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  • Author or Editor: S.-P. Wang x
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High ozone (O3) can cause great damage to plants. However, the effect of high O3 on nitrogen (N) absorption, distribution, and utilization in rice at different growth stages under different planting densities is poorly understood. In the present study, a conventional cultivar (Yangdao 6) and a hybrid cultivar (II You 084) with different planting densities were exposed to an elevated amount of O3 (E-O3; 50% higher than that of the control, C-O3) under a freeair gas concentration enrichment (FACE) system. N absorption, distribution, and utilization of the green leaves, stems, and shoots at tillering, jointing heading, and maturity were investigated. Results showed that E-O3 significantly increased the N content in the shoots of Yangdao 6 by 7.5%, 12.7%, and 19.6%, respectively, at jointing, heading, and maturity. Also, the N content in the shoots of II You 084 increased by 5.4%, 6.5%, and 8.4% at the corresponding growth stage upon E-O3 application. E-O3 significantly decreased N accumulation of II You 084 by 8.3%, 4.9%, 4.7%, and 19.2%, respectively, at tillering, jointing, heading, and maturity. Further, E-O3 had a decreasing effect on the N distribution in green leaves (p ≤ 0.05) of both cultivars, but exerted an increasing effect on that in the stems of both cultivars (p ≤ 0.05). In addition, E-O3 significantly decreased the N use efficiency (NUE) for biomass of the two cultivars in all growth stages. These results revealed that E-O3 could increase the N content in rice plants but decrease the N accumulation and utilization in both cultivars. The effects of E-O3 on N absorption, distribution, and utilization were not affected by planting density.

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Fusarium head blight (FHB, caused by Fusarium graminearum) is a severe disease which threatens the yield and quality of harvested grain products, and hence causes major economic losses in wheat (Triticum spp.) and other small grain cereals. One of the infection routes for the pathogen is believed to be through the extruded anther. In order to study the role of the anther on FHB infection, FHB resistance was measured among wheat (Triticum aestivum L.) cultivars with non-extruded infertile anthers in cytoplasmic male sterile (CMS) lines and with extruded fertile anthers in their alloplasmic maintainer lines, and in an unrelated restorer line. We artificially inoculated the lines with F. graminearum (isolate NE 90) at 1.0 × 105 or 2.0 × 105 spores mL−1 for 72 or 96 hours. The results indicated that CMS cultivars were significantly more resistant than the maintainer and restorer cultivars. As the CMS lines differed from the maintainer lines by cytoplasm, anther health, anther extrusion, and seed set, additional experiments are needed to determine the role of each factor in infection. However, this research indicates that fertile anthers most likely are an important part of the infection pathway and of susceptibility to FHB.

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New high-molecular-weight glutenin (HMW glutenin) sequences isolated from six Psathyrostachys juncea accessions by thermal asymmetric interlaced PCR differ from previous sequences from this species. They showed novel modifications in all of the structural domains, with unique C-terminal residues, and their N-terminal lengths were the longest among the HMW glutenins reported to date. In their repetitive domains, there were three repeatable motif units: 13-residue [GYWH(/I/Y)YT(/Q)S(/T)VTSPQQ], hexapeptide (PGQGQQ), and tetrapeptide (ITVS). The 13-residue repeats were restricted to the current sequences, while the tetrapeptides were only shared by D-hordein and the current sequences. However, these sequences were not expressed as normal HMW glutenin proteins because an in-frame stop codon located in the C-termini interrupted the intact open reading frames. A phylogenetic analysis supported different origins of the P. juncea HMW glutenin sequences than that revealed by a previous study. The current sequences showed a close relationship with D-hordein but appeared to be more primitive.

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