A major problem in hybrid rice production is the occurrence of leaf senescence during the grain filling stage that can result in reduction of yield. Changes in contents of several endogenous hormones are related to le...A major problem in hybrid rice production is the occurrence of leaf senescence during the grain filling stage that can result in reduction of yield. Changes in contents of several endogenous hormones are related to leaf senescence. The relationship between endogenous hormones and leaf senescence in the rice hybrid Tiyou 418 and its parents Tijin and C418, was undertaken for investigation. Indicators of leaf senescence, including superoxide dismutase (SOD) activity, malondialdehyde (MDA) accumulation and chlorophyll content, as well as the contents of abscisic acid (ABA), zeatin riboside (ZR), gibberellin (GA1/3) and auxin (IAA) in the leaves were determined. Different rates of leaf senescence were observed in the three materials. Senescence occurred earliest and fastest in Tijin, followed by Tiyou 418 and then C418. A similar trend was recorded in ABA, ZR, and IAA contents during the grain filling stage in the three materials. Changes in (GA1/3+ZR+IAA)/ABA ratios were also similar, being quite stable during the early stage of leaf senescence, and decreasing markedly during the late stage. The ratio declined more dramatically in Tijin, in accordance with its faster leaf senescence. The results suggest that the ratio of (GA1/3+ZR+IAA)/ABA regulates chlorophyll content, SOD activity, MDA content and membrane lipid peroxidation. It is postulated that endogenous hormones may play a role in the regulation of leaf senescence in a systematic way.展开更多
The crystal and molecular structures of O-ethyl-N-(2,3,4-tri-O-acetyl-β-D-xylopyranosyl)-thiocarbamate were determined by X-ray crystallography. It crystallizes in the orthorhombic system with space group P2(1)2(1)2(...The crystal and molecular structures of O-ethyl-N-(2,3,4-tri-O-acetyl-β-D-xylopyranosyl)-thiocarbamate were determined by X-ray crystallography. It crystallizes in the orthorhombic system with space group P2(1)2(1)2(1), lattice parameters a=0.90636(18) nm, b=0.94716(19) nm, c=2.1855(4) nm, V=1.8762(7) nm 3, and Z=4. All the substituents are in equatorial positions. There are four intramolecular interactions, each forming a five-membered ring. The molecules are linked by interactions to form three-dimensional framework. Atoms O6 and O8 show positional disorder.展开更多
The crystal structure of 5-nitro-4-salicylideneamino-3-methyl-1,2,4-triazole-5-thione ([C 10 H 9N 5O 3S]·HCON(CH 3) 2, M r=352.38)(CCDC No. 216094) was determined by the single crystal X-ray diffraction...The crystal structure of 5-nitro-4-salicylideneamino-3-methyl-1,2,4-triazole-5-thione ([C 10 H 9N 5O 3S]·HCON(CH 3) 2, M r=352.38)(CCDC No. 216094) was determined by the single crystal X-ray diffraction method. The crystal belongs to a triclinic system, the space group is P1 with unit cell constants a= 0.6113(2) nm, b=1.0836(4) nm, c=1.3132(5) nm, α=74.523(7)°, β=117.68(3)°, γ= 79.769(7)°, V=0.8245(5) nm 3, Z=2, D c=1.419 g/cm 3, μ=0.228 mm -1 , F(000)=368, R and wR are 0.0579 and 0.1040, respectively, beasd on 3348 unique reflections of which 1925 reflections were observed[I>2σ(I)]. The results indicate that the title compound can be assigned to the thione tautomeric form rather than the thiol tautomeric form. It contains a five membered triazole ring and a phenyl ring with a dihedral angle of 4.35°. The intermolecular hydrogen bond N3_H3…S1, O1_H1…O4 can be observed.展开更多
文摘A major problem in hybrid rice production is the occurrence of leaf senescence during the grain filling stage that can result in reduction of yield. Changes in contents of several endogenous hormones are related to leaf senescence. The relationship between endogenous hormones and leaf senescence in the rice hybrid Tiyou 418 and its parents Tijin and C418, was undertaken for investigation. Indicators of leaf senescence, including superoxide dismutase (SOD) activity, malondialdehyde (MDA) accumulation and chlorophyll content, as well as the contents of abscisic acid (ABA), zeatin riboside (ZR), gibberellin (GA1/3) and auxin (IAA) in the leaves were determined. Different rates of leaf senescence were observed in the three materials. Senescence occurred earliest and fastest in Tijin, followed by Tiyou 418 and then C418. A similar trend was recorded in ABA, ZR, and IAA contents during the grain filling stage in the three materials. Changes in (GA1/3+ZR+IAA)/ABA ratios were also similar, being quite stable during the early stage of leaf senescence, and decreasing markedly during the late stage. The ratio declined more dramatically in Tijin, in accordance with its faster leaf senescence. The results suggest that the ratio of (GA1/3+ZR+IAA)/ABA regulates chlorophyll content, SOD activity, MDA content and membrane lipid peroxidation. It is postulated that endogenous hormones may play a role in the regulation of leaf senescence in a systematic way.
文摘The crystal and molecular structures of O-ethyl-N-(2,3,4-tri-O-acetyl-β-D-xylopyranosyl)-thiocarbamate were determined by X-ray crystallography. It crystallizes in the orthorhombic system with space group P2(1)2(1)2(1), lattice parameters a=0.90636(18) nm, b=0.94716(19) nm, c=2.1855(4) nm, V=1.8762(7) nm 3, and Z=4. All the substituents are in equatorial positions. There are four intramolecular interactions, each forming a five-membered ring. The molecules are linked by interactions to form three-dimensional framework. Atoms O6 and O8 show positional disorder.
基金the Natural Science Foundation of Shandong Province(Y2 0 0 3B0 1,Z2 0 0 2 B0 2 ),the Outstanding Adult-young Scientific Research Encouraging Foundation of Shandong Province(No. 0 3BS0 81) and the National Natural ScienceFoundation of China(No. 2 0 2 75 0
文摘The crystal structure of 5-nitro-4-salicylideneamino-3-methyl-1,2,4-triazole-5-thione ([C 10 H 9N 5O 3S]·HCON(CH 3) 2, M r=352.38)(CCDC No. 216094) was determined by the single crystal X-ray diffraction method. The crystal belongs to a triclinic system, the space group is P1 with unit cell constants a= 0.6113(2) nm, b=1.0836(4) nm, c=1.3132(5) nm, α=74.523(7)°, β=117.68(3)°, γ= 79.769(7)°, V=0.8245(5) nm 3, Z=2, D c=1.419 g/cm 3, μ=0.228 mm -1 , F(000)=368, R and wR are 0.0579 and 0.1040, respectively, beasd on 3348 unique reflections of which 1925 reflections were observed[I>2σ(I)]. The results indicate that the title compound can be assigned to the thione tautomeric form rather than the thiol tautomeric form. It contains a five membered triazole ring and a phenyl ring with a dihedral angle of 4.35°. The intermolecular hydrogen bond N3_H3…S1, O1_H1…O4 can be observed.
