Bundle Sheath Parenchyma Cells Research Articles

Anatomical characteristics of fusoid cells and vascular bundles in Fargesia yunnanensis leaves

As of today, the functions of fusoid cell, and the transport and loading pathways of photoassimilate in bamboo leaves are still not clear. In this paper, the leaves of Fargesia yunnanensis from a greenhouse and the wild were respectively used as samples to analyze the anatomical characteristics of fusoid cells and vascular bundles. The results showed that the bamboo leaves from greenhouse got shorter and thinner with fewer layers of palisade parenchyma cells than those from the wild. The volumes of fusoid cells were also increased. Fusoid cells originated from a huge parenchyma cell as testified by the observed nuclei. Several fusoid cells usually formed one cell complex close to the midrib. Crystals were detected in fusoid cells but no pits or plasmodesmata on their walls, suggesting that fusoid cells had the function of regulating water. The presence of fusoid cells determined the major difference between a leaf blade and sheath. There were prominent chloroplasts with simple stroma lamellae in the parenchymatous bundle sheath cells and starch grains were also observed in these chloroplast. Photoassimilates could be transported across vascular bundle sheath via symplasmic pathways for an abundant of plasmodesmata in sheath cell walls, and transported into phloem tube by apoplastic pathway as there were no pits in the walls of companion cells and phloem tubes.

Balancing supply and demand: the spatial regulation of carbon metabolism in grass and cereal leaves.

Leaf primary metabolism responds to changes in both supply of inputs and demand for products. Metabolic control in leaves changes both spatially and temporally. Using leaves of C(3) temperate Gramineae, the spatial control of carbohydrate metabolism has been studied using a range of approaches. Single-cell sampling and subsequent analysis of metabolites, proteins and transcripts has indicated significant differences between epidermal, mesophyll and parenchymatous bundle sheath cells. These differences correlate with differentiated function as heterotrophic, autotrophic and transport pathway components of the leaf. The review emphasizes the key role of sucrose and discusses its catabolism to hexoses and its anabolism to fructans as mechanisms for the preservation of sucrose gradients within the leaf.

Rubisco small subunit, chlorophyll a/b-binding protein and sucrose:fructan-6-fructosyl transferase gene expression and sugar status in single barley leaf cells in situ. Cell type specificity and induction by light.

We describe a highly efficient two-step single-cell reverse transcriptase-polymerase chain reaction technique for analyzing gene expression at the single-cell level. Good reproducibility and a linear dose response indicated that the technique has high specificity and sensitivity for detection and quantification of rare RNA. Actin could be used as an internal standard. The expression of message for Rubisco small subunit (RbcS), chlorophyll a/b-binding protein (Cab), sucrose (Suc):fructan-6-fructosyl transferase (6-SFT), and Actin were measured in individual photosynthetic cells of the barley (Hordeum vulgare) leaf. Only Actin was found in the non-photosynthetic epidermal cells. Cab, RbcS, and 6-SFT genes were expressed at a low level in mesophyll and parenchymatous bundle sheath (BS) cells when sampled from plants held in dark for 40 h. Expression increased considerably after illumination. The amount of 6-SFT, Cab, and RbcS transcript increased more in mesophyll cells than in the parenchymatous BS cells. The difference may be caused by different chloroplast structure and posttranscriptional control in mesophyll and BS cells. When similar single-cell samples were assayed for Suc, glucose, and fructan, there was high correlation between 6-SFT gene expression and Suc and glucose concentrations. This is consistent with Suc concentration being the trigger for transcription. Together with earlier demonstrations that the mesophyll cells have a higher sugar threshold for fructan polymerization, our data may indicate separate control of transcription and enzyme activity. Values for the sugar concentrations of the individual cell types are reported.

Tissue distribution of primary metabolism between epidermal, mesophyll and parenchymatous bundle sheath cells in barley leaves

