Maize cryptochromes 1a1 and 1a2 promote seedling photomorphogenesis and shade resistance in Zea mays and Arabidopsis

Maize growth and development are regulated by light quality,intensity and photoperiod.Cryptochromes are blue/ultraviolet-A light receptors involved in stem elongation,shade avoidance,and photoperiodic flowering.To investigate the function of cryptochrome 1(CRY1) in maize,where it is encoded by Zm CRY1,we obtained two Zm CRY1a genes(Zm CRY1a1 and Zm CRY1a2),both of which share the highest similarity with other gramineous plants,in particular rice CRY1a by phylogenetic analysis.In Arabidopsis,overexpression of Zm CRY1a genes promoted seedling de-etiolation under blue and white light,resulting in dwarfing of mature plants.In seedlings of the maize inbred line Zong 31(Zm CRY1aOE),overexpression of Zm CRY1a genes caused a reduction in the mesocotyl and first leaf sheath lengths due to down-regulation of genes influencing cell elongation.In mature transgenic maize plants,plant height,ear height,and internode length decreased in response to overexpression of Zm CRY1a genes.Expression of Zm CRY1a were insensitive to low blue light(LBL)-induced shade avoidance syndrome(SAS) in Arabidopsis and maize.This prompted us to investigate the regulatory role of the gibberellin and auxin metabolic pathways in the response of Zm CRY1a genes to LBL treatment.We confirmed a link between Zm CRY1a expression and hormonal influence on the growth and development of maize under LBL-induced SAS.These results reveal that Zm CRY1a has a relatively conservative function in regulating maize photomorphogenesis and may guide new strategies for breeding high density-tolerant maize cultivars.

Jiao-tai-wan Up-regulates Hypothalamic and Peripheral Circadian Clock Gene Cryptochrome and Activates PI3K/AKT Signaling in Partially Sleep-deprived Rats

This study aims to explore the effect and mechanism of Jiao-tai-wan （JTW） on systemic and tissue-specific inflammation and insulin resistance in obesity-resistant （OR） rats with chronic partial sleep deprivation （PSD）. OR rats with PSD were orally given JTW and Estazolam for 4 weeks. The amount of food intake and metabolic parameters such as body weight increase rate, fasting plasma glucose （FPG）, fasting insulin （FINS）, homeostasis model assessment-insulin resistance （HOMA-IR） and plasma inflammatory markers were measured. The expression levels of circadian proteins cryptochrome 1 （Cryl） and cryptochrome 2 （Cry2） in hypothalamus, adipose and liver tissues were also determined. Meanwhile, the mRNA expression of inflammatory markers, activity of nuclear factor kappa B （NF-κB） p65 protein, as well as the expression levels of insulin signaling pathway proteins in hypothalamus, adipose and liver tissues were measured. Additionally, cyclic adenosine 3＇, 5＇-monophosphate （cAMP） and activity of vasodilator-stimulated phosphoprotein （VASP） in hypothalamus tissue were measured. JTW significantly decreased the body weight increase rate and food intake, ameliorated systemic inflammation and insulin resistance. JTW effectively ameliorated inflammation and increased PI3K/AKT signaling activation in hypothalamus, adipose and liver. Interestingly, all these changes were associated with the up-regulation of circadian gene Cryl and Cry2 protein expression. We also found that in hypothalamus tissue of PSD rats, down-regulation of Cryl and Cry2 activated cAMP/PKA signaling and then led to inflammation, while JTW inhibited this signaling. These results suggested that JTW has the beneficial effect on ameliorating inflammation and insulin resistance in partially sleep-deprived rats by up-regulating Cry expression.

