Effect Of Different Light Regimes Research Articles

Arabidopsis callus grafts: a system to study symplasmic intercellular macromolecular transport and gene silencing spread.

In the present study, we present callus grafting, comprising a method for reproducibly generating tissue chimeras from callus cultures of Arabidopsis thaliana. In this way, callus cultures of different genetic backgrounds may be co-cultivated such that cell-to-cell connectivity is achieved as a chimeric tissue is formed. To track intercellular connectivity and transport between non-clonal callus cells, we used transgenic lines expressing fluorescently tagged mobile and non-mobile fusion constructs. Using fluorescently-labelled reporter lines that label plasmodesmata, we show that secondary complex plasmodesmata are present at the cell walls of connected cells. We use this system to investigate cell-to-cell transport across the callus graft junction and show that different proteins and RNAs are mobile between non-clonal callus cells. Finally, we take advantage of the callus culture system to probe intercellular connectivity of grafted leaf and root calli and the effect of different light regimes of cell-to-cell transport. Taking advantage of the ability of callus to be cultivated in the complete absence of light, we show that the rate of silencing spread is significantly decreased in chimeric calli cultivated in total darkness. We propose that callus grafting is a fast and reliable method for analysing the capacity of a macromolecule to be exchanged between cells independent of the vasculature.

Contrasting effects of different light regimes on the photoreactivities of allochthonous and autochthonous chromophoric dissolved organic matter

Chromophoric dissolved organic matter (CDOM) plays an important role in ultraviolet (UV) light absorption in the ocean. CDOM is known to originate from either an allochthonous or autochthonous source and has varying compositions and levels of reactivity; however, the effects of individual radiation treatments and the combined effects of UVA and UVB on allochthonous and autochthonous CDOM remain poorly understood. Thus, here, we measured changes in the common optical properties of CDOM collected from China's marginal seas and the Northwest Pacific, using full-spectrum, UVA (315–400 nm), and UVB (280–315 nm) irradiation to induce photodegradation over the same time period (60 h). Excitation–emission matrices (EEMs) combined with parallel factor analysis (PARAFAC) identified four components: marine humic-like C1, terrestrial humic-like C2, soil fulvic-like C3, and tryptophan-like C4. Although the behaviours of these components during full-spectrum irradiation exhibited similar decreasing tendencies, three components (C1, C3, and C4) underwent direct photodegradation under UVB exposure, whereas C2 was more susceptible to UVA degradation. The diverse photoreactivities of the source-dependent components to different light treatments led to differing photochemical behaviours of other optical indices [aCDOM(355), aCDOM(254), SR, HIX, and BIX]. The results indicate that irradiation preferentially reduced the high humification degree or humic substance content of allochthonous DOM, and promoted the transformation from the allochthonous humic DOM components to recently produced components. Although values for the samples from different sources overlapped frequently, principal component analysis (PCA) indicated that the overall optical signatures could be linked to the original CDOM source features. The degradation of CDOM humification, aromaticity, molecular weight, and autochthonous fractions under exposure can drive the CDOM biogeochemical cycle in marine environments. These findings can aid in a better understanding of the effects of different combinations of light treatments and CDOM characteristics on CDOM photochemical processes.

Effects of different light regimes on Dunaliella salina growth and β-carotene accumulation

Outdoor cultivations of microalgae for commercial scale production usually rely on natural sunlight following ‘Sine’ regime, but most lab scale studies adopt ‘Block’ or ‘Continuous’ regimes, leading to poor prediction of outdoor cultivation results. To fill this gap on β-carotene production by Dunaliella salina, the effects of light regimes (‘Block’, ‘Sine’, ‘Continuous’) on cell growth and β-carotene accumulation in D. salina were investigated in this study. The results showed significant difference between these regimes. When receiving the same amount of illumination, ‘Sine’ mode inferred 10–55% higher biomass yield and 31–58% higher β-carotene yield than those under the ‘Block’ mode. The biomass concentration, as well as protein and total fatty acid (TFA) content, has no significant difference between different light regimes, but the starch content in the ‘Continuous’ light regime was higher than that of ‘Sine’ and ‘Block’ regime. β-carotene accumulation under ‘Continuous in summer’ and ‘Simulated diurnal irradiance in summer’ regimes were correlated with increase (C18:1, C18:2) and decrease (C16:4, C18:3) of specific fatty acids (FAs) contents, rather than TFA content. Meanwhile, it was found that β-carotene accumulation was correlated with periodical Fv/Fm fluctuations under different light regimes, and indicate that exposure to periodical strong light is more favorable for β-carotene accumulation, rather than continuous light. These results indicated the significance of using ‘Sine’ light regime since it not only provided better predictions on outdoor production, but also helpful for increase biomass and β-carotene productivities.

