Aparajita Das

The root endophyte fungus Piriformospora indica leads to early flowering, higher biomass and altered secondary metabolites of the medicinal plant, Coleus forskohlii

This study was undertaken to investigate the influence of plant probiotic fungus Piriformospora indica on the medicinal plant C. forskohlii. Interaction of the C. forskohlii with the root endophyte P. indica under field conditions, results in an overall increase in aerial biomass, chlorophyll contents and phosphorus acquisition. The fungus also promoted inflorescence development, consequently the amount of p-cymene in the inflorescence increased. Growth of the root thickness was reduced in P. indica treated plants as they became fibrous, but developed more lateral roots. Because of the smaller root biomass, the content of forskolin was decreased. The symbiotic interaction of C. forskohlii with P. indica under field conditions promoted biomass production of the aerial parts of the plant including flower development. The plant aerial parts are important source of metabolites for medicinal application. Therefore we suggest that the use of the root endophyte fungus P. indica in sustainable agriculture will enhance the medicinally important chemical production.

Fungal Siderophores: Structure, Functions and Regulation

Fungi are eukaryotic, nonphotosynthetic organisms, and most are multicellular heterotrophs. Classically, the following groups of fungi have been considered: 1) Slime molds have a feeding phase of the life cycle (the trophic phase) that are motile and lack cell wall. Foods particles are ingested. 2) Aquatic fungi have cell wall and absorb nutrients rather than ingest them. The sex cells and spores of aquatic fungi are motile (zoospores). 3) Terrestrial fungi have cell wall and absorb nutrients rather than ingest them. The sex cells and spores are not motile (zoospores). Three major groups of fungi recognized are Zygomycetes (e.g., black bread mold, animal dung fungi), Ascomycetes (e.g., cup fungi, truffles) and Basidiomycetes (e.g., mushrooms or toadstools, puff balls, rusts, smuts). For details see Table 1.1; c.f. Giri et al. (2005)

Symbiosis: The Art of Living

Plants are the very foundations of life on the earth. Almost all the divisions of plant kingdom — namely bryophytes, pteridophytes, gymnosperms, and angiosperms — form a symbiotic relationship with bacteria, cyanobacteria, or actinomycetes. Symbiotic relationships in which both the species of the association benefit are mutualistic. Mutualistic relations between plants and fungi are recognized, as Mycorrhizae are quite common in nature. The fungus helps the host plant absorb inorganic nitrogen and phosphorus from the soil. Some mycorrhizal fungi also secrete antibiotics which may help protect their host from invasion by parasitic fungi and bacteria. One of the most important examples of mutualism in the overall economy of the biosphere is the symbiotic relationship between certain nitrogen-fixing bacteria and their legume hosts. This chapter deals with all the types of mutualistic symbiotic relationship formed in the plant kingdom.

Interactions of Piriformospora indica with Medicinal Plants

The microbial world exerts a negative as well a positive impact on living plants and animals, and forms an association either pathogenic or symbiotic with the other partners of the living world. Mycorrhiza refers to an association or symbiosis between plants and fungi that colonize the roots during periods of active plant growth. The intimate symbiotic relationships developed between mycorrhizal fungi and plants, since the colonization of land by the latter, have led to interdependence between these organisms for many basic processes. The fungi require plants to accomplish their life cycle. Plants depend heavily on mycorrhizal fungi for many different functions, such as mineral nutrition and abiotic and biotic stress resistance. Substantial evidence has accumulated in the recent past about how the use of the microsymbiont could significantly contribute in decreasing use of fertilizers and pesticides in agriculture, forestry and flori-hortriculture, especially if combined with other beneficial soil microorganisms. The most common and prevalent arbuscular mycorrhizal fungi play an indispensable role in upgrading plant growth, vigor and survival by a positive impact on the nutritional and hydratic status of the plant and on soil health, by increasing the reproductive potential, improving root performance, and providing a natural defence against invaders, including pests and pathogens. The described species of arbuscular mycorrhizal fungi mainly belong to Zygomycetes placed in the order Glomerales. However, the growing of arbuscular mycorrhizae in pure culture in the absence of living host roots is a matter of global concern. Unfortunately, their biotechnological applications cannot be exploited to the level they deserve due to their axenically unculturable nature.

