Effects of Lead (Pb) and Benzo [a] Pyrene (B[a]P) and their Combined Exposure on Element Accumulation in Ryegrass (Lolium perenne L.).

It was observed in this work that application of Pb and B[a]P co-exposure significantly (p < 0.05) reduced Pb content in ryegrass leaves and roots. The effect of Pb dominated the change of N, P, K, Cu, and Cr content in leaves and roots of ryegrass under joint stress of Pb and B[a]P. Principal component analysis showed that the foliar spraying of 400 µmol L-1 Pb and 80 µmol L-1 B[a]P had the best effect on improving the mineral element absorption under combined pollution. Ryegrass has strong resistance and certain Pb and B[a]P absorptive capacities, and can resist combined contamination by transferring N, P, K, Zn, Cu, and Cr contents between the overground and the root. These results highlight the potential capacity of ryegrass for use in the phytoremediation of soils contaminated by Pb and B[a]P.

Functional characterization of squalene epoxidase and NADPH-cytochrome P450 reductase in Dioscorea zingiberensis.

Dioscorea zingiberensis is a perennial medicinal herb rich in a variety of pharmaceutical steroidal saponins. Squalene epoxidase (SE) is the key enzyme in the biosynthesis pathways of triterpenoids and sterols, and catalyzes the epoxidation of squalene in coordination with NADPH-cytochrome P450 reductase (CPR). In this study, we cloned DzSE and DzCPR gene sequences from D. zingiberensis leaves, encoding proteins with 514 and 692 amino acids, respectively. Recombinant proteins were successfully expressed in vitro, and enzymatic analysis indicated that, when SE and CPR were incubated with the substrates squalene and NADPH, 2,3-oxidosqualene was formed as the product. Subcellular localization revealed that both the DzSE and DzCPR proteins are localized to the endoplasmic reticulum. The changes in transcription of DzSE and DzCPR were similar in several tissues. DzSE expression was enhanced in a time-dependent manner after methyl jasmonate (MeJA) treatments, while DzCPR expression was not inducible.

GC-MS-based identification and statistical analysis of liposoluble components in the rhizosphere soils of Panax notoginseng.

Continuous cropping obstacle, mainly caused by microorganisms and organic components in soil, has become a serious problem for the plantation of Panax notoginseng (Araliaceae) due to the rapidly increased demands of this famous herbal medicine in recent decades. The rhizosphere soils cultivated with 3-year-old healthy and ill notoginseng were chemically investigated by gas chromatography-mass spectrometry (GC-MS) and compared with the corresponding soils without the plantation of notoginseng. Totally 47 liposoluble components were identified. Furthermore, the multiple statistical analysis showed that these constituents were qualitatively and quantitatively associated with the differences between the cultivated soil with P. notoginseng and the uncultivated soil. Among them, neophytadiene (4), d-α-tocopherol (38), (3ß,22E,24S)-ergosta-5,22-dien-3-ol (39), (3ß,24R)-ergost-5-en-3-ol (40), stigmasta-5,22-dien-3-ol (41), stigmast-4-en-3-one (44) and (5α)-stigmastane-3,6-dione (47) contributed most to the significant differences between the cultivated and uncultivated soils, whereas cyclopentadecane (3), octadecanoic acid methyl ester (16), docosanoic acid ethyl ester (31), nonacosane (34), 38 and 39 were found in much higher amount in the soils with ill P. notoginseng as compared to the case of those with the healthy P. notoginseng. On the other hand, liposoluble components in different cultivation areas were of great diversity; however, they were able to remain relatively consistent across the overall trend of differential substances.

Lipid profiles reveal different responses to brown planthopper infestation for pest susceptible and resistant rice plants.

INTRODUCTION: Brown planthopper (BPH) is the most destructive insect pest for rice, causing major reductions in rice yield and large economic losses. More than 31 BPH-resistance genes have been located, and several of them have been isolated. Nevertheless, the metabolic mechanism related to BPH-resistance genes remain uncharacterized. OBJECTIVES: To elucidate the resistance mechanism of the BPH-resistance gene Bph6 at the metabolic level, a Bph6-transgenic line R6 (BPH-resistant) and the wild-type Nipponbare (BPH-susceptible) were used to investigate their lipid profiles under control and BPH treatments. METHODS: In conjunction with multivariate statistical analysis and quantitative real-time PCR, BPH-induced lipid changes in leaf blade and leaf sheath were investigated by GC-MS-based lipidomics. RESULTS: Forty-five lipids were identified in leaf sheath extracts. Leaf sheath lipidomics analysis results show that BPH infestation induces significant differences in the lipid profiles of Nipponbare and R6. The levels of hexadecanoic acid, methyl ester, linoleic acid, methyl ester, linolenic acid, methyl ester, glycidyl palmitate, eicosanoic acid, methyl ester, docosanoic acid, methyl ester, beta-monolinolein, campesterol, beta-sitosterol, cycloartenol, phytol and phytyl acetate had undergone enormous changes after BPH feeding. These results illustrate that BPH feeding enhances sterol biosynthetic pathway in Nipponbare plants, and strengthens wax biosynthesis and phytol metabolism in R6 plants. The results of quantitative real-time PCR of 5 relevant genes were consistent with the changes in metabolic level. Forty-five lipids were identified in the leaf blade extracts. BPH infestation induces distinct changes in the lipid profiles of the leaf blade samples of Nipponbare and R6. Although the lipid changes in Nipponbare are more drastic, the changes within the two varieties are similar. Lipid profiles in leaf sheath brought out significant differences than in leaf blade within Nipponbare and R6. We propose that Bph6 mainly affects the levels of lipids in leaf sheath, and mediates resistance by deploying metabolic re-programming during BPH feeding. CONCLUSION: The results indicate that wax biosynthesis, sterol biosynthetic pathway and phytol metabolism play vital roles in rice response to BPH infestation. This finding demonstrated that the combination of lipidomics and quantitative real-time PCR is an effective approach to elucidating the interactions between brown planthopper and rice mediated by resistance genes.