How do plants resist disease?

 

How do plants resist disease?

Plants are constantly exposed to a wide range of pathogens, such as fungi, bacteria, viruses, and pests, that can cause diseases and damage to their tissues, organs, and metabolic processes. However, plants have evolved sophisticated mechanisms to detect, respond, and resist these threats, using their innate immune system and other defense strategies. In this blog, we will explore some of the key ways that plants resist disease, based on scientific research and medical knowledge.

Physical barriers

One of the simplest ways that plants resist disease is by creating physical barriers that prevent pathogens from entering their tissues. For example, plants have thick cell walls, cuticles, and waxy layers that can prevent bacteria and fungi from penetrating their leaves and stems. They also have trichomes, hairs, and spines that can deter herbivores and other pests from feeding on them. Additionally, plants can produce tough and woody tissues, such as bark and cork, that can resist decay and rot caused by fungi and other microorganisms.

Chemical defenses

Plants also produce a wide range of chemical compounds that can inhibit or kill pathogens and pests, or attract beneficial organisms that can help to control them. Some of these compounds are produced constitutively, meaning that they are always present in the plant's tissues, while others are induced in response to specific threats. Examples of chemical defenses include alkaloids, terpenes, phenolics, and glycosides, which can have antifungal, antibacterial, insecticidal, or antiviral properties. Plants can also produce volatile organic compounds that can signal to neighboring plants and insects that they are under attack.

Systemic acquired resistance

Plants can also activate a complex system of defense responses called systemic acquired resistance (SAR), which involves the production and transport of signaling molecules, such as salicylic acid, throughout the plant's tissues. SAR can induce a range of defense mechanisms, such as the expression of pathogenesis-related (PR) proteins, the accumulation of phytoalexins, and the reinforcement of cell walls. SAR can also prime the plant's immune system to respond more effectively to future attacks, even from different types of pathogens.

RNA interference

RNA interference (RNAi) is a mechanism that allows plants to silence or degrade specific genes and gene products, including those of pathogens that have invaded their tissues. RNAi involves the production of small RNA molecules, such as microRNAs (miRNAs) and small interfering RNAs (siRNAs), that can bind to and degrade complementary messenger RNAs (mRNAs), or prevent their translation into proteins. RNAi can thus inhibit the replication and spread of viruses and other pathogens, and also regulate the expression of the plant's own genes.

Symbiotic relationships

Finally, plants can establish symbiotic relationships with other organisms, such as mycorrhizal fungi and rhizobia, that can provide them with nutrients, water, and other benefits, while also enhancing their resistance to diseases and stresses. Mycorrhizal fungi can form mutualistic associations with the roots of plants, allowing them to absorb more nutrients and water from the soil, and also stimulate their immune system. Rhizobia are bacteria that can fix atmospheric nitrogen in nodules on the roots of leguminous plants, providing them with a vital nutrient and reducing their dependence on fertilizers. Rhizobia can also induce systemic resistance to diseases and improve the plant's stress tolerance.

In conclusion, plants have evolved a variety of complex and interrelated mechanisms to resist diseases and other threats, using physical barriers, chemical defenses, systemic acquired resistance, RNA interference, and symbiotic relationships. Understanding these mechanisms can help us to develop more sustainable and effective strategies for managing plant diseases, and also inspire new insights into.