medium patches occur predominantly on freehold land with grazing as a major land use, whereas large patches occur predominantly on crown land with conservation and production forestry as the major land uses. One feature of the State's native vegetation is the large tract of native vegetation ecosystems in western Tasmania. Opportunities arise to sustain the resilience of these native ecosystems both by consolidating the formal protection of vegetation within catchments such as the Arthur and Pieman and by strengthening environmental management in adjacent areas. Bioregions and catchments where climate change may be of particular concern for biodiversity conservation and management include the Tasmanian Northern Midlands bioregion and Cam catchment in north-western Tasmania. The maintenance and enhancement of patches of remnant vegetation in these areas will be challenging and appears likely to require strategic, multiscale and coordinated natural resource management over decades. Limiting the loss of native vegetation across the entire range of landscape states in Tasmania appears essential to mitigate the further decline of biodiversity. [ABSTRACT FROM AUTHOR]

Xylella fastidiosa is a xylem-limited bacterium responsible for important plant diseases, like citrus-variegated chlorosis (CVC) and grapevine Pierce's disease (PD). Interestingly, in vitro growth of X. fastidiosa in chemically defined media that resemble xylem fluid has been achieved, allowing studies of metabolic processes used by xylem-dwelling bacteria to thrive in such nutrient-poor conditions. Thus, we performed microarray hybridizations to compare transcriptomes of X. fastidiosa cells grown in 3G10-R, a medium that resembles grape sap, and in Periwinkle Wilt (PW), the complex medium traditionally used to cultivate X. fastidiosa. We identified 299 transcripts modulated in response to growth in these media. Some 3G10R-overexpressed genes have been shown to be upregulated in cells directly isolated from infected plants and may be involved in plant colonization, virulence and environmental competition. In contrast, cells cultivated in PW show a metabolic switch associated with increased aerobic respiration and enhanced bacterial growth rates. [ABSTRACT FROM AUTHOR]

In the photosynthetic apparatus, a major target of photodamage is the D1 reaction center protein of photosystem II (PSII). Photosynthetic organisms have developed a PSII repair cycle in which photodamaged D1 is selectively degraded. A thylakoid membrane-bound metalloprotease, FtsH, was shown to play a critical role in this process. Here, the effect of FtsHs in D1 degradation was investigated in Arabidopsis (Arabidopsis thaliana) mutants lacking FtsH2 (yellow variegated2 [var2]) or FtsH5 (van). Because these mutants are characterized by variegated leaves that sometimes complicate biochemical studies, we employed another mutation,fu-gaeri1 (fug1), that suppresses leaf variegation in van and var2 to examine D1 degradation. Two- dimensional blue native PAGE showed that var2 has less PSII supercomplex and more PSII intermediate lacking CP43, termed RC47, than the wild type under normal growth light. Moreover, our histochemical and quantitative analyses revealed that chloroplasts in var2 accumulate significant levels of reactive oxygen species, such as superoxide radical and hydrogen peroxide. These results indicate that the lack of FtsH2 leads to impaired D1 degradation at the step of RC47 formation in PSII repair and to photooxidative stress even under nonphotoinhibitory conditions. Our in vivo D1 degradation assays, carried out by nonvariegated var2 fug1 and var1 fug1 leaves, demonstrated that D1 degradation was impaired in different light conditions. Taken together, our results suggest the important role of chloroplastic FtsHs, which was not precisely examined in vivo. Attenuated D1 degradation in the nonvariegated mutants also suggests that leaf variegation seems to be independent of the PSII repair. [ABSTRACT FROM AUTHOR]

Abstract: Citrus variegated chlorosis (CVC) is a disease caused by the bacterium Xylella fastidiosa. The most productive areas for citrus in Brazil are the northwestern and the northern regions of the São Paulo state, where CVC incidence is more severe. Additionally, these areas have the highest temperatures as well as significant vapor pressure deficits (VPD) and seasonal droughts. Environmental stresses are known to affect CVC-infected plants under semi-controlled conditions, but it is unclear whether similar effects occur in the field. The objective of this work was to evaluate the CVC leaf symptoms and environmental influences on fruit yield and size, and physiological parameters of healthy and CVC-affected plants (including both non-symptomatic and symptomatic leaves) in the morning and afternoon during the wet and dry seasons of 2003 in the southern, central and northern regions of the São Paulo state, Brazil. Increased VPD caused the stomatal conductance (gs) and CO2 assimilation rates (A) to drop in healthy plants, but diseased plants had low VPD influences on gs, especially closer to the northern region and in leaves that were more symptomatic, confirming that diseased plants do not respond to changes in environmental VPD, corroborating several results reported in the literature. Although symptomatic northern leaves exhibited low stomatal apertures, the northern region had the highest air temperatures and VPDs, increasing the water loss in these plants, suggesting that towards the northern region plants face greater atmospheric and soil water stress. The fruit size of diseased plants diminished towards the north, while the fruit size of healthy plants must have been influenced by the tree fruit load. We suggest that CVC-affected plants suffer greater physiological damage if grown under environmental constraint, such as that found in the northern region of the São Paulo state. [Copyright &y& Elsevier]

