Growth, chlorophyll content, chlorophyll fluorescence parameters and activity of antioxidant enzymes in corn seedlings were investigated under hydroponics supplied with different concentrations of Cu. Root growth of corn seedlings was significantly inhibited and dry weight was decreased with 5-20 μmol.L-1 Cu. Chlorophyll content and Fv/Fm, ETR, qP and qy in leaves were also significantly decreased under excess Cu. The Cu concentrations in shoots and roots increased with increasing Cu concentration in the nutrient solution. However, most absorbed Cu by corn seedling was located in roots. At all levels of Cu treatment, the amount of Cu was substantially higher in roots than in shoots. During the 10-day Cu treatment, the activities of SOD, POD, CAT and GR initially increased and then decreased in roots. But for the leaves, short-term treatment with excess Cu had no significant effect on these enzyme activities. Prolonged exposure for 4 days resulted in increased enzyme activities. Thus, antioxidant enzymes have functions to alleviate the toxic effects of oxidative stress caused by excess Cu.

Phaeocystis globosa, which causes harmful algae bloom (HAB), was isolated from the South China Sea and grown in modified F/2 medium under varying nitrate concentrations. Cell growth and nitrate reductase (NR) activity were investigated. P. globosa grown without nitrate showed low-level NR activity, inhibited algal cell growth and no growth curve. The optimal nitrate concentration for algal cell growth and NR activity was 3.62 mmol.L-1. Under 4 different levels of nitrate, NR activity in cells peaked at day 9, but cell density peaked at day 16. Cell density and NR activity differed significantly nitrate concentration. Thus, eutrophic sea water with a high nitrate concentration is suitable for the growth of P. globosa and has great potential for developing into red tide.

Dunaliella salina is known as probably the most halotolerant eukaryotic organism living in various salt habitats, and glycerol metabolism plays an important role in its osmoregulation. We investigated the growth, intracellular glycerol content and activities of enzymes in glycerol metabolism under NaCl stress. Growth of D. salina was inhibited in solutions containing 4.0, 3.0, 0.8, and 0.6 mol.L-1 NaCl. The intracellular glycerol content accumulated and activities of glycerol 3-phosphate phosphatase and dihydroxyacetone reductase catalyzing dihydroxyacetone to glycerol were enhanced in response to hyperosmotic stress. However, glycerol content decreased and the activities of glycerol 3-phosphate phosphatase lost and dihydroxyacetone reductase catalyzing glycerol to dihydroxyacetone increased when adapting to hypo-osmotic stress. The paper discusses the association of glycerol metabolism with the osmoregulation mechanism of D. salina.

We studied variation in 37 simple sequence repeats (SSRs) in 2 populations of common wild rice Oryza rufipogon from Qionghai and Sanya in Hainan. SSRs had more genetic variability in the Sanya than in the Qionghai population. The genetic identity and distance between the 2 populations were 0.6385 and 0.4486 cM, respectively. The result of Wright’s FST showed that 37 SSRs had moderate genetic differentiation within the Qionghai and Sanya populations, with an FST=0.3909,which was mainly caused by lower gene flow, with an Nm=0.3895.

We used fluorescence observation to examine pollen germination and growth following reciprocal crosses between Brassica juncea and B. pekinesis. When B. juncea was used as the seed parent, the pollen grains on the stigma could sprout as usual, and most of the pollen tubes could reach the ovule through the style and finish fertilization. With fertilization type, porogamy, chalazogamy and misogamy included, only a few pollen tubes grew poorly and gave rise to the end being swollen and twisted as well as branched pollen tubes. With B. pekinesis used as a seed parent, the growth of the pollen tube was restrained, so only a little tube could go into the ovule and fertilize the eggs because of papilla cells with strong callose effects. The development of a hybrid embryo derived from the reciprocal crosses was observed by means of the paraffin-cut section method. B. juncea and B. pekinesis crossed embryos developed early and in general grew to maturity, and the growth of the embryo and endosperm was relatively normal, whereas in the B. pekinesis and B. juncea hybrid embryo, growth stopped at the heart-shaped stage as did growth of the endosperm at the dissoluble nuclear stage, and finally disappeared in the seed. Thus, B. juncea and B. pekinesis and its crosses are incompatible to some degree.

The distribution characteristics and dynamic variations of glycyrrhizic acid (GA) in Glycyrrhizic uralensis has been studied by ultrasonic extraction and High Performance Liquid Chromatography (HPLC). The content of GA of underground parts of both wild and cultivated liquorices were greater than that of aboveground parts and that in inconstant roots was close to that of taproots. The monthly variation in GA content was similar among wild and cultivated liquorices. The amplitude of variation of GA in rhizomes was greater than that in taproots and inconstant roots. During a growing season, the content of GA in taproots of cultivated liquorices increased, peaking in October. Therefore, the optimal picking time is in late autumn. GA content in taproots of cultivated liquorices at 1.0 m soil depth was higher a trend to increase, so such planting model could reduce root harvest which displayed. To solve such problems, further exploration is needed for effective cultivation techniques for liquorice.

