Leaf Pigment Research Articles

SPECIFIC FEATURES OF INTRODUCTION AND PROSPECTS OF THE GENUS ROBINIA L. USE IN LANDSCAPING OF VINNITYSA

After analyzing data from the literature sources, it was found that R. viscosa, which ranks second after R. pseudoacacia in terms of the introduction process involvement, is characterized by less winter hardiness. According to Kachalov A.A. [10], R. viscosa proved its winter-hardiness in conditions of the east, northern and middle parts of Ukraine and Transcarpathia. In Vinnytsia conditions, it withstands frosts up to -30˚С. In Moldova (Chisinau R. pseudoacacia tolerates winter well and bears fruit. As a result of the research, it was established that winter hardiness of the genus Robinia L. species in conditions of introduction was 1-2 (3) points. The introduced genus Robinia L. species and forms, which were objects of the research, in conditions of Vinnytsia were able to withstand negative temperatures (up to -32˚C) without significant damage. According to the obtained data, it was established that the genus Robinia L. representatives belong to the drought-resistant species and are able to withstand a long period of dry and rainless weather. The level of drought resistance of the studied species and forms according to the Pyatnytskyi S.S. scale equals to 4-5 points. According to the Pyatnytskyi S.S. light-demanding scale, R. pseudoacacia belongs to the most photophilous tree species – heliophytes. It was also defined that such species as R. pseudoacacia, R. holdtii, R. ambigua are fully acclimatized, R. viscosa, R. luxurians are well acclimatized. Their acclimatization numbers are: R. pseudoacacia = 100, R. viscosa = 86, R. luxurians = 86, R. holdtii = 95, R. ambigua = 94. Having analyzed the studied species in terms of their decorative characteristics, it was found that the time of decorativeness in the genus Robinia L. species is divided into two periods: the first is the flowering one, and the second – the time of leaf pigmentation change. According to our observations, the studied representatives received 5 points of decorativeness according to the Kalinichenko O.A. method in the following time periods: 1) from 05.15.2022 to 06.15.2022 – the time of flowering; 2) from 18.08.2022 to 20.09.2022 – leaf colour change.

Shining a light on duckweed: exploring the effects of artificial light at night (ALAN) on growth and pigmentation.

Artificial light at night (ALAN) is a novel environmental stressor of global concern. Various sources of artificial light are now common in urbanized areas and have diverse negative effects on many species of animals and plants. However, ALAN has also been shown to have no effect or a positive effect on some organisms. This study investigates the impact of ALAN on the growth and leaf pigmentation of a common floating freshwater plant species. We exposed wild-derived dotted duckweed (Landoltia punctata) to either darkness during the night (Control group) or to artificial light at night (ALAN group) for 49 days. We set up two large boxes of eighty samples each with 2-3 leaves of duckweed in each sample at the start of the experiment. The ALAN box had an opaque lid with a small lamp that was turned on at night. The Control box was also covered at night with an opaque lid but without a lamp. During the day, plants in both boxes were exposed to natural light. We counted the number of leaves in each sample weekly. We took photos of the samples on day 28 to measure the total leaf surface area per sample. On day 49, we took photos of the underside of the leaves for analyses of the relative levels of dark pigmentation across all samples. We found that ALAN-exposed plant samples had, on average, more leaves than control plants after a few weeks of exposure. They also had a more variable number of leaves per sample. The total leaf area per sample on day 28 was larger in the ALAN samples. The underside of the leaves on day 49 was, on average, darker in the ALAN plants than in the control plants. There is a significant growth-enhancing effect from exposure to artificial light at night on Landolita punctata. However, higher variability induced by ALAN exposure indicates that ALAN is also a stressful condition for these plants. This is in line with our finding of the presence of larger amounts of dark pigments in the leaves of ALAN-exposed plants. Dark pigmentation in duckweed species could be a defence mechanism protecting tissues from stress-induced oxidative damage. Overall, both positive and negative effects of ALAN can be observed simultaneously in different traits of the same organism. Increased individual variation can facilitate population-level adaptation to stressful conditions. As such, this work contributes to our knowledge of the effects of light pollution in urban environments on common plants.

