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et al., 2012 ), the relationship—if any exists—between photosynthesis and chloroplast ultrastructure has not been widely characterized. Phloem sieve elements are nonnucleated cells, largely controlled by their nucleolated companion cells, and their

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elements (SE)/companion cells (CC), SE/PP, CC/PP, and PP/PP in each selected field. The results of the plasmodesmal counting were given as the number of plasmodesmata per micron of specific cell/cell interface length in the transverse section, which is

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Abstract

Freshly harvested sweet potatoes [Ipomoea batatas (L.) Lam. c. Jewel] are cured by holding them at 80–95% relative humidity and 29.4°C for 5 to 7 days. Curing heals wounds inflicted during harvest, thus minimizing loss from microbial decay during subsequent storage. The wound healing process was followed by applying a saturated solution of phloroglucinol in strong acid (PG) to the underside of detached wound tissue and scoring the intensity of the color developed. Microscopic examination of companion tissue with PG showed that color intensity was due to the layers of cells in which PG positive material was deposited. Wound periderm formation was observed to occur simultaneously with development of the most intense color, indicating that the test may be useful in the evaluation of curing progress.

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). Therefore, it is important to investigate crop production systems that incorporate companion plantings that attract honeybees and other pollinators to agricultural crops. Even though a diverse plant community is important to support and maintain pollinator

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Abstract

Celery (Apium graveolens L.) is a favorable plant material for phloem loading studies, because vascular bundles and phloem tissue can be isolated from fleshy petioles with minimal manipulations. Uptake kinetics for sucrose loaded into phloem are different than uptake by phloem-free tissue. In isolated vascular bundles, uptake of phloem sugars (sucrose and mannitol) were biphasic kinetics, consisting of an active, saturating component operating at low sugar concentrations, and linear kinetics at higher sugar concentrations. Glucose uptake exhibited linear kinetics. However, when the glucose analog, 3-0-methyl glucose (unmetabolized) was used, biphasic kinetic profiles were obtained. Sucrose and mannitol uptake in isolated phloem tissue consisted of one saturating component showing Michaelis-Menten kinetics. In the homogenous storage parenchyma tissue, sucrose uptake kinetics were by diffusion and insensitive to carbonyl cyanide m-chlorophenyl hydrazone (identical to that of L-glucose). The data suggested the presence of different mechanisms for sucrose uptake across the sieve-tube companion cell complex and nonphloem cells. It is proposed that celery may be a useful system to obtain direct evidence on mechanism of solute loading. Chemical names used: carbonyl cyanide m-chlorophenyl hydrazone (CCCP).

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signal was concentrated in the cells surrounding the xylem and phloem ( Fig. 2A ). In addition, a strong IAA signal was also detected in companion cells of the phloem. The cytoplasm of the parenchymal cells between the vascular bundles and between the

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the maturation of sieve cells and companion cells toward the periphery. The phloem sieve elements and their companion cells are some of the smallest cells in the plant ( Knoblauch and Oparka, 2012 ), have thin primary walls, and in petioles are often

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pollenizers could be sold as seeded fruit as well as these that are more suitable for production with specific triploid cultivars. Materials and Methods Treatments. Thirteen pollenizer cultigens were evaluated: ‘Companion’, ‘Jenny’, ‘High Set 11’, ‘Mickylee

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., 2005 ), our results demonstrate, for the first time, the process of endocytosis in phloem cells (companion cells and/or the enucleated sieve elements). The implications from these studies are also significant in that they establish that NPs can be

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transport in the phloem. This chapter outlines the structures and functions of the sieve elements, companion cells, and plasmodesmata connecting these cells. The composition and water relations of phloem are presented in many paragraphs describing the

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