Morphometric characteristics of the ventrolateral preoptic nucleus of the hypothalamus of mature rats under modification of the photoperiod

The aim of the study is to investigate the effect of different light regimes and melatonin on the morphometric characteristics of the ventrolateral preoptic (anterior-lateral preoptic) nucleus of the hypothalamus of mature rats.Material and methods. The experiments were performed on 28 white non-linear male rats. Animals in the first series were under normal light conditions. Animals of the second series were under light deprivation. The rats of the third series were under light stimulation. The fourth series were rats under light stimulation and intraperitoneally injection of melatonin (Sigma, USA) at a dose of 0.5 mg/ kg of body weight. Morphological analysis of neurons was performed using a LUMAM-8 microscope.Results. The asymmetric location of ventrolateral preoptic nuclei of the hypothalamus in the cerebral hemispheres has been revealed. The nucleus on the sections had a spherical or oval shape, and the neurons were the same in the center and periphery of the nucleus. The morphometric data indicate that in the studied parameters (average neurocyte volume, average neurocyte nucleus volume, the nuclear-cytoplasmic ratio in neurocytes, and average neurocyte count in the standard histological slice plane), no clear differences were observed in the mean trends.Conclusions. The histological examinations indicate that the studied parameters do not respond to the light conditions and time of day when the corresponding experimental conditions were simulated.

Influence of the photoperiod and light intensity on growth performance, Melatonin and Insulin-like growth factors gene expression on Acipenser persicus during the embryonic stage

The effects of different light regimes (24L: 0D, 150 lux, 12L: 12D, 300lux, 0L: 24D, 0 lux, and control treatment) on growth, melatonin concentration, and Insulin-like growth factors gene expression of Persian sturgeon (Acipenser persicus) embryos were evaluated. Four groups of Persian sturgeon eggs (450 g) were incubated in Youshchenkov[X1] incubators with three replications for each treatment. The experiment was conducted during an 8- day period of incubation. Growth rate, plasma melatonin levels, and IGF-growth factors were investigated at 1, 4, and 8 days post fertilization. Results showed that higher mean weights growth were observed in fertilized eggs exposed to a 24L: 0D photoperiod with 150lux light intensity (p<0.05). The larval body length and hatching rate of fertilized eggs were significantly higher in embryos incubated at 12L: 12D with 300lux. The melatonin hormone level between sampling days and treatments were significantly different and it would be concluded that it may be related to the species. During the first-day post fertilization, the IGF-I and IGF-IR gene expression were significantly higher than other days. However, IGF-I and IGF-IR gene expression at different treatments showed no significant difference at day 4 and 8 post fertilization. According to the results, the stimulating role of IGF-I and IGF-IR gene expression in growth at the one-day post fertilization under different light regimes can be concluded. These findings suggest that the 12L:12D photoperiod with 300lux light intensity is the appropriate light regime for Persian sturgeon eggs incubation. The results of the present study would provide fundamental information for further use of light regimes during the early development of sturgeon larvae to optimize rearing protocols in sturgeon hatcheries.

The Light Regime Effect on Triacylglycerol Accumulation of Isochrysis zhangjiangensis

Stress state of microalgal cells is caused under unfavorable conditions such as disordered light regime and depleted nitrogen. The stress state can impair photosynthetic efficiency, inhibit cell growth and result in the accumulation of triacylglycerol (TAG) from protective mechanisms. Continuous light or nitrogen starvation was applied on microalgae and performed effectively on inducing TAG production. To evaluate the light regime effect on inducing TAG production, the effect of different light regimes on nitrogen-starved Isochrysis zhangjiangensis was investigated in this work. The continuous light and nitrogen starvation elevated TAG content of biomass by 73% and 193%, respectively. Furthermore, the TAG accumulation of I. zhangjiangensis cell under nitrogen starvation decreased under aggravated stress from continuous illumination. Our results demonstrated that culturing the cells with 14L: 10D light regime under nitrogen starvation is the optimal mode to achieve maximal accumulation of TAG. A recovery in light regime was necessary for I. zhangjiangensis cultivation.