The dual-action mechanism of Arabidopsis cryptochromes

Photoreceptor cryptochromes (CRYs) mediate blue-light regulation of plant growth and development. It has been reported that Arabidopsis CRY1and CRY2 function by physically interacting with at least 84 proteins, including transcription factors or co-factors, chromatin regulators, splicing factors, messenger RNA methyltransferases, DNA repair proteins, E3 ubiquitin ligases, protein kinases and so on. Of these 84 proteins, 47 have been reported to exhibit altered binding affinity to CRYs in response to blue light, and 41 have been shown to exhibit condensation to CRY photobodies. The blue light-regulated composition or condensation of CRY complexes results in changes of gene expression and developmental programs. In this mini-review, we analyzed recent studies of the photoregulatory mechanisms of Arabidopsis CRY complexes and proposed the dual mechanisms of action, including the “Lock-and-Key” and the “Liquid-Liquid Phase Separation (LLPS)” mechanisms. The dual CRY action mechanisms explain, at least partially, the structural diversity of CRY-interacting proteins and the functional diversity of the CRY photoreceptors.

Knockout of cryptochrome 1 disturbs the locomotor circadian rhythm and development of Plutella xylostella

Cryptochrome 1(CRY1)functions as a light-responsive photoreceptor,which is crucial for circadian rhythms.The identity and function of CRY1 in Plutella xylostella remain unknown.In this study,cryl was cloned and identified in P xylostella.Then,a cry1-knockout strain(Cry1-KO)of P xylostella with a 2-bp deletion was established from the strain Geneva 88(G88)using the CRISPR/Cas9 technology.No daily temporal os-cillation of cryl was observed in G88 and Cry1-KO,and cryl mean daily transcription of Cry1-KO was lower than that of G88.Both G88 and Cry1-KO demonstrated rhythmic locomotion under the light/dark condition with Cryl-KO being more active than G88 in the daytime,whereas Cry1-KO completely lost rhythmicity under constant darkness.The developmental period of pre-adult of Cry1-KO was longer than that of G88;the lifespan of the Cry1-KO male adult was shorter than that of G88;the fecundity of Cry1-KO was lower than that of G88;and Cry1-KO showed lower intrinsic rate of increase(r),net repro-duction rate(Ro),finite increase rate(a),and longer mean generation time(T)than G88.Our results indicate that cryl is involved in the regulation of locomotor circadian rhythm and development in P xylostella,providing a potential target gene for controlling the pest and a basis for further investigation on circadian rhythms in lepidopterans.

CRYPTOCHROME 1 Is Implicated in Promoting R Protein-Mediated Plant Resistance to Pseudomonas syringae in Arabiclopsis

Plants have evolved complex mechanisms to defend themselves against pathogens. It has been shown that several defense responses are influenced by light, and the red/far-red light photoreceptor phytochromes （PHY） modulate plant defense responses in Arabidopsis. Blue light receptor cryptochromes （CRY） work together with PHY to regulate many light-controlled responses, including photomorphogenesis, floral induction, and entrainment of the circadian clock. We report here that the Arabidopsis blue light photoreceptor CRY1 positively regulates inducible resistance to Pseudomonas syringae under continuous light conditions. By challenging plants with R syringae pv. tomato （Pst.） DC3000 carrying avrRpt2, we demonstrate that effector-triggered local resistance is down-regulated in the cry1 mutant, leading to more pathogen multiplication. In plants overexpressing CRY1 （CRYl-ovx）, however, local resistance is significantly up-regulated. We also show that systemic acquired resistance （SAR） is positively regulated by CRY1, and that salicylic acid （SA）-induced pathogenesis-related gene PR-1 expression is reduced in the cry1 mutant, but enhanced in CRYl-ovx plants. However, our results in- dicate that CRY1 only modestly influences SA accumulation and has no effect on hypersensitive cell death. These results suggest that CRY1 may positively regulate R protein-mediated resistance to P. syringae with increased PR gene expression.

