Abstract:The microsporogenesis and development of male gametophyte in Tsoongiodendron odorum Chun were observed by using the paraffin section method. The anther was tetrasporangiate, originated from the stamen primordium. The anther wall was composed of epidermis, fibrous endothelium, middle layer (2~3 layers) and tapetum (1~2 layers). The middle layers became smaller at the tetrad stage, and disappeared at last. The tapetum was of glandular type, which degenerated to supply the nutrient to the pollens and finally disappeared when the pollens were mature. The primary sporogenous cells divided into the second sporogenous cells which would turn into microspore mother cells in a microsporangium. The cytokinesis in meiosis of the microspore mother cells was of modified simultaneous type, forming the decussate, isobilateral or T-shaped (rarely) tetrads. Mature pollen grains, which were dispersed at anthesis, were 2-celled type and degenerated seriously.

Abstract:Microsporogenesis and male gametophyte development of Uncaria hirsuta Havil. (Rubiaceae) were studied under light microscopy (LM) and transmissiom electron microscopy (TEM). Flowers of U. hirsuta are monoclinous, which each have five stamens, and the anther is tetralocular. The anther wall is composed of epidermis, endothecium, middle layer(s) and tapetum, the endothecium becomes fibrously thickened at anther dehiscence. The development of the anther wall is the dicotyledonous type, the cytokinesis following meiosis is simultaneous, producing tetrahedral tatrads and rarely isobilateral ones. The exine deposition is initiated during the tetrad stage, and the intine formation begins at vacuolated microspore stage. Mature pollen grains are two-cell type. The ontogenetic features of microsporogenesis and male gametophyte development in U. hirsuta basically follow the pattern of Rubiaceae. The tapetum is secretory type, and dual ontogeny, originating from the parietal layers and connective-derived layer, respectively. Tapetum begins to degenerate at the early stage of free microspore, producing lots of ubisch bodies, and it becomes completely degenerated at anther dehiscence. Protruding onci occur at uninucleate microspore stage, most of which shed during binucleate microspore stage. It is preliminarily presumed that the protruding onci might play an important role in pollen development.

Abstract:Microsporogenesis development of male sterile of Lavandula pinnata grown in South China was observed by light and electron microscopy. The results showed that the male flowers of L. pinnata had four stamens, each bears four microsporangia. Development of anther wall belonged to Dicotyledonous Type, and the anther wall was composed of an epidermis, endothecium, middle layer(s) and glandular tapetum. The cytokinesis following meiosis was simultaneous, producing tetrahedral and decussational tetrads. The development of the microspore could be divided into sporogenous stage, meiosis stage, and the early and late stage of the microspore. Binucleate pollen stage and mature pollen stage were not observed. Sterile pollens occured in the mononuclear pollen stage, the cytoplasm degenerated and disappeared developing abnormal pollen grains. Microsporogenesis were normal before the mononuclear pollen stage. The sterile characteristics showed tapetal cells degenerated too early and mictochondria was abnormal during the tetrad stage, there were abnormal spaces between callus wall and mother microspores wall, and the granules appeared in the anther wall cells unconventionally.

Abstract:In order to study the role of salicylic acid carboxyl methyltransferase (SAMT) in plant defense system, a full-length cDNA of Mikania micrantha SAMT was cloned from the SMART cDNA library by RACE, then the exogenous expression and induction pattern by SA were studied. The results showed that the full-length cDNA was 1299 bp, with a 1089 bp-length coding sequence (CDS) encoding a protein of 362 amino acids. Blast result showed 74% similarity with the amino acids of Clarkia breweri CbSAMT, confirming that Mikania micrantha SAMT may play a role in methylating SA into MeSA. Therefore this gene was named as MmSAMT and its GenBank accession number was FJ869889. Subsequently the CDS of MmSAMT was integrated into pET-32a(+), then the recombinant plasmid was transformed into Rosetta-gami (DE3) for exogenous expression. A specific monomer about 40 kD could be detected by SDS-PAGE, which was consistent with prediction. Western blot showed that the efficient solubility could be obtained cultured under 20℃,0.05 mmol/L IPTG、180 r min-1 for 6 hours. The transcription profile of MmSAMT in M. micrantha leaves sprayed 100µmol/L SA revealed that it could be activated by SA and reached a peak after 48 hours. It implied that MmSAMT may participate in the SA signaling pathway via MeSA, and induce the systemic acquired resistance (SAR) as a key signal and enhance the plant defense system.

