ABSTRACT
Lead (Pb) is a heavy metal pollutant and negatively affects agriculture and ecosystems. Pb can cause oxidative stress and abnormal plant growth. The ascorbic acid-glutathione (AsA-GSH) cycle mainly exists in chloroplasts and resists oxidative stress, scavenges reactive oxygen radicals, and maintains normal photosynthesis. However, the dosage related effects of Pb on pakchoi photosynthesis, via oxidative stress and the AsA-GSH system, remains unclear. In this study, various Pb dosage stress models were tested (low: 300 mg/kg; medium: 600 mg/kg; high: 900 mg/kg). Pb stress induced a dose-dependent increase in Pb content in pakchoi leaves (P < 0.05). Principal component analysis showed that Se, B, and Pb were significantly and negatively correlated. Pb stress also increased MDA content and decreased antioxidant enzymes SOD, GSH-Px, and T-AOC activities (P < 0.05). We also found that Vc content, as well as the GSH/GSSG ratio, decreased. Additionally, Pb stress destroyed chloroplast structure, decreased photosynthesis indicators Pn, Tr, Gs, Ci and VPD, and attenuated Fv/Fm and Fv/Fo (P < 0.05). In the high-dose group, the contents of chlorophyll a, chlorophyll b, and carotenoids decreased significantly, while the expression of chloroplast development genes (GLK, GLN2) decreased (P < 0.05). Our data suggest that Pb stress leads to dosage-dependent, aberrant photosynthesis by inhibiting the AsA-GSH system in pakchoi. This study expands the Pb toxicology research field and provides indications for screening antagonists.
ABSTRACT
Cabbage black rot caused by Xanthomonas campestris pv. campestris (Xcc) leads to decrease of the production of up to 70%. Copper biocides are widely used to control this disease because of their low-cost application and broad-spectrum antimicrobial activities. Extensive spraying of traditional copper biocides would cause undesirable effects on plants and the environment. In this work, a novel copper-based microbicide was prepared by binding copper with glycine in sodium hydroxide solution (Gly-Cu(OH)2 NPs) and characterized by inductively coupled plasma atomic emission spectroscopy, high-resolution transmission electron microscopy, Fourier transformation infrared spectroscopy, and dynamic light scattering. The results showed that the prepared Gly-Cu(OH)2 NPs had a mean diameter of 240 nm with copper content more than 25.0% and their antimicrobial efficacies against Xcc were significantly better than Kocide 3000 at 400-800 mg L-1 of copper after spraying for 14 days. The phytotoxicity tests under greenhouse conditions showed that Gly-Cu(OH)2 NPs were safer to plants than Kocide 3000 and obviously promoted the growth of plants, which led to the increase of fresh weights of Chinese cabbage and tomato seedlings by 6.34% and 3.88% respectively at a concentration of 800 mg L-1 of copper. As a novel copper-based microbicide, the Gly-Cu(OH)2 NPs can improve effective utilization of copper-based bactericides and reduce phytotoxicity to plants and would be a potential alternative for sustainable plant disease management.
ABSTRACT
Dasineura jujubifolia Jiao & Bu, sp. nov., a gall midge feeding on jujube, Ziziphus jujuba Miller (Rhamnaceae), a fruit tree cultivated extensively in large areas of China, is described and illustrated based on specimens collected from Alar (Xinjiang, China). The new gall midge species causes rolled leaf galls on Ziziphus jujuba in Northwestern China. Brief notes on the biology of the jujube gall midge are given.
Subject(s)
Diptera , Animals , China , Chironomidae , Fruit , ZiziphusABSTRACT
The pear pyralid moth, Euzophera pyriella Yang, is an important fruit pest in Xinjiang, China. Here, we report the complete mitochondrial genome of E. pyriella which was 15,184 bp and composed of 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes, and a control region. 21 genes were in majority strand and 16 genes were in minority strand. ATG, ATT, CGA, GAT were initiation codons and TAA, TA, T were termination codons. The tRNA genes ranged in length from 63 to 72 bp. The length of 12S and 16S rRNA genes were 773 and 1330 bp, respectively. The species belong to the family Pyralidae and have a closer relationship according to the phylogenetic analyses.
