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1.
AhGLK1 affects chlorophyll biosynthesis and photosynthesis in peanut leaves during recovery from drought.
Liu, X, Li, L, Li, M, Su, L, Lian, S, Zhang, B, Li, X, Ge, K, Li, L
Scientific reports. 2018;(1):2250
Abstract
Peanut is an important edible oil crop plant whose quality and yield are greatly affected by drought. The process and molecular mechanisms of recovery from drought are also critical to its productivity, but are currently poorly characterized. Here, we investigate the involvement of peanut AhGLK1 in recovery from drought, and in particular its relationship with AhPORA, which encodes a key enzyme in chlorophyll biosynthesis. We found that chlorophyll content, chlorophyll fluorescence, AhPORA protein level and genes related to chlorophyll biosynthesis and photosynthesis declined markedly under drought conditions, but all increased during recovery. Consistent with this, AhGLK1 expression decreased during water stress and increased when the stress was removed. When AhGLK1 was transformed into Arabidopsis glk1glk2 mutant, it increased the survival rate of the mutant during recovery from drought and fully rescued the mutant's pale-green phenotype. In addition, chlorophyll content and fluorescence, and the expression of genes related to chlorophyll biosynthesis and photosynthesis, were all increased. Bioinformatics analysis and experimental evidence suggested that AhGLK1 augments the expression of AhPORA by binding to its promoter. Our findings confirm that AhGLK1 plays a role as a transcription factor that upregulates expression of AhPORA during post-drought recovery, thereby stimulating chlorophyll biosynthesis and photosynthesis.
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2.
Effects of heat stress in the leaf mitotic cell cycle and chromosomes of four wine-producing grapevine varieties.
Carvalho, A, Leal, F, Matos, M, Lima-Brito, J
Protoplasma. 2018;(6):1725-1740
Abstract
Grapevine varieties respond differentially to heat stress (HS). HS ultimately reduces the photosynthesis and respiratory performance. However, the HS effects in the leaf nuclei and mitotic cells of grapevine are barely known. This work intends to evaluate the HS effects in the leaf mitotic cell cycle and chromosomes of four wine-producing varieties: Touriga Franca (TF), Touriga Nacional (TN), Rabigato, and Viosinho. In vitro plants with 11 months were used in a stepwise acclimation and recovery (SAR) experimental setup comprising different phases: heat acclimation period (3 h-32 °C), extreme HS (1 h-42 °C), and two recovery periods (3 h-32 °C and 24 h-25 °C), and compared to control plants (maintained in vitro at 25 °C). At the end of each SAR phase, leaves were collected, fixed, and used for cell suspensions and chromosome preparations. Normal and abnormal interphase and mitotic cells were observed, scored, and statistically analyzed in all varieties and treatments (control and SAR phases). Different types of chromosomal anomalies in all mitotic phases, treatments, and varieties were found. In all varieties, the percentage of dividing cells with anomalies (%DCA) after extreme HS increased relative to control. TF and Viosinho were considered the most tolerant to HS. TF showed a gradual MI reduction from heat acclimation to HS and the lowest %DCA after HS and 24 h of recovery. Only Viosinho reached the control values after the long recovery period. Extrapolating these data to the field, we hypothesize that during consecutive hot summer days, the grapevine plants will not have time or capacity to recover from the mitotic anomalies caused by high temperatures.
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3.
Membrane Dynamics and Multiple Functions of Oil Bodies in Seeds and Leaves.
Shimada, TL, Hayashi, M, Hara-Nishimura, I
Plant physiology. 2018;(1):199-207
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Abstract
Oil bodies have multiple functions: oleosin-mediated freezing tolerance of seeds, direct interaction with glyoxysomes for lipid degradation in seedlings, and antifungal compound production in leaves.
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4.
Reactive oxygen species and redox regulation in mesophyll and bundle sheath cells of C4 plants.
Turkan, I, Uzilday, B, Dietz, KJ, Bräutigam, A, Ozgur, R
Journal of experimental botany. 2018;(14):3321-3331
Abstract
Redox regulation, antioxidant defence, and reactive oxygen species (ROS) signalling are critical in performing and tuning metabolic activities. However, our concepts have mostly been developed for C3 plants since Arabidopsis thaliana has been the major model for research. Efforts to convert C3 plants to C4 to increase yield (such as IRRI's C4 Rice Project) entail a better understanding of these processes in C4 plants. Various photosynthetic enzymes that take part in light reactions and carbon reactions are regulated via redox components, such as thioredoxins as redox transmitters and peroxiredoxins. Hence, understanding redox regulation in the mesophyll and bundle sheath chloroplasts of C4 plants is of paramount importance: it appears impossible to utilize efficient C4 photosynthesis without understanding its exact redox needs and the regulation mechanisms used during light reactions. In this review, we discuss current knowledge on redox regulation in C3 and C4 plants, with special emphasis on the mesophyll and bundle sheath differences that are found in C4. In these two cell types in C4 plants, linear and cyclic electron transport in the chloroplasts operate differentially when compared to C3 chloroplasts, changing the redox needs of the cell. Therefore, our focus is on photosynthetic light reactions, ROS production dynamics, antioxidant defence, and thiol-based redox regulation, with the aim of providing an overview of our current knowledge.
