Search

• Concentrations of atmospheric CO2 and tropospheric ozone (O3) are rising concurrently in the atmosphere, with potentially antagonistic effects on forest net primary production (NPP) and implications for terrestrial carbon sequestration. • Using free-air CO2 enrichment (FACE) technology, we exposed north-temperate forest communities to concentrations of CO2 and O3 predicted for the year 2050 for the first 7 yr of stand development. Site-specific allometric equations were applied to annual nondestructive growth measurements to estimate above- and below-ground biomass and NPP for each year of the experiment. • Relative to the control, elevated CO2 increased total biomass 25, 45 and 60% in the aspen, aspen–birch and aspen–maple communities, respectively. Tropospheric O3 caused 23, 13 and 14% reductions in total biomass relative to the control in the respective communities. Combined fumigation resulted in total biomass response of −7.8, +8.4 and +24.3% relative to the control in the aspen, aspen–birch and aspen–sugar maple communities, respectively. • These results indicate that exposure to even moderate levels of O3 significantly reduce the capacity of NPP to respond to elevated CO2 in some forests. [ABSTRACT FROM AUTHOR]

The global flora is thought to contain a large proportion of herbs, and understanding the general spatiotemporal processes that shaped the global distribution of these communities is one of the most difficult issues in biogeography., We explored patterns of world-wide biogeography in a species-rich herbaceous group, the paper daisy tribe Gnaphalieae (Asteraceae), based on the hitherto largest taxon sampling, a total of 835 terminal accessions representing 80% of the genera, and encompassing the global geographic range of the tribe, with nuclear internal transcribed spacer (ITS) and external transcribed spacer (ETS) sequences., Biogeographic analyses indicate that Gnaphalieae originated in southern Africa during the Oligocene, followed by repeated migrations into the rest of Africa and the Mediterranean region, with subsequent entries into other continents during various periods starting in the Miocene., Expansions in the late Miocene to Pliocene appear to have been the driving force that shaped the global distribution of the tribe as forests were progressively broken up by the mid-continent aridification and savannas and grasslands expanded into the interior of the major continents. This pattern of recent colonizations may explain the world-wide distribution of many other organisms in open ecosystems and it is highlighted here as an emerging pattern in the evolution of the global flora. [ABSTRACT FROM AUTHOR]

In the basic pure-culture technique, fungus for inoculum is grown on stiff absorbent paper card over Potato Dextrose Agar, then this paper is removed aseptically and laid, fungus-side down, Oil to a two-dimensional array of roots of seedlings grown axenically on filter paper over a mineral salts agar medium. With the high inoculum potential achieved by this technique, ectomycorrhizas have been formed within one week of inoculating Pisolithus tinctorius Coker & Couch or Paxillus involutus (Batsch. ex Fr.) Fr. on to Eucalyptus globulus Subsp. bicostata (Maid. et al.) Kirkp., and over 50%, of root apices were converted to ectomycorrhizas within two weeks. The paper-based inoculum has also been applied successfully to convert peripheral roots of seedlings grown in peat-moss within clay pots. [ABSTRACT FROM AUTHOR]

• Concentrations of atmospheric CO2 and tropospheric ozone (O3) are rising concurrently in the atmosphere, with potentially antagonistic effects on forest net primary production (NPP) and implications for terrestrial carbon sequestration. • Using free-air CO2 enrichment (FACE) technology, we exposed north-temperate forest communities to concentrations of CO2 and O3 predicted for the year 2050 for the first 7 yr of stand development. Site-specific allometric equations were applied to annual nondestructive growth measurements to estimate above- and below-ground biomass and NPP for each year of the experiment. • Relative to the control, elevated CO2 increased total biomass 25, 45 and 60% in the aspen, aspen–birch and aspen–maple communities, respectively. Tropospheric O3 caused 23, 13 and 14% reductions in total biomass relative to the control in the respective communities. Combined fumigation resulted in total biomass response of −7.8, +8.4 and +24.3% relative to the control in the aspen, aspen–birch and aspen–sugar maple communities, respectively. • These results indicate that exposure to even moderate levels of O3 significantly reduce the capacity of NPP to respond to elevated CO2 in some forests. [ABSTRACT FROM AUTHOR]

Interspecific C transfer was studied in laboratory microcosms containing pairs of 6-month-old Betula papyrifera Marsh. and Pseudotsuga menziesii (Mirb.) Franco seedlings growing in individual, root-restrictive (28 μm pore size) pouches filled with field soil. Interspecific transfer was examined by reciprocal labelling of seedlings with 13CO2(gas) and 14CO2(gas). At the time of labelling, the root zones of ectomycorrhizal (EM) B. papyrifera and P. menziesii were interconnected by an extensive network of EM mycelium. Carbon transferred through EM connections was distinguished from that through soil pathways by comparing microcosms where interconnecting hyphae were left intact vs. those where they were severed immediately before labelling. Transfer was bidirectional, and represented 5% of total isotope uptake by both B. papyrifera and P. menziesii together. P. menziesii received on average 50% more 14C and 66% more 13C from paper birch than vice versa, however, differences between species were not statistically significant. Neither net nor bidirectional transfer differed between severing treatments, leaving in question the relative importance of EM hyphae versus soil transfer pathways. The tendency for P. menziesii to receive more isotope than B. papyrifera corresponded with a 10-fold greater net photosynthetic rate per seedling and two-fold greater foliar N concentration of B. papyrifera than P. menziesii. [ABSTRACT FROM AUTHOR]