Cocultivation of Piriformospora indica with Medicinal Plants: Case Studies

Piriformospora indica is an axenically cultivable phytopromotional root endosymbiont, which mimics the capabilities of typical arbuscular mycorrhizal fungi. The fungus is of utmost biotechnological importance and is multifunctional. The fungus is mass multiplied on cheap and simplified medium. Medicinal plants play an important role in supporting the health care system of both developing and developed countries. Herbal medicines are gaining popularity in day-to-day life because they are cheap, easily available and have rare or no side effects. Over 80 % of world population relies on traditional medicines, largely plant based for their primary health care needs. Therefore, awareness in the direction for enhancement of the yield of medicinal plants is one of the main objectives of the current research. In this context, arbuscular mycorrhizal fungi and other endophytes like P. indica play a significant role.

In vitro plant development and root colonization of Coleus forskohlii by Piriformospora indica

The present study was conducted for optimization of in vitro substrates under aseptic conditions for interaction of Piriformospora indica with the medicinal plant Coleus forskohlii. It aims to test the effects of different substrates on P. indica colonization as well as growth parameters of the in vitro raised C. forskohlii. Interaction of in vitro C. forskohlii with root endophyte P. indica under aseptic condition resulted in increase in growth parameters in fungus colonized plants. It was observed that P. indica promoted the plant’s growth in all irrespective of substrates used for co-culture study. The growth was found inferior in liquid compared to semisolid medium as well as there was problem of hyperhydricity in liquid medium. P. indica treated in vitro plantlets were better adapted for establishment under green house compared to the non treated plants due to fungal intervention.

Contaminated Soil: Physical, Chemical and Biological Components

Soil can be described by its texture, referring to the size distribution of soil particles and the relative percentage of sand, silt and clay particles, and soil structure, the arrangement of soil particles into groups that help in water and nutrient supplying ability of the soil, and air supply to plants’ roots. The most important way in which soil texture and structure affect plant growth is the provision of water and, with it, the nutrient supply. Oxygen is required by rhizosphere microbes as well as plant roots for respiration. Soil pollution by both organic and inorganic contaminants such as fuel hydrocarbons, polynuclear aromatic hydrocarbons, polychlorinated biphenyls, chlorinated aromatic compounds, detergents, and pesticides or nitrates, phosphates, and heavy metals, inorganic acids and radionuclides reduce plant growth. Among the sources of these contaminants are agricultural runoffs, acidic precipitates, industrial waste materials and radioactive fallout. This chapter provides an overview of the contaminated soils, their physical, chemical and biological components and briefly discusses the importance of heavy metal tolerant AM fungi and heavy metal tolerant plants for reclamation of degraded soils.

Ex Situ Conservation Strategies in Litchi Germplasm

The delicious fruit Litchi chinensis is a commercially important heterozygous cross-pollinated fruit species of the world. To increase its production of this fruit, plant breeding is required. Henceforth, the conservation of its germplasm resources is an important step toward improvement of new cultivars resistant to abiotic and biotic stresses through selection and breeding technologies. Two major approaches used for conservation of plant genetic resources are in situ and ex situ. Both approaches are important and complementary to each other for sustainable agriculture. It is challenging to conserve litchi germplasm through seed, field maintenance, and in vitro storage because of its recalcitrant nature and owing to various biotic and abiotic factors. Of all the various strategies of ex situ conservation of litchi, cryopreservation of litchi germplasm using its embryonic axis or pollens is a promising option for conservation of germplasm.

Roots of Medicinal Importance

Medicinal plants have a long history in treatment of human ailments. The scientific work on different plants in the past ages has gained confidence among researchers worldwide that the global plant diversity holds the cure for many unresolved human ailments. The extensive traditional knowledge that is treasured in different parts of the globe has contributed immensely in exploring many medicinal plants, using modern biology tools. A large part of the biologically active plant-derived compounds used commercially have come into light through follow-up research to verify the authenticity of traditional knowledge. Different parts of the plant or plant as a whole has served as the source of bioactive compounds for purpose of investigation, as well as for commercial drug production. Roots are the ground anchoring part of the plant that harbors various bioactive molecules which display curative possibilities for many human ailments like cancer, diabetes, ulcer, and liver diseases. Scientific investigations in the past have helped in uncovering many phytochemicals from plant roots, some of which are now in clinical use and many others are in various stages of preclinical and clinical studies. The vast diversity of plants on the planet gives a promising journey ahead in quest for knowledge and cure for many diseases.