Leaf Growth Activity Research Articles

Rethinking temperature effects on leaf growth, gene expression and metabolism: Diel variation matters.

Plants have evolved to grow under prominently fluctuating environmental conditions. In experiments under controlled conditions, temperature is often set to artificial, binary regimes with constant values at day and at night. This study investigated how such a diel (24 hr) temperature regime affects leaf growth, carbohydrate metabolism and gene expression, compared to a temperature regime with a field‐like gradual increase and decline throughout 24 hr. Soybean (Glycine max) was grown under two contrasting diel temperature treatments. Leaf growth was measured in high temporal resolution. Periodical measurements were performed of carbohydrate concentrations, carbon isotopes as well as the transcriptome by RNA sequencing. Leaf growth activity peaked at different times under the two treatments, which cannot be explained intuitively. Under field‐like temperature conditions, leaf growth followed temperature and peaked in the afternoon, whereas in the binary temperature regime, growth increased at night and decreased during daytime. Differential gene expression data suggest that a synchronization of cell division activity seems to be evoked in the binary temperature regime. Overall, the results show that the coordination of a wide range of metabolic processes is markedly affected by the diel variation of temperature, which emphasizes the importance of realistic environmental settings in controlled condition experiments.

Molecular characterization and functional analysis of “fruit-weight2.2-like” gene family in rice

Tomato fruit-weight 2.2 (FW2.2) was reported to control up to 30 % fruit weight. Recent studies demonstrated that FW2.2-like (FWL) genes also play important roles in plant growth and development. For instance, a maize homolog of FW2.2, named cell number regulator 1 (CNR1), negatively regulates plant and organ size. However, FWL genes in rice have not been characterized yet. In this study, eight FWL genes were identified in rice genome and designated as OsFWL1-8. The chromosome location, gene structure, protein motif, and phylogenetic relationship of OsFWL genes were analyzed. RT-PCR result and microarray data revealed that OsFWL genes exhibited diverse expression patterns and the detailed expression patterns of OsFWL5, 6, and 7 negatively correlated with leaf growth activity. Rice protoplast transient transformation experiment showed that most OsFWL proteins locate at cell membrane but OsFWL8 is present in the nucleus. In addition, the functions of OsFWL genes were investigated by analyzing two T-DNA insertion lines for OsFWL3 and 5. Compared with wild type, the grain weight of osfwl3 mutant and the plant height of osfwl5 mutant were increased by 5.3 and 12.5 %, respectively. We also found that the increase in grain length of osfwl3 mutant was due chiefly to incremental cell number, not cell size and the expression of OsFWL3 negatively correlated with glume growth activity. These results provide a comprehensive foundation for further study of OsFWL functions in rice.

Apoplastic pH and growth in expanding leaves of Vicia faba under salinity

Salinity affects water availability in the soil and subsequently the plant uptake capacity. Upon exposure to salt stress, leaf growth in monocot plants has been shown to be reduced instantaneously, followed by a gradual acclimation. The growth reactions are caused by an initial water deficit and an accompanied osmotic effect, followed by an IAA-induced sequestration of protons into the apoplast that increases leaf growth again as explained by the acid growth theory. In this study, we investigated the dynamics of growth reactions and apoplastic pH in leaves of the dicot Vicia faba in the presence of NaCl during the initiation of salt stress. Concurrent changes in apoplastic pH were detected by ratiometric fluorescence microscopy using the fluorescent dye fluorescein tetramethylrhodamine dextran. To elucidate the possible relation between the dynamics of leaf growth and apoplastic pH, results of the ratio imaging technique were combined with an in vivo growth analysis imaging approach. Leaf growth rate of V. faba was highest in the dusk and the early night phase; at this time a concomitant decrease of the apoplastic pH was observed. Under salinity, the apoplastic pH in leaves of V. faba increased with a simultaneous decrease of leaf growth towards increasing developmental stages, but with complex aberrations in the 24-h-leaf-growth pattern compared to control leaves. In conclusion, these results show that salt stress leads to an increase in apoplastic pH and to a declined leaf growth activity with complex 24-h-interactions of growth and pH in V. faba.