Strigolactone-Regulated Hypocotyl Elongation Is Dependent on Cryptochrome and Phytochrome Signaling Pathways in Arabidopsis

Seedling development including hypocotyl elongation is a critical phase in the plant life cycle. Light regula- tion of hypocotyl elongation is primarily mediated through the blue light photoreceptor cryptochrome and red/far-red light photoreceptor phytochrome signaling pathways, comprising regulators including COP1, HY5, and phytochrome- interacting factors （PIFs）. The novel phytohormones, strigolactones, also participate in regulating hypocotyl growth. However, how strigolactone coordinates with light and photoreceptors in the regulation of hypocotyl elongation is largely unclear. Here, we demonstrate that strigolactone inhibition of hypocotyl elongation is dependent on cryp- tochrome and phytochrome signaling pathways. The photoreceptor mutants cry1 cry2, phyA, and phyB are hyposensi- tive to strigolactone analog GR24 under the respective monochromatic light conditions, while cop1 and pifl pif3 pif4 pif5 （pifq） quadruple mutants are hypersensitive to GR24 in darkness. Genetic studies indicate that the enhanced respon- siveness of cop1 to GR24 is dependent on HY5 and MAX2, while that of pifq is independent of HY5. Further studies demonstrate that GR24 constitutively up-regulates HY5 expression in the dark and light, whereas GR24-promoted HY5 protein accumulation is light- and cryptochrome and phytochrome photoreceptor-dependent. These results suggest that the light dependency of strigolactone regulation of hypocotyl elongation is likely mediated through MAX2-dependent promotion of HY5 expression, light-dependent accumulation of HY5, and PIF-regulated components.

Photoexcited CRYPTOCHROME 1 Interacts Directly with G-Protein 13 Subunit AGB1 to Regulate the DNA-Binding Activity of HY5 and Photomorphogenesis in Arabidopsis

Light and the heterotrimeric G-protein are known to antagonistically regulate photomorphogenesis in Arabidopsis. However, whether light and G-protein coordinate the regulation of photomorphogenesis is largely unknown. Here we show that the blue light photoreceptor cryptochrome 1 （CRY1） physically inter-acts with the G-protein β subunit, AGB1, in a blue light-dependent manner. We also show that AGB1 directly interacts with HY5, a basic leucine zipper transcriptional factor that acts as a critical positive regulator of photomorphogenesis, to inhibit its DNA-binding activity. Genetic studies suggest that CRY1 acts partially through AGB1, and AGB1 acts partially through HY5 to regulate photomorphogenesis. Moreover, we demonstrate that blue light-triggered interaction of CRY1 with AGB1 promotes the dissociation of HY5 from AGB1. Our results suggest that the CRY1 signaling mechanism involves positive regulation of the DNA-binding activity of HY5 mediated by the CRY1-AGB1 interaction, which inhibits the association of AGB1 with HY5. We propose that the antagonistic regulation of HY5 DNA-binding activity by CRY1 and AGB1 may allow plants to balance light and G-protein signaling and optimize photomorphogenesis.

Molecular characterization, tissue and developmental expression profiles of cryptochrome genes in wing dimorphic brown planthoppers, Nilaparvata lugens

Cryptochromes （CRYs） are blue and UV light photoreceptors, known to play key roles in circadian rhythms and in the light-dependent magnetosensitivity of insects. Two novel cryptochrome genes were cloned from the brown planthopper, and were given the designations of Nlcryl and Nlcry2, with the accession numbers KM108578 and KM108579 in GenBank. The complementary DNA sequences ofNlcryl andNlcry2 are 1935 bp and 2463 bp in length, and they contain an open reading frame of 1629 bp and 1872 bp, encoding amino acids of 542 and 623, with a predicted molecular weight of 62.53 kDa and 70.60 kDa, respectively. Well-conserved motifs such as DNA-photolyase and FAD-binding-7 domains were observed in Nlcry1 and Nlcry2. Phylogenetic analysis demonstrated the proteins of Nlcry1 and Nlcry2 to be clustered into the insect＇s cryptochrome 1 and cryptochrome 2, respectively. Quantitative polymerase chain reaction showed that the daily oscillations of messenger RNA （mRNA） expression in the head of the brown planthopper were mild for Nlcryl, and modest for Nlcry2. Throughout all developmental stages, Nlcryl and Nlcry2 exhibited extreme fluctuations and distinctive expression profiles. Cryptochrome mRNA expression peaked immediately after adult emergence and then decreased subsequently. The tissue expression profiles of newly emerged brown planthopper adults showed higher expression levels of CRYs in the head than in the thorax or abdomen, as well as significantly higher levels of CRYs in the heads of the macropterous strain than in the heads of the brachypterous strain. Taken together, the results of our study suggest that the two cryptochrome genes characterized in the brown planthopper might be associated with developmental physiology and migration.