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5.
Potential of vegetation indices combined with laser-induced fluorescence parameters for monitoring leaf nitrogen content in paddy rice.
Yang, J, Du, L, Gong, W, Shi, S, Sun, J, Chen, B
PloS one. 2018;(1):e0191068
Abstract
Nitrogen (N) is important for the growth of crops. Leaf nitrogen content (LNC) serves as a crucial indicator of the growth status of crops and can help determine the dose of N fertilizer. Laser-induced fluorescence (LIF) technology and the reflectance spectra of crops are widely used to detect the biochemical content of leaves. Many vegetation indices (VIs) and fluorescence parameters have been developed to estimate LNC. However, the comparison among VIs and between fluorescence parameters and VIs has been rarely studied in the estimation of LNC. In this study, the performances of several published empirical VIs and fluorescence parameters for the estimation of paddy rice LNC were analyzed using the support vector machine (SVM) algorithm. Then, the optimal VIs (TVI, MTVI1, MTVI2, and MSAVI) and fluorescence parameters (F735/F460 and F685/F460), which were suitable for LNC monitoring in this study, were chosen. In addition, the combination of the VIs and fluorescence parameters was proposed as the input variables in the SVM model and used to estimate the LNC. Experimental results exhibited the promising potential of the LIF technology combined with reflectance for the accurate estimation of LNC, which provided guidance for monitoring the LNC.
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6.
The NAC Transcription Factor SlNAP2 Regulates Leaf Senescence and Fruit Yield in Tomato.
Ma, X, Zhang, Y, Turečková, V, Xue, GP, Fernie, AR, Mueller-Roeber, B, Balazadeh, S
Plant physiology. 2018;(3):1286-1302
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Abstract
Leaf senescence is an essential physiological process in plants that supports the recycling of nitrogen and other nutrients to support the growth of developing organs, including young leaves, seeds, and fruits. Thus, the regulation of senescence is crucial for evolutionary success in wild populations and for increasing yield in crops. Here, we describe the influence of a NAC transcription factor, SlNAP2 (Solanum lycopersicum NAC-like, activated by Apetala3/Pistillata), that controls both leaf senescence and fruit yield in tomato (S. lycopersicum). SlNAP2 expression increases during age-dependent and dark-induced leaf senescence. We demonstrate that SlNAP2 activates SlSAG113 (S. lycopersicum SENESCENCE-ASSOCIATED GENE113), a homolog of Arabidopsis (Arabidopsis thaliana) SAG113, chlorophyll degradation genes such as SlSGR1 (S. lycopersicum senescence-inducible chloroplast stay-green protein 1) and SlPAO (S. lycopersicum pheide a oxygenase), and other downstream targets by directly binding to their promoters, thereby promoting leaf senescence. Furthermore, SlNAP2 directly controls the expression of genes important for abscisic acid (ABA) biosynthesis, S. lycopersicum 9-cis-epoxycarotenoid dioxygenase 1 (SlNCED1); transport, S. lycopersicum ABC transporter G family member 40 (SlABCG40); and degradation, S. lycopersicum ABA 8'-hydroxylase (SlCYP707A2), indicating that SlNAP2 has a complex role in establishing ABA homeostasis during leaf senescence. Inhibiting SlNAP2 expression in transgenic tomato plants impedes leaf senescence but enhances fruit yield and sugar content likely due to prolonged leaf photosynthesis in aging tomato plants. Our data indicate that SlNAP2 has a central role in controlling leaf senescence and fruit yield in tomato.
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Olive tree (Olea europaea L.) leaf as a waste by-product of table olive and olive oil industry: a review.
Şahin, S, Bilgin, M
Journal of the science of food and agriculture. 2018;(4):1271-1279
Abstract
Research into finding new uses for by-products of table olive and olive oil industry are of great value not only to the economy but also to the environment where olives are grown and to the human health. Since leaves represent around 10% of the total weight of olives arriving at the mill, it is worth obtaining high added-value compounds from those materials for the preparation of dietary supplements, nutraceuticals, functional food ingredients or cosmeceuticals. In this review article, olive tree (Olea europaea L.) leaf is reviewed as being a potential inexpensive, renewable and abundant source of biophenols. The importance of this agricultural and industrial waste is emphasised by means of describing its availability, nutritional and therapeutic effects and studies conducted on this field. © 2017 Society of Chemical Industry.
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Effects of Chicory Leaf Extract on Serum Oxidative Stress Markers, Lipid Profile and Periodontal Status in Patients With Chronic Periodontitis.