LED lighting affects the composition and biological activity of Cannabis sativa secondary metabolites

Growth conditions are expected to alter the relative and absolute content of the hundreds of phytochemicals produced by Cannabis sativa L.; some of these possess biological activity on the human body. However, relatively little information exists regarding the effects of different light regimes on the composition of C. sativa secondary metabolites and thus on their biological activity. In this study, we investigated how light quality influences the production and final content of secondary metabolites, as well as their bioactive properties. Toward these, plant growth and blooming were carried out at different illumination conditions, utilizing light-emitting diode (LED) fixtures vs. conventional fluorescent and high-pressure sodium (HPS) lamps as controls. Inflorescences were sampled at different time points along the blooming; extract compositions were analyzed by HPLC and GC/MS, and the biological activity of the extracted material was assessed using cell viability assays. We found that growth and blooming under LED illumination considerably changed shoot architecture and inflorescence mass. Moreover, the content of cannabinoids, terpenes, and alkanes were altered in the inflorescences of LED-grown plants during the flowering period as well as in the harvested flowers. In particular, significantly higher quantities of cannabigerolic acid accumulated in the inflorescences that flowered under LED fixtures, with a cannabigerolic acid to Δ9-tetrahydrocannabinolic acid (CBGA:THCA) ratio of 1:2 as opposed to 1:16 when grown under HPS. Notably, the cytotoxic activities of extracts derived from plants grown under the different illumination regimes were different, with extracts from LED-grown plants possessing higher cytotoxicity along the flowering stage. Our results thus indicate that the transition to indoor growth of C. sativa under LED lighting, which can have significant impacts on cannabinoid and terpene content, and also on the bioactive properties of the plant extracts, should proceed with thorough consideration.

The effect of different light regimes on pigments in Coscinodiscus granii.

The influence of six different light regimes throughout the photosynthetically active radiation range (from 400 to 700nm, including blue, green, yellow, red-orange, red, and white) at two intensities (100 and 300µmolphotonsm-2s-1) on pigmentation was assessed for the centric marine diatom Coscinodiscus granii for the first time. Chlorophyll (Chl) a and fucoxanthin were the dominating pigments in all treatments. The cellular concentrations of light harvesting pigment (Chl a, Chl c1 + c2, and fucoxanthin) were higher at 100 than at 300µmolphotonsm-2s-1 at all wavelengths, with the largest increases at red and blue light. The normalized concentrations of photoprotective pigments (violaxanthin, zeaxanthin, diadinoxanthin, and diatoxanthin) were higher at high light intensity than in cells grown at low light intensity. An increase in β-carotene in low light conditions is expected as the increased Chl a was related to increased photosynthetic subunits which require β-carotene (bound to photosystem core). At 300µmolphotonsm-2s-1, yellow light resulted in significantly lower concentration of most of the detected pigments than the other wavelengths. At 100µmolphotonsm-2s-1, W and B light led to statistically lower and higher concentration of most of the detected pigments than the other wavelengths, respectively.

The effect of different light regimes on diatom frustule silicon concentration

Significant changes in frustule morphology of Coscinodiscus granii induced by different light regimes have previously been observed, but whether these changes are companied by similar changes in cellular silicon concentration or are solely due to reorganization is unknown. The influence of six different light regimes, blue (B), green (G), yellow (Y), red-orange (RO), red (R) and white (W), at two intensities (100 and 300μmolphotonsm−2s−1) on cellular silicon content was therefore assessed for C. granii. Both the cellular Si content and the Si concentration per surface area were higher at 300 than at 100μmolphotonsm−2s−1 for all tested wavelengths, except Y light. At the same light intensity, cells grown at B light had the highest cellular Si content (except W at 300μmolphotonsm−2s−1) and Si concentration per surface area. At R, OR, G, B and W light, high intensity led to higher cellular Si content although the mean frustule size was smaller (opposite for Y light). As the higher Si content was not due to a larger cell size, we hypothesize that the effect is due to changes in valve thickness. The underlying adaptive significance of this phenomenon might be that at low irradiance (100μmolphotonsm−2s−1), diatom buoyancy is modulated by accumulating less silicon in the cells, as the less silicified cells may have lower sinking rate and thus remain longer at the higher light in the upper part of the water column, which could partly contribute to the ecological success of the diatom.