As proposed at the Second International Symposium on Fructan, a paper for discussion has been prepared which suggests alternative schemes based on that by A. L. Waterhouse circulated at the Symposium. This scheme has itself been modified in collaboration with N. J. Chatterton and published together with a glossary of terms. This glossary, also slightly modified, is reproduced here. The principal alternative (and additional) proposals have been made by N. C. Carpita, C. J. Pollock and D. H. Lewis, and compiled and edited by the last of this trio. [ABSTRACT FROM AUTHOR]

The chalazal end of the egg projects beyond the synergids while the micropylar end is in contact with the nucellar epidermis. The egg nucleus and nucleolus are large and, along with most of the cytoplasm, are located chalazally while a large vacuole occupies the micropylar end. The egg cell wall is attenuated chalazally but, based on preliminary light microscope observations, it does appear to surround the entire cell in some cases. The synergids each have a large chalazal vacuole with the majority of their cytoplasm in the micropylar half of the cell. Nuclei and nucleoli are large and other organelles are numerous. Plastids and endoplasmic reticulum (ER) are more numerous chalazally while mitochondria appear to be evenly distributed. Filiform apparatus (FA) formation occurs late in synergid maturation. The FA is large, well developed, and is surrounded by a vacuolate zone. Various sized vesicles with fibrillar or flocculent contents occur within the FA. The FA stains for both protein and RNA in addition to carbohydrate which is the dominant component. The synergid walls have a knobbed ingrowth around the periphery of their micropylar end. Neither egg nor synergids store any metabolites. This information, coupled with overwhelming evidence from the literature reviewed, has led me to conclude all angiosperm synergids are active in synthesizing and, via the FA, in secreting a substance(s) which influences the final phases of pollen tube growth. Movement of materials into a megagametophyte via the FA seems unlikely, but if it does occur, it is probably an inconsistent feature and only of trivial consequence. [ABSTRACT FROM AUTHOR]

Ornithogalum ovules are crassinucellate, and the nucellar epidermis forms a nucellar cap which is secretory. The nucellus accommodates archespore and megaspore mother cell expansion by a concurrent increase in its size. It accommodates functional megaspore and megagametophyte expansion by simultaneously undergoing growth and partial degeneration. Nucellar degeneration is centrifugal and appears to be an autolytic process rather than a result of mechanical pressure from the growing megagametophyte. Megagametophyte development is of the Polygonum type. Mitotic divisions of the functional megaspore and its daughter cells are characterized by a perinuclear distribution of organelles. Some starch is stored in the micropylar end of the nucellus, but the majority is stored in the chalazal end around the hypostase. A strand of cytoplasm extends between the egg apparatus and antipodals. The micropylar polar nucleus moves across the central cell's vacuole in this strand to reach its mate. Antipodals initially are vacuolate but later fill with dense cytoplasm and numerous starch grains. Preliminary evidence from light microscopic investigation indicates a thin layer of wall material surrounds the egg apparatus. However, around the chalazal end of the egg this layer may be disjointed islands of wall material rather than a continuous wall. Synergid cytoplasm contains an abundance of organelles and a large filiform apparatus (FA) projects into it. In addition to the FA, synergid walls have a knobbed in growth around their micropylar end. We propose that the antipodals and central cell function initially as storage cells for nutrient reserves and later as nurse cells for embryo and endosperm whereas the synergids function as secretory cells which produce an agent(s) which attracts pollen tubes and, via the filiform apparatus, as cells which receive the pollen tube. [ABSTRACT FROM AUTHOR]

Archesporial cell differentiation begins when ovules are four or five cells long. One parietal cell separates the archespore and nucellar epidermis. The parietal cell divides once anticlinally and its daughter cells divide once or twice periclinally resulting in four or six parietal cells. Archespore cytoplasm contains numerous small vacuoles and numerous circular, rod-shaped bodies which stain for protein. RNA content is high. Archesporial cells increase two- or threefold in size and produce a megaspore mother cell which is circular in cross-section and elliptical in longisection. Vacuoles seem to shrink slightly during the archespore/megaspore mother cell transition. Meiosis produces four megaspores separated from each other and from the nucellus by walls which stain intensely with basic fuchsin but do not fluoresce with Aniline blue. The chalazalmost megaspore typically becomes the functional megaspore while the others degenerate. Carbohydrates accumulate in the functional megaspore during the meiotic/mitotic interphase, and by metaphase, organelles, including amyloplasts, are in a perinuclear arrangement. [ABSTRACT FROM AUTHOR]

