Endophytic Trichoderma citrinoviride isolated from mountain-cultivated ginseng (Panax ginseng) has great potential as a biocontrol agent against ginseng pathogens.

BACKGROUND: Ginseng (Panax ginseng Meyer) is an invaluable medicinal plant containing various bioactive metabolites (e.g., ginsenosides). Owing to its long cultivation period, ginseng is vulnerable to various biotic constraints. Biological control using endophytes is an important alternative to chemical control. METHODS: In this study, endophytic Trichoderma citrinoviride PG87, isolated from mountain-cultivated ginseng, was evaluated for biocontrol activity against six major ginseng pathogens. T. citrinoviride exhibited antagonistic activity with mycoparasitism against all ginseng pathogens, with high endo-1,4-ß-D-glucanase activity. RESULTS: T. citrinoviride inoculation significantly reduced the disease symptoms caused by Botrytis cinerea and Cylindrocarpon destructans and induced ginsenoside biosynthesis in ginseng plants. T. citrinoviride was formulated as dustable powder and granules. The formulated agents also exhibited significant biocontrol activity and induced ginsenosides production in the controlled environment and mountain area. CONCLUSION: Our results revealed that T. citrinoviride has great potential as a biological control agent and elicitor of ginsenoside production.

Effect of Hybridization on Somatic Mutations and Genomic Rearrangements in Plants.

Hybridization has been routinely practiced in agriculture to enhance the crop yield. Principally, it can cause hybrid vigor where hybrid plants display increased size, biomass, fertility, and resistance to diseases, when compared to their parents. During hybridization, hybrid offspring receive a genomic shock due to mixing of distant parental genomes, which triggers a myriad of genomic rearrangements, e.g., transpositions, genome size changes, chromosomal rearrangements, and other effects on the chromatin. Recently, it has been reported that, besides genomic rearrangements, hybridization can also alter the somatic mutation rates in plants. In this review, we provide in-depth insights about hybridization triggered genomic rearrangements and somatic mutations in plants.

Constitutive over-expression of rice chymotrypsin protease inhibitor gene OCPI2 results in enhanced growth, salinity and osmotic stress tolerance of the transgenic Arabidopsis plants.

Protease inhibitors are involved primarily in defense against pathogens. In recent years, these proteins have also been widely implicated in response of plants to diverse abiotic stresses. Rice chymotrypsin protease inhibitor gene OCPI2 is highly induced under salt and osmotic stresses. The construct containing the complete coding sequence of OCPI2 cloned downstream to CaMV35S promoter was transformed in Arabidopsis and single copy, homozygous transgenic lines were produced. The transgenic plants exhibited significantly enhanced tolerance to NaCl, PEG and mannitol stress as compared to wild type plants. Importantly, the vegetative and reproductive growth of transgenic plants under unstressed, control conditions was also enhanced: transgenic plants were more vigorous than wild type, resulting into higher yield in terms of silique number. The RWC values and membrane stability index of transgenic in comparison to wild type plants was higher. Higher proline content was observed in the AtOCPI2 lines, which was associated with higher transcript expression of pyrroline-5-carboxylate synthase and lowered levels of proline dehydrogenase genes. The chymotrypsin protease activities were lower in the transgenic as against wild type plants, under both unstressed, control as well as stressed conditions. It thus appears that rice chymotrypsin protease inhibitor gene OCPI2 is a useful candidate gene for genetic improvement of plants against salt and osmotic stress.