&lt;b&gt;Shading effects on leaf life span and functional traits in the widespread species &lt;i&gt;Enterolobium contortisiliquum&lt;i&gt; (Vell.) Morong

Enterolobium contortisiliquum occurs in native forests formations from southeast to northeast Brazil, and too in Argentina, Bolivia and Paraguay. The objective of this study was to evaluate shading effects in the early growth of E. contortisiliquum plants. We measured leaf gas exchange, chlorophyll content index, biomass allocation and leaf development in plants in sunny and shaded areas. The experiment was performed in Universidade Federal de Vicosa , campus Florestal, Minas Gerais, Brazil. To determine the effects of different light regimes (full sunlight and shade) on the growth of E. contortisiliquum plants, we divided plants into two groups: plants grown in a greenhouse under full sunlight, and plants grown under 70% shade tissue. E. contortisiliquum plants grown in full sunlight showed an increase in maximum net photosynthesis, root, stem, and leaf dry mass, root length, root/stem ratio, and length of the stem. However, E. contortisiliquum under shade showed larger specific leaf area, leaf area ratio, chlorophyll content, long leaf life span, and slow growth. These ecophysiological adjustments in sunny and shaded areas may explain the wide geographical distribution of E. contortisiliquum in many vegetation types.

&lt;b&gt;Light regime and temperature on seed germination in &lt;i&gt;Salvia hispanica&lt;/i&gt; L.

This study evaluated the effects of different light regimes and temperatures on the germination of S. hispanica seeds and used a factorial scheme in a completely randomized experimental design, in which three light conditions were combined with six temperatures (constant 20, 25, 30 and 35°C and alternating 20-30 and 25-30°C), totaling 18 treatments with four 50-seed replications. The seeds were sown on blotting paper in transparent plastic boxes and then allowed to germinate in Biochemical Oxygen Demand germinators. The seeds were evaluated over a period of eight days with respect to the following variables: germination percentage, average germination time, shoot and root lengths, shoot and root dry weights and root-shoot ratio. The data were submitted to Tukey's test (p ≤ 0.05%). The S. hispanica seed (beige colored) germination test can be carried out at constant (25°C) or alternating (25-30°C) temperatures. The germination of the seeds was indifferent to the light conditions evaluated; however, there was increased seedling growth and dry matter accumulation in the presence of light. The duration of the S. hispanica seed germination test can be five days, with the first count on the second day after sowing.

Short-day signals are crucial for the induction of anthocyanin biosynthesis in Begonia semperflorens under low temperature condition

The leaves of Begonia semperflorens accumulate anthocyanins and turn red in autumn in sub-temperate areas. This induction of anthocyanin biosynthesis in autumn has been attributed to the effects of low temperature, but the effects of different light regimes on this process are still being debated. In the present work, short days were found to be necessary for anthocyanin biosynthesis at low temperature. Under the same low-temperature conditions, Begonia seedlings grown under the short-day condition accumulated more carbohydrates and abscisic acid (ABA), which both induce anthocyanin biosynthesis. However, fewer carbohydrates and more gibberellin (GA) accumulated under the long-day conditions to maintain growth, which blocked anthocyanin biosynthesis and resulted in a lack of increases in the activities of dihydroflavonol 4-reductase (DFR) and flavonoid-3-O-glucosyl transferase (UFGT). Consequently, carbon flux, which was altered due to the blockade of anthocyanin synthesis, was channelled into the production of quercetin and phenolic acids but not lignin.

Effect of different light regimes on fitness of two species of Drosophila montium subgroup

Most organisms possess “biological chronometers” in the form of circadian clocks. Organism possessing circadian clock gains fitness advantage in two ways, by synchronizing its behavior through physiological process and secondly by coordinating its internal metabolic process. Environmental manipulations of circadian clocks have been shown to affect many life-history-related traits. Life-history traits are important components of fitness. To enhance individual fitness, organism has to synchronize the physiology with the surrounding environment. The present investigations were made to understand whether rhythm changes affect fitness of two co-existing species of montium a subgroup of Drosophila. The stocks were maintained at 20 ± 1 °C with 75% RH. Fitness such as fecundity, male lifetime fertility, female lifetime fertility, and longevity was assessed in LD (light/dark), LL (continuous light), and DD (continuous dark) for 15 and 30th generations. Fecundity was assessed in 25 pairs of flies for 20 days, and fertility and longevity was assessed in 10 pairs of flies until lifetime. The result revealed differential effect of light regimes on the two different species of Drosophila. Although the two species are related, effect of the three light regimes, LD, LL, and DD on them was different. It is evident that these two species although genetically related exhibit different responses to different light regimes.