Ornithogalum ovules are bitegmic: the inner is initiated first, but both attain maturity at the same time. Both integuments are derived from the epidermal layer of the nucellus and are covered by a cuticle. Inner integument cells define the micropyle and those which line it are secretory. An outer integument is present only on the distal (non-funicular) side of the ovule. Its proximal portion apparently is fused congenitally with the funiculus. A funiculus attaches the ovule (and seed) to placental tissue. Proliferation of cells at the base of the funiculus contributes to development of the obturator. Funicular curvature causes the ovules to assume an anatropous orientation. A procambial strand branches from a ventral vein of the carpels and differentiates acropetally in the funiculus. At ovule maturity, vascular tissue terminates in the chalaza a few cells removed from the hypostase. Terminal cells of the vascular bundle consist only of tracheary elements with annular thickenings. [ABSTRACT FROM AUTHOR]

Summary: Drought is intensifying globally with climate change, creating an urgency to understand ecosystem response to drought both during and after these events end to limit loss of ecosystem functioning. The literature is replete with studies of how ecosystems respond during drought, yet there are far fewer studies focused on ecosystem dynamics after drought ends. Furthermore, while the terms used to describe drought can be variable and inconsistent, so can those that describe ecosystem responses following drought. With this review, we sought to evaluate and create clear definitions of the terms that ecologists use to describe post‐drought responses. We found that legacy effects, resilience and recovery were used most commonly with respect to post‐drought ecosystem responses, but the definitions used to describe these terms were variable. Based on our review of the literature, we propose a framework for generalizing ecosystem responses after drought ends, which we refer to as 'the post‐drought period'. We suggest that future papers need to clearly describe characteristics of the imposed drought, and we encourage authors to use the term post‐drought period as a general term that encompasses responses after drought ends and use other terms as more specific descriptors of responses during the post‐drought period. [ABSTRACT FROM AUTHOR]

Details a study which examined the accumulation of H2O2 within the leaf mesophyll of Populus tremuloides aspen genotypes and seedlings of paper birch Betula papyrifera. Gene expression of catalase; Effects of ozone and carbon dioxide on the structure of ozone-tolerant aspen; Correlation between aspen clones, elevated ozone, birch and peroxisomes levels.

• Ectomycorrhizal (ECM) fungal communities of Douglas-fir ( Pseudotsuga menziesii) and paper birch ( Betula papyrifera) were studied along a chronosequence of forest development after stand-replacing disturbance. Previous studies of ECM succession did not use molecular techniques for fungal identification or lacked replication, and none examined different host species. • Four age classes of mixed forests were sampled: 5-, 26-, 65-, and 100-yr-old, including wildfire-origin stands from all four classes and stands of clearcut origin from the youngest two classes. Morphotyping and DNA sequences were used to identify fungi on ECM root tips. • ECM fungal diversities were lower in 5-yr-old than in older stands on Douglas-fir, but were similar among age classes on paper birch. Host-specific fungi dominated in 5-yr-old stands, but host generalists were dominant in the oldest two age classes. ECM fungal community compositions were similar in 65- and 100-yr-old stands but differed among all other pairs of age classes. • Within the age range studied, site-level ECM fungal diversity reached a plateau by the 26-yr-old age class, while community composition stabilized by the 65-yr-old class. Simple categories such as ‘early stage’, ‘multi stage’, and ‘late stage’ were insufficient to describe fungal species’ successional patterns. Rather, ECM fungal succession may be best described in the context of stand development. [ABSTRACT FROM AUTHOR]

• Over the last decade, technological developments have made it possible to quickly and nondestructively assess, in situ, the chlorophyll (Chl) status of plants. We evaluated the performance of these optical methods, which are based on the absorbance or reflectance of certain wavelengths of light by intact leaves. • As our benchmark, we used standard extraction techniques to measure Chla, Chlb, and total Chl content of paper birch (Betula papyrifera) leaves. These values were compared with the nominal Chl index values obtained with two hand-held Chl absorbance meters and several reflectance indices correlated with foliar Chl. • The noninvasive optical methods all provided reliable estimates of relative leaf Chl. However, across the range of Chl contents studied (0.0004-0.0455 mg cm[sup -2]), some reflectance indices consistently out-performed the hand-held meters. Most importantly, the reflectance indices that performed best (Chl NDI = (R[sub 750] - R[sub 705])/ (R[sub 750] + R[sub 705]), RII =∫750 705 (RλR/[sub 705] - 1) dλ) were not those most commonly used in the literature. • We report equations to convert from index values to actual Chl content, but caution that differences in leaf structure may necessitate species-specific calibration equations. [ABSTRACT FROM AUTHOR]

Non-mycorrhizal Betula papyrifera Marsh. seedlings and seedlings infected with Lactarius rufus (Scop. ex Fr.) Fr. or Scleroderma flavidum, E. & E. were treated with nutrient solutions containing 85 μM Ni or no Ni for 21 weeks. Ni was concentrated in the roots, with the highest concentrations being in the roots of plants infected with S. flavidum; Ni concentrations in stems were lowest in these seedlings. In general, Ni reduced the concentration of P, Mg, Ca, and Fe in shoot tissues. The concentration of P was correlated with that of Ni in the stems and roots. High P concentrations in the roots of S. flavidum-infected seedlings could be correlated with potential Ni-binding sites, allowing the Ni to be detoxified. Although Ni treatment reduced chlorophyll concentrations in L. rufus- infected and uninfected seedlings, this did not appear to be related to differences in tolerance caused by the fungi. [ABSTRACT FROM AUTHOR]