Babaei, H, Forouzandeh, F, Maghsoumi-Norouzabad, L, Yousefimanesh, HA, Ravanbakhsh, M, Zare Javid, A
Journal of the American College of Nutrition. 2018;(6):479-486
Abstract
AIM: The aim of present study was to evaluate the effects of chicory leaf extract on serum oxidative stress markers, lipid profile, and periodontal status in patients with chronic periodontitis. METHODS In this double-blind, randomized controlled clinical trial 40 patients with chronic periodontitis were allocated to intervention and control groups. The intervention group received a 1-gram chicory leaf methanolic extract capsule twice daily for 8 weeks. In the control group, participants received a placebo capsule (containing 1 gram wheat flour) twice daily for 8 weeks. All participants had nonsurgical periodontal therapy during the study. Anthropometric measurements, dietary intake, total antioxidant capacity (TAC), malondialdehyde (MDA), uric acid, lipid profile (total cholesterol [TC], triglycerides [TG], low-density lipoprotein cholesterol [LDL-C], and high-density lipoprotein cholesterol [HDL-C]), and pocket depth (PD) were assessed before and after intervention. RESULTS The results showed that mean serum TAC, uric acid, and HDL-C increased and mean serum MDA, TG, LDL-C, and TC decreased significantly in the intervention group compared to their baseline and the control group post-intervention. A significant difference was observed in mean PD between the two groups. CONCLUSION Chicory leaf extract as an adjunct nutritional approach with nonsurgical periodontal therapy may be helpful in controlling periodontal status.
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9.
Functional Genomics and Genetic Control of Compound Leaf Development in Medicago truncatula: An Overview.
Chen, R
Methods in molecular biology (Clifton, N.J.). 2018;:197-203
Abstract
Diverse forms of leaves are present in nature. However, the regulatory mechanisms that underpin the development of diverse leaf forms remain enigmatic. The initiation of leaf primordia from the periphery of shoot apical meristem (SAM) requires downregulation of the class 1 knotted-like homeobox KNOXI proteins. In plants with simple leaves, this downregulation is permanent, consistent with leaves being determinant organs. In most of plants with compound leaves, the KNOXI proteins are reactivated in developing leaf primordia, and this reactivation is required for the development of compound leaves in these plants. Surprisingly, in Medicago truncatula and pea (Pisum sativum) that belong to the so-called inverted repeat-lacking clade (IRLC) of legume plants, the KNOXI proteins are not reactivated in leaf primordia and therefore not likely involved in the development of compound leaves in these plants. Instead, the legume FLORICAULA/LEAFY orthologues, UNIFOLIATA (UNI) and SINGLE LEAFLET1 (SGL1), are required for the initiation and development of lateral leaflet primordia in pea and M. truncatula plants, respectively. On the other hand, PALMATE-LIKE PENTAFOLIATA1 (PALM1) encoding a novel Cys(2)His(2) zinc finger transcription factor is required to suppress a morphogenetic activity at the leaf margin by negatively regulating SGL1 gene expression, and FUSED COMPOUND LEAF1 (FCL1) encoding a class M KNOX protein is required for the development of the leaf proximo-distal axis and organ boundary separation in M. truncatula. Thus, these recent studies have shown that SGL1/UNI, FCL1, and PALM1 provide a genetic framework for our understanding of compound leaf development in the legume plants.
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10.
Metabolomics analysis reveals that elevated atmospheric CO2 alleviates drought stress in cucumber seedling leaves.
Li, M, Li, Y, Zhang, W, Li, S, Gao, Y, Ai, X, Zhang, D, Liu, B, Li, Q
Analytical biochemistry. 2018;:71-85
Abstract
Elevated atmospheric CO2 alleviates moderate to severe drought stresses at physiological level in cucumber. To investigate the underlying metabolic mechanisms, cucumber seedlings were treated with two [CO2] and three water treatments combinations, and their leaves were analyzed using a non-targeted metabolomics approach. The results showed that elevated [CO2] changed 79 differential metabolites which were mainly associated with alanine, aspartate and glutamate metabolism; arginine and proline metabolism; TCA cycle; and glycerophospholipid metabolism under moderate drought stress. Moreover, elevated [CO2] promoted the accumulation of secondary metabolites; including isoferulic acid, m-coumaric acid and salicyluric acid. Under severe drought stress, elevated [CO2] changed 26 differential metabolites which mainly involved in alanine, aspartate and glutamate metabolism; pyruvate metabolism; arginine and proline metabolism; glyoxylate and dicarboxylate metabolism; cysteine and methionine metabolism; starch and sucrose metabolism; glycolysis or gluconeogenesis; and pyrimidine metabolism. In addition, elevated [CO2] accumulated carbohydrates, 1,2,3-trihydroxybenzene, pyrocatechol, glutamate, and l-gulonolactone, to allow adaption to severe drought. In conclusion, the metabolites and metabolic pathways associated with the alleviation of drought stresses by elevated [CO2] were different according to the level of drought stress. Our results may provide a theoretical basis for CO2 fertilization and application of exogenous metabolites to enhance drought tolerance of cucumber.