The loss, alteration and fragmentation of faunal habitat affects the ability of species to persist in the landscape. Effective management and reconstruction of habitat to enhance species persistence needs to be informed by organism-centric approaches to evaluating alternative habitat scenarios. Such approaches need to be founded on sound ecological theory, be capable of integrating knowledge of dynamic ecological processes with data on the distribution and quality of habitat in spatially complex landscapes, and yet be simple and efficient enough for broad application. We describe a new methodology – rapid evaluation of metapopulation persistence (REMP) – that integrates a cost-benefit approach to measuring landscape connectivity, using continuously variable (i.e. raster) habitat surfaces, with existing analytical techniques for determining the metapopulation capacity of a given landscape and for predicting occupancy patterns within this landscape. By adapting these existing techniques to work with raster data structures REMP is particularly well-suited to analysis of highly variegated landscapes. REMP produces results rapidly using best-available habitat suitability mapping and a limited set of parameters defining species movement abilities and habitat area requirements. These parameters can be estimated from expert knowledge when no empirical data are available. The approach has been successfully integrated into landscape scenario development and evaluation systems, supporting conservation planning for native fauna in NSW, Australia. [Copyright &y& Elsevier]

Variegated plants typically have green- and white-sectored leaves. Cells in the green sectors contain normal-appearing chloroplasts, whereas cells in the white sectors lack pigments and appear to be blocked at various stages of chloroplast biogenesis. Variegations can be caused by mutations in nuclear, chloroplast or mitochondrial genes. In some plants, the green and white sectors have different genotypes, but in others they have the same (mutant) genotype. One advantage of variegations is that they provide a means of studying genes for proteins that are important for chloroplast development, but for which mutant analysis is difficult, either because mutations in a gene of interest are lethal or because they do not show a readily distinguishable phenotype. This paper focuses on Arabidopsis variegations, for which the most information is available at the molecular level. Perhaps the most interesting of these are variegations caused by defective nuclear gene products in which the cells of the mutant have a uniform genotype. Two questions are of paramount interest: (1) What is the gene product and how does it function in chloroplast biogenesis? (2) What is the mechanism of variegation and why do green sectors arise in plants with a uniform (mutant) genotype? Two paradigms of variegation mechanism are described: immutans ( im) and variegated2 ( var2). Both mechanisms emphasize compensating activities and the notion of plastid autonomy, but redundant gene products are proposed to play a role in var2, but not in im. It is hypothesized that threshold levels of certain activities are necessary for normal chloroplast development. [ABSTRACT FROM AUTHOR]

Xylella fastidiosa (Xf) is a fastidious, xylem-inhabiting, Gram-negative bacterium that causes serious plant diseases in a wide range of plant species. The most serious diseases are Pierce's Disease (PD) of grape and Citrus Variegated Chlorosis (CVC). Functional genomic analyses of Xf have been severely limited by lack of a stable replicative shuttle vector. Plamsid pUFR047, small, stable, wide host range, conjugative and repW shuttle vector have been successfully transferred into Xf strains by electroporation. The vector replicated in a stable manner for over thirty generations of growth in the absence of antibiotic selection in Xf strains. [ABSTRACT FROM AUTHOR]

Fractionation of the lipid extract from rhizomes of Iris variegata Linn, resulted in the isolation of one new and four known iridals. The latter wore identified by comparison with authentic standards and NMR-spectroscopic analyses as 21-hydroxyiridal 1, 21-hyclroxy-10-deoxyirid;d 2, 16-hydroxyirida! 3 and 22-methyl-γ-cycloiridal 4. The (R) configuration of C21 in compound 2 was determined by the exciton chirality method. The same stereochemistry has previously been found for the appropriate moieties in 1 and 3, Bused on its spectroscopic properties the new triterpenoid was shown lo be the 23-hydroxyiridal 5. [ABSTRACT FROM AUTHOR]

In the ‘Rhapsody’ cultivar of the carnation, which bears white flowers variegated with red flecks and sectors, a transposable element, dTdic1, belonging to the Ac/Ds superfamily, was found within the dihydroflavonol 4-reductase (DFR) gene. The red flecks and sectors of ‘Rhapsody’ may be attributable to a reversion to DFR activity after the excision of dTdic1. The yellow color of the carnation petals is attributed to the synthesis and accumulation of chalcone 2′-glucoside. In several of the carnation cultivars that bear yellow flowers variegated with white flecks and sectors, both the chalcone isomerase (CHI) and DFR genes are disrupted by dTdic1. [ABSTRACT FROM PUBLISHER]

Variegated flower phenotypes were generated using the Arabidopsis transposon Tag1 and the maize R regulatory gene. Tag1 was inserted between the CaMV 35S promoter and the maize R gene and transformed into tobacco plants. In half of the transgenic plants, variegated flower patterns were observed. Each line had a different pattern, with varying intensities with three lines showing only tiny sectors indicative of late excision and one showing large sectors indicative of earlier excision. [ABSTRACT FROM PUBLISHER]

