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Abstract
Plant dry weight of tomato (Lycopersicon esculentum Mill.) grown in aged bark media was equal to or greater than that of those cultured in a control medium of perlite-sand. Plant growth in fresh bark was inhibited initially and then recovered. Zn concentration and total content per plant were high for plants cultured in bark media even when little or no Zn was applied. The intereaction between media and applied Zn was significant. Plant Zn increased with increasing amount of applied soluble Zn when cultured in perlite-sand, but did not normally change for plants cultured in bark. High Zn concentration of plants cultured in fresh bark was too low to account for the initial growth inhibition. N concentration and content per plant were normally lower for plants grown in fresh bark. N of plants in aged bark was similar to plants in the standard medium. Growth inhibition of plants in fresh bark did not appear to be due to N deficiency.
Sweet potato virus disease (SPVD) is the most devastating disease of sweetpotato [Ipomoea batatas (L.) Lam.] globally. It is caused by the co-infection of plants with a potyvirus, sweet potato feathery mottle virus (SPFMV), and a crinivirus, sweet potato chlorotic stunt virus (SPCSV). In this study we report the use of cDNA microarrays, containing 2765 features from sweetpotato leaf and storage root libraries, in an effort to assess the effect of this disease and its individual viral components on the gene expression profile of I. batatas cv. Beauregard. Expression analysis revealed that the number of differentially expressed genes (P < 0.05) in plants infected with SPFMV alone and SPCSV alone compared to virus-tested (VT) plants was only 3 and 14, respectively. However, these findings are in contrast with SPVD-affected plants where more than 200 genes were found to be differentially expressed. SPVD-responsive genes are involved in a variety of cellular processes including several that were identified as pathogenesis- or stress-induced.