Q1. Compare and contrast the mode of nutrition in mycoorhiza and mycoheterotrophs.
Answers
Explanation:
The mycorrhizal symbiosis is arguably the most important symbiosis on earth. Fossil records indicate that arbuscular mycorrhizal interactions evolved 400 to 450 million years ago [1] and that they played a critical role in the colonization of land by plants. Approximately 80 % of all known land plant species form mycorrhizal interactions with ubiquitous soil fungi[2]. The majority of these mycorrhizal interactions is mutually beneficial for both partners and is characterized by a bidirectional exchange of resources across the mycorrhizal interface. The mycorrhizal fungus provides the host plant with nutrients, such as phosphate and nitrogen, and increases the abiotic (drought, salinity, heavy metals) and biotic (root pathogens) stress resistance of the host. In return for their beneficial effect on nutrient uptake, the host plant transfers between 4 and 20% of its photosynthetically fixed carbon to the mycorrhizal fungus [3]. In contrast to mutually beneficial mycorrhizal interactions, some mycoheterotrophic plants (approximately 400 plant species from different plant families, such bryophytes, pteridophytes, and angiosperms) rely on mycorrhizal fungi for their carbon supply. These plants have lost their photosynthetic capabilities and parasitize mycorrhizal fungi that are associated with neighbor autotrophic plants.