[Relationships between H2O2 metabolism and Ca2+ transport in dormancy-breaking process of nectarine floral buds].

In order to explore regulatory function of H2O2 in bud dormancy release, main effects of three dormancy-breaking treatments (high temperature, hydrogen cyanamide and TDZ) on H2O2 metabolism were determined, and impacts of H2O2 on Ca2+ transport were tested using non-invasive micro-test technique. The results showed that both high temperature and hydrogen cyanamide induced H2O2 accumulation and CAT inhibition were efficient in breaking dormancy during deep dormancy period. However, TDZ showed little impacts on H2O2 metabolism and was much less effective in breaking dormancy. Dormant floral primordium was absorbing state to exogenous Ca2+ due to active calcium channels. The Ca2+ transport could be changed by exogenous H2O2. H2O2 of low concentration reduced the absorption rate of Ca2+, and at high concentration, it changed the Ca2+ transport direction from absorption to release. The results indicated that H2O2 signals were related with Ca2+ signals in dormant buds. Ca2+ signal regulated by H2O2 accumulation might be important in the dormancy-breaking signal transduction process induced by high temperature and hydrogen cyanamide.

[Effects of exogenous nitric oxide on highbush blueberry PSII photochemical activity and antioxidant system under high temperature stress].

Taking the test tube 'Duke' highbush blueberry (Vaccinium corymbosum) seedlings having been transplanted to the field for 6 months as test materials, this paper studied the effects of exogenous nitric oxide (NO) on their growth, PS II photochemical activity, and antioxidant system under high temperature stress. Applying 0.2, 0.5, and 1.0 mmol x L(-1) of exogenous sodium nitroprusside (SNP) could alleviate the decrease of maximum photochemical efficiency (Fv/Fm), actual photochemical efficiency under light (phi PS II), photochemical quench (q(P)), and nonphotochemical quench (NPQ) caused by high temperature, and prevented the damage of high temperature on photosynthetic apparatus. Comparing with the control, treatments NO decreased the leaf membrane permeability and MDA content, increased the SOD and CAT activities significantly, and promoted proline accumulation. Appropriate concentration SNP could significantly alleviate the damage of high temperature stress on highbush blueberry seedlings, and 0.5 mmol x L(-1) of SNP had the most satisfactory effect.

[Study on the genetic diversity of natural chestnut of Shandong by ISSR].

The genetic diversity of 279 indivdiuals from 10 populations in Shandong Province was investigated using inter-simple sequence repeat (ISSR) markers. As a result, 116 bands were amplified by 10 informative and reliable primers, of which 101 were polymorphic loci. A relatively high level of genetic diversity was revealed: PPL = 87.07, He = 0.2697, H0 = 0.3999 (at the species level); PPL = 64.58, He = 0.2004, H0 = 0.3010 (at the population level). A higher level of genetic differentiation was detected among populations with Nei's G(ST) analysis and the analysis of molecular variance (AMOVA; G(ST) = 0.2414, F(ST) = 0.2224). Habitat fragmentation and gene flow may result in genetic differentiation. UPGMA cluster analysis indicated that the four populations from Linshu, Junan, Tancheng and Feixian grouped together, whereas Laiyang populations clustered in an isolated clade. The results showed that a mixed mating system was possibly the main factor influencing the genetic structure of this species. These results, combined with other information about Castanea mollissima, may provide a valuable basis for proposing conservation strategies.