Cryptochrome 1 Inhibits Shoot Branching by Repressing the Self-Activated Transciption Loop of PIF4 in Arabidopsis

Cryptochrome 1(CRY1)is an important light receptor essential for de-etiolation of Arabidopsis seedlings.However,its function in regulating plant architecture remains unclear.Here,we show that mutation in CRY1 resulted in increased branching of Arabidopsis plants.To investigate the underlying mechanism,we analyzed the expression profiles of branching-related genes and found that the mRNA levels of Phytochrome Interaction Factor 4(PIF4)and PIF5 are significantly increased in the cry1 mutant.Genetic analysis showed that the pif4 or pif4pif5 mutant is epistatic to the cry1 mutant,and overexpression of PIF4 conferred increased branching.Moreover,we demonstrated that PIF4 proteins physically associate with the G-box motif within the PIF4 promoter to form a self-activated transcriptional feedback loop,while CRY1 represses this process in response to blue light.Taken together,this study suggests that the CRY1–PIF4 module regulates gene expression via forming a regulatory loop and shoot branching in response to ambient light conditions.

Identification of zebrafish magnetoreceptor and cryptochrome homologs

Magnetoreception is essential for magnetic orientation in animal migration. The molecular basis for magnetoreception has recently been elucidated in fruitfly as complexes between the magnetic receptor magnetoreceptor(Mag R) and its ligand cryptochrome(Cry). Mag R and Cry are present in the animal kingdom. However, it is unknown whether they perform a conserved role in diverse animals. Here we report the identification and expression of zebrafish Mag R and Cry homologs towards understanding their roles in lower vertebrates. A single magr gene and 7 cry genes are present in the zebrafish genome. Zebrafish has four cry1 genes(cry1aa, cry1 ab, cry1 ba and cry1bb) homologous to human CRY1 and a single ortholog of human CRY2 as well as 2 cry-like genes(cry4 and cry5). By RT-PCR, magr exhibited a high level of ubiquitous RNA expression in embryos and adult organs, whereas cry genes displayed differential embryonic and adult expression. Importantly, magr depletion did not produce apparent abnormalities in organogenesis. Taken together, magr and cry2 exist as a single copy gene, whereas cry1 exists as multiple gene duplicates in zebrafish. Our result suggests that magr may play a dispensable role in organogenesis and predicts a possibility to generate magr mutants for analyzing its role in zebrafish.

Arabidopsis cryptochrome 1 promotes stomatal development through repression of AGB1 inhibition of SPEECHLESS DNA-binding activity

Cryptochromes are blue light photoreceptors that mediate various light responses in plants and mammals. The heterotrimeric G-protein is known to regulate various physiological processes in plants and mammals. In Arabidopsis, cryptochrome 1(CRY1) and the G-protein β subunit AGB1 act antagonistically to regulate stomatal development.The molecular mechanism by which CRY1 and AGB1 regulate this process remains unknown.Here, we show that Arabidopsis CRY1 acts partially through AGB1, and AGB1 acts through SPEECHLESS(SPCH), a master transcription factor that drives stomatal initiation and proliferation, to regulate stomatal development. We demonstrate that AGB1 physically interacts with SPCH to block the b HLH DNA-binding domain of SPCH and inhibit its DNA-binding activity. Moreover, we demonstrate that photoexcited CRY1 represses the interaction of AGB1 with SPCH to release AGB1 inhibition of SPCH DNA-binding activity, leading to the expression of SPCH-target genes promoting stomatal development. Taken together, our results suggest that the mechanism by which CRY1 promotes stomatal development involves positive regulation of the DNA-binding activity of SPCH mediated by CRY1 inhibition of the AGB1-SPCH interaction. We propose that the antagonistic regulation of SPCH DNA-binding activity by CRY1 and AGB1 may allow plants to balance light and G-protein signaling and optimize stomatal density and pattern.

