Carbohydrate Accumulation Patterns Research Articles

Desde el cámbium hasta el bosque: evaluando las respuestas de Juniperus thurifera L. a los condicionantes ambientales y antrópicos a múltiples escalas

Olano, J.M., Rozas, V. 2015. From cambium to woodland: analyzing Juniperus thurifera L. response to environmental constraints at multiple scales. Ecosistemas 24(2): 60-68. Doi.: 10.7818/ECOS.2015.24-2.09. Juniperus thurifera L. (Cupressaceae) is a dioecious tree inhabiting the Western Mediterranean Basin in areas under Mediterranean continental climate. Spain (95.1%) and Morocco (4.8%) host the largest populations. Diverse dendroecological research developed during the last years has improved our knowledge about this species functioning and its forest dynamics. This review approaches the advances produced on several topics including xylogenesis, climate forcing of secondary growth and xylem anatomy, regional variability on climate control, water-use efficiency, non-structural carbohydrates dynamics and present and future dynamics of its Iberian forests. A special point is paid on sex-related differences between male and female junipers, including non-structural carbohydrate accumulation patterns, secondary growth and response to summer drought, the main climatic factor limiting growth. This review aims to synthesize the available knowledge about this species at multiple spatio-temporal scales, being particularly useful for researchers and managers interested in the investigation, management and conservation of Iberian Juniperus thurifera woodlands.

Effect of developmental stage on carbohydrate accumulation patterns during winter of timothy and perennial ryegrass

Changes in non-structural carbohydrates before and during winter are one of the major plant responses to winter stress. However, the observed pattern of changes is variable, not only between grass species but also between different experiments. This study examined the effect of developmental stage on carbohydrate reserves during winter in two grass species differing in winter hardiness. Timothy (Phleum pratense L.) and perennial ryegrass (Lolium perenne L.), sown early or late in the growing season, were sampled for total non-structural carbohydrates (TNC) in late October (end of main growing season), and then in late January, early March and late April. Quantitative and qualitative patterns of carbohydrate accumulation in crown segments were influenced both by plant genotype and developmental stage of the plants prior to winter. TNC increased from October to March, demonstrating considerable cell activity during winter, and declined to their lowest level in April. Sucrose proved to be the major reserve carbohydrate, followed by fructans. The highest content of TNC was found in the most winter-hardy cultivars, particularly in January and March. Early-sown plants accumulated higher levels of fructans than of sucrose, whereas late-sown plants mainly accumulated sucrose. These differences persisted during the winter. It can be concluded that the pattern of carbohydrate accumulation during winter differed between the two species studied and it was strongly affected by both cultivar and plant-developmental stage.

Changes in Carbon Partitioning and Accumulation Patterns during Drought and Recovery for Colonial Bentgrass, Creeping Bentgrass, and Velvet Bentgrass

Efficient carbon distribution and utilization may enhance drought survival and recovery ability for perennial grasses. The objectives of this study were to examine changes in carbon partitioning and carbohydrate accumulation patterns in shoots and roots of colonial bentgrass (Agrostis capillaris L.), creeping bentgrass (A. stolonifera L.), and velvet bentgrass (A. canina L.) in response to drought and re-watering following drought, and to determine whether species variation in drought tolerance and recuperative potential is related to differences in the patterns of carbon partitioning and accumulation. The experiment consisted of three treatments: 1) well-watered control; 2) drought, irrigation completely withheld for 18 days; and 3) drought recovery, a group of drought-stressed plants were re-watered at the end of the drought treatment (18 days). Drought tolerance and recuperative ability of three species was evaluated by measuring turf quality and leaf relative water content. These parameters indicated that velvet bentgrass was most drought tolerant while colonial bentgrass had highest recuperative ability among the three species. Plants were labeled with 14CO2 to determine carbon partitioning to shoots and roots. Carbohydrate accumulation was assessed by total nonstructural carbohydrate (TNC) content. The proportion of newly photosynthesized 14C partitioned to roots increased at 12 days of drought compared to the pre-stress level, to a greater extent for velvet bentgrass (45%) than for colonial bentgrass (35%) and creeping bentgrass (30%). In general, the proportion of 14C was highest in roots, intermediate in stems, and lowest in leaves at 12 days of drought treatment for all three bentgrass species. As drought duration and severity increased (18 days), 14C partitioning increased more in leaves and stems relative to that in roots for all three species. Stem TNC content was significantly greater for drought-stressed plants of colonial bentgrass and velvet bentgrass compared to their respective well-watered control plants, whereas no differences in stem TNC content were observed between drought-stressed and well-watered creeping bentgrass. Our results suggest that increased carbon partitioning to roots during initial drought stress represented an adaptive response of bentgrass species to short-term drought stress, and increased carbon partitioning and carbohydrate accumulation in stems during prolonged period of drought stress could be beneficial for rapid recovery of turf growth and water status upon re-watering.