Abstract:The promoter region of hsp90 with 864 bp (GenBank No. FJ434253), from invasive weed Ageratina adenophora was amplified based on PCR methods, which are available as chromosome walking from a known sequence to an unknown region. Moreover, another promoter region of hsp17.66 with 1 485 bp (GenBank No. FJ434252) was cloned by thermal asymmetric interlaced PCR (TAIL-PCR). Both of the 5′-flanking regions of hsp90 and hsp17.66 contained specific HSE element and several cis-acting elements, such as TATA-box, CAAT-box, et al.

Abstract:The effects of different light treatments and GA3 on hook opening, twining and parasitism of Cuscuta australis were studied using LED as light sources for the first time. The results showed that light was a necessary factor for dodders to parasitize the hosts successfully and chemical signals might facilitate host recognition and twining. GA3 involved in controlling twining response，but no distinct effect on hook opening. Furthermore, besides typical phytochrome reaction, another photoreaction called HER was involved in these processes, which could be caused by 879 nm far red light. So it demonstrated directly that there was not only HER in dodders, but also dark conversion from Pfr to Pr, and there were mutual interaction of phytochromes and cryptochromes in twining.

Abstract:The nitrogenase activities of endophytic diazotrophs in Neyraudia reynaudiana and Cynodon dactylon, which are the pioneer grasses for soil and water conservation, were studied by acetylene reduction assay (ARA). The results showed that the communities of the endophytic diazotrophs isolated from the stems of Neyraudia reynaudiana and the leaves of Cynodon dactylon showed high nitrogenase activities. Forty strains were isolated and purified on nitrogen-free medium, in which twenty-six strains showed weak nitrogenase activities, and fourteen had no nitrogenase activities. The natural communities of endophytic diazotrophs showed high nitrogenase activity under facultative anaerobic conditions or covered by paraffine. The communities of endophytic diazotrophs under laboratory-cultured showed lower nitrogenase activity than that of the natural communities.

Abstract:Effects of tannin extracted from Casuarina equisetifolia branchlets on the growth and tannin contents of its seedlings were studied. The tannins extracted from C. equisetifolia branchlets significantly inhibited the seedling growth, and the inhibition enhanced with increasing of tannin concentration. Under the same concentrations of tannins, sprout growth was inhibited more significantly than root growth treated after 15 days. The contents of tannins, especially total phenolics and extractable condensed tannins in seedlings decreased with increasing of extracted tannin concentrations. The significant linear negative correlation between them demonstrated that tannins extracted from C. equisetifolia branchlets had significant allelophthic effects on the seedlings. The allelophthic effects impacted not only the growth of C. equisetifolia seedlings, but also resistance against herbivore and other detrimental factors through impacting the formation of secondary metabolites in seedlings.

Abstract:The effects of 2,4-dinitrophenol (DNP, a uncouple agent for respiratory) on lipoxygenase (LOX) activity, fatty acid constituents in membrane lipids and cellular membrane permeability in harvested longan (Dimocarpus longan Lour. ‘Fuyan’) pericarp were investigated and the relationship to pericarp browning was analysed. The results showed that the cellular membrane permeability, LOX activity and browning index increased treated with DNP, the saturated fatty acids, such as palmitic acid (C16:0) and stearic acid (C18:0) increased, and the unsaturated fatty acids, such as linoleic acid (C18:2), linolenic acid (C18:3) and gondoic acid (C20:1), and index of unsaturated fatty acids (IUFA) and unsaturation degree of fatty acids decreased. It suggested that the pericarp browning of longan induced by DNP might be due to increasing LOX activity, enhancing degradation of membrane unsaturated fatty acid and reducing integrity of cellular membrane, which it lead to finally the contact of phenolase with phenolic substrates to produce browning polymers.

Abstract:The contents of eight metal elements, such as Au, Pb, Cu, Zn, Ca, Mg, Hg and As in Pogonatum neesii (C. Muell.) Dozy and soil on Lateritic Gold Deposit in Southwest Guizhou Province were analysed by Atomic Absorption Spectrometry, and the correlationship between plant and metal elements, and the accumulation of the moss to metals were further discussed. The results showed that the metal contents in P. neesii were higher than in soil, and the accumulation capacity of the plant to different metals varied greatly. Ca-Mg showed significantly coefficient at 0.01 level, so did Cu-Zn and Hg-As at 0.05 level. P. neesii had strong accumulation function to Hg and As elements.