Effect of Low Temperature on Photosynthetic Characteristics, Senescence Characteristics, and Endogenous Hormones of Winter Wheat “Ji Mai 22” during the Jointing Stage

To investigate the effects of low-temperature (LT) stress on photosynthetic properties and senescence characteristics of winter wheat leaves during the jointing stage, an environmental temperature control experiment was designed at Nanjing University of Information Science and Technology in 2023, using Triticum aestivum L. cv. “Ji Mai 22” as the test material. Four different temperature levels were set: 18 °C/8 °C (daily maximum/daily minimum temperature; CK), 13 °C/3 °C, 10 °C/0 °C, and 7 °C/3 °C. The duration of each treatment was 2, 4, and 6 days, respectively. The experimental findings reveal that the changes in physiological parameters of winter wheat leaves under low-temperature stress treatments are nonlinear. Under the 3 °C LT treatment, the photosynthetic parameters and endogenous hormone levels of wheat leaves significantly decrease after 6 days of stress. Under the 0 °C LT treatment, the photosynthetic parameters, leaf pigment content, and endogenous hormones of wheat decrease significantly, while under the −3 °C LT treatment, all the parameters of winter wheat leaves show a significant decline. Generally, the “Ji Mai22” wheat cultivar has a lower growth temperature limit of −3 °C during the jointing stage.

Production of bioactive and aroma volatile compounds of Lawsonia inermis L. cultivated under different growth conditions

The present study aimed to investigate the influence of different growing conditions on the amount of leaf pigments (chlorophylls, carotenoids), bioactive metabolites, such as polyphenols, flavonoids, lawsone and volatile organic compounds (VOCs) of Lawsonia inermis L. (henna) plants. Young henna plants were cultivated for two months in a growth chamber (GC) and in open-air conditions during summer under the Mediterranean climate (OF), and leaves were analysed to evaluate their adaptive responses. The different growth conditions modified the carbon allocation priorities, increasing antioxidant metabolites (e.g. phenolic and flavonoid compounds) while decreasing lawsone in GC conditions. Quali-quantitative changes were observed for VOCs. This study revealed that GC conditions permit an alternative use of Lawsonia cultivation, because of the increase in the endogenous content of bioactive secondary metabolites with many potential biological activities.

Process efficiency and life cycle assessment of novel waste-derived Chl/TiO2 photocatalyst for rhodamine B removal

Visible-light photocatalysis is a promising approach toward cleaner production and environmental impact reduction. Dye sensitization of TiO2 nanoparticles with chlorophyll (Chl) pigments is a potential alternative for the improvement of photocatalysis efficiency but must be modified for higher activity in visible light. Herein, a novel and green Chl/TiO2 photocatalyst was constructed for rhodamine B removal using the TiO2 waste of the gas refinery Clause process, sensitized with extracted chlorophyll from orange tree leaf pigments. The effects of pH, pigment ratios, photocatalyst dosage, and temperature on the Chl/TiO2 photocatalyst performance accompanied by its environmental impacts were investigated. The results indicated that the pristine TiO2 before sensitization could degrade ~30 % of rhodamine B while the photocatalytic activity was enhanced to ~98 % after modification by 0.6 wt% chlorophyll pigments. The optimum conditions were achieved at 25 mg/l Chl/TiO2, pH = 4, and 50 mg/l rhodamine B after 2 h irradiation of visible light (LED lamp 50 W). Recycling studies showed a rhodamine B decolorization of 90 % after 5 cycles and demonstrated that Chl/TiO2 is a promising heterogeneous photocatalyst for the long-term removal of dyes from wastewater. The Chl/TiO2 followed the pseudo-first-order kinetic model and illustrated negative impacts on global warming (6.3 kg CO2) and terrestrial ecotoxicity (10.7 kg 1.4-DCB) from a life cycle assessment (LCA) perspective, originating from electricity consumption and acetone. Summing up, the present study offers a new and eco-efficient photocatalyst to facilitate wastewater treatment in real-world applications and gives perspectives to manage its long-term concern.