This paper originates from a presentation at the International Conference on Assimilate Transport and Partitioning, Newcastle, NSW, August 1999 In order to investigate the roles of different cell types, metabolite compartmentation in barley (Hordeum vulgare L.) leaf tissue was mapped at the single-cell level, using single-cell sampling and analysis (SiCSA) techniques. The partitioning of recently fixed photoassimilate was investigated for the first time at single-cell resolution, using BAMS (biological accelerator mass spectroscopy) for precise measurement of 14C in femtomole quantities. The data obtained by BAMS qualitatively reflect concentrations of sugars in different cell types measured by SiCSA. Calculation of 14C-specific activities showed that the radioactive label saturated the mesophyll and parenchymatous bundle sheath (PBS) pools within the 45-min labelling period. During the photoperiod, sucrose concentration increased to 200 mM in mesophyll cells. The concentration of malate also increased during the photoperiod in mesophyll and PBS cells. Epidermal cells contained very low concentrations of sugar but high concentrations of malate (120–180 mM) and did not show significant diurnal changes. Accumulation of sugars and fructan synthesis could be induced in mesophyll and PBS cells by reduced export of sugars from leaves or, alternatively, when sugars were supplied from excised leaf blade bases immersed in a sucrose solution in the dark. The epidermis accumulated additional malate in step with the accumulation of sugar by the mesophyll/PBS cells during the long-term reduction of export. Immunolocalisation of Rubisco and cytochrome oxidase proteins was used to analyse the distribution of enzymes of photoassimilation and respiration between functionally different cells in mature leaves of barley.

Visualizing the distribution of elements within barley leaves by energy dispersive X-ray image maps (EDX maps).

X-ray image maps of transverse sections of barley leaf blades were compared with individual X-ray emission spectra from vacuoles of barley leaf mesophyll, epidermis and parenchymatous bundle sheath cells. Both forms of X-ray analysis revealed distinct patterns in element distribution within the leaf blade. Calcium and Cl predominated within the epidermal cell vacuoles whilst P appeared mainly in the mesophyll cell layer. Apparent accumulation of S and Mg within the bundle sheath cell vacuoles is discussed in relation to xylem unloading and sulphur assimilation.

Occurrence of the suberized lamella in leaves of grasses of different photosynthetic types. I. In parenchymatous bundle sheaths and PCR (?Kranz?) sheaths

Leaf blades of 42 grasses (Poaceae) have been examined ultrastructurally for the occurrence of a suberized lamella in walls of parenchymatous bundle sheaths and PCR (= “Kranz”) sheaths in both large and small vascular bundles. The sample includes species from a range of major grass taxa, and represents all photosynthetic types found in the grasses. Three grasses with unusual C4 leaf anatomy were also included:Alloteropsis semialata, Aristida biglandulosa, Arundinella nepalensis. The presence of a suberized lamella in PCR cell walls was perfectly correlated with photosynthetic type. All PEP-carboxykinase type and NADP-malic enzyme type C4 species examined possessed a suberized lamella in outer tangential and radial walls, but with variable presence in inner tangential walls. PCR cells of bothAlloteropsis semialata andArundinella nepalensis also possessed a suberized lamella. A lamella was totally absent from parenchymatous bundle sheath cells of the C3 species examined (5 spp.) and ofPanicum milioides, a C3-C4 intermediate. It was also absent from PCR cells of NAD-malic enzyme type C4 species (14 spp.) andAristida biglandulosa. The results are discussed in relation to the leakage of CO2 from PCR cells, and to differences between C4 types in δ13C values, chloroplast position in PCR cells, and other anatomical characteristics.

Intracellular structures of Puccinia Poarum on its alternate hosts

A morphological and quantitative comparison has been made of the development of intracellular structures of the heteroecious rust, Puccinia poarum , in tissues of its pycnial-aecial host, Tussilago farfara and of its uredinial-telial host, Poapratensis . The relatively unspecialized intracellular hyphae of pycnial-aecial pustules differ from haustoria of uredinial-telial stages in their greater length, more irregular growth with occasional septation, and in their lack of a clear neck region or recognizable haustorium mother cell. Intracellular structures of P. poarum were found in epidermal, mesophyll and bundle sheath cells of both hosts, occurring in greater concentration in the bundle sheath than in the mesophyll. In Tussilago , infection of the vascular tissue was demonstrated. The frequency of penetration of mesophyll cells by haustoria in Poa was greater than that by intracellular hyphae in Tussilago . The volume of haustoria present in cells of the different types of infected tissue in Poa leaves was inversely related to host cell size, being highest in bundle sheath parenchyma cells and lowest in the epidermis. Haustoria in mesophyll cells increased in size and complexity throughout successive sub-stages of uredinial and telial development. The effects of infection of P. poarum on host tissue included reduced growth of Tussilago mesophyll cells adjacent to pycnia, increased volume of nuclei in infected cells of both hosts and a typically close association between nuclei of infected Poa cells and haustoria. These differences between monokaryotic intracellular hyphae and dikaryotic haustoria in growth habit, frequency of penetration of host cells, association with host nuclei and ability to infect vascular tissue suggest that the alternating phases of the rust life-cycle differ in their nutrition and physiology, requiring two types of intracellular structure.