The effect of human activity on the ecosystem has become one of the hot topics in recent studies of ecology. However, few studies have investigated the comprehensive impact of cultivating trees on the ecological characteristics of local ecosystems. In this study, we used a sample method (quadrat investigation method) to compare ecological characteristics, such as life-form and leaf-size spectra, the composition of plant species, species’ richness and diversity, and floristic elements and biomass, of 12-year-old Betula alnoides in the pure forest and mountainous rain forest in southern subtropical mountain regions of Yunnan Province. Life-form and leaf-size spectra and floristic elements did not differ significantly between forest and mountainous rain forest. However, artificial forest had higher species richness than rain forest. The two kinds of forests had a similar Shannon-Wiener value (H'). The main species composition of B. alnoides in the forest was very different from that in the ountainous rain forest. So developing an appropriate area of artificial forest for local economy and vegetation restoration is necessary.

This paper deals with the community plant genetic resources in Manlun, a Dai village in Xishuangbanna, through ethnobotanical and anthropological approaches. Rich plant genetic resources (PGRs) are still conserved in the village. The cultivated plants belong to 68 families, 136 genera and 204 species, which are used for edible, medicinal, ornamental and religious purposes. Many landraces are concentrated in 8 families such as Cucurbitaceae, Araceae, Gramineae. The local society have a very close relationship with the formation and development of PGRs. They play an important role in the conservation and utilization of PGRs. In recent years, PGRs are decreasing because of economic development, population increase and other factors. The indigenous knowledge and local culture are also facing challenges of loss of PGRs, which is a key to encouraging the local people’s participation in PGR conservation.

Performing clonal propagation and developing the genetic transformation for exploring somatic embryogenesis is important. We studied the embryonic callus induction and culture in vitro of immature embryos by hormone control and produced embryogenic calli on 1/2 LM medium, with a high induction rate of 52.7%, but calli were not differentiated after subculture. We also produced plantlets directly from cotyledon immature embryos at a rate of 92%. Our studies confirm that embryo development stages have a great effect on embryonic callus induction, and we discuss the culture conditions of somatic embryogenesis of Pinus armandii.

Because explants of Momordica charantia were apt to form callus rather than adventitious buds during in vitro culture, we studied the contents of endogenous hormones in explants at different developing stages to explore the relation between adventitious bud differentiation and endogenous hormones and factors that limit the formation of adventitious buds. Use of enzymelinked immunosorbent assay (ELISA) revealed that (1) explants had higher content of indole-3-acetic acid (IAA) and lower content of iPAs, which resulted in difficulty in adventitious bud formation; (2) the differentiation of adventitious buds was tightly related with the ratio of IAA to iPAs; and (3)during in vitro culture, adventitious bud differentiation was promoted with a suitable level of cytokinin (such as Zeatin) and subculture in time.

Plant growth and development is generally controlled by selective removal of short-lived regulatory proteins. One major pathway is represented by the ubiquitin (Ub)/26S proteasome pathway.In this pathway, ubquitin and 26S proteasome play essential roles. Ub is attached to proteins destined for degradation by a 3-step enzymatic (E1-E2-E3) conjugation cascade, and the resulting Ubprotein conjugates are then recognized and degraded by the 26S proteasome. The arm repeat-containing 1 (ARC1) and the skp1-cul1-F-box (SCF) proteins, belonging to the family of E3 Ub ligases,function in both the sporophytic and gametophytic self-incompatible responses, respectively. This review highlights the recent progress toward understanding the role of the Ub/26S proteasome pathway during self-incompatible responses.

Polyploidization has long been recognized as a prominent force in the evolution of plant species. Allopolyploids in early generations often show rapid changes in gene expression. This review summarizes changes in gene expression, including silencing, activation, and altered expression of homoeologous gene pairs and discusses the molecular mechanisms of these changes and their biological significance. Finally, the existing problems in relevant research are analyzed and future studies proposed.

Pentosan is a group of nonstarch polysaccharides in cereal seeds, particularly wheat. It is an important functional component of wheat flour, affecting many properties such as bread-making quality. In the last 50 years, a large number of studies have been performed on pentosan for its potential broad applications in making bread and other health products. This article reviews the latest research into pentosan, including its composition and structure, methods of content measurement and its applications in bread-making.