Organization of Photosynthetic System of Dorsiventral Leaves as Adapted to the Irradiation from the Adaxial Side

1986 ◽  
pp. 219-230 ◽  
Author(s):  
I. Terashima ◽  
A. Takenaka
Keyword(s):  
Adaxial Side ◽  
Photosynthetic System

scholarly journals Roles of Si and SiNPs in Improving Thermotolerance of Wheat Photosynthetic Machinery via Upregulation of PsbH, PsbB and PsbD Genes Encoding PSII Core Proteins

Horticulturae ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 16
Author(s):  
Heba Hassan ◽  
Aishah Alatawi ◽  
Awatif Abdulmajeed ◽  
Manal Emam ◽  
Hemmat Khattab
Keyword(s):  
Photosystem Ii ◽  
Global Climate ◽  
Soluble Sugars ◽  
Triticum Aestivum L ◽  
Pcr Analysis ◽  
Silicon Dioxide Nanoparticles ◽  
System Productivity ◽  
Photosynthetic System ◽  
Core Proteins ◽  
Genes Encoding

Photosystem II is extremely susceptible to environmental alterations, particularly high temperatures. The maintenance of an efficient photosynthetic system under stress conditions is one of the main issues for plants to attain their required energy. Nowadays, searching for stress alleviators is the main goal for maintaining photosynthetic system productivity and, thereby, crop yield under global climate change. Potassium silicate (K2SiO3, 1.5 mM) and silicon dioxide nanoparticles (SiO2NPs, 1.66 mM) were used to mitigate the negative impacts of heat stress (45 °C, 5 h) on wheat (Triticum aestivum L.) cv. (Shandawelly) seedlings. The results showed that K2SiO3 and SiO2NPs diminished leaf rolling symptoms and electrolyte leakage (EL) of heat-stressed wheat leaves. Furthermore, the maximum quantum yield of photosystem II (Fv/Fm) and the performance index (PIabs), as well as the photosynthetic pigments and organic solutes including soluble sugars, sucrose, and proline accumulation, were increased in K2SiO3 and SiO2NPs stressed leaves. At the molecular level, RT-PCR analysis showed that K2SiO3 and SiO2NPs treatments stimulated the overexpression of PsbH, PsbB, and PsbD genes. Notably, this investigation indicated that K2SiO3 was more effective in improving wheat thermotolerance compared to SiO2NPs. The application of K2SiO3 and SiO2NPs may be one of the proposed approaches to improve crop growth and productivity to tolerate climatic change.

scholarly journals Exogenous melatonin improves the salt tolerance of cotton by removing active oxygen and protecting photosynthetic organs

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Dan Jiang ◽  
Bin Lu ◽  
Liantao Liu ◽  
Wenjing Duan ◽  
Yanjun Meng ◽  
...  
Keyword(s):  
Salt Stress ◽  
Salt Tolerance ◽  
Oxidative Damage ◽  
Photosynthetic Capacity ◽  
Photochemical Efficiency ◽  
Photochemical Quenching ◽  
Plant Tolerance ◽  
Signal Molecule ◽  
Ion Balance ◽  
Photosynthetic System

Abstract Background As damage to the ecological environment continues to increase amid unreasonable amounts of irrigation, soil salinization has become a major challenge to agricultural development. Melatonin (MT) is a pleiotropic signal molecule and indole hormone, which alleviates the damage of abiotic stress to plants. MT has been confirmed to eliminate reactive oxygen species (ROS) by improving the antioxidant system and reducing oxidative damage under adversity. However, the mechanism by which exogenous MT mediates salt tolerance by regulating the photosynthetic capacity and ion balance of cotton seedlings still remains unknown. In this study, the regulatory effects of MT on the photosynthetic system, osmotic modulators, chloroplast, and anatomical structure of cotton seedlings were determined under 0–500 μM MT treatments with salt stress induced by treatment with 150 mM NaCl. Results Salt stress reduces the chlorophyll content, net photosynthetic rate, stomatal conductance, intercellular CO2 concentration, transpiration rate, PSII photochemical efficiency, PSII actual photochemical quantum yield, the apparent electron transfer efficiency, stomata opening, and biomass. In addition, it increases non-photochemical quenching. All of these responses were effectively alleviated by exogenous treatment with MT. Exogenous MT reduces oxidative damage and lipid peroxidation by reducing salt-induced ROS and protects the plasma membrane from oxidative toxicity. MT also reduces the osmotic pressure by reducing the salt-induced accumulation of Na+ and increasing the contents of K+ and proline. Exogenous MT can facilitate stomatal opening and protect the integrity of cotton chloroplast grana lamella structure and mitochondria under salt stress, protect the photosynthetic system of plants, and improve their biomass. An anatomical analysis of leaves and stems showed that MT can improve xylem and phloem and other properties and aides in the transportation of water, inorganic salts, and organic substances. Therefore, the application of MT attenuates salt-induced stress damage to plants. Treatment with exogenous MT positively increased the salt tolerance of cotton seedlings by improving their photosynthetic capacity, stomatal characteristics, ion balance, osmotic substance biosynthetic pathways, and chloroplast and anatomical structures (xylem vessels and phloem vessels). Conclusions Our study attributes help to protect the structural stability of photosynthetic organs and increase the amount of material accumulation, thereby reducing salt-induced secondary stress. The mechanisms of MT-induced plant tolerance to salt stress provide a theoretical basis for the use of MT to alleviate salt stress caused by unreasonable irrigation, fertilization, and climate change.