Photooligomerization Determines Photosensitivity and Photoreactivity of Plant Cryptochromes

Plant and non-plant species possess cryptochrome(CRY)photoreceptors to mediate blue light regulation of development or the circadian clock.The blue light-dependent homooligomerization of Arabidopsis CRY2 is a known early photoreaction necessary for its functions,but the photobiochemistry and function of light-dependent homooligomerization and heterooligomerization of cryptochromes,collectively referred to as CRY photooligomerization,have not been well established.Here,we show that photooligomerization is an evolutionarily conserved photoreaction characteristic of CRY photoreceptors in plants and some non-plant species.Our analyses of the kinetics of the forward and reverse reactions of photooligomerization of Arabidopsis CRY1 and CRY2 provide a previously unrecognized mechanism underlying the different photosensitivity and photoreactivity of these two closely related photoreceptors.We found that photooligomerization is necessary but not sufficient for the functions of CRY2,implying that CRY photooligomerization is presumably accompanied by additional function-empowering conformational changes.We further demonstrated that the CRY2-CRY1 heterooligomerization plays roles in regulating functions of Arabidopsis CRYs in vivo.Taken together,these results suggest that photooligomerization is an evolutionarily conserved mechanism determining the photosensitivity and photoreactivity of plant CRYs.

Molecular Cloning and Expression Analysis of Cryptochrome Gene Ps CRY2in Tree Peony

Cryptochromes are blue/ultraviolet-A(UV-A) light receptors involved in regulating various aspects of plant growth and development.Investigations of the structure and functions of cryptochromes in plants have largely focused on herbaceous plants. However, few data on the function of CRY2 are available in woody plants. In this study, a cryptochrome 2(CRY2) gene was isolated from Paeonia suffruticosa by Reverse Transcription Polymerase Chain Reaction(RT-PCR). Sequence alignment and motif analysis showed that the deduced amino acids contained a PHR domain near the amino terminus and a CCT domain near the carboxy terminus. Ps CRY2 showed high identity with At CRY2 of Arabidopsis.Phylogenetic analysis indicated that it was closely related to Citrus sinensis. Gene expression analysis revealed that the highest expression levels of Ps CRY2 occurred in the bud and seed embryo of P. suffruticosa, followed by the roots, stems, and leaves. Ps CRY2 was upregulated during the entire process of bud differentiation, whereas this was downregulated during the early stage of bud development and upregulated in the middle and late stages. The highest level of Ps CRY2 expression was observed in the big bell-like flower buds. These results suggested that Ps CRY2 plays an important role in both bud differentiation and bud development. The expression patterns of Ps CRY2 in the buds of ‘Luoyanghong' and ‘Qiufa1' were similar, whereas that in the buds of ‘Qiufa 1' was significantly higher than in the buds of ‘Luoyanghong'. The buds of plants subjected to different photoperiod treatments exhibited variations in Ps CRY2 expression patterns. The expression of Ps CRY2 decreased during bud sprouting and in the small bell-like flower buds that were subjected to short-day photoperiod compared to that observed under long-day photoperiod.