Assessing the Water Status and Leaf Pigment Content of Olive Trees: Evaluating the Potential and Feasibility of Unmanned Aerial Vehicle Multispectral and Thermal Data for Estimation Purposes

Global warming presents a significant threat to the sustainability of agricultural systems, demanding increased irrigation to mitigate the impacts of prolonged dry seasons. Efficient water management strategies, including deficit irrigation, have thus become essential, requiring continuous crop monitoring. However, conventional monitoring methods are laborious and time-consuming. This study investigates the potential of aerial imagery captured by unmanned aerial vehicles (UAVs) to predict critical water stress indicators—relative water content (RWC), midday leaf water potential (ΨMD), stomatal conductance (gs)—as well as the pigment content (chlorophyll ab, chlorophyll a, chlorophyll b and carotenoids) of trees in an olive orchard. Both thermal and spectral vegetation indices are calculated and correlated using linear and exponential regression models. The results reveal that the thermal vegetation indices contrast in estimating the water stress indicators, with the Crop Water Stress Index (CWSI) demonstrating higher precision in predicting the RWC (R2 = 0.80), ΨMD (R2 = 0.61) and gs (R2 = 0.72). Additionally, the Triangular Vegetation Index (TVI) shows superior accuracy in predicting the chlorophyll ab (R2 = 0.64) and chlorophyll a (R2 = 0.61), while the Modified Chlorophyll Absorption in Reflectance Index (MCARI) proves most effective for estimating the chlorophyll b (R2 = 0.52). This study emphasizes the potential of UAV-based multispectral and thermal infrared imagery in precision agriculture, enabling assessments of the water status and pigment content. Moreover, these results highlight the vital importance of this technology in optimising resource allocation and enhancing olive production, critical steps towards sustainable agriculture in the face of global warming.

Effect of foliar application of phosphorus nanoparticles on the performance and sustainable agriculture of sweet corn

Traditional phosphorus fertilizers are necessary for plant growth but about 80–90% are lost into the surrounding environment via irrigation, therefore nano-fertilizers have been developed as slow-release fertilizers to achieve sustainable agriculture. This trial investigated the impact of the foliar application of hydroxyapatite nanoparticles (HA-NPs) as a source of nano-phosphorus (P-NPs) on two cultivars of sweet corn (yellow and white) throughout two seasons. The morphology and structure of the prepared HA-NPs were characterized via transmission electron microscopy (TEM) and X-ray diffractometry (XRD). In addition, agro-morphological criteria, chemical contents (i.e., photosynthetic pigments, phenols, indoles, minerals, etc.), and genomic template stability percentage (GTS%) were evaluated in the produced sweet corn. The application of 50 mg/l HA-NPs improved the growth characteristics, yield per hectare, leaf pigments, and chemical content of yellow sweet corn, whereas the application of 100 mg/l of HA-NPs to white sweet corn enhanced the vegetative characteristics, production, photosynthetic pigments, phenols, and indoles. The difference in results may be due to the presence of a +ve unique band with SCoT-4 and SCot-2 primers at 1250 and 470 bp in yellow and white corn treated with 50 and 100 mg/l, respectively. The minimum GTS% was recorded at a concentration of 75 mg/l for both white and yellow corn. The HA-NPs can be applied as a foliar source of P-NPs to achieve agricultural sustainability.

Mechanisms for leaf color changes in Osmanthus fragrans ‘Ziyan Gongzhu’ using physiology, transcriptomics and metabolomics

BackgroundColor-leaved O. fragrans is a variety of Osmanthus fragrans, which has both the fragrance of Osmanthus and the color of color-leaved plants. However, the molecular mechanism of color change of color-leaved O. fragrans is not clear. In this study, we analyzed the regulatory mechanism of four different color leaves of ‘Ziyan Gongzhu’ through physiological, transcriptome and metabolome levels.ResultsFirstly, we measured the leaf pigments content and leaf chromatic parameters for correlation analysis, indicating a significant correlation between them. Overall, the content of chlorophyll a + b is low and the content of anthocyanin is high in T1 and T2 leaves, along with low expression of chlorophyll synthesis genes (HEMA, CHLG, and CAO, etc.) and high expression of anthocyanin synthesis genes (F3H, F3’H, DFR and ANS, etc.), resulting purple red and light purple in T1 and T2 leaves, respectively. It was also found that the pigment closely related to the color leaves of ‘Ziyan Gongzhu’ was cyanidin. The content anthocyanins, may be regulated by two putative MYB activators (OfMYB3 and OfMYB4) and two putative MYB repressors (OfMYB1 and OfMYB2). In contrast, the content of chlorophyll a + b is high and the content of anthocyanin is low in T3 and T4 leaves, along with high expression of chlorophyll synthesis genes and low expression of anthocyanin synthesis genes, resulting yellow green and dark green in T3 and T4 leaves, respectively. And abnormal chloroplast development affects chlorophyll content in T1, T2, and T3 leaves. Although the content of carotenoids first dropped in T2 leaves, it then rapidly accumulated in T4 leaves, in sync with the increase in the expression of genes related to carotenoid biosynthesis (ZDS, LHYB, and ZEP, for example). Analysis of photosynthetic, carbohydrate and hormone-related differentially abundant metabolites (DAMs) and DEGs found that they may participate in the regulation of leaf color change of ‘Ziyan Gongzhu’ by affecting pigment synthesis.ConclusionOur results pave the way for a comprehensive knowledge of the regulatory processes governing leaf color in ‘Ziyan Gongzhu’ and identify possible genes for application regarding molecular colored-leaf cultivar breeding.