Surface and Internalized Escherichia coli O157:H7 on Field-Grown Spinach and Lettuce Treated with Spray-Contaminated Irrigation Water

2010 ◽  
Vol 73 (6) ◽  
pp. 1023-1029 ◽  
Author(s):  
MARILYN C. ERICKSON ◽  
CATHY C. WEBB ◽  
JUAN CARLOS DIAZ-PEREZ ◽  
SHARAD C. PHATAK ◽  
JOHN J. SILVOY ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Irrigation Water ◽  
Enrichment Culture ◽  
Field Studies ◽  
Plate Count ◽  
Escherichia Coli O157 ◽  
Adaxial Side ◽  
Abaxial Side ◽  
E Coli ◽  
Contaminated Irrigation Water

Numerous field studies have revealed that irrigation water can contaminate the surface of plants; however, the occurrence of pathogen internalization is unclear. This study was conducted to determine the sites of Escherichia coli O157:H7 contamination and its survival when the bacteria were applied through spray irrigation water to either field-grown spinach or lettuce. To differentiate internalized and surface populations, leaves were treated with a surface disinfectant wash before the tissue was ground for analysis of E. coli O157:H7 by direct plate count or enrichment culture. Irrigation water containing E. coli O157:H7 at 102, 104, or 106 CFU/ml was applied to spinach 48 and 69 days after transplantation of seedlings into fields. E. coli O157:H7 was initially detected after application on the surface of plants dosed at 104 CFU/ml (4 of 20 samples) and both on the surface (17 of 20 samples) and internally (5 of 20 samples) of plants dosed at 106 CFU/ml. Seven days postspraying, all spinach leaves tested negative for surface or internal contamination. In a subsequent study, irrigation water containing E. coli O157:H7 at 108 CFU/ml was sprayed onto either the abaxial (lower) or adaxial (upper) side of leaves of field-grown lettuce under sunny or shaded conditions. E. coli O157:H7 was detectable on the leaf surface 27 days postspraying, but survival was higher on leaves sprayed on the abaxial side than on leaves sprayed on the adaxial side. Internalization of E. coli O157:H7 into lettuce leaves also occurred with greater persistence in leaves sprayed on the abaxial side (up to 14 days) than in leaves sprayed on the adaxial side (2 days).

Effect of Fe Deficiency on the Photosynthetic System of Maize

1992 ◽  
Vol 140 (5) ◽  
pp. 527-530 ◽  
Author(s):  
Samir Sharma ◽  
G.G. Sanwal
Keyword(s):  
Fe Deficiency ◽  
Photosynthetic System

scholarly journals Floral Scent Emission from Nectaries in the Adaxial Side of the Innermost and Middle Petals in Chimonanthus praecox

2018 ◽  
Vol 19 (10) ◽  
pp. 3278 ◽  
Author(s):  
Zhineng Li ◽  
Yingjie Jiang ◽  
Daofeng Liu ◽  
Jing Ma ◽  
Jing Li ◽  
...  
Keyword(s):  
Developmental Stages ◽  
Floral Scent ◽  
Flower Bud ◽  
Adaxial Side ◽  
Open Flower ◽  
Qrt Pcr ◽  
Relative Expression Level ◽  
Flower Stage ◽  
Chimonanthus Praecox ◽  
Deciduous Shrub

Wintersweet (Chimonanthus praecox) is a well-known traditional fragrant plant and a winter-flowering deciduous shrub that originated in China. The five different developmental stages of wintersweet, namely, flower-bud period (FB), displayed petal stage (DP), open flower stage (OF), later blooming period (LB), and wilting period (WP) were studied using a scanning electron microscope (SEM) to determine the distribution characteristics of aroma-emitting nectaries. Results showed that the floral scent was probably emitted from nectaries distributed on the adaxial side of the innermost and middle petals, but almost none on the abaxial side. The nectaries in different developmental periods on the petals differ in numbers, sizes, and characteristics. Although the distribution of nectaries on different rounds of petals showed a diverse pattern at the same developmental periods, that of the nectaries on the same round of petals showed some of regularity. The nectary is concentrated on the adaxial side of the petals, especially in the region near the axis of the lower part of the petals. Based on transcriptional sequence and phylogenetic analysis, we report one nectary development related gene CpCRC (CRABS CLAW), and the other four YABBY family genes, CpFIL (FILAMENTOUS FLOWER), CpYABBY2, CpYABBY5-1, and CpYABBY5-2 in C. praecox (accession no. MH718960-MH718964). Quantitative RT-PCR (qRT-PCR) results showed that the expression characteristics of these YABBY family genes were similar to those of 11 floral scent genes, namely, CpSAMT, CpDMAPP, CpIPP, CpGPPS1, CpGPPS2, CpGPP, CpLIS, CpMYR1, CpFPPS, CpTER3, and CpTER5. The expression levels of these genes were generally higher in the lower part of the petals than in the upper halves in different rounds of petals, the highest being in the innermost petals, but the lowest in the outer petals. Relative expression level of CpFIL, CpCRC, CpYABBY5-1, and CpLIS in the innermost and middle petals in OF stages is significant higher than that of in outer petals, respectively. SEM and qRT-PCR results in C. praecox showed that floral scent emission is related to the distribution of nectaries.

