Endophytic bacteria have been shown to increase resistance against biotic stress and tolerance to abiotic stress in many plants. The objective of this study was to evaluate the effect of an endophytic bacterium, Clavibacter sp. strain Enf12, in regenerated plantlets of Chorispora bungeana subjected to chilling stress (0°C). Aerial biomass and physiological markers for chilling stress, such as electrolyte leakage, lipid peroxidation, reactive oxygen species (ROS) accumulation, proline content and activities of superoxide dismutase (EC 1.15.1.1), catalase (EC 1.11.1.6), guaiacol peroxidase (EC 1.11.1.7) and ascorbate peroxidase (EC 1.11.1.11), were assessed. We demonstrated that Clavibacter sp. strain Enf12 was capable of colonizing internal tissues of regenerated plantlets of C. bungeana and maintained stable population densities under both normal (20°C) and chilling (0°C) conditions. Inoculation enhanced plantlet growth under both conditions and significantly attenuated the chilling-induced electrolyte leakage, lipid peroxidation and ROS accumulation. The endophyte significantly increased the activities of antioxidant enzymes and proline content in C. bungeana plantlets under chilling stress. These findings suggest that Clavibacter sp. strain Enf12 inoculation stimulates the growth of C. bungeana plantlets and improves their tolerance to chilling stress through enhancing the antioxidant defense system.

Methyl salicylate produced by Viburnum odoratissimum is known to exert lethal or sublethal effects on insects. Replacing conventional pesticides with insecticidal plants is necessary for environmental protection. We evaluated the behavioral and toxicological responses of the red imported fire ant (RIFA Solenopsis invicta)( Hymenopter: Buren Formicidae) at different soil depths in the rhizosphere of V. odoratissimum. Results of insecticidal activity bioassays indicated that the mortality for minor and major ants in soil at depths of 0-10 cm at days 11 and 12 both ranged from 68.75% to 100.00%, with repellent rates of 83.54%–100.00% and 85.31%–100.00%, respectively. In behavioral ability tests, 85.45%–100.00% of minor ants and 86.74%–94.85% of major ants lost their ability to grasp after nine days, with crawl rates at only 0.00%–29.25% and 0.00%–55.77%, respectively. Therefore, we conclude from the result that the soil under V. odoratissimum at depths of 0-10 cm exhibited excellent insecticidal effect in controlling RIFA.Methyl salicylate produced by Viburnum odoratissimum is known to exert lethal or sublethal effects on insects. Replacing conventional pesticides with insecticidal plants is necessary for environmental protection. We evaluated the behavioral and toxicological responses of the red imported fire ant (RIFA Solenopsis invicta, Buren) (Hymenoptera: Formicidae) at different soil depths in the rhizosphere of V. odoratissimum. Results of insecticidal activity bioassays indicated that the mortality for minor and major ants in soil at depths of 0-10 cm at days 11 and 12 both ranged from 68.75% to 100.00%, with repellency rates of 83.54%-100.00% and 85.31%-100.00%, respectively. In behavioral ability tests, 85.45%-100.00% of minor ants and 86.74%-94.85% of major ants lost their ability to grasp after nine days, with crawling rates at only 0.00%-29.25% and 0.00%-55.77%, respectively. Therefore, we conclude from the result that the soil under V. odoratissimum at depths of 0-10 cm exhibited excellent insecticidal effect in controlling RIFA.

Anubias spp. are very popular aquatic plants that are native to Africa. Anubias barteri is a broadleaf Anubias and is a popular choice for aquariums because of its robust size. In China, broadleaf Anubias is usually planted in sand, with sponges around the rhizome, in small plastic baskets in aquatic plant nurseries. In December 2010, a survey of phytoparasitic nematodes was conducted in the nurseries in Guangzhou, Guangdong Province. Many second-stage juveniles of a Meloidogyne sp. were detected from the roots of A. barteri, but no root galls were found. To identify these juveniles, molecular identification was performed with PCR. The DNA sequence between CO II and l-rRNA of the mitochondrial gene of single juveniles was amplified with universal primers of Meloidogyne, #C2F3 (5′-GGTCAATGTTCAGAAATTTGTGG-3′) and #1108 (5′-TACCTTTGACCAATCACGCT-3′) (3). The amplified fragments were approximately 1.1 kb long and could not be digested with restrictive enzyme HinfI. The specific fragments were then sequenced. The blast search result revealed that the DNA sequence (GenBank Accession No. JQ446377) had 99 to 100% identity with submitted sequences of Meloidogyne arenaria (GenBank Accession Nos. EU364879, GQ266686, and AY635610). The other extracted juveniles were inoculated into sterile, potted, water spinach (Ipomoea aquatica) in the greenhouse to obtain more nematodes. After 40 days, root galls and female egg masses were clearly observed, and biochemical, molecular, and morphological identifications were conducted. Isoenzyme phenotype (esterase and malate dehydrogenase (MDH) patterns) and the perineal pattern of several gravid females were the same as M. arenaria (1,2), and PCR amplification of single juveniles produced identical fragments as previously found. Single egg masses were collected and juveniles were hatched out and inoculated onto 10 nematode-free plants of A. barteri in a greenhouse. After 40 days, roots of A. barteri exhibited inconspicuous small galls, and the same identification procedures were conducted as mentioned previously. Isoenzyme phenotypes, perineal patterns of adult females, and amplified fragments of single juveniles were identical to those of M. arenaria. M. arenaria is one of the most important root-knot nematodes and causes great losses in many crops around the world (2). To our knowledge, this is the first record of M. arenaria parasitizing aquatic plants of broadleaf Anubias in China and elsewhere, and A. barteri is a new host of M. arenaria. The economic importance of this nematode to A. barteri production is currently unknown. However, because A. barteri is a commercial aquatic plant, more attention should be given by producers to prevent this nematode from becoming an important pathogen. In addition, this finding is very helpful for relevant plant nematode quarantine work. References: (1) P. R. Esbenshade and A. C. Triantaphyllou. J. Nematol. 17:1, 1985. (2) R. N. Perry et al. Root-Knot Nematodes. CABI. Wallingford, UK, 2009. (3) T. O. Powers and T. S. Harris. J. Nematol. 25:1, 1993.