Morphological, stomatal, pigmentation, and biomolecular characteristics of a few epiphytic orchid species of India

In order to identify suitable species that can be used for cross-breeding and propagation for horticulture purposes four endemic and epiphytic orchid species, Aerides crispa Lindl., A. maculosa Lindl., A. ringens Fischer. and A. odorata Lour. were studied by comparing their leaf morphology, stomata, pigmentation, and biomolecules. Standard methods were used for the evaluation. A. odoratum, native to the lowest altitude, was characterized by thin, long leaves with the lowest specific leaf area and higher water content. Among the four species studied, stomata were bigger in size and less in number in A. odoratum. Maximum total soluble sugars, soluble proteins, amino acids, and starch contents, an indicator of a better photosynthesis rate were noted in A. odoratum. Total chlorophyll and carotenoid contents per unit leaf area were higher in A. odoratum and A. ringens. Our results concluded that variation in environmental temperature, humidity, sunlight intensity, and exposure of orchids at different altitudes may cause alteration in traits that can be inherited over a period.

Seasonal pigment fluctuation in diploid and polyploid Arabidopsis revealed by machine learning-based phenotyping method PlantServation

Long-term field monitoring of leaf pigment content is informative for understanding plant responses to environments distinct from regulated chambers but is impractical by conventional destructive measurements. We developed PlantServation, a method incorporating robust image-acquisition hardware and deep learning-based software that extracts leaf color by detecting plant individuals automatically. As a case study, we applied PlantServation to examine environmental and genotypic effects on the pigment anthocyanin content estimated from leaf color. We processed >4 million images of small individuals of four Arabidopsis species in the field, where the plant shape, color, and background vary over months. Past radiation, coldness, and precipitation significantly affected the anthocyanin content. The synthetic allopolyploid A. kamchatica recapitulated the fluctuations of natural polyploids by integrating diploid responses. The data support a long-standing hypothesis stating that allopolyploids can inherit and combine the traits of progenitors. PlantServation facilitates the study of plant responses to complex environments termed “in natura”.

Structural complexity biases vegetation greenness measures.

Vegetation 'greenness' characterized by spectral vegetation indices (VIs) is an integrative measure of vegetation leaf abundance, biochemical properties and pigment composition. Surprisingly, satellite observations reveal that several major VIs over the US Corn Belt are higher than those over the Amazon rainforest, despite the forests having a greater leaf area. This contradicting pattern underscores the pressing need to understand the underlying drivers and their impacts to prevent misinterpretations. Here we show that macroscale shadows cast by complex forest structures result in lower greenness measures compared with those cast by structurally simple and homogeneous crops. The shadow-induced contradictory pattern of VIs is inevitable because most Earth-observing satellites do not view the Earth in the solar direction and thus view shadows due to the sun-sensor geometry. The shadow impacts have important implications for the interpretation of VIs and solar-induced chlorophyll fluorescence as measures of global vegetation changes. For instance, a land-conversion process from forests to crops over the Amazon shows notable increases in VIs despite a decrease in leaf area. Our findings highlight the importance of considering shadow impacts to accurately interpret remotely sensed VIs and solar-induced chlorophyll fluorescence for assessing global vegetation and its changes.

Metabolic and Transcriptomic Analyses Reveal Different Metabolite Biosynthesis Profiles between Purple and Green Pak Choi.