The role of ectomycorrhizas in the metal tolerance of birch seedlings from Sudbury, Ontario was investigated. Betula papyrifera Marsh. is one of the few tree species able to survive in the copper- and nickel-polluted area near Sudbury. Two types of birch seedlings were tested; those inoculated with Laccaria proxima (Boud.) Pat., Lactarius hibbardae Peck, Lactarius rufus (Scop. ex Fr.) Fries, or Scleroderma fiavidum E. & E. isolates originating from the Sudbury area, and those which were not inoculated. Once the seedlings were infected, they were grown in sand culture containing 34 or 85 μM Ni, 32 or 63 μM Cu, or a control solution. At the low nickel concentration, the mycorrhizal plants, especially those infected with S. fiavidum, grew significantly better than did non-mycorrhizal plants. At the higher nickel concentration, S. fiaviduminfected seedlings weighed 86 % of controls without nickel, while the other seedlings weighed only 52 to 61% of control. The good growth of S. fiavidum-infected birch seedlings may have been due to retention of nickel in the mycorrhizas. These seedlings had the highest root nickel contents and the lowest stem nickel contents. At the high concentration of copper, growth of the mycorrhizal seedlings was significantly reduced compared with the non-mycorrhizal seedlings. This reduction in growth of infected seedlings did not relate to an increase in the uptake or translocation of copper. Under the low copper treatment, infection with mycorrhizal fungi did not affect seedling growth. The potential role of iron and phosphorus in affecting host metal tolerance was investigated. Changes in the tissue concentrations of these elements did not relate to the effect of the fungi on metal tolerance. [ABSTRACT FROM AUTHOR]

Soluble polysaccharides, of natural and synthetic origins, are immobilized by nylon, nitrocellulose, and polyvinylidene difluoride blotting membranes. Retention of an acid and a neutral polysaccharide, measured using radioactive pectin and xyloglucan-rich hemicellulose, exceeded 90% on some blotting membranes eluted in aqueous media. The two polysaccharides displayed different binding characteristics. Several polyanionic uronic acid polysaccharides, bound strongly to nylon 66 (Hybond N, Amersham) and to positively charge-modified or cationic nylon blotting membranes (Hybond N+, Amersham), but much less strongly to paper, nitrocellulose or polyvinylidene difluoride. Fragments of pectin, including Rhamnogalacturonan I and Rhamnogalacturonan II, and galacturonic acid oligosaccharides as small as the dimer also bind to nylon membranes, and can he detected using cationic dyes or by means of their radioactivity. Xyloglucan-rich hemicellulose in general binds more strongly than pectin to the same substrates. Of the substrates tested charge-modified nylon gave best retention of pectin, and paper gave best retention of xyloglucan during washes in water and solutions of salts, acids and bases. The influence of pH and solutions of mono, di- and tri-valent salts on the retention of some pectic polysaccharides by nylon was investigated. A large proportion, in excess of 70% of pectin applied to charge-modified nylon, remained tightly bound at all salt concentrations up to 2 M. Soluble acid polysaccharides immobilized on blotting membranes could be detected by staining with cationic dyes, such as ruthenium red, alcian blue 8GX, and coriphosphine O, providing facile detection and a simple means of characterizing the cytochemical specificity of their staining reactions. Immobilized neutral polysaccharides, which do not react with cationic dyes, could usually be detected by the periodate-Schiff reaction, or, if labelled with radionuclides, by autoradiography or scintillation counting. Soluble polysaccharides, like proteins and nucleic acids, may therefore be immobilized on blotting membranes for investigation with cytochemical, immunocytochemical, and other molecular probing and detection procedures. Quantitative binding data showed marked differences in the affinity of different polysaccharides for blotting substrates. Detailed characterization of the binding behaviour is therefore a prerequisite for optimization and rational application of polysaccharide blotting. [ABSTRACT FROM AUTHOR]

A method for the combined estimation of caffeine, theophylline and theobromine in plant material is presented. The method involved a chloroform-ammonia extraction, separation of the bases in the chloroform extract by thin layer or paper chromatography and finally estimation of the eluted bases by spectrophotometry. Good recoveries of all three compounds were recorded. The method was used to estimate the level of these compounds in tea, coffee beans and cocoa cotyledons. [ABSTRACT FROM AUTHOR]

The combination of autoradiography and a filter paper 'sandwich' technique using wheat plants labelled with [SUP14]C has shown that roots of wheat exude two types of compounds, viz. (a) non-diffusible material released from the apices of both primary and lateral roots and (b) diffusible material released along the whole length of the roots. The high amount of non-diffusible material compared with diffusible material suggests that the former may be more significant than previously anticipated in relation to root functions and microorganisms in the rhizosphere. [ABSTRACT FROM AUTHOR]

