Screening relatives of wheat for snow mold resistance and freeing tolerance

Four hundred and eighty one accessions of species and subspecies of genera Triticum and Aegilops were evaluated for resistance to speckled snow mold caused by Typhula ishikariensis and for freezing tolerance. All Triticum and seven of Aegilops species were severely affected by snow mold. Among surviving Aegilops spp., only the Ae. cylindrica accessions exhibited resistance similar to that of the most resistant winter wheat cultivar, PI 173438. After repeated screening of accessions of Ae. cylindrica, 12 accessions were identified as having resistance similar to that of PI 173438; eleven of those were considered more freezing tolerant than PI 173438, but less than wheat cv. Valjevskaya, the freezing tolerant check. Accessions of Ae. cylindrica with snow mold resistance exceeding that of PI 173438, and with freezing tolerance, are currently being screened. This revised version was published online in August 2006 with corrections to the Cover Date.     

Formation of a one-dimensional array of oxygen in a microporous metal-organic solid

We report the direct observation of dioxygen molecules physisorbed in the nanochannels of a microporous copper coordination polymer by the MEM (maximum entropy method)/Rietveld method, using in situ high-resolution synchrotron x-ray powder diffraction measurements. The obtained MEM electron density revealed that van der Waals dimers of physisorbed O2 locate in the middle of nanochannels and form a one-dimensional ladder structure aligned to the host channel structure. The observed O-O stretching Raman band and magnetic susceptibilities are characteristic of the confined O2 molecules in one-dimensional nanochannels of CPL-1 (coordination polymer 1 with pillared layer structure).