Effect of different light regimes on esterase isozyme profiles of three species of Drosophila

Circadian rhythm has been identified in every organism studied, from unicellular marine algae to man, and in virtually all physiological and biochemical functions. The endogenous circadian system functions to organize behaviour and physiology to adapt to and anticipate environment changes in light and temperature. The present study is an attempt to understand enzyme profiles (alpha and beta esterases) of Drosophila melanogaster (Oregon-K strain), Drosophila gangotrii and Drosophila jambulina under light/dark (LD), continuous light (LL) and continuous dark (DD) conditions over 30 generations. A polyacrylamide gel electrophoresis (7.5% – native gel) was used to study the esterase isozyme banding patterns in three species of Drosophila. It has been noticed that there were three alpha esterase loci in Drosophila species which were designated as α-est 1, α-est 2 and α-est 3. Similarly there were three beta esterase loci which were designated as β-est 1, β-est 2 and β-est 3. Flies maintained in different light regimes showed differences in their allelic patterns with respect to alpha and beta esterases. It was observed that there was expression of some bands at a given light regime and the absence of the same in another regime. This shows that the different light regimes affect the expression of esterase isozymes.

Effect of different light regimes on the maturational progress of the whitespotted rabbitfish ( Siganus sutor )

In this study, the effects of different light regimes on the reproductive activity of a typical IndoPacific coral reef rabbitfish, Siganus sutor , were evaluated. Forty- five adult fish were exposed to nine different photoperiod (8L: 16D, 12L: 12D, 16L: 8D) and light intensity (1000, 2000, 3000 lux) combinations with three replicates and five other fishes reared under indoor light condition (Control). Gonadosomatic Index (GSI) and Hepatosomatic Index (HSI) were calculated after 60 days and compared among different experimental regimes in males and females. In the control group, GSI and HSI mean values were 4.67 and 3.24%, respectively, for females and 10.05 and 2.10%, respectively, for males, and these fish showed differences in comparison with the exposed fish. Females kept under 1000 and 2000 lux light intensities had a higher GSI mean value (9.26 and 10.39%, respectively) and also lower average HSI (2.10 and 2.31%, respectively) in 16L: 8D treatment. A similar result was also obtained for males, whereas the 3000 lux light intensity, 8L: 16D day length combination led to more gonadal development (GSIs of 16.41% in females and 12.03% in males). A comparison of results among different photoperiods also confirmed that maturation was induced better in fish maintained under 16L: 8D in both sexes. This investigation revealed the visible role of both photoperiod and light intensity on inducing maturity in the whitespotted rabbitfish, S. sutor . Thus, rearing of adults exposed to an artificial light regime, including 16L: 8D and 2000 lux light intensity, promotes more gonadal development than that occurring in the wild.

Resting Egg Production and Fatty Acid Enhancement in the Waterflea, Ceriodaphnia quadrangula, by Using Combination of Light Regime and Food

AbstractCombined effects of different light regimes, 6L:6D and 12L:12D (hours light : hours dark, L:D) and algal foods of Scenedesmus quadricauda (S) and Chlorella vulgaris (C) on ephippia production and fatty acid (FA) profile of Ceriodaphnia quadrangula were investigated. The highest resting egg production, density, and specific growth rate were obtained with 6L:6D+S; followed by 12L:12D+S treatment. The C16:0 varied from 16.2 to 22.16 mg/g dry weight (d.w.); C18:1n−9 from 11.03 to 14.94 mg/g d.w; C18:2n−6 from 9.79 to 20.24 mg/g d.w; and C18:3n−3 from 6.98 to 16.02 mg/g d.w. The amounts of C20:4n−6 (4.36 mg/g d.w) and C20:5n−3 (3.35 mg/g d.w) at 6L:6D+S were highest compared to other treatments. The maximum saturated fatty acids and monounsaturated fatty acids were obtained at 6L:6D+C while maximum polyunsaturated fatty acids observed at 6L:6D+S and 12L:12D+C. The resting egg production and FAs profile could be improved when the frequency of changes from light to dark were increased. Our findings also indicate a significant increase in the quantity of C18:3n−3 in C. quadrangula populations during resting egg formation, hence, implying that manipulation of light regime and algal food can improve performance of C. quadrangula as a live food in aquaculture industries, especially for larval feeding.

