Osteoclast-Forming Suppressive Compounds from Makomotake,Zizania latifoliaInfected withUstilago esculenta

Recent advances in Zizania latifolia: A comprehensive review on phytochemical, health benefits and applications that maximize its value

Zizania latifolia is an aquatic and medicinal plant with a long history of development in China and the East Asian region. The smut fungus "Ustilago esculenta" parasitizes Z. latifolia and induces culm expansion to form a vegetable named Jiaobai, which has a unique taste and nutritional attributes. However, the postharvest quality of water bamboo shoots is still a big challenge for farmers and merchants. This paper traced the origin, development process, and morphological characteristics of Z. latifolia. Subsequently, the compilation of the primary nutrients and bioactive substances are presented in context to their effects on ecology a postharvest storage and preservation methods. Furthermore, the industrial, environmental, and material science applications of Z. latifolia in the fields of industry were discussed. Finally, the primary objective of the review proposes future directions for research to support the development of Z. latifolia industry and aid in maximizing its value. To sum up, Z. latifolia, aside from its potential as material it can be utilized to make different productions and improve the existing applications. This paper provides an emerging strategy for researchers undertaking Z. latifolia.

Diploid mycelia of Ustilago esculenta fails to maintain sustainable proliferation in host plant

Smut fungi display a uniform life cycle including two phases: a saprophytic phase in vitro and a parasitic phase in host plants. Several apathogenic smut fungi are found, lacking suitable hosts in their habitat. Interestingly, MT-type Ustilago esculenta was found to maintain a parasitic life, lacking the saprophytic phase. Its long period of asexual proliferation in plant tissue results in severe defects in certain functions. In this study, the growth dynamics of U. esculenta in plant tissues were carefully observed. The mycelia of T- and MT-type U. esculenta exhibit rapid growth after karyogamy and aggregate between cells. While T-type U. esculenta successfully forms teliospores after aggregation, the aggregated mycelia of MT-type U. esculenta gradually disappeared after a short period of massive proliferation. It may be resulted by the lack of nutrition such as glucose and sucrose. After overwintering, infected Zizania latifolia plants no longer contained diploid mycelia resulting from karyogamy. This indicated that diploid mycelia failed to survive in plant tissues. It seems that diploid mycelium only serves to generate teliospores. Notably, MT-type U. esculenta keeps the normal function of karyogamy, though it is not necessary for its asexual life in plant tissue. Further investigations are required to uncover the underlying mechanism, which would improve our understanding of the life cycle of smut fungi and help the breeding of Z. latifolia.

Mating Types of Ustilago esculenta Infecting Zizania latifolia Cultivars in Japan Are Biased towards MAT-2 and MAT-3

Zizania latifolia cultivars infected by the endophytic fungus Ustilago esculenta develop an edible stem gall. Stem gall development varies among cultivars and individuals and may be affected by the strain of U. esculenta. To isolate haploids from two Z. latifolia cultivars in our paddy fields, Shirakawa and Ittenkou, we herein performed the sporadic isolation of U. esculenta strains from stem gall tissue, a PCR-based assessment of the mating type, and in vitro mating experiments. As a result, we obtained heterogametic strains of MAT-2 and MAT-3 as well as MAT-2, but not MAT-3, haploid strains. Another isolation method, in which we examined poorly growing small clusters of sporidia derived from teliospores, succeeded in isolating a MAT-3 haploid strain. We also identified the mating types of 10 U. esculenta strains collected as genetic resources from different areas in Japan. All strains, except for one MAT-1 haploid strain, were classified as MAT-2 haploid strains or heterogametic strains of MAT-2 and MAT-3. The isolated strains of MAT-1, MAT-2, and MAT-3 mated with each other to produce hyphae. Collectively, these results indicate that the mating types of U. esculenta infecting Z. latifolia cultivars in Japan are biased towards MAT-2 and MAT-3 and that U. esculenta populations in these Japanese cultivars may be characterized by the low isolation efficiency of the MAT-3 haploid.

Cloning and characterization of the UePrf1 gene in Ustilago esculenta

Ustilago esculenta, an obligate parasite of Zizania latifolia, is a typical dimorphic fungus which induces host stem swelling and inhibits host inflorescence development, but is not found in host leaves. Previous studies have shown that dimorphic switching is essential for fungal pathogenicity and is regulated by protein kinase A and mitogen-activated protein kinase (MAPK) signaling pathways that are integrated by Prf1 in Ustilago maydis. In this study we identified a Prf1 homolog in U. esculenta, designated UePrf1, encoding 830 amino acids with a conserved high mobility group domain located between amino acids 124 and 195. UePrf1 was upregulated during the mating process, which induces dimorphism in U. esculenta. In vitro, UePrf1 mutants showed defects in the mating process, including cell fusion and hyphal growth. UePrf1 mutants also show reduced expression of a genes, even during the cell fusion process. Additionally, the defect in hyphal growth of the UeKpp2 and UeKpp6 mutants (MAPK signaling pathway mutants) was partially counteracted by UePrf1 overexpression, along with induced b gene expression. These results provide evidence that UePrf1 is a key factor coordinating dimorphism in U. esculenta and suggest a conserved role for UePrf1 in the regulation of the a and b genes.