Pak choi is one of the most important leafy vegetables planted in East Asia and provides essential nutrients for the human body. Purple pak choi differs mainly in leaf colour but exhibits distinct nutritional profiles from green pak choi. In this study, we performed metabolic and transcriptomic analyses to uncover the mechanisms underlying the differences in metabolite biosynthesis profiles between the two pak choi varieties. Metabolite profiling revealed significant differences in the levels of metabolites, mainly amino acids and their derivatives and flavonoids. Furthermore, 34 flavonoids significantly differed between green and purple pak choi leaves, and cyanidin and its derivative anthocyanins were abundant in purple pak choi. In addition, we found that the structural genes CHS, DFR, ANS, and UGT75C1, as well as the transcription factor MYB2, play a major role in anthocyanin synthesis. These results provide insight into the molecular mechanisms underlying leaf pigmentation in pak choi and offer a platform for assessing related varieties.

LEAF PIGMENT AND TOTAL CARBOHYDRATE CONTENT AT EARLY STAGES OF HERITIERA FOMES BUCH. SEEDLINGS GROWN AT THREE SALINE ZONES OF THE SUNDARBANS, BANGLADESH

The experiment was conducted to find the leaf pigments and carbohydrate content in Heritiera fomes at different growth stages exposed to different salinity levels in the Sundarbans areas, Bangladesh. Three leaf pigments, viz., chlorophyll a, chlorophyll b, and carotenoid, total chlorophyll, and total carbohydrate content of Heritiera fomes Buch. Ham seedlings were determined in the leaves grown in the oligohaline, mesohaline, and polyhalite zones at early (6 and 9 months) and survival ages (30 months) following standard methods. Leaves from seedlings at the age of 30 months (survival aged) show relatively high leaf pigments than that of the 6 and 9-month-old seedlings grown in the three saline zones. Total chlorophyll content in leaves was found low in the oligohaline zone at the early and survival ages, but higher in the polyhalite zone at the early ages, and higher in the mesohaline zone at the survival age. Chlorophyll b was relatively higher than chlorophyll a. Leaves of 30 months seedlings showed relatively higher chlorophyll a than chlorophyll b at the polyhalite zone, but higher chlorophyll b was noted at the mesohaline zone. The highest content of total carbohydrates was observed in the shoots of 6, 9, and 30 months ages H. fomes seedlings in the polyhalite zone, while the lowest was in the mesohaline zone. At the same age periods in the mesohaline zone, the roots of the H. fomes seedlings showed relatively higher carbohydrate content and lower at the 30 months seedlings in the all saline zones. Chlorophyll a was found to be more sensitive than chlorophyll b and carotenoid at different salinity levels tested. Higher carbohydrate content was discovered as an additional mechanism to prevent salt toxicity at early ages of high saline conditions (polyline zone).

Research Progress on Anthocyanin-Mediated Regulation of 'Black' Phenotypes of Plant Organs.

The color pattern is one of the most important characteristics of plants. Black stands out among the vibrant colors due to its rare and distinctive nature. While some plant organs appear black, they are, in fact, dark purple. Anthocyanins are the key compounds responsible for the diverse hues in plant organs. Cyanidin plays an important role in the deposition of black pigments in various plant organs, such as flower, leaf, and fruit. A number of structural genes and transcription factors are involved in the metabolism of anthocyanins in black organs. It has been shown that the high expression of R2R3-MYB transcription factors, such as PeMYB7, PeMYB11, and CsMYB90, regulates black pigmentation in plants. This review provides a comprehensive overview of the anthocyanin pathways that are involved in the regulation of black pigments in plant organs, including flower, leaf, and fruit. It is a great starting point for further investigation into the molecular regulation mechanism of plant color and the development of novel cultivars with black plant organs.

Drought Stress Decreases Morphophysiological Characteristics of Pongamia pinnata (L.) Pierre a Biodiesel Tree.

<b>Background and Objective:</b> Drought stress is a condition of water shortage in plants. One tree species targeted for planting on marginal lands is <i>Pongamia pinnata</i> which produces oil for biodiesel feedstock. The aims of the present study were to evaluate the morphophysiological response of <i>Pongamia pinnata</i> and its resistance mechanism under drought stress at the seedling stage. <b>Materials and Methods:</b> Three months old Pongamia seedlings were given 4 treatments of watering intervals, namely every day (control) and every 7th, 14th and 21st day at field capacity indicating no stress, moderate stress, high stress and very high stress, respectively. Measurement of growth parameters was carried out every month for 4 months. Data were analyzed using one-way analysis of variance at a significance level of 5%. <b>Results:</b> Very high drought stress reduced plant survival to 60% at 3 MAP (month after planting) and dead at 4 MAP. Both moderate and high drought stresses slow down height growth. Both specific leaf area and leaf area ratio decreased dramatically by 45.7 and 63.74%, respectively at a very high drought stress treatment at 3 MAP. Root length decreased slightly by 18.40% at very high drought stress. Total plant dry weight decreased by 15.9 and 46.4% by high and very high drought stress respectively. Leaf pigment content decreased sharply to very high drought stress. <b>Conclusion:</b> Pongamia seedlings survived under moderate and high drought stress. This was achieved by reducing plant height, leaf area, dry weights and pigment content. The resistance mechanism was drought avoidance, achieved by dropping leaves and maintaining root growth.