Blue light-induced phosphorylation of Arabidopsis cryptochrome 1 is essential for its photosensitivity

Plants possess two cryptochrome photoreceptors,cryptochrome 1(CRY1)and cryptochrome 2(CRY2),that mediate overlapping and distinct physiological responses.Both CRY1 and CRY2 undergo blue light-induced phosphorylation,but the molecular details of CRY1 phosphorylation remain unclear.Here we identify 19 in vivo phosphorylation sites in CRY1 using mass spectrometry and systematically analyze the physiological and photobiochemical activities of CRY1 variants with phosphosite substitutions.We demonstrate that nonphosphorylatable CRY1 variants have impaired phosphorylation,degradation,and physiological functions,whereasphosphomimeticvariants mimic the physiological functions of phosphorylated CRY1 to constitutively inhibit hypocotyl elongation.We further demonstrate that phosphomimetic CRY1 variants exhibit enhanced interaction with the E3 ubiquitin ligase COP1(CONSTITUTIVELY PHOTOMORPHOGENIC 1).This finding is consistent with the hypothesis that phosphorylation of CRY1 is required for COP1-dependent signaling and regulation of CRY1.We also determine that PHOTOREGULATORY PROTEIN KINASEs(PPKs)phosphorylate CRY1 in a blue light-dependent manner and that this phosphorylation is critical for CRY1 signaling and regulation.These results indicate that,similar to CRY2,blue light-dependent phosphorylation of CRY1 determines its photosensitivity.

The involvement of the N-terminal PHR domain of Arabidopsis cryptochromes in mediating light signaling

Light is a key environmental cue that fundamentally regulates all aspects of plant growth and development,which is mediated by the multiple photoreceptors including the blue light photoreceptors cryptochromes(CRYs).In Arabidopsis,there are two well-characterized homologous CRYs,CRY1 and CRY2.Whereas CRYs are flavoproteins,they lack photolyase activity and are characterized by an Nterminal photolyase-homologous region(PHR)domain and a C-terminal extension domain.It has been established that the C-terminal extension domain of CRYs is involved in mediating light signaling through direct interactions with the master negative regulator of photomorphogenesis,COP1.Recent studies have revealed that the N-terminal PHR domain of CRYs is also involved in mediating light signaling.In this review,we mainly summarize and discuss the recent advances in CRYs signaling mediated by the N-terminal PHR domain,which involves the N-terminal PHR domain-mediated dimerization/oligomerization of CRYs and physical interactions with the pivotal transcription regulators in light and phytohormone signaling.

An early-morning gene network controlled by phytochromes and cryptochromes regulates photomorphogenesis pathways in Arabidopsis

Light perception at dawn plays a key role in coordinating multiple molecular processes and in entraining the plant circadian clock.The Arabidopsis mutant lacking the main photoreceptors,however,still shows clock entrainment,indicating that the integration of light into the morning transcriptome is not well understood.In this study,we performed a high-resolution RNA-sequencing time-series experiment,sampling every 2 min beginning at dawn.In parallel experiments,we perturbed temperature,the circadian clock,photoreceptor signaling,and chloroplast-derived light signaling.We used these data to infer a gene network that describes the gene expression dynamics after light stimulus in the morning,and then validated key edges.By sampling time points at high density,we are able to identify three light-and temperature-sensitive bursts of transcription factor activity,one of which lasts for only about 8 min.Phytochrome and cryptochrome mutants cause a delay in the transcriptional bursts at dawn,and completely remove a burst of expression in key photomorphogenesis genes(HY5 and BBX family).Our complete network is available online(http://www-users.york.ac.uk/∼de656/dawnBurst/dawnBurst.html).Taken together,our results show that phytochrome and cryptochrome signaling is required for fine-tuning the dawn transcriptional response to light,but separate pathways can robustly activate much of the program in their absence.