Pea plants (Pisum sativum L. cv. Melbourne Market), each with a single developing pod, were pulse-fed with [14C]glutamine supplied through the cut stern. Hull and seed tissues were removed after a suitable interval (usually 24 h) and frozen for later analysis. The fruit received substantial label at all stages analysed (from 12 to 31 d after full blossom). Except at the youngest stage, most of the label recovered from the fruit was present in the seeds. The distribution of label in soluble metabolites of the hull, seedcoats, embryo sac liquid and embryo was determined by paper chromatography and radioautography. The results confirm that glutamine is utilized as a major source of carbon by pea embryos throughout their development. [ABSTRACT FROM AUTHOR]

Pea plants (Pisum sativum L. cv. Melbourne Market), each with a single developing pod, were pulse-fed with [14C]homoserine supplied through the cut stem at stages of pod development ranging from 12 to 21 d after full blossom. The pods were removed after 24 h and the hulls and seed components were frozen for later analysis. Except at the youngest stage, or unless the pod had been enclosed in foil to prevent the development of chloroplasts, the seeds received a higher proportion of total label in the fruit (about 60 %). The distribution of label in soluble metabolites of the hull, seedcoats, embryo sac liquid and embryo was determined by paper chromatography and radioautography. The results indicate turnover of homoserine within the hull, and confirm that the seedcoats are responsible for a shift in metabolism leading to secretion of threonine into the embryo sac instead of homoserine. [ABSTRACT FROM AUTHOR]

'Stalagmiform' roots are here defined as dense, stalagmite-like aggregations of roots and rootlets which protrude from the sandy floor of certain limestone caves. Paper chromatography showed these structures were associated with large trees of Eucalyptus gomphocephala growing above the caves. They seem to form in response to localized abundance of water at sites beneath drip-points in the cave ceiling. The anatomy of ectomycorrhizal and non-infected stalagmiform rootlets was similar to that of Eucalypt rootlets. Non-pathogenic endophytes were also often present, giving many rootlets an endomycorrhizal character. This unusual combination of features places the stalagmiform root in a separate category from other specialized root structures. [ABSTRACT FROM AUTHOR]

In addition to studies on central carbon and whole plant metabolism, with isotopes, investigations into lipid metabolism are also an important focus and greatly intrigue me. Carbon assimilation, carbon partitioning, central carbon metabolism, isotope labeling, lipid metabolism, metabolic flux analysis, spatiotemporal metabolism, emergent properties Therefore, it should not be too surprising that the papers I mention here emphasize dynamic central carbon or lipid metabolism or whole plant metabolism unveiled using isotopes, by some excellent scientists in the field. Keywords: carbon assimilation; carbon partitioning; central carbon metabolism; emergent properties; isotope labeling; lipid metabolism; metabolic flux analysis; spatiotemporal metabolism EN carbon assimilation carbon partitioning central carbon metabolism emergent properties isotope labeling lipid metabolism metabolic flux analysis spatiotemporal metabolism 710 713 4 01/09/23 20230201 NES 230201 What inspired your interest in plant science?. [Extracted from the article]

Antony N. Dodd is a plant scientist who is interested in chronobiology and circadian rhythms. He was inspired to study plant biology after attending lectures by Howard Griffiths, which showed how biochemical processes in plants could be studied over 24-hour cycles. Dodd pursued a career in research because he was fascinated by the control of daily cycles of Crassulacean acid metabolism in plants. He is motivated by the social element of science and the interactions with his research group and colleagues. Dodd provides advice for scientists, such as investing time to get things right, not only chasing big papers, and being collegial. He also discusses his favorite New Phytologist papers, which explore the use of chemical biology to study circadian rhythms in plants. Dodd mentions two favorite plant species, Agave americana and Aegagropila linnaei, and their significance in his research. [Extracted from the article]

A detailed analysis of MYCOLIT, a comprehensive bibliographic database of mycorrhizal research containing almost 12000 references, showed some interesting trends over the past 40yr. During the last four decades, the average number of papers published per year were 84, 110, 214 and 488, respectively. The current rate of publication is about 700 papers per year. Much research has focused on nutrient dynamics, inoculum production, mycorrhiza formation, and morphology and physiology of both vesicular-arbuscular mycorrhizas (VAM) and ectomycorrhizas (EM). There has been a shift of attention from Em to VAM since 1970. Very little work has been done on the other kinds of mycorrhizas. Barriers to progress in some areas, such as our inability to grow the Glomales in axenic culture, have stimulated a large number of methodological papers over the past decade, while the genetics and molecular biology, especially of VAM, have been neglected. Ecological studies were more numerous than any other kind. However, there was a bias towards laboratory studies as opposed to field studies. Within field studies, researchers focused on agricultural ecosystems, while neglecting disturbed and especially natural systems. This analysis also suggests that we may know less than we think about mycorrhizas, since we have consistently base broad hypotheses and conclusions on studies of a small number of taxa. Future research should be directed towards correcting the various imbalances revealed by this analysis. [ABSTRACT FROM AUTHOR]

Attention is drawn to an error in two earlier papers on seed dispersal (Beer and Swaine, 1977; Swaine and Beer, 1977). The correction of the error leads to quantitative changes in the earlier results which do not substantially affect the biological conclusions drawn. [ABSTRACT FROM AUTHOR]

