Comparative transcriptomics and bioinformatics analysis of genes related to photosynthesis in Eucalyptus camaldulensis.

The timber species Eucalyptus camaldulensis is one of the most important in southern China. Therefore, it is essential to understand the photosynthetic pattern in eucalyptus leaves. In the present study, eighteen photosynthesis-related genes were analyzed using bioinformatics methods. The results indicated that there were ten differentially expressed ribose-5-phosphate isomerase genes (RPI), and six of them were up-regulated in the mature leaves compared to the young leaves, while others were down-regulated. The differential expression of four rubisco methyltransferase genes (RBCMT) were observed. Two of them were up-regulated, while two were down-regulated in mature leaves compared to young leaves. Furthermore, two ribulose-phosphate-3-epimerase genes (RPE) were up-regulated in the mature leaves compared to the young leaves. In contrast, two genes involved in triosephosphate isomerase (TIM) were down-regulated in mature leaves compared with young leaves. The current study provides basic information about the transcriptome of E. camaldulensis and lays a foundation for further research in developing and utilizing important photosynthetic genes.

Chlorothalonil: an effective bacteriostatic agent for bud induction of Acacia auriculiformis under open condition (non-axenic).

BACKGROUND: Open tissue culture technique could be simplified by using different bacteriostatic agents. There is a great difference in the bacteriostatic effects of different antimicrobial agents on various explants. However, there is no report about the effective bacteriostatic agent for open tissue culture of Acacia auriculiformis. RESULTS: We carried out the bud induction trials under open conditions to screen out an effective antibacterial agent for open tissue culture of A. auriculiformis. The results showed that the suitable type and concentration of bacteriostatic agent was 0.2 g L-1 Chlorothalonil, and the suitable explant type was middle shoot section with leaves (the shoot section with third to fifth axillary bud). The treatment of 0.8 g L-1 Carbendazim for 3 min was the most suitable strategy for explants disinfection, and October was the best time for explants collection. The suitable bud induction medium was 1/8 MS + agar 7 g L-1 + Chlorothalonil 0.2 g L-1 + 6-BA 1.5 mg L-1, and the bud induction rate was 99.54%. CONCLUSIONS: Our results revealed that Chlorothalonil is an effective bacteriostatic agent for bud induction of A. auriculiformis under open condition. These results would be very helpful for further establishment of open tissue culture technology for A. auriculiformis.

[Growth effect of eucalyptus-acacia mixed plantation in South China].

Eucalyptus U6 and Acacia crassicarpa were mixed planted with different ratios and modes to investigate the growth parameters of the two tree species. In the 2-3 years old mixed plantation, the wind-throw of A. crassicarpa decreased markedly with increasing ratio of Eucalyptus U6, the decrement being 26.14% when the Eucalyptus U6/A. crassicarpa ratio was 3 : 1, but the survival rates of Eucalyptus U6 and A. crassicarpa had no significant difference under different planting modes. Mixed planting retarded the A. crassicarpa growth to some extent, with the DBH being 90% of that in pure A. crassicarpa stand. The mixed planting had little effects on the height growth of Eucalyptus U6, but promoted its DBH growth markedly, and the beneficial effect increased with increasing ratio of A. crassicarpa. In the 6 years old 1 : 1 Eucalyptus U6/A. crassicarpa plantation, the Eucalyptus U6 individuals with DBH > 15 cm occupied 32.1%; while in pure Eucalyptus U6 stand, they only accounted for 5.83%. Mixed planting with 2 : 1 Eucalyptus U6/A. crassicarpa could obtain a maximum total biomass of 198.8 m3 x hm(-2), which was 118.8% of the total biomass in pure Eucalyptus U6 stand, or 169.9% of that in pure A. crassicarpa stand. Mixture of Eucalyptus with Acacia would be a good choice to produce Eucalyptus trees with larger DBH.

[SSR molecular markers related to wood density and fibre traits in poplar].

In this study, field experiment was carried out following the randomized complete block design with five replications in 1999. F2 population was derived from a cross between the female ZH3 and the male ZH1 (ZH3, ZH1 were selected from F1 individuals derived from the cross of Populus deltoides with P. cathayana, produced by HUANG Dong-Sen in 1973). Sixty-eight F2 populations, four F1 individuals (included ZH3, ZH1) and both parents (Populus deltoides and P. cathayana) were measured for wood densities, fibre lengths, fibre widths and fibre angles. The results indicated that the trait of fibre length has obviously heterosis, there may have positive effects among the genes controlling the trait of fibre length, but may have negative effects among the genes controlling the trait of wood density. Using the method of single factor variance, the SSR markers correlated with wood density, fibre length, fibre width and fibre angle were identified to be 5, 7, 4 and 2, respectively. There were some useful markers among the above traits in P. cathayana, such as PMGC2873-1 for wood density (its contribution was 4.88%), PMGC456-3, PMGC2702-2 for fibre length (their contribution were 22.96% and 9.17%, respectively), PMGC2408-1 for fibre width (its contribution was 7.18%), and PMGC2525-1 for fibre angle (its contribution was 16.59%), these markers might be useful for wood property improvement if using them correctly in breeding program.

[Studies of genetic analysis and SSR linked marker location of gene resistance to southern rust in inbred line P25 of maize].

Using P25 (immune inbred line), F349 (susceptible inbred line) and the derived population F1, F2, B1 and B2 as materials, we investigated the heredity the of disease resistance gene to maize southern rust (Puccinia polysora Underw.) through the major-gene and polygene inheritance model. The results indicate that a major resistance gene exists in the inbred line P25 and expresses with additive effect. We didn't find any multi-genes. The inheritabilities of this major resistant gene among F2, B1 and B2 were 81.88%, 38.14% and 55.1%, respectively. We constructed a maize SSR linkage map using P25 x F349 F2:3 population, and located the resistant gene on chromosome 10. The genetic distance between this gene and phi059 marker was 5.8 cM.

[Construction the RFLP linkage map and location the NCBL QTL of maize].

There exists the race differential phenomenon in Exserohilum turcicum (namely NCBL). At present, there are 5 identified races of NCBL and some un-known races in China. For improvement of maize resistance to NCBL, a basic method is to improve maize quantitative resistance. To identify the numbers and effects of the quantitative resistant loci to NCBL in maize, we constructed F2:3 population from resistant line P138 as male parent cross with sensitive line Z3 as female parent. Using RFLP marker technique, the RFLP linkage map of maize was cons cracted covering 1999. 8 cM, and the average distance between markers was 16.5 cM. Identified QTL of NCBL lesion length, width, and area were 3, 3, 2, respectively. The combined contribution ratios of these QTL were 58.1%, 71.5%, 27.5%, respectively. No QTL was identified NCBL lesion number per leaf, it was a trait that might be controlled by one- or oligo-genes. Finally, authors discussed and prospected the maize NCBL research in future.