Cellular and proteomic events associated with the localized formation of smut-gall during Zizania latifolia-Ustilago esculenta interaction

The perennial wild rice Zizania latifolia is confined in the swampy habitat and wetland of the Indo-Burma biodiversity hotspot of India and infection by the biotrophic fungus Ustilago esculenta is hallmarked by swellings that develop to form localized smut-gall at the topmost internodal region. The cellular and proteomic events involved in the non-systemic colonization of Z. latifolia by U. esculenta leading to smut-gall formation is poorly understood. Proteins were extracted from the smut-gall region at the topmost internodal region below the apical meristematic tissue from the infected and uninfected parts of Z. latifolia. By combining transmission electron microscopy (TEM) and fluorescent microscopy (FM), we showed that U. esculenta hyphal morphological transitions and movement occurred both intercellularly and intracellularly while sporulation occurred intracellularly in selective cells. Following proteome profiling using two dimensional SDS-PAGE at different phenological phases of smut-gall development and U. esculenta infection, differentially expressed proteins bands and their relative abundance were detected and subjected to liquid chromatography-tandem mass spectrometric (LC-MS/MS) analysis. Importantly, the fungus explores at least 7 metabolic pathways and 5 major biological processes to subdue the host defense and thrive successfully on Z. latifolia. The fungus U. esculenta produces proteases and energy acquisition proteins those enhance it's defensive and survival mode in the host. The identified differentially regulated proteins shed-light into why inflorescence is being replaced by bulbous smut-gall at late stages of the disease, as well as the development of resistance in some Z. latifolia plants against U. esculenta infection.

Morphological Characteristics, Nutrients, and Bioactive Compounds of Zizania latifolia, and Health Benefits of Its Seeds

Zizania latifolia (tribe Oryzeae Dum., subfamily Oryzoideae Care, family Gramineae) is native to East Asian countries. The seeds of Z. latifolia (Chinese wild rice) have been consumed as a cereal in China for >3000 years. Z. latifolia forms swollen culms when infected with Ustilago esculenta, which is the second most-cultivated aquatic vegetable in China. The current review summarizes the nutrients and bioactive compounds of Z. latifolia, and health benefits of its seeds. The seeds of Z. latifolia contain proteins, minerals, vitamins, and bioactive compounds, the activities of which—for example, antioxidant activity—have been characterized. Various health benefits are associated with their consumption, such as alleviation of insulin resistance and lipotoxicity, and protection against cardiovascular disease. Chinese wild rice may be used to prevent and treat metabolic disease, such as diabetes, obesity, and cardiovascular diseases. Various compounds were isolated from the swollen culm, and aerial parts of Z. latifolia. The former suppresses osteoclast formation, inhibits growth of rat glioma cells, and may act as antioxidants and immunomodulators in drugs or foods. The latter exerts anti-fatigue, anti-inflammatory, and anti-allergic effects. Thus, Z. latifolia may be used to produce nutraceuticals and functional foods.

Investigation on the differentiation of two Ustilago esculenta strains - implications of a relationship with the host phenotypes appearing in the fields

BACKGROUND

Ustilago esculenta, a pathogenic basidiomycete fungus, infects Zizania latifolia to form edible galls named Jiaobai in China. The distinct growth conditions of U. esculenta induced Z. latifolia to form three different phenotypes, named male Jiaobai, grey Jiaobai and white Jiaobai. The aim of this study is to characterize the genetic and morphological differences that distinguish the two U. esculenta strains.

RESULTS

In this study, sexually compatible haploid sporidia UeT14/UeT55 from grey Jiaobai (T strains) and UeMT10/UeMT46 from white Jiaobai (MT strains) were isolated. Meanwhile, we successfully established mating and inoculation assays. Great differences were observed between the T and MT strains. First, the MT strains had a defect in development, including lower teliospore formation frequency and germination rate, a slower growth rate and a lower growth mass. Second, they differed in the assimilation of nitrogen sources in that the T strains preferred urea and the MT strains preferred arginine. In addition, the MT strains were more sensitive to external signals, including pH and oxidative stress. Third, the MT strains showed an infection defect, resulting in an endophytic life in the host. This was in accordance with multiple mutated pathogenic genes discovered in the MT strains by the non-synonymous mutation analysis of the genome re-sequencing data between the MT and T strains (GenBank accession numbers of the genome re-sequencing data: JTLW00000000 for MT strains and SRR5889164 for T strains).

CONCLUSION

The MT strains appeared to have defects in growth and infection and were more sensitive to external signals compared to the T strains. They displayed an absolutely stable endophytic life in the host without an infection cycle. Accordingly, they had multiple gene mutations occurring, especially in pathogenicity. In contrast, the T strains, as phytopathogens, had a complete survival life cycle, in which the formation of teliospores is important for adaption and infection, leading to the appearance of the grey phenotype. Further studies elucidating the molecular differences between the U. esculenta strains causing differential host phenotypes will help to improve the production and formation of edible white galls.

Indole-3-acetic acid-producing yeasts in the phyllosphere of the carnivorous plant Drosera indica L

Yeasts are widely distributed in nature and exist in association with other microorganisms as normal inhabitants of soil, vegetation, and aqueous environments. In this study, 12 yeast strains were enriched and isolated from leaf samples of the carnivorous plant Drosera indica L., which is currently threatened because of restricted habitats and use in herbal industries. According to similarities in large subunit and small subunit ribosomal RNA gene sequences, we identified 2 yeast species in 2 genera of the phylum Ascomycota, and 5 yeast species in 5 genera of the phylum Basidiomycota. All of the isolated yeasts produced indole-3-acetic acid (IAA) when cultivated in YPD broth supplemented with 0.1% L-tryptophan. Growth conditions, such as the pH and temperature of the medium, influenced yeast IAA production. Our results also suggested the existence of a tryptophan-independent IAA biosynthetic pathway. We evaluated the effects of various concentrations of exogenous IAA on yeast growth and observed that IAA produced by wild yeasts modifies auxin-inducible gene expression in Arabidopsis. Our data suggest that yeasts can promote plant growth and support ongoing prospecting of yeast strains for inclusion into biofertilizer for sustainable agriculture.