[Responses and corresponding physiological mechanisms of different wheat varieties in their nitrogen efficiency and nitrogen uptake to nitrogen supply].

In this paper, the biological traits, physiological parameters, and enzyme activities related to N assimilation and metabolism of wheat varieties with different nitrogen (N) efficiency were studied under low and high N supply. The results showed that under low N supply, the dry mass of root, leaf, and stem as well as the accumulated N amount in plant were in the order of high N efficiency variety > mid N efficiency variety > low N efficiency variety. The variety with high N uptake efficiency (Ji 97-6360) under low N supply had the highest root active absorption area and TTC-reductive activity and the highest leaf nitrate reductase activity and NO3- content, while the variety with high N physiological efficiency (Shixin 5418) had higher nitrite reductase and glutamine synthetase activities but lower NO3- content and NR activity in its leaf. There was a significant positive correlation between nitrogen use efficiency (NUE) and nitrogen uptake index (NUI) under low N supply. The biological traits, physiological parameters, and enzyme activities related to nitrogen assimilation and metabolism of test wheat varieties were not always the same under high and low N supply.

[Photosynthesis and active-oxygen-scavenging enzyme activities in rice varieties with different phosphorus efficiency under phosphorus stress].

Using six rice varieties with different phosphorus (P) use efficiency as the materials, the photosynthesis and active-oxygen-scavenging enzyme activities of the rice varieties under different P conditions were studied. Under deficient P condition, the photosynthetic rate (Pn) and soluble protein content (pro) were all gradually decreased with the growth process in the six tested varieties. The Pn and pro were always lower under deficient P condition than those under sufficient P condition. The Pn (ranging from 10.06-10.83 micromol CO2 x m(-2) x s(-1)), chlorophyll content (ranging from 3.32-3.56 mg x g(-1) FM) and pro (ranging from 33.08-33.95 mg x g(-1) FM) were all the highest in varieties with high-P efficiency, then in varieties with mid-P efficiency, and the lowest in varieties with low-P efficiency. There were no obvious differences on stomatal conductance (Gs) among the varieties. Meanwhile, the superoxide dismutase (SOD) activities of the tested varieties were all decreased with the process of deficient P stress. The SOD activities were also shown to be the highest in the varieties with high-P efficiency, then in the varieties with mid-P efficiency, and the lowest in the varieties with low-P efficiency under deficient P conditions. The malondialdehyde (MDA) contents in the tested varieties showed a reverse pattern of the SOD activities, with the highest in varieties with low-P efficiency and lowest in varieties with high-P efficiency. There was not an obvious change pattern on POD activity among the tested varieties under different P conditions. Under deficient P condition, the higher SOD activity and lower peroxidation degree of cell membrane system play important roles in improving the photosynthesis of the varieties with high-P efficiency.

[Ultracytochemical localization of enzymes and DNA analysis during the development of garlic].

It is believed that during storage, the parenchyma cells of garlic (Allium sativum L.) bulb would wither and fade gradually, and nutrients released inside the cells become available for the germination and growth of the young bud. In this study, The distributions of acid phosphatase (APase) and Adenosine Triphosphatase (ATPase) during germination were analyzed based on the method of lead precipitation at the electron microscopic level. It was found that their activities presenting in plasma membrane, cell wall and plasmodesma increased along the different developmental periods during storage. The fact that the most intensive enzymatic activity of APase and ATPase appeared at germination indicates that degradation, transformation and exportation of cell matrix are helpful in complete translocation of nutrient to new bud. The DNA in the degrading parenchyma cells was analyzed using the agarose electrophoresis. Results clearly showed a typical DNA ladder on the gel, indicating that gene-controlled, programmed cell death may contribute to the degradation of garlic parenchyma cells.

[Histological observation on programmed cell death in wheat-leaf rust fungus intreaction].

The biochemical character of PCD in different interaction between wheat and Puccinia recondita f. sp tritici was observed using DNA agarose gel electrophoresis and end labeling in situ (Terminal Deoxynucleotidyl Transferase-mediated dUTP Nick End TUNEL). The DNA ladder, which is the typical character of programmed cell death(PCD), was observed in incompatible combination (cv.lorvin10 x race 162) and the positive reaction in wheat leaves of incompatible combination since 12h after inoculation also appeared. The results, coupled with the previous study, indicated that HR was a typical form of PCD in incompatible combination between wheat and wheat leaf fungus.

[Studies on the change of intercellular connection and the appearance and function of ectodesmata-like structure in garlic clove during the dormancy development].

The characteristics of intercellular connection have been observed during the dormancy development of garlic by the transmission electron microscope (TEM). The results indicated that the appearances of the different states of intercellular connection were physiological adaptation to the development of garlic clove during storage. Ectodesmata-like existed at the wall boundary between the declining tissue and the living cells in the garlic during germination period. By Confocal Laser Scanning Microscopy (CLSM) combined with fluorescence probe, 457Da Lucifer Yellow (LYCH) which was impermeable to the membrane, could enter the living parenchyma cell through symplastic route. The result proved that ectodesmata-like structure, which may be recognized as the modified plasmodesata, still retained physiological activity during a certain time and function as the channels of the symplastic transport of nutrient.

[Histological observation on programmed cell death in wheat--leaf rust fungus intreactioin].

The ultrastructural features of mesophyll cell surrounding the fungus in different interaction between wheat and Puccinia recondita f. sp tritici were observed with transmission electron microscopy. In incompatible combination(cv. lorvin 10 x race 162), the nuclei gradually became irregular with highly condensed chromatin towards the nuclear envelope, while the chloroplast became swelling since 12 h to 24 h after inoculation(a.i.). At 48 h a.i., the condensation of the chromatin became more prominent and the chloroplast began to disintegrate. Finally, when some mitochondria started to degrade at 72 h a.i., the nuclei and the chloroplast became disruption completely. During the process, endoplasmic reticulum and vesicles did play a vital role in the further degeneration of other organelles and protoplasmic components just similar to the lysosome acting in the animal cells. These results suggest that the ultrastructural feature of cell death is a form of programmed cell death (PCD). In compatible combination (cv. lorvin 10 x race 165), ultrastructural of mesophyll cell exhibited different features from incompatible combination. At 24 h a.i., the plasmic membrane showed sunken and the chloroplast slightly exhibited swelling. Since 48 h to 72 h a.i., most of the swelling chloroplasts were observed while the other organelles still remained unaltered. At the same time, the hypha and haustorium mother cell in the intracellular space also could be observed.