Variegated leaves are often caused by a nuclear recessive mutation in higher plants. Characterization of the gene responsible for variegation has shown to provide several pathways involved in plastid differentiation. Here we describe an Arabidopsis variegated mutant isolated by T-DNA tagging. The mutant displayed green and yellow sectors in all green tissues except for cotyledons. Cells in the yellow sector of the mutant contained both normal-appearing and mutant chloroplasts. The isolated mutant was shown to be an allele of the previously reported mutant, yellow variegated (var2). Cloning and molecular characterization of the VAR2 locus revealed that it potentially encodes a chloroplastic homologue of FtsH, an ATP-dependent metalloprotease that belongs to a large protein family involved in various cellular functions. ftsH-like genes appear to comprise a small gene family in Arabidopsis genome, since at least six homologues were found in addition to VAR2. Dispensability of VAR2 was therefore explained by the redundancy of genes coding for FstHs. In the yellow regions of the mutant leaves, accumulation of photosynthetic protein components in the thylakoid membrane appeared to be impaired. Based on the role of FtsH in a protein degradation pathway in plastids, we propose a possibility that VAR2 is required for plastid differentiation by avoiding partial photooxidation of developing chloroplasts. [ABSTRACT FROM PUBLISHER]

Provides information on citrus blight (CB) and other diseases of recalcitrant etiology. Historical background on CB; Diagnostic tests for CB; Experimental transmission of CB; Discussion on variegated chlorosis; Diseases of complex etiology.

Variegated mesocosms, which provide spatial cues lacking in planktonkreisels, facilitated morphological and behavioral studies of plankton from marine lakes. A mesocosm and its application to marine lake studies are described, then several modifications to the present design suggested. Variegated mesocosms are a neglected resource in plankton research. [ABSTRACT FROM PUBLISHER]

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Soluble amino acid analyses of the green and chlorotic areas of several variegated plants generally showed that amino acids accumulated in the chlorotic tissues. Asparagine levels were consistently and conspicuously higher in the chlorotic areas. This pattern is discussed in the context of other physiological chloroses. [ABSTRACT FROM AUTHOR]

The author discusses the principles that she applies in caring for her variegated African violets in New England. She focuses on the options of the grower to keep the plants cool so that leaves will continue to have their lighter coloring, control of fertilizers and maintenance of good air circulation. She explores the advantage of knowing the differences between variegated plants to understand their special needs.

Ruditapes philippinarum and R. variegate are commercially important shellfish in Korea. In order to understand the processes and organization of genetic diversity and genetic resources for the sustainable management of fisheries resources we developed 13 primer pairs for microsatellite loci in R. philippinarum and tested their cross-amplification in R. variegate. Twelve primers amplified in both species. Nine loci were polymorphic in R. philippinarum and eight in R. variegate, each with nine to 26 alleles per locus. Unbiased expected heterozygosity levels varied from 0.73 to 0.94 in R. philippinarum. All polymorphic loci possessed species-specific alleles. No linkage disequilibrium was found. Results indicated that these microsatellite were highly polymorphic and will be useful for conservation genetics of both species. [ABSTRACT FROM AUTHOR]

Five ornamental grasses {little bluestem [Schizachyrium scoparium (Michx.) Nash], prairie dropseed [Sporobolus heterolepis (A. Gray) A. Gray], feather reedgrass [Calamagrostis xacutiflora (Schrad.) DC. Karl Foerster], flamegrass (Miscanthus Anderss. Purpuraseens), and variegated Japanese silvergrass (Miscanthus sinensis Anderss. Variegatus)} were propagated by transplanting plugs or field divisions into 480-mL (10-era round), 2.7-L (no. 1), and 6.2-L (no. 2) nursery containers with media ratios (v/v) of 0:1, 1:1, 2:1, 3:1, 1:0 rice hulls to sand, resulting in aeration porosities in 2.7-L containers of 5%, 12%, 22%, 28%, and 41%, respectively. Planting dates were between 28 Oct and 10 Nov. 1997; 30 Apr. and 7 May 1998; and 23-28 Oct. 1998 and 1-10 May 1999. Plants were covered with plastic and straw from the second week in November until the second week in April. Winter survival was evaluated 6 weeks after uncovering and for finished dates every 2 weeks thereafter. Species had a significant effect on overwintering survival, but container size and media did not. Sporobolus heterolepis and M. sinensis Variegatus had significantly lower overwintering survival than the other species. Container size significantly influenced growth; the 6.2-L containers had the highest values for all growth parameters. Growth response to media was a weak (nonsignificant) quadratic response, indicating for these species no clear trend for the best media aeration porosity. [ABSTRACT FROM AUTHOR]

The complete mitochondrial genome of Eumeta variegate, largest bagworm moth in Japan, has been sequenced using a nanopore sequencer as a single long read. The genome has a total length of 16,601 bp, consisting of 13 protein-coding genes, 20 tRNA, 2 rRNA genes, and an AT-rich control region. The nucleotide composition was extremely AT-rich, with 42.4% A, 40.4% T, 6.67% G, and 10.6% C. This is the second report of a complete mitochondrial genome of Psychidae, and the sequence information together with a phylogenetic analysis would provide a reference data in the future studies of Lepidoptera and Psychidae. [ABSTRACT FROM AUTHOR]