Summary: Cellulose is an essential component of plant cell walls and an economically important source of food, paper, textiles, and biofuel. Despite its economic and biological significance, the regulation of cellulose biosynthesis is poorly understood. Phosphorylation and dephosphorylation of cellulose synthases (CESAs) were shown to impact the direction and velocity of cellulose synthase complexes (CSCs). However, the protein kinases that phosphorylate CESAs are largely unknown. We conducted research in Arabidopsis thaliana to reveal protein kinases that phosphorylate CESAs.In this study, we used yeast two‐hybrid, protein biochemistry, genetics, and live‐cell imaging to reveal the role of calcium‐dependent protein kinase32 (CPK32) in the regulation of cellulose biosynthesis in A. thaliana.We identified CPK32 using CESA3 as a bait in a yeast two‐hybrid assay. We showed that CPK32 phosphorylates CESA3 while it interacts with both CESA1 and CESA3. Overexpressing functionally defective CPK32 variant and phospho‐dead mutation of CESA3 led to decreased motility of CSCs and reduced crystalline cellulose content in etiolated seedlings. Deregulation of CPKs impacted the stability of CSCs.We uncovered a new function of CPKs that regulates cellulose biosynthesis and a novel mechanism by which phosphorylation regulates the stability of CSCs. [ABSTRACT FROM AUTHOR]

Summary: A surge of papers have reported low leaf vulnerability to xylem embolism during drought. Here, we focus on the less studied, and more sensitive, outside‐xylem leaf hydraulic responses to multiple internal and external conditions. Studies of 34 species have resolved substantial vulnerability to dehydration of the outside‐xylem pathways, and studies of leaf hydraulic responses to light also implicate dynamic outside‐xylem responses. Detailed experiments suggest these dynamic responses arise at least in part from strong control of radial water movement across the vein bundle sheath. While leaf xylem vulnerability may influence leaf and plant survival during extreme drought, outside‐xylem dynamic responses are important for the control and resilience of water transport and leaf water status for gas exchange and growth. [ABSTRACT FROM AUTHOR]

Summary: Seminal scientific papers positing that mycorrhizal fungal networks can distribute carbon (C) among plants have stimulated a popular narrative that overstory trees, or 'mother trees', support the growth of seedlings in this way. This narrative has far‐reaching implications for our understanding of forest ecology and has been controversial in the scientific community. We review the current understanding of ectomycorrhizal C metabolism and observations on forest regeneration that make the mother tree narrative debatable. We then re‐examine data and conclusions from publications that underlie the mother tree hypothesis. Isotopic labeling methods are uniquely suited for studying element fluxes through ecosystems, but the complexity of mycorrhizal symbiosis, low detection limits, and small carbon discrimination in biological processes can cause researchers to make important inferences based on miniscule shifts in isotopic abundance, which can be misleading. We conclude that evidence of a significant net C transfer via common mycorrhizal networks that benefits the recipients is still lacking. Furthermore, a role for fungi as a C pipeline between trees is difficult to reconcile with any adaptive advantages for the fungi. Finally, the hypothesis is neither supported by boreal forest regeneration patterns nor consistent with the understanding of physiological mechanisms controlling mycorrhizal symbiosis. [ABSTRACT FROM AUTHOR]

I saw the huge amount of work that went into the Arabidopsis genome whilst I was a postdoc, and now my students are assembling genomes as part of their PhDs. Keywords: bioinformatics; plant genomes; plant speciation; Profile; speciation genetics EN bioinformatics plant genomes plant speciation Profile speciation genetics 1505 1507 3 02/06/23 20230301 NES 230301 What inspired your interest in plant science? Plant genomes, bioinformatics, plant speciation, Profile, speciation genetics. [Extracted from the article]

Summary: Greenbeards are selfish genetic elements that make their bearers behave either altruistically towards individuals bearing similar greenbeard copies or harmfully towards individuals bearing different copies. They were first proposed by W. D. Hamilton over 50 yr ago, to illustrate that kin selection may operate at the level of single genes. Examples of greenbeards have now been reported in a wide range of taxa, but they remain undocumented in plants. In this paper, we discuss the theoretical likelihood of greenbeard existence in plants. We then question why the greenbeard concept has never been applied to plants and speculate on how hypothetical greenbeards could affect plant–plant interactions. Finally, we point to different research directions to improve our knowledge of greenbeards in plants. [ABSTRACT FROM AUTHOR]

The article discusses the protocol for the simultaneous quantification of chlorophyll (Chl) a and b described by D. I. Arnon in 1949. Topics covered include the citations received by Arnon's study, the imprecision of Arnon's equations, and an unusual bimodal pattern revealed in a chronological analysis of the citations of Arnon's paper.

Copyright of New Phytologist is the property of Wiley-Blackwell 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.)

Gary Loake, a professor of plant molecular sciences at the University of Edinburgh, shares his journey and passion for plant science. Growing up in a rural area, Loake developed a love for nature and biology, which led him to pursue a career in research. He transitioned from studying microbes to plants and has since focused on understanding and enhancing plant immunity. Loake is motivated by making new discoveries, solving problems, and mentoring students. He has also been involved in industry collaborations and founded a plant biotechnology company. Loake highlights the importance of role models in his career and mentions his favorite papers from the New Phytologist journal. He also shares his favorite plant, the horse chestnut tree, and discusses his work with the model plant Marchantia polymorpha. Unfortunately, the article notes that Loake passed away in March 2024. [Extracted from the article]

A letter to the editor is presented which discusses the use of photosynthetic parameter estimation in determining the approximated rate of maximum potential electron transport.