Seasonal dynamics of non-structural carbohydrates in two species of mediterranean sub-shrubs with different leaf phenology

The seasonal dynamics of non-structural carbohydrates in the woody organs of two co-existing mediterranean sub-shrubs were analyzed. The two species show different leaf phenology during summer: Linum suffruticosum, maintains many of its green leaves, while Lepidium subulatum sheds most of its leaves. These different leaf phenologies are related to different strategies with regard to summer stress. The maintenance of leaves in Linum is related to its stress tolerance while Lepidium avoids stress by shedding its leaves. The main objectives were to: (1) determine the differences in the seasonal dynamics of non-structural carbohydrates among the main woody organs of both species; (2) verify if differences in the leaf phenology, and hence in the strategy with regard to summer drought, lead to different seasonal patterns of carbohydrate storage and use between the two species; (3) compare the seasonal dynamics of carbohydrates of the two studied sub-shrubs with those of mediterranean trees and shrubs previously reported in the literature. The concentration of soluble sugars (SS), starch and total non-structural carbohydrates (TNC) were assessed monthly, over 17 months, in the main roots, stems and the transition zone between root and shoot systems of both species. Starch storage capacity and SS, starch and TNC pools were calculated. The seasonal pattern of carbohydrate accumulation was similar among the woody organs analyzed, but it differed with those reported for mediterranean trees and shrubs. The two species showed different pools and seasonal patterns of non-structural carbohydrate concentrations in its woody organ, which corresponded to their different extent of leaf shedding. The stress-avoider Lepidium accumulated starch during spring shoot growth as a carbon store for summer respiration and had low pools of SS, whereas the stress-tolerant Linum increased SS during summer drought to maintain photosynthetic activity during summer and had low starch pools and storage capacity. However, irrespective of their different leaf shedding patterns, both species had a similar relative variation of their TNC concentration, which contrasts with previous results on deciduous and evergreen woody species.

Carbohydrate accumulation in leaves of plants treated with the herbicide chlorsulfuron or imazethapyr is due to a decrease in sink strength.

Herbicides that inhibit branched chain amino acid biosynthesis produce a rapid carbohydrate increase in leaves of treated plants. The relationship between these processes is not known nor is the importance of carbohydrate accumulation in the growth inhibition caused by these herbicides. This work analyzes carbohydrate concentration in sources and sinks after herbicide treatments in pea (Pisum sativum L.), as well as photosynthetic carbon assimilation, using two classes of chemicals, chlorsulfuron and imazethapyr, applied to roots or leaves. The most remarkable result was that, in addition to carbohydrate accumulation in leaves, accumulation of sucrose and/or starch in roots was detected. This pattern of carbohydrate accumulation was similar for both herbicides and independent of whether the herbicides were applied to leaves or roots. This indicates that root growth inhibition was not caused by sugar starvation in sinks. Nevertheless, the results are consistent with a decrease in sink strength, leading to the inhibition of photoassimilate translocation.

Infection with Phloem Limited Abutilon Mosaic Virus Causes Localized Carbohydrate Accumulation in Leaves of Abutilon striatum: Relationships to Symptom Development and Effects on Chlorophyll Fluorescence Quenching During Photosynthetic Induction

Abstract: Infection with phloem limited Abutilon Mosaic Virus caused localized carbohydrate accumulation (high levels of starch, sucrose, and hexoses) in leaves of Abutilon striatum during early symptom development. In mature leaves with attenuated symptoms, tissues showing faint vein‐clearing had markedly higher carbohydrate contents than uniformly green areas of the same leaf. A similar pattern of carbohydrate accumulation was found in pale‐green mosaics in mature leaves with overt symptoms when compared to green‐islands of the same leaf, but overnight carbohydrate loses were comparable to controls. Because leaves with attenuated symptoms showed no further symptom development whereas the pale‐green mosaics became yellow and eventually necrotic in leaves with overt symptoms, it seems unlikely that carbohydrate accumulation following impaired translocation was responsible for symptom expression. High carbohydrate status in leaves with attenuated symptoms had little effect on nonphotochemical quenching during early stages of photosynthetic induction. In leaves with overt symptoms, areas of high carbohydrate status with pale‐green mosaics showed markedly slower nonphotochemical quenching. Early symptom areas of young leaves, and advanced symptom areas of mature leaves had low starch contents but were otherwise similar to controls in carbohydrate status. Impaired nonphotochemical quenching in these tissues tended to reflect the state of symptom development, rather than carbohydrate status. Plants with overt symptoms grew about half as fast as plants with attenuated symptoms.