Abstract:On the basis of frostless climate characteristic in winter of Nanning, Guangxi Province, the cutting propagation and perennial cultivation of genic male sterile upland cotton (Gossypium hirsutum L. ‘Dong A’), and their heterosis utilization were studied, including growth, development, yield and fiber quality. The results showed that 1-year-old cutting plants flowered earlier and were significantly better at stem diameter, internode length of main stem, boll weight and seed index, than that of the seeding plants, however, the seed yield of the cutting plants were significantly lower than that of the seeding plants, because 23.04% cutting plants derived from boll-bearing branches produced stunty plants, and the cutting plants were all male sterile plants, while the seeding plants were about 50%. There were no significant differences between 2-year-old cutting plants and seeding plants in all the investigated characters, also in yield and fibre quality of F1 hybrids. It suggested that cutting genic male sterile cotton and perennial cultivation used for producing hybrid seeds were feasible, but it must select the vegetative branches for cutting plants.

Abstract:The carbon stocks and dynamics in Acacia mangium plantation ecosystem in Heshan, Guangdong Province were simulated from 1985 to 2100 by BIOME-BGC Model. The results showed that the biomass of Acacia mangium plantation increased rapidly in the first 12 years, and then increased slowly up to 300 t hm-2. The proportions of biomass allocated to leaves, stems and roots were 4.35%, 73.91% and 21.74%, respectively. The carbon storage at the ecosystem level had the similar tendency, it reached 325 t C hm-2 at last, and the proportions of carbon storage in vegetation, soil and litter fall were 43.08%、52.30% and 4.62%, respectively. It was found that the net primary productivity (NPP) of Acacia mangium planation was high at the age of 4 to 12 years up to 11 t hm-2, and then stabilized at 3~6 t hm-2 later. The leaf area index (LAI) increased rapidly at the first three years and reached 7.84 at 5-year-old, but then decreased to 2.7~5.0. It indicated that LAI might be the main control factor of NPP by regression analysis. Our simulation results demonstrated that the Acacia mangium planation grew fast at the first 12 years. when Acacia mangium was used as pioneer tree species for forest vegetation restoration in lower subtropical region, it suggested on taking stand improvement after the age of 12 years.

Abstract:The characteristics of soil nutrients in primary and secondary forests of Mulun Karst forest of Guangxi, China were studied, and the contents of SOM, N, P and K at 0~5 cm depth soil from the three main landforms, such as steep slope, gentle slope and depression, were detected, each including rock-soil (shallow and scattered soil) and soil surface microhabitat (relatively thick and continuous soil). The results showed that the contents of SOM, TN and AN were high in primary forest with high species diversity, with 345 g kg-1 of SOM in rock-soil surface microhabitat of gentle slope, while above 80 g kg-1 in soil surface microhabitat of depression. However, those decreased in secondary forest dominated by Alchornea trewioides, Mallotus conspuyrcatus, Eurycorymbus cavaleriei with lower species diversity. The SOM contents in rock-soil (110 g kg-1) and soil surface microhabitat (77 g kg-1) in gentle slope decreased significantly, which were only 32% and 35% of that in primary forest, respectively; but there were not significant differences in SOM, TN and AN contents in depression between the two vegetations. There were not obvious regularities in TP, AP, TK and AK contents between the two vegetations. The soil nutrient contents (except for TK) raged in order: gentle slope > steep slope > depression, but there were not significant differences among the three landforms in secondary forest. The soil nutrient contents (besides TK) in rock-soil surface microhabitat were higher than that in soil surface microhabitat.

Abstract:The preponderant endophytic fungi of rice in Guangdong Province were Fusarium spp. In order to study the function of secondary metabolites from endophytic fungi on bio-control to rice paddy disease, a strain of endophtic fungus Fusarium moniliform ZSU-1 from sterily rice stem was ferment cultured, four secondary metabolites was isolated and purified by silica column and sephadex LH-20 chromatogram. On the basis of 1D、2D NMR and mass spectral data, there were fusaric acid (1), fusaric and 9,10-dehydrofusaric acids(1: 1) (2), beauvericin (3) and mannitol (4). The components 1 and 2 have strong antibacterial activities, they might be used for bio-control to rice paddy disease.

Abstract:Mitogen-activated protein kinase (MAPK) is an important component in signal transduction pathway of MAPK cascade reaction. It is involved in the biotic and abiotic stress responses, hormone responses and also regulating cell differentiation and development processes by transferring internal and external cellular signals. The studies on rice (Oryza sativa L.) MAPK family, such as its structure, mechanism, classification and functions in stress responses and biological processes were reviewed, it can provide the references for the further studies and application of rice MAPK.