Integrated Transcriptome and Biochemical Analysis Provides New Insights into the Leaf Color Change in Acer fabri

Acer fabri is a widely distributed ornamental tree with colorful leaves and high ornamental value. Its young leaves change from red to red and green until turning fully green. To understand the mechanism of leaf color change, transcriptome sequencing and pigment content determination were performed in three stages during the leaf color change of A. fabri. In total, 53,550 genes, including 838 transcription factors (TFs), were identified by transcriptome sequencing. In addition, the results of orthogonal partial least squares-discriminant analysis (OPLS-DA) of three pigments in the three stages of leaf color development suggested that carotenoids played a major role in the process of leaf color change from red to red-green, whereas anthocyanins played an important role in the process of leaf color change from red to green. Based on weighted gene co-expression network analysis (WGCNA), Af0034384 (HSFB2A), Af0051627 (NMT1), and Af0052541 (THY-1) were selected as hub genes from characteristic modules with significant correlation between carotenoids and anthocyanins. The results of gene network regulation maps and real-time fluorescence quantitative PCR (qRT-PCR) showed that Af0010511 (NAC100) upregulated the expression of Af0034384 (HSFB2A), leading to an increase in carotenoid content and the gradual greening of leaves during the transition from red to green. However, during the transition from red to green leaves, Af0033232 (NAC83) and Af0049421 (WRKY24) downregulated the expression of Af0051627 (NMT1) and Af0052541 (THY-1), respectively, leading to a decrease in anthocyanin content and the complete greening of leaves. These results could provide new ideas for studying the molecular mechanism of leaf color change in A. fabri and other species.

GlandSegNet: Semantic segmentation model and area detection method for cotton leaf pigment glands

Pigment glands in cotton store gossypol, which is a highly valuable substance in agriculture and medicine. Therefore, obtaining phenotype information on cotton pigment glands is essential for evaluating gossypol content. However, the current research on pigment glands in cotton leaves faces several challenges, including a small proportion of pigment glands in the leaf area, a small segmentation target, a large number of glands at the leaf edge, and the interference of leaf veins, making the whole-leaf phenotype detection difficult. To address these challenges, this study proposes a deep learning-based semantic segmentation model named GlandSegNet. The GlandSegNet uses a specific encoder architecture formed by fusing the upsampling process and feature-extraction networks. In the decoder part, pooling and skip-connection operations are performed, and the network is optimized by embedding the ECA attention module. The experimental results show that the GlandSegNet can achieve area accuracy rates of 0.9842 and 0.9510, with corresponding error areas of 0.6966 mm2 and 4.1258 mm2, on test set 1 consisting of intact leaves from a single species and test set 2 consisting of randomly selected leaves from multiple species, respectively. The results demonstrate that the GlandSegNet semantic segmentation method can exhibit excellent performance in the cotton leaf pigment gland area detection tasks. Compared with traditional microscopic observation methods, the GlandSegNet is characterized by high efficiency and the ability to quantitatively analyze the glandular phenotype. Thus, the GlandSegNet could provide an effective tool and technical support for large-scale cotton pigment gland research and could be of great significance for the phenotype evaluation of cotton pigment glands and gossypol content evaluation.

A Frameshift Mutation in the Mg-Chelatase I Subunit Gene OsCHLI Is Associated with a Lethal Chlorophyll-Deficient, Yellow Seedling Phenotype in Rice.

