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Mehrassa Khademi, David S. Koranski, David J. Hannapel, Allen D. Knapp, and Richard J. Gladon

Water uptake by impatiens (Impatiens wallerana Hook. f. cv. Super Elfin Coral) seeds was measured as an increase in fresh weight every 24 hours during 144 hours of germination. Seeds absorbed most of the water required for germination within 3 hours of imbibition and germinated at 60% to 67% moisture on a dry-weight basis. Germination started at 48 hours and was complete by 96 hours at 25C. Water stress of -0.1, -0.2, -0.4, and -0.6 MPa, induced by polyethylene glycol 8000, reduced germination by 13%, 49%, 91%, and 100%, respectively, at 96 hours. Under the same water-stress conditions, increases in fresh weight were inhibited by 53%, 89%, 107%, and 106%, respectively. Three distinct groups of storage proteins were present in dry seed; their estimated molecular weights were 1) 35, 33, and 31 kDa; 2) 26, 23, and 21 kDa; and 3) two bands <14 kDa. Major depletion of storage proteins coincided with the completion of germination. Water potentials that inhibited germination also inhibited degradation of storage proteins. During germination under optimum conditions, the soluble protein fraction increased, coinciding with a decrease in the insoluble fraction.

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Paula P. Chee and Jerry L. Slightom

Cotyledon explants of cucumber (Cucumis sativus L. cv. Poinsett 76) seedlings were cocultivated with disarmed Agrobacterium strain C58Z707 that contained the binary vector plasmid pGA482GG/cpCMV19. The T-DNA region of this binary vector contains plant-expressible genes for neomycin phosphotransferase II (NPT II), β -glucuronidase (GUS), and the coat protein of cucumber mosaic virus strain C (CMV-C). After infection, the cotyledons were placed on Murashige and Skoog medium containing 100 mg kanamycidliter. Putative transformed embryogenic calli were obtained, followed by the development of mature embryos and their germination to plants. All transformed RO cucumber plants appeared morphologically normal and tested positive for NPT IL Southern blot analysis of selected cucumber DNAs indicated that NPT II, GUS, and CMV-C coat protein genes were integrated into the genomes. Enzyme-linked immunosorbent assay and Western blot analysis indicated that the CMV-C coat protein is present in the protein extracts of progeny plants. These results show that the Agrobacterium-mediated gene transfer system and regeneration via somatic embryogenesis is an effective method for producing transgenic plants in Cucurbitaceae.

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Shao-Ling Zhang and Shin Hiratsuka

Cultivars of the Japanese pear [Pyrus pyrifolia (Burm.) Nakai] have variable degrees of self-incompatibility (SI) and can be classified into at least three groups: strong, intermediate, or weak SI; as shown by the extent of self-pollen tube growth in the style, and the percentage of fruit set following self-pollination. Following self-pollination, the elongation of pollen tubes in the detached styles of `Kosui' and `Kikusui' became increasingly suppressed from 4 days before anthesis (–4 DAA) to 2 days after anthesis (2 DAA). Tube growth of `Kosui' was more suppressed than that of `Kikusui' during this period. In `Osa-Nijisseiki', however, the rate of tube growth did not vary with stage of stylar development, from –8 to 2 DAA. Pollen tubes elongated much better after cross-pollination than after self-pollination at all stages tested, and the extent of the elongation increased as the styles matured. The concentration of total S-protein (sum of two S-proteins per buffer-soluble protein) increased with stylar development, but the rate of increase varied with the cultivar. The rate was significantly greater in the strongly self-incompatible `Kosui' than in the moderately self-incompatible `Kikusui', and was slowest in the weakly self-incompatible `Osa-Nijisseiki' at all developmental stages. During stylar maturation, the concentration of S4-protein, which is common in all cultivars, was highest in `Kosui', followed by `Kikusui' and `Osa-Nijisseiki'. Thus, the cultivar differences in SI expression in the Japanese pear are determined about –4 DAA and appear to be regulated, in part, by the concentration of S-proteins produced in the style.

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K. Roberts, J. Williamson, J. Wright, C. Biles, and V. Russo

Senescence and levels of minerals, sugars, and proteins were determined in stalk internodes of corn (Zea mays L.) cv. Illini Gold, a shrunken2 hybrid, from from mid-whorl (V9; internodes completely juvenile) to fresh-market maturity (FM; internodes exhibiting stages of senescence). Senescence was rated in internodes near the base of the stalk (I7), below the ear (I9), and between the ear and tassel (I11). Tissues were extracted and analyzed by carbon-nuclear magnetic resonance spectroscopy (C-nmr) and SDS-PAGE electrophoresis. Senescence rating increased from V9 to FM. Through silk emergence (R1) C-nmr carbohydrate spectra were similar, regardless of internode, with chemical shifts between 61 and 104 ppm, mostly of glucose, fructose, and sucrose. At FM, additional lines were found that were not associated with a saccaride. The highest concentration of sucrose was at R1, fructose at tasseling (VT), and R1, and for glucose from VT to FM. The protein profile present through R1 in I7 was not present at FM. In I9, the protein profile was similar throughout. In I11, numbers, or density, of protein bands decreased through FM. Mineral concentrations did not change, decreased, or fluctuated. Levels of N, Cl, or Na at VT, R1, and FM, respectively, were negatively correlated with senescence. In I7 and I9, senescence ratings were negatively correlated with levels of Mg, NO 3, or SO2– 4. Senescence appears to be associated with concentrations of some minerals, a reduction in levels of sucrose, and with the presence or absence of some proteins; however, cause and effect remains to be established. This research was hosted by USDA/SCARL at Lane, Okla., and made use of NMR equipment provided through USAF/AFOSR Grant F49620-95-1-0316 and NIH/NIGMS Grant GM 08003.

