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521.
P. B. GAHAN 《Botanical journal of the Linnean Society. Linnean Society of London》1989,100(4):319-321
GAHAN, P. B., 1989. How stable are cambial initials? An autoradiographic study of the incorporation of [3H] thymidine into nuclei of cambial initials in stems of Lycopersicon esculentum has permitted the identification of subpopulations of cambial cells with differing rates of turnover. It is proposed that the true cambial initial cells have a very low rate of turnover and merely provide a population of daughter cells which are the readily identifiable, frequently dividing cambial cells. 相似文献
522.
Hatem Zgallai Kathy Steppe Raoul Lemeur 《植物学报(英文版)》2006,48(6):679-685
A greenhouse experlment was performed In order to Investigate the effects of dlfferent levels of water stress on leaf water potentlal (ψw), stomatal resistance (rs), protein content and chlorophyll (Chl) content of tomato plants (Lycoperslcon esculentum Mill. cv. Nlkita). Water stress was Induced by addlng polyethylene glycol (PEG 6 000) to the nutrlent solution to reduce the osmotlc potential (ψs). We Investlgated the behavlor of antl-oxldant enzymes, such as catalase (CAT) and superoxide dlsmutase (SOD), durlng the development of water stress. Moderate and severe water stress (i.e. ψs= -0.51 and -1.22 MPa, respectlvely) caused a decrease In ψw for all treated (water-stressed) plants compared with control plants, wlth the reductlon belng more pronounced for severely stressed plants. In addltion, rs was slgnlflcantly affected by the Induced water stress and a decrease in leaf soluble protelns and Chl content was observed. Whereas CAT actlvlty remained constant, SOD actlvlty was increased in water-stressed plants compared wlth unstressed plants. These results Indicate the possible role of SOD as an anti-oxidant protector system for plants under water stress condltlons. Moreover, It suggests the possibllity of using this enzyme as an addltional screening crlterlon for detecting water stress in plants. 相似文献
523.
524.
Characterization of disease resistance gene-like sequences in near-isogenic lines of tomato 总被引:5,自引:0,他引:5
T. Ohmori M. Murata F. Motoyoshi 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,96(3-4):331-338
We examined near-isogenic lines (NILs) carrying either of the tomato mosaic virus (ToMV) resistance genes Tm-1 and Tm-2 for sequences homologous to the isolated disease-resistance genes. DNA fragments were amplified from the genomic DNA of the
NILs by the polymerase chain reaction (PCR) using primers designed on the basis of sequences of certain domains conserved
among some disease-resistance genes. Of ten PCR products cloned, five were identified as having homology to either of the
two classes of disease-resistance genes. The first class encoded proteins containing leucine-rich repeats (LRRs) and a nucleotide-binding
site (NBS), such as the RPS2 gene in Arabidopsis and the N gene in tobacco. The second class encoded proteins containing a C-terminal membrane anchor but no NBS, such as the Cf 2 and Cf 9 genes in tomato. In Southern hybridization of the genomic DNAs of the NILs carrying either Tm-1 or Tm-2 and their parental NIL carrying neither of these resistance genes, multiple bands could be detected with most of the clones
used as probes. This suggests that the genomes of the NILs contain multiple copies of sequences homologous to some of the
known disease-resistance genes. No evidence was obtained to show that the Tm-1 and/or Tm-2 loci encode either class of protein, since no polymorphic band patterns between the NILs were detected by Southern hybridization.
Received: 15 August 1997 / Accepted: 2 September 1997 相似文献