Lack of Internalization of Escherichia coli O157:H7 in Lettuce (Lactuca sativa L.) after Leaf Surface and Soil Inoculation

2009 ◽  
Vol 72 (10) ◽  
pp. 2028-2037 ◽  
Author(s):  
GUODONG ZHANG ◽  
LI MA ◽  
LARRY R. BEUCHAT ◽  
MARILYN C. ERICKSON ◽  
VANESSA H. PHELAN ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Leaf Surface ◽  
Escherichia Coli O157 ◽  
Adaxial Side ◽  
Abaxial Side ◽  
E Coli ◽  
Lactuca Sativa L ◽  
Leaf Surfaces ◽  
Leaves And Roots ◽  
Leaf Lettuce

Survival and internalization characteristics of Escherichia coli O157:H7 in iceberg, romaine, and leaf lettuce after inoculation of leaf surfaces and soil were determined. A five-strain mixture of E. coli O157:H7 in water and cow manure extract was used as an inoculum for abaxial and adaxial sides of leaves at populations of 6 to 7 log and 4 log CFU per plant. The five strains were individually inoculated into soil at populations of 3 and 6 log CFU/g. Soil, leaves, and roots were analyzed for the presence and population of E. coli O157:H7. Ten (4.7%) of 212 samples of leaves inoculated on the adaxial side were positive for E. coli O157:H7, whereas 38 (17.9%) of 212 samples inoculated on the abaxial side were positive. E. coli O157:H7 survived for at least 25 days on leaf surfaces, with survival greater on the abaxial side of the leaves than on the adaxial side. All 212 rhizosphere samples and 424 surface-sanitized leaf and root samples from plants with inoculated leaves were negative for E. coli O157:H7, regardless of plant age at the time of inoculation or the location on the leaf receiving the inoculum. The pathogen survived in soil for at least 60 days. Five hundred ninety-eight (99.7%) of 600 surface-sanitized leaf and root samples from plants grown in inoculated soil were negative for E. coli O157:H7. Internalization of E. coli O157:H7 in lettuce leaves and roots did not occur, regardless of the type of lettuce, age of plants, or strain of E. coli O157:H7.

scholarly journals Use of morphological and anatomical characters to delimit varieties of Paliurus spina-christi Mill. (Rhamnaceae)

2018 ◽  
Vol 6 (2) ◽  
pp. 1-14
Author(s):  
Saleem E. Shahbaz ◽  
Nazar M. Shareef
Keyword(s):  
Stomatal Density ◽  
Vascular Bundles ◽  
Epidermal Layer ◽  
Adaxial Side ◽  
Anatomical Features ◽  
Northern Iraq ◽  
Anatomical Characters ◽  
Palisade Cells ◽  
Different Parts ◽  
Fruit Diameter

Introduction: Paliurus spina-christi Mill is a species with two varieties namely Paliurus spina-christi L. var. spina-christi and Paliurus spina-christivar. macrocarpa Beck native to mountains of Kurdistan, rarely growing in the upper plains of northern Iraq. Materials and Methods: A total of 15 plants from different parts of Kurdistan region were sampled. 30measurements for each characters of Leaf, Inflorescence, Flowers, Fruit, seeds, and leaf anatomical characters were measured for comparison between the two varieties. Results and Discussion: Fruit diameter of var. macrocarpa is significantly larger than fruit diameter of var. spina-christi. Most mean flower parts especially the ovary, in addition to seed size is larger in var. macrocarpa. Upper epidermal layer is always thicker than the lower epidermal layer for the same blade. The isobilateral mesophyll includes 2 layers of long palisade cells adaxially and 2-3 layers of short cells abaxially. Many vascular bundles are seen equally spaced in the mesophyll tissue.With the exception of the presence of simple hairs on the petiole adaxial side of the var. spina-cristi and the absence of these hairs from the same site of var. macrocarpa, all other anatomical features are considered to be of no taxonomic application. Stomatal density of the adaxial leaf side is up to 19 stomata per mm² in var. spina-christi while it is up to 38 stomata per mm² in var. macrocarpa. Conclusions: Both fruit diameter and the stomatal density of the adaxial leaf side constitute diagnostic characters for separating between the two varieties of Paliurus spina-christi Mill

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