Carbon metabolism in the subantarctic Kerguelen cabbage Pringlea antiscorbutica R. Br.: environmental controls over carbohydrates and proline contents and relation to phenology

The subantarctic Brassicaceae Pringlea antiscorbutica R. Br. (Kerguelen cabbage) was used as a model to study the physiological adaptations of higher plants to the subantarctic environment. 13C‐nuclear magnetic resonance permitted, in combination with biochemical methods, the identification and quantification of the major solutes in leaves, stem and roots. As characterized in many Brassicaceae, proline was a major solute in all organs of the plants, and its accumulation was mainly controlled by salt stress rather than temperature. Glucose was the major soluble sugar in the leaves, whilst sucrose and starch accumulated in stems and roots. Over a period of 1 year we found strong correlations between (i) glucose content in leaves and irradiance, and (ii) starch content in non‐photosynthetic organs and air temperature. The pattern of carbohydrate accumulation indirectly indicated that photosynthetis was sustained throughout the year, even during cold days when the temperature remained near 0 °C. This is consistent with the direct gas exchange measurements showing that photosynthetic capacity is mainly influenced by irradiance and weakly by temperature. Taken together, these characteristics demonstrated that the growth and development cycle occurs without a period of dormancy.

Carbohydrate partitioning in the leaves of Bromeliaceae performing C3 photosynthesis or Crassulacean acid metabolism

Carbohydrate accumulation was measured in the leaves of 11 speciesrepresenting the three subfamilies of Bromeliaceae. In the Tillandsioideae the C3 species Vriesea carinata Wawra accumulated starch and sucrose while the Crassulacean acid metabolism (CAM)species Tillandsia tricolor Schlechtendal & Chamissoaccumulated mainly starch. In the Pitcairnioideae the C3species Pitcairnia paniculata Ruiz & Pavon and two CAM species Dyckia sp. andFosterella schidosperma Barker accumulated sucrose butnot starch. Of six CAM species in the Bromelioideae, threeCryptanthus zonatus (Visiani) Beer,Neoregalia spectabilis Moore andPortea petropolitana Wawra accumulated starch but notsoluble sugars while three (Ananus comosus Linnaeus,Orthophytum vagans M.B. Foster andNidularium bilbergioides Schultes filius) accumulatedstarch as well as soluble sugars. Carbohydrate accumulation patterns weresimilar for species within each subfamily in that the Pitcairnioideae speciesdid not accumulate starch but accumulated sucrose while species from theTillandsioideae and Bromelioideae all accumulated starch (some alsoaccumulated soluble sugars). Carbohydrate accumulation patterns were notsimilar for C3 species versus CAM species from thedifferent subfamilies. These data suggest that variations in carbohydratebiochemistry resulting from different evolutionary histories have a greaterinfluence on carbohydrate accumulation patterns in CAM bromeliads than theconstraints of the CAM pathway itself.

Seasonal Changes of Carbohydrate Constituents in Ponkan (Citrus reticulata Blanco)

The annual partitioning dynamics of assimilated photosynthates in a low yielding ponkan (Citrus reticulata Blanco cv. Yoshida) and a high yielding cultivar, satsuma mandarin (Citrus unshiu Marc.) were compared. Starch, soluble sugars and hemicellulose in all above ground tissues were monitored at monthly intervals over a period of one year. Ponkan showed a continuous decrease of sugars and starch in all tissues except for mature wood from anthesis (May) until the end of fruit set period (July). Towards fruit maturity and approach of winter, there was a high accumulation of non-structural carbohydrates in the tissues. Maximum carbohydrate content in most tissues was reached in mid-winter (December to Januuary). A close relationship was found between non-structural carbohydrate accumulation patterns in the new leaves and shoots and fruit growth rate indicating that low sink strength of the developing ponkan fruit and inefficient mobilization of non-structural carbohydrates from the current season' s source leaves and mature wood caused low fruit set and yield in ponkan, in contrast to the satsuma mandarin fruit.

Barley Yellow Dwarf Virus Effects on Fructan and Sugar Concentration in Winter Oat Crowns

Barley yellow dwarf virus (BYDV) significantly alters carbohydrate metabolism in cereal leaf tissue. If carbohydrate accumulation in overwintering storage organs (crowns) is affected by the virus, winter survival and subsequent regrowth in spring could also be affected. To determine if BYDV alters carbohydrate accumulation patterns in winter oat (Avena sativa L.) crowns, l‐wk‐old seedlings of two cultivars were infected with the PAV isolate of BYDV. After a 3‐wk hardening period at 2 °C, carbohydrates were extracted with ethanol/water and analyzed by high‐pressure liquid chromatography. No significant differences were observed in BYDV content of leaf tissue between the two oat cultivars based on enzyme immunoassay data. Infected plants had significantly (P < 0.05) less total carbohydrate in crowns. Fructan (except that with a degree of polymerization of 3) comprised a significantly lower (P < 0.01) percentage of total carbohydrate in infected plants, while the percentage of sucrose, glucose, and fructose was significantly (P < 0.01) higher in infected plants. Results suggest that BYDV infection may alter fructan metabolism, possibly by reducing substrate levels and/or by altering enzyme activity.