Roles of ß-Indole Acetic Acid (IAA) Producing Endophytic Bacteria on the Recovery of Plant Growth and Survival Ability of Sugarcane Infected White Leaf Disease (SWLD).

ß-Indole acetic acid is produced in the rhizosphere by endophytic bacteria and promotes plant growth. Effects of bacterial IAA producers (BIPs) on plant growth and recovery of sugarcane seedlings infected with phytoplasma causing white leaf disease (SWLD) were examined. Fifty-five endophytic bacteria isolated from rice roots were collected from the Mekong River Delta, Vietnam. Seven isolates showed ß-Indole acetic acid production in culture medium supplemented with tryptophan. Interestingly, two of them (BC17 and BTII2) produced the highest ß-Indole acetic acid after 4 days of culture. Based on 16S rRNA sequences and phylogenetic analysis, the BC17 and BTII2 isolates were identified as Delftia lacustris and Rahnella aquatilis, respectively. Plant growth induced by the BC17 and BTII2 isolates showed statistically significant differences in height, root length and fresh weight of rice seedlings compared with non-treatment as the control. Treatment of two bacterial isolates in SWLD infected sugarcane plants also showed differences in height of sugarcane seedlings, while gradual symptoms of exposure decreased plant mortality compared to non-treatment as the control. BIPs were shown to be efficient biofertilizer inoculants that promoted plant growth and also ameliorated damage caused by phytoplasma-associated diseases at the sugarcane seedling stage.

Labdane-type diterpenoids from Vitex limonifolia and their antivirus activities.

Phytochemical investigation of the methanol extract of Vitex limonifolia leaves led to the isolation of three new labdane-type diterpenoids, vitexlimolides A-C (1-3) and eight known compounds, 5,4'-dihydroxy-3,7-dimethoxyflavone (4), vitecetin (5), 5,4'-dihydroxy-7,3'-dimethoxyflavone (6), verrucosin (7), 2α, 3α-dihydroxy-urs-12-en-28-oic acid (8), euscaphlic acid (9), 18,19-seco, 2α, 3α-dihydroxy-19-oxo-urs-11,13(18)-dien-28-oic acid (10), and maslinic acid (11). Their chemical structures were elucidated by physical and chemical methods. All compounds were evaluated for antiviral activities against CVB3, HRV1B, and EV71 viruses. As a result, compounds 4 and 6 showed potent antiviral activity against CVB3 infection with IC50 values of 0.12 ± 0.06 and 1.86 ± 0.18 (µM), respectively.