Tessa joined New Phytologist as an Advisor in 2022.For more information on Tessa, visit https://www.danforthcenter.org/our-work/principal-investigators/tessa-burch-smith/ ORCID: Tessa Burch-Smith https://orcid.org/0000-0002-5994-4343 Why did you decide to pursue a career in research? One recent I New Phytologist i paper that I enjoyed was 'Structural and functional relationships between plasmodesmata and plant endoplasmic reticulum-plasma membrane contact sites consisting of three synaptotagmins' (Ishikawa I et al i ., 2020) from the Shimada group. Keywords: intercellular trafficking; microscopy; Nicotiana benthamiana; plant viruses; plasmodesmata EN intercellular trafficking microscopy Nicotiana benthamiana plant viruses plasmodesmata 2155 2157 3 08/22/22 20220915 NES 220915 What inspired your interest in plant science?. [Extracted from the article]

Summary: If trees minimize self‐shading, new foliage in shaded parts of the crown should remain minimal. However, many species have abundant foliage on short shoots inside their crown. In this paper, we test the hypothesis that short shoots allow trees to densify their foliage in self‐shaded parts of the crown thanks to reduced costs.Using 30 woody species in Mediterranean and tropical biomes, we estimated the contribution of short shoots to total plant foliage, calculated their costs relative to long shoots including wood cost and used 3D plant simulations calibrated with field measurements to quantify their light interception, self‐shading and yield.In species with short shoots, leaves on short shoots account for the majority of leaf area. The reduced cost of short stems enables the production of leaf area with 36% less biomass. Simulations show that although short shoots are more self‐shaded, they benefit the plant because they cost less. Lastly, the morphological properties of short shoots have major implications for whole plant architecture.Taken together, our results question the validity of only assessing leaf costs to understand leaf economics and call for more integrated observations at the crown scale to understand light capture strategies in woody plants. [ABSTRACT FROM AUTHOR]

Summary: Leaf phosphorus (P) comprises four major fractions: inorganic phosphate (Pi), nucleic acids, phospholipids, P‐containing metabolites and a residual fraction. In this review paper, we investigated whether allocation of P fractions varies among groups of terrestrial vascular plants, and is indicative of a species' strategy to use P efficiently. We found that as leaf total P concentration increases, the Pi fraction increases the most, without a plateau, while other fractions plateau. Variability of the concentrations of leaf P fractions is greatest among families > species(family) > regions > plant life forms. The percentage of total P allocated to nucleic acid‐P (20–35%) and lipid‐P (14–34%) varies less among families/species. High photosynthetic P‐use efficiency is associated with low concentrations of all P fractions, and preferential allocation of P to metabolite‐P and mesophyll cells. Sequential resorption of P from senescing leaves starts with Pi, followed by metabolite‐P, and then other organic P fractions. Allocation of P to leaf P fractions varies with season. Leaf phytate concentrations vary considerably among species, associated with variation in photosynthesis and defence. Plasticity of P allocation to its fractions is important for acclimation to low soil P availability, and species‐specific P allocation is needed for co‐occurrence with other species. [ABSTRACT FROM AUTHOR]

Summary: Leaf structure plays an important role in photosynthesis. However, the causal relationship and the quantitative importance of any single structural parameter to the overall photosynthetic performance of a leaf remains open to debate. In this paper, we report on a mechanistic model, eLeaf, which successfully captures rice leaf photosynthetic performance under varying environmental conditions of light and CO2.We developed a 3D reaction‐diffusion model for leaf photosynthesis parameterised using a range of imaging data and biochemical measurements from plants grown under ambient and elevated CO2 and then interrogated the model to quantify the importance of these elements.The model successfully captured leaf‐level photosynthetic performance in rice. Photosynthetic metabolism underpinned the majority of the increased carbon assimilation rate observed under elevated CO2 levels, with a range of structural elements making positive and negative contributions. Mesophyll porosity could be varied without any major outcome on photosynthetic performance, providing a theoretical underpinning for experimental data.eLeaf allows quantitative analysis of the influence of morphological and biochemical properties on leaf photosynthesis. The analysis highlights a degree of leaf structural plasticity with respect to photosynthesis of significance in the context of attempts to improve crop photosynthesis. [ABSTRACT FROM AUTHOR]

An introduction is presented in which the editor discusses the contribution of former editor-in-chiefs (EiCs) Peter Ayres and Ian Woodward within the issue.