Supplemental blue and red light promote lycopene synthesis in tomato fruits

Lycopene, one of the strongest natural antioxidants known and the main carotene in ripe tomato, is very important for human health. Light is well known to be one of the most important environmental stimuli influencing lycopene biosynthesis; specifically, red light induces higher lycopene content in tomato. However, whether blue light promotes lycopene synthesis remains elusive and exactly how light stimulation promotes lycopene synthesis remains unclear. We applied supplemental blue and red lighting on tomato plants at anthesis to monitor the effect of supplemental blue and red lighting on lycopene synthesis. Our results showed that supplemental blue/red lighting induced higher lycopene content in tomato fruits; furthermore, we found that the expression of key genes in the lycopene synthesis pathway was induced by supplemented blue/red light. The expression of light signaling components, such as red-light receptor phytochromes(PHYs), blue-light receptor cryptochromes(CRYs) and light interaction factors, phytochrome-interacting factors(PIFs) and ELONGATED HYPOCOTYL 5(HY5) were up-or down-regulated by blue/red lighting. Thus, blue and red light increased lycopene content in tomatoes by inducing light receptors that modulate HY5 and PIFs activation to mediate phytoene synthase 1(PSY1) gene expression. These results provide a sound theoretical basis for further elucidation of the light regulating mechanism of lycopene synthesis in tomatoes, and for instituting a new generation of technological innovations for the enhancement of lycopene accumulation in crop production.

Optogenetic activation of intracellular signaling based on light-inducible protein-protein homo-interactions

Dynamic protein-protein interactions are essential for proper cell functioning.Homointeraction events—physical interactions between the same type of proteins—represent a pivotal subset of protein-protein interactions that are widely exploited in activating intracellular signaling pathways.Capacities of modulating protein-protein interactions with spatial and temporal resolution are greatly desired to decipher the dynamic nature of signal transduction mechanisms.The emerging optogenetic technology,based on genetically encoded light-sensitive proteins,provides promising opportunities to dissect the highly complex signaling networks with unmatched specificity and spatiotemporal precision.Here we review recent achievements in the development of optogenetic tools enabling light-inducible protein-protein homo-interactions and their applications in optical activation of signaling pathways.

Effects of Suppressing OsCRY1a Gene Expression on Rice Agronomic Traits

Using primers designed according to the published sequence of rice OsCRY1a gene, we obtained part of the gene fragment by PCR and constructed an RNA interference expression vector with it. To down-regulate the expression level of the gene or lead to the loss-of-function of the gene, the vector was then introduced into rice via Agrobacterium-mediated transformation. Based on the performance of the transgenic plants, the functions of the gene were analyzed and deduced. The results indicated that suppressing the expression of the gene retarded flowering for 16 d in rice with the plant height and grain length significantly increasing whereas other important agronomic traits observed remained unchanged apparently.

<i>Pinus taeda</i>cDNA Microarray as a Tool for Candidate Gene Identification for Local Red/Far-Red Light Adaptive Response in <i>Pinus sylvestris</i>

Light quality response is a vital environmental cue regulating plant development. Conifers, like angiosperms, respond to the changes in light quality including the level of red (R) and far-red (FR) light, which follows a latitudinal cline. R and FR wavelengths form a significant component of the entire plant life cycle, including the initial developmental stages such as seed germination, cotyledon expansion and hypocotyl elongation. With an aim to identify differentially expressed candidate genes, which would provide a clue regarding genes involved in the local adaptive response in Scots pine (Pinus sylvestris) with reference to red/far-red light;we performed a global expression analysis of Scots pine hypocotyls grown under two light treatments, continuous R (cR) and continuous FR (cFR) light;using Pinus taeda cDNA microarrays on bulked hypocotyl tissues from different individuals, which represented different genotypes. This experiment was performed with the seeds collected from northern part of Sweden (Ylinen, 68?N). Interestingly, gene expression pattern with reference to cryptochrome1, a blue light photoreceptor, was relatively high under cFR as compared to cR light treatment. Additionally, the microarray data analysis also revealed expression of 405 genes which was enhanced under cR light treatment;while the expression of 239 genes was enhanced under the cFR light treatment. Differentially expressed genes were re-annotated using Blast2GO tool. These results indicated that cR light acts as promoting factor whereas cFR antagonises the effect in most of the processes like C/N metabolism, photosynthesis and cell wall metabolism which is in accordance with former findings in Arabidopsis. We propose cryptochrome1 as a strong candidate gene to study the adaptive cline response under R and FR light in Scots pine as it shows a differential expression under the two light conditions.