Dynamics of seedling growth acclimation towards altered light conditions can be quantified via GROWSCREEN: a setup and procedure designed for rapid optical phenotyping of different plant species

Using a novel setup, we assessed how fast growth of Nicotiana tabacum seedlings responds to alterations in the light regime and investigated whether starch-free mutants of Arabidopsis thaliana show decreased growth potential at an early developmental stage. Leaf area and relative growth rate were measured based on pictures from a camera automatically placed above an array of 120 seedlings. Detection of total seedling leaf area was performed via global segmentation of colour images for preset thresholds of the parameters hue, saturation and value. Dynamic acclimation of relative growth rate towards altered light conditions occurred within 1 d in N. tabacum exposed to high nutrient availability, but not in plants exposed to low nutrient availability. Increased leaf area was correlated with an increase in shoot fresh and dry weight as well as root growth in N. tabacum. Relative growth rate was shown to be a more appropriate parameter than leaf area for detection of dynamic growth acclimation. Clear differences in leaf growth activity were also observed for A. thaliana. As growth responses are generally most flexible in early developmental stages, the procedure described here is an important step towards standardized protocols for rapid detection of the effects of changes in internal (genetic) and external (environmental) parameters regulating plant growth.

Total synthesis of optically active cotylenol, a fungal metabolite having a leaf growth activity. Intramolecular ene reaction for an eight-membered ring formation

Starting from condensation of two iridoid synthons, (3 S,8 R)-benzyloxy-1-iriden-7-al and (3 R)-7-chloro-1-iridene, cotylenol, one of the representative fusicoccane diterpenoids having 5-8-5-membered tricyclic carbon framework, is now synthesized for the first time via an eight-membered ring formation by an intramolecular ene reaction and subsequent introduction of an α-hydroxyl group.

ChemInform Abstract: Total Synthesis of (‐)‐Cotylenol, a Fungal Metabolite Having Leaf Growth Activity.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Total Synthesis of (−)-Cotylenol, a Fungal Metabolite Having a Leaf Growth Activity

Abstract Cotylenol, one of the representative fusicoccane diterpenoids having 5-8-5-membered tricyclic carbon framework, is now synthesized for the first time via an eight-membered ring formation by an intramolecular ene reaction followed by an oxidative formation of the 8β,9α-glycol function on the central eight-membered ring.

アサツキの生長力の季節的変動と休眠

Asatsuki is a bulbous Allium species and is cultivated for its edible leaves, which are harvested in late winter and early spring. Asatsuki grows from autumn to spring and dies down after producing dormant bulbs in early summer.Innate dormancy of roots of asatsuki bulbs ended in early July, and that of leaves in early August. However, hot summer temperatures of 25°Cor higher inhibited rooting and sprouting of the bulbs in the field, so that the bulbs rooted from early August onwards and sprouted from late August onwards.Optimum temperatures for root growth after rooting were 21 to 25°C, and those for leaf growth after sprouting were 17 to 25°C.After termination of innate dormancy, root growth activity (which comprises rooting and root elongation after rooting) and leaf growth activity increased gradually; the former reached a maximum in late August and the latter in mid-September. Asatsuki plants grew vigorously in September and early October. During this period the mean air temperatures are close to the optimum temperatures for growth.After reaching their maxima, both growth activities decreased; root growth activity reached a minimum in mid- or late October and leaf growth activity in mid- or late November. Thus, growth was suspended in late autumn. In early or mid-December root growth activity began to increase again and in early January leaf growth activity began to increase again. Root growth activity reached a maximum in February and leaf growth activity in mid-March. In late January some plants initiated storage leaf primordia, but the plants appeared to be in a state of imposed dormancy until early spring.Roots resumed growth in, late March but in mid-April rooting activity was lost and there was no increase in root weight per plant from mid-April onwards. Leaves resumed slow growth in early or mid-March, but vigorous growth of leaves did not occur until after the continuous snow cover had melted off (in early April). Leaf growth activity almost ceased in late May, and growth of tops ceased in late May. All storage leaf primordia were initiated by mid-April and those developed into cloves. The cloves grew rapidly from mid-April to mid-June. Browning of tops and dying of roots progressed rapidly from mid-June onwards, so that tops had almost died down by late June.Leaf and root growth activities varied considerably from month to month (except for the dormant summer months). Growth activities became extremely low during late autumn and early winter, and asatsuki plants hardly grew at any temperatures between 9 and 25°C, showing that the plants were in the state of innate dormancy. Accordingly, it is concluded that asatsuki plants fall into innate dormancy twice a year, both in summer and in late autumn or early winter. However, the late autumn (or early winter) dormancy was not so deep as the summer dormancy. It is assumed that cool temperatures in October induced the late autumn dormancy in asatsuki plants.

Synthesis of Isokinetin, 2-N-furfurylaminopurine and its Leaf-growth Activity (Studies of Isokinetin and its Analogs. Part I)

Synthesis of Isokinetin, 2-N-furfurylaminopurine and its Leaf-growth Activity (Studies of Isokinetin and its Analogs. Part I)