Keywords: alternative oxidase (AOX); fruit ripening; mitochondria; nitric oxide (NO); pomegranate EN alternative oxidase (AOX) fruit ripening mitochondria nitric oxide (NO) pomegranate 2410 2412 3 02/05/21 20210301 NES 210301 What inspired your interest in plant science? Professor Kaiser became my PhD supervisor and introduced me to nitric oxide (NO) research, which at that time was a "hot topic". From 2012 to 2014, he was a Marie Curie Fellow at the Department of Plant Sciences, University of Oxford (UK) working on the role of nitric oxide in the low oxygen stress response in plants. Alternative oxidase (AOX), fruit ripening, mitochondria, nitric oxide (NO), pomegranate. [Extracted from the article]

The article discusses a comment made by Bourke et al. regarding the method described in Chen et al.'s paper on mapping quantitative trait loci (QTL) in autotetraploids. Chen et al. argue that their comment is correct based on facts and statistical principles. They explain that the method used in Bourke et al.'s paper lacks an essential component, which is genetic linkage analysis between QTLs and surrounding markers for QTL mapping in an outbred autotetraploid segregating population. Chen et al. also address the terminology and methodology used by Bourke et al., pointing out inconsistencies and inaccuracies. They conclude that their own method enables QTL mapping in autotetraploid species under a novel tetrasomic inheritance model and is based on rigorous scientific and statistical principles. [Extracted from the article]

The Holocene history of the forest-alpine tundra ecotone in Central Sweden (Scandes Mountains) is inferred from radiocarbon analyses of subfossil wood remains. Pinus sylvestris was the dominant subalpine tree species during the early Holocene, when it ascended almost 200 m higher than currently. A short climatic episode (less than 100 years) is postulated to have triggered erosional processes around 6300 B.P., and extinguished the upper part of the subalpine pine woodland. Subsequently, a subalpine belt of Betula pubescens ssp. tortuosa and Alnus incana developed. A Holocene thermal optimum occurred around 6100 B.p., when the birch/alder belt flourished and the tree-limits probably reached their highest levels during the Holocene. Shortly after 6000 B.P., a long-term pine forest retrogression started and the birch/alder belt was disrupted by expanding snow-beds. Pine receded slightly at its tree-limit, but the uppermost belt of closed pine forest (presently dominated by birch) remained intact until c. 3300 B.p., when a severe climatic deterioration occurred. The present-day subalpine belt of pure birch forest developed successively and increased in vertical extent after c. 5300 B.P., when summer temperature declined. The evolution of the birch belt is postulated to have been ultimately a response to decreased seasonality, which favoured birch at the expense of pine. Because of the 'inertia' characterizing the highest pine forest, the birch belt was relatively narrow until a major thermal decline c. 3300 B.P., when it made a massive downslope expansion. The latest phase of pine recession was during the Little Ice Age, 800-300B.P. [ABSTRACT FROM AUTHOR]

This 'Tansley Review' paper takes as its starting point a paper of mine published in 1961, which explored the shape and size of modern Angiosperm families and genera as a product of taxonomic practice over centuries. It considers how far the conclusion - that our existing scientific classification, based on Linnaeus' masterly standardization in the eighteenth century, is very markedly 'Eurocentric' - has been criticized, accepted or modified by subsequent writers. In particular, it assesses the important contribution made in recent years by ethnobiologists using expert knowledge from social anthropology, linguistics and other disciplines. Finally, the paper considers briefly the broader aspects of current controversies about the nature and purpose of taxonomic activity, including the argument about its relevance to evolutionary knowledge and speculation. It concludes that, to a remarkable degree, practising taxonomists ignore conceptual or philosophical difficulties and are able to co-operate, although their leisurely and arcane procedures may not measure up to the 'information explosion'. [ABSTRACT FROM AUTHOR]

This article is a Commentary on the Virtual Issue 'Methane emissions from tree stems – current knowledge and challenges' that includes the following papers: Barba et al. (2019), Bréchet et al. (2021), Covey & Megonigal (2019), Feng et al. (2022), Flanagan et al. (2021), Jeffrey et al. (2019, 2021, 2023), Kohl et al. (2019), Machacova et al. (2021a,b, 2023), Megonigal et al. (2020), Pangala et al. (2013, 2014), Pitz & Megonigal (2017), Plain et al. (2019), Putkinen et al. (2021), Sjögersten et al. (2020), Takahashi et al. (2022), Tenhovirta et al. (2022), Wang et al. (2016), and Yip et al. (2018). Access the Virtual Issue at www.newphytologist.com/virtualissues. [ABSTRACT FROM AUTHOR]

Summary: Light intensity and quality influence photosynthesis directly but also have an indirect effect by increasing stomatal apertures and enhancing gas exchange. Consequently, in areas such as the upper canopy, a high water demand for transpiration and temperature regulation is created. This paper explores how light intensity and the natural high Blue‐Light (BL) : Red‐Light (RL) ratio in these areas, is important for controlling leaf hydraulic conductance (Kleaf) by BL signal transduction, increasing water permeability in cells surrounding the vascular tissue, in supporting the enormous water demands. Conversely, shaded inner‐canopy areas receive less radiation, have lower water and cooling demands, and exhibit reduced Kleaf due to diminished intensity and BL induction. Intriguingly, shaded leaves display higher water‐use efficiency (compared with upper‐canopy) due to decreased transpiration and cooling requirements while the presence of RL supports photosynthesis. [ABSTRACT FROM AUTHOR]