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Md. Jahedur Rahman, Md. Quamruzzaman, Jasim Uddain, Md. Dulal Sarkar, Md. Zahidul Islam, Most. Zannat Zakia, and Sreeramanan Subramaniam

., chlorophyll content (Chl a and Chl b), ascorbic acids, total carotenoids, protein, total soluble solids (TSS), and reducing sugar were measured. Data recording procedure. The leaf chlorophyll content was measured by following Dey et al. (2016) procedure. The

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Kenneth G. McCabe, Christopher J. Currey, James A. Schrader, David Grewell, Jake Behrens, and William R. Graves

and discovered that bioplastics that contain soy proteins can supply nutrients to plants growing in the containers. Soy bioplastics show strong potential for use in fertilizers that can be more sustainable than common synthetic fertilizers. Soy

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Kathryn C. Taylor and Danielle R. Ellis

A 5-kDa zinc-binding protein (ZBP) accumulates in the phloem above the graft union in citrus trees affected by two citrus decline disorders, citrus blight and Macrophylla decline. Citrus blight and Macrophylla decline are decline disorders of unknown etiology. Citrus blight has historically been restricted to humid production regions, and Macrophylla decline occurs in arid regions. A causal agent has not been identified for either disorder. Levels of the 5 kDa ZBP are increased 2.5- and 1.5-fold, respectively, in the phloems above the graft union in trees with citrus blight and Macrophylla decline. The protein was purified from citrus phloem and a partial N-terminal sequence was obtained. The protein has homology to the cystein-rich chitin binding domain of several plant chitinases and hevein. Hevein and class I chitinases, which have this N-terminal chitin binding domain, have antifungal activity and antibacterial activity and are induced by wounding and several other stresses. Oligonucleotides corresponding to the greatest conserved region in the N-terminal domain of the ZBP were produced. They were used as primers for PCR reactions against a citrus leaf cDNA library. Four PCR products were obtained from these reactions. The products are being subcloned and sequenced. They will be used to probe the citrus cDNA library to obtain the cDNA clone for the 5 kDa ZBP.

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Seenivasan Natarajan and Jeff Kuehny

Small heat shock proteins (sHSP) are a specific group of highly conserved proteins produced in almost all living organisms under heat stress. These sHSP have been shown to help prevent damage at the biomolecular level in plants. One of the greatest impediments to production of marketable herbaceous plants and their longevity is high temperature stress. The objectives of this experiment were to study the plant responses in terms of sHSP synthesis, single leaf net photosynthesis, total water-soluble carbohydrates (WSC), and overall growth for two S. splendens cultivars differing in performance under heat stress. `Vista Red' (heat tolerant) and `Sizzler Red' (heat sensitive) were exposed to short duration (3 hours) high temperature stresses of 30, 35, and 40 °C in growth chambers. Increasing the temperature to about 10 to 15 °C above the optimal growth temperature (25 °C, control) induced the synthesis of sHSP 27 in S. splendens. Expression of these proteins was significantly greater in the heat-tolerant vs. the heat-sensitive cultivar. Soluble carbohydrate content was greater in `Vista Red', and in both the cultivars raffinose was the primary soluble carbohydrate in heat-stressed plants. Overall growth of plants was significantly different in the two cultivars studied in terms of plant height, stem thickness, number of days to flower, and marketable quality. The better performance of `Vista Red' under heat stress was attributed to its morphological characteristics, including short stature, thicker stems and leaves. sHSPs and WSC are also found to be associated with heat tolerance and heat adaptation in S. splendens.

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C.C. Lim and R. Arora

A time-course study was conducted to characterize seasonal patterns of cold hardiness (CH) and protein profiles in the leaf tissue of five Rhododendron cultivars (`Grumpy Yellow', `Vulcan's Flame', `Autumn Gold', `Chionoides', and `Roseum Elegans'). Leaf samples were collected monthly (starting in mid September) and leaf discs were subjected to controlled freezing and thawing regimes. CH (LT50 defined as temperature causing 50% injury) was assessed by electrolyte leakage and visual observations. Data indicate that cultivars varied in their CH in nonacclimated state and in their ability to cold acclimate. Results obtained in September showed `Grumpy Yellow' to be least hardy (about –3°C) and `Roseum Elegans' to be most hardy (about –7°C). All cultivars exhibited successive increases in CH during fall and winter. Maximum CH in all cultivars occurred by December/January with `Chionoides' being most hardy (about –31°C) while `Grumpy Yellow' was least hardy (about –20°C). LT50 based on electrolyte leakage was highly correlated with visual rating. Seasonal changes of protein profiles and relationship of specific stress proteins to cultivars' CH and cold acclimation ability are discussed.

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Wol-Soo Kim* and Sang-Hyun Lee

In order to investigate the cause of differences of mature pollen in Asian pear (Pyrus phyfolia) that are collected from various sources for the artificial pollination, various factors were measured as below: the composition of nonstructural carbohydrate in bud at 30 days after full bloom, the contents of crude protein in skin, cytosol and membrane, and the affinity for lectin (CON-A: Concanavalin, type III A) of glycoprotein in cytosol of pollen were measured. Contents of sucrose and glucose in buds influenced pollen germination rate and pollen tube growth, respectively. Therefore, soluble types of carbohydrates stored in bud were regarded as influencing on pollen germination rate and pollen tube growth. Pollen, which showed low activity, had low affinity on CON-A, lectin of glycoprotein, because it had fragile membrane, proteins in cells were denatured to pollen surface and certain enzymes concerned in pollen germination lost stability and activity. Pollens that showed high activity contained 92 kDa protein while others not. This was assumed as influencing on control of pollen viability.