Effects of different light/dark regimes and algal food on growth, fecundity, ephippial induction and molting of freshwater cladoceran, Ceriodaphnia quadrangula

Combined effects of different light regimes and algal foods on population growth, ephippia (resting eggs) production, fecundity, molting and body size of Ceriodaphnia quadrangula were investigated. Four light/dark regimes in combination with two algal diets of Scenedesmus quadricauda (S) and Chlorella vulgaris (C) namely: 4L: 4D+S, 6L: 6D+S, 8L: 8D+S, 12L: 12D+S, 4L: 4D+C, 6L: 6D+C, 8L: 8D+C, and 12L: 12D+C were assigned to present study. The highest population density and growth rate were obtained at 12L:12D+C (1860 ind/l and 0.29/day) and 6L:6D+C (1760ind./l and 0.28/day), which were significantly different from other treatments (p<0.05). Ephippium production was affected by light/dark period, decreasing with increasing light duration when fed on S. quadricauda and increasing when fed C. vulgaris. Although the ephippium was observed at all treatments, significantly higher ephippium (285 eggs/l) were recorded at 4L:4D+S (p<0.05). Fecundity ranged between 0.67 and 3.00/female/day, with the lowest value occurring at 4L:4D+S and the highest at 6L:6D+S. The molting rate was significantly (p<0.05) different among the various treatments. The range of molting was 1.59–8.43/female/week, lowest at 4L:4D+C and the highest with 12L:12D+S. Based on our results, 12L:12D+S is recommended for growth and molting, and 4L:4D+S for ephippium production in C. quadrangula.

Effect of different light regimes on eclosion rhythm of Drosophila agumbensis and Drosophila nagarholensis

An endogenous control of timing of many events like oviposition, eclosion, and hatching occurs at a particular time of the day, which enhances the survival of an organism. The present study is an attempt to understand the effect of different light regimes on eclosion rhythm of Drosophila agumbensis and Drosophila nagarholensis. The eclosion rhythm of the two species were analyzed under constant conditions such as continuous light (LL), continuous dark (DD), and 12-h light and 12-h dark condition. Eclosion occurred only during morning period. The peak of eclosion was observed during 10 h in the morning in all the three light regimes of both the species in 10th and 20th generation. Analysis of variance revealed that there is a significant difference in the eclosion between light/dark, DD, and LL condition and Student t test revealed that there is no significant difference between the two species.

Adaptive significance of circadian rhythms of montium a subgroup of Drosophila: I – locomotor behaviour

The rest/activity rhythm is an innate ubiquitous and complex biological phenomenon. It is essential/crucial for an organism's survival such as feeding, mate choice, escape from the predator, etc. Studies have shown that locomotor behaviour is sensitive to environment. The present investigations were made to understand the effect of different light regimes on locomotor behaviour of the two co-existing species of montium, a subgroup of Drosophila. Locomotor activity rhythms were assayed using Drosophila Activity Monitor. The activity of two species was analyzed in light/dark (LD), continuous dark (DD) and continuous light (LL) for 15th and 30th generations and the amount of activity was measured. The results revealed that the mean activity recorded for D. gangotrii and D. jambulina was significant. Unlike that of Drosophila melanogaster, these species entrain to LD, arrhythmic in LL and free runs in DD. Activity was either unimodal or bimodal. There was tremendous reduction in the activity in 30th generation flies compared to the 15th generation ones. Interestingly, period (τ) in all the groups was approximately 24 h.

Differential regulation of two sucrose transporters by defoliation and light conditions in perennial ryegrass

Sucrose transport between source and sink tissues is supposed to be a key-step for an efficient regrowth of perennial rye-grass after defoliation and might be altered by light conditions. We assessed the effect of different light regimes (high vs low light applied before or after defoliation) on growth, fructans and sucrose mobilization, as well as on sucrose transporter expression during 14 days of regrowth. Our results reported that defoliation led to a mobilization of C reserves (first sucrose and then fructans), which was parallel to an induction of LpSUT1 sucrose transporter expression in source and sink tissues (i.e. leaf sheaths and elongating leaf bases, respectively) irrespective to light conditions. Light regime (high or low light) had little effects on regrowth and on C reserves mobilization during the first 48 h of regrowth after defoliation. Thereafter, low light conditions, delaying the recovery of photosynthetic capacities, had a negative effect on C reserves re-accumulation (especially sucrose). Surprisingly, high light did not enhance sucrose transporter expression. Indeed, while light conditions had no effect on LpSUT1 expression, LpSUT2 transcripts levels were enhanced for low light grown plants. These results indicate that two sucrose transporter currently identified in Lolium perenne L. are differentially regulated by light and sucrose.