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Ellen T. Paparozzi, Joshua R. Widhalm, and M. Elizabeth Conley

Common swedish ivy plants when exposed to nitrogen (N) stress display typical nitrogen deficiency symptoms such as reddening of stems and petioles and yellowing of leaves. When N levels are restored, leaves of swedish ivy plants will re-green without leaf loss. An experiment was conducted to determine how proteins change when leaves were re-greened after N deficiency. Cuttings of Plectranthus australis were rooted under mist and allowed to yellow. Plants were then potted up and fertilized with one of two treatments: complete nutrients with N at 150 ppm or complete nutrients with 0.8 ppm N. The experimental design was a randomized complete-block design with six blocks. Each block had the two N treatments and six plants per treatment. After 3–4 weeks, all plants in the 150-ppm N treatment had re-greened and leaf samples for protein analysis were taken. Plants in four of the six blocks were then switched to the other treatment. After leaves had re-greened once again, leaf samples were taken and the experiment was terminated. Two-dimensional polyacrylamide gel electrophoresis was used to compare the treatments. No obvious differences in protein absence or presence were noted. However, Rubisco appeared to be differentially expressed between the two treatments. 2-D gel analysis with subsequent Western blots showed that for most of the leaf samples, the large subunit of Rubisco (56kD) was quantitatively about 1.3 times more concentrated in the N-deficient plants and possibly modified. The small subunit (12kD) was not reliably detectable. Additional protein results for repeated leaf re-greening and the role Rubsico may play in leaf re-greening will be discussed.

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Ellen T. Paparozzi, Jazbaat K. Chahal, Petre Dobrev, Elizabeth A. Claassen, Walter W. Stroup, and Radomira Vankova

., 2009 ; Kiba et al., 2011 ). As cytokinins, often referred to as the leaf regreening hormone, also exhibit positive effects on chlorophyll concentration in leaves we decided to compare the dynamics of the response to N deficiency and subsequent N

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Dean A. Kopsell, James T. Brosnan, Gregory R. Armel, and J. Scott McElroy

, pigments increased beyond untreated levels by the end of the study. We hypothesize that temporary cessation of phytoene desaturase activity resulted in accumulations of phytoene in treated plants. On regreening of leaf tissues, and resurgence of phytoene

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Mahalaxmi Veerasamy, Yali He, and Bingru Huang

Temperatures greater than the optimal growth temperature negatively affect plant growth and induce various physiological and metabolic changes, including premature leaf senescence. Leaf senescence is characterized by loss of chlorophyll and

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Qi Chai, Fang Jin, Emily Merewitz, and Bingru Huang

important role in leaf dehydration tolerance as the coupled changes may prevent plasma membrane separation from cell walls or plasmolysis, which is critical for the maintenance of cell turgor and cell growth ( Nilsen and Orcutt, 1996 ). Re-greening and

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Timothy K. Broschat

( Ogden et al., 1987 ). Nitrogen, like P, K, and Mg, is a mobile element within palms. That is, under conditions of deficiency, the palm is able to extract N from the oldest leaves in the canopy and translocate it to the growing new leaf (spear leaf) to

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Brandon R. Smith and Lailiang Cheng

; Gonzalez-Vallejo et al., 2000 ; Larbi et al., 2001 ). It has been proposed that bicarbonate uptake increases the pH of xylem sap and leaf apoplast and interferes with foliar Fe utilization ( Mengel et al., 1984a , 1984b ), but this is not well-agreed on

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Charalambos I. Siminis and Manolis N. Stavrakakis

(II) to enable its transportation in the mesophyll cells ( Hell and Stephan, 2003 ). Ferric reduction capacity of leaf cells has been until now estimated in a few plant species with the use of intact leaves ( Kosegarten et al., 1999 ), excised leaf pieces

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Monica Ozores-Hampton

interveinal chlorosis with a yellowing of the leaf tissue in the interveinal region while the veins remain green. Due to poor mobility within the plant, Fe deficiency symptoms are common in the youngest leaves first, especially at the base of the leaves. Under

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Graham H. Barry and Smit le Roux

) applications required to improve the rind color of citrus fruit. z Prohexadione–calcium (Regalis® containing 10% ProCa) was applied as a medium-cover spray to just before runoff with a handheld spray gun by targeting the outer leaf canopy and adjacent