Chlorophyll biosynthesis is a crucial biological process in plants, and chlorophyll content is one of the most important traits in rice breeding programs. In this study, we identified a lethal, chlorophyll-deficient, yellow seedling (YS) phenotype segregating in progeny of CR5055-21, an F2 plant derived from a backcross between Korean japonica variety 'Hwaseong' (Oryza sativa) and CR5029, which is mostly Hwaseong with a small amount of Oryza grandiglumis chromosome segments. The segregation of the mutant phenotype was consistent with a single gene recessive mutation. Light microscopy of YS leaf cross-sections revealed loosely arranged mesophyll cells and sparse parenchyma in contrast to wildtype. In addition, transmission electron microscopy showed that chloroplasts did not develop in the mesophyll cells of the YS mutant. Quantitative trait loci (QTL)-seq analysis did not detect any significant QTL, however, examination of the individual delta-SNP index identified a 2-bp deletion (AG) in the OsCHLI gene, a magnesium (Mg)-chelatase subunit. A dCAPs marker was designed and genotyping of a segregating population (n = 275) showed that the mutant phenotype co-segregated with the marker. The 2-bp deletion was predicted to result in a frameshift mutation generating a premature termination. The truncated protein likely affects formation and function of Mg-chelatase, which consists of three different subunits that together catalyze the first committed step of chlorophyll biosynthesis. Transcriptome analysis showed that photosynthesis and carbohydrate metabolism pathways were significantly altered although expression of OsCHLI was not. Chlorophyll- and carotenoid-related genes were also differentially expressed in the YS mutant. Our findings demonstrated that OsCHLI plays an important role in leaf pigment biosynthesis and leaf structure development in rice.

Comparative Study of Photosynthesis Performance of Herbicide-Treated Young Triticale Plants during Drought and Waterlogging Stress

Owing to global climate changes, periods of soil drought or waterlogging occur. Each of these factors causes negative effects on plant physiological processes and growth. Weeds are another factor that limits plant productivity. The main task of this study is to investigate the physiological reactions of triticale to herbicide treatment and subsequent drought or waterlogging. Young triticale plants were treated with Serrate® (selective herbicide produced by Syngenta) and exposed for 7 days to drought or waterlogging. Plant growth, chlorophyll and carotenoids content, the net photosynthesis rate and chlorophyll a fluorescence were measured during the stress period and after 4 days of plant recovery. Herbicide by itself did not induce considerable changes in the abovementioned parameters during the stress period. Serrate® did not affect strongly the efficiency of the photosynthetic machinery under harsh conditions. A significant reduction in fresh weight (85%), water content (93%), net photosynthesis rate, chlorophyll a fluorescence indices Fv/Fm and Fv/F0, and leaf pigments (58% for chlorophyll a, 53% for chlorophyll b, and 45% for carotenoids) was found because of drought. Waterlogging also influenced negatively these parameters but to a smaller extent. After resuming the normal irrigation, the photosynthesis and chlorophyll a fluorescence tended to increase and showed signs of recovery. The comparative analysis of growth and photosynthetic parameters demonstrated that triticale plants subjected to waterlogging could recover to a higher degree than those exposed to drought.

Correlation of the SPAD index with absolute leaf pigments in irrigated lettuce culture in the Northwest Paraná, Brazil

Photosynthesis is the most important biochemical process that takes place in plants and chlorophyll is the main pigment involved in it. Current destructive methods for determining chlorophyll content are accurate, but time-consuming and relatively expensive. The SPAD (Soil Plant Analysis Development) is a portable chlorophyll meter that provides an instant and nondestructive reading of the green color of leaves. As an important source of vitamins and antioxidants such as vitamins C, carotenoids and fiber content, lettuce (Lactuca sativa L.) plays a crucial role in human nutrition, being one of the most popular staple plant foods among the population. Considering the possibility of management based on the characteristics of photosynthetic pigments, the study aimed to relate the SPAD index values with the content of leaf pigments in lettuce. The study was conducted in the Northwest region of Paraná, Brazil. The experiment was carried out in a completely randomized design with 48 leaf samples being determined the SPAD index and the content of leaf pigments. The determination of the SPAD index was performed with the SPAD-502 equipment (Minota®) with three readings per sample. For the extraction of leaf pigments, chlorophyll (a; b), total chlorophyll (a + b) and carotenoids, acetone was used as an extractor and the reading was performed in a spectrophotometer. The SPAD index was correlated with the levels of chlorophyll a (0.93), chlorophyll b (0.89), total chlorophyll (0.93) and carotenoids (0.95) in lettuce leaves. Through the SPAD, the chlorophyll content in lettuce leaves can be determined in a representative way.