Endophytes: Colonization, Behaviour, and Their Role in Defense Mechanism

Abstract

Biotic and abiotic factors cause an enormous amount of yield and economical loss. However, endophytes can play a significant role in enhancing the tolerance of plants. Endophytes systematically colonize different parts of the host, but plants use a variety of defense mechanisms towards microbial infection. However, they have to survive the oxidative environments, and endophytes like Enterobacter sp. encode superoxide dismutases, catalases, and hydroperoxide reductases to cope up the oxidative stress during colonization. On the contrary, others produce subtilomycin which binds with flagella to affect flg22-induced plant defense. The behavior of endophytes can be affected by different genes in hydrolase activity when they come into contact with the host plant. The lifestyle of endophytes is influenced by environmental factors, the host, and microbial genotypes, as well as an imbalance in nutrient exchange between the microbe and the host. For instance, induction of PiAMT1 in root endophyte Piriformospora indica indicates depletion of nitrogen which plays as a triggering factor for activation of the saprotrophic program. Microbes enhance disease resistance through induced systemic resistance (ISR), and Bacillus cereus triggers ISR against Botrytis cinerea through an accumulation of the PR1 protein and activates MAPK signaling and WRKY53 gene expression by the JA/ET signaling pathway. Similarly, Trichoderma arundinaceum produces trichodiene that affects Botrytis cinerea through induction of defense-related genes encoding salicylic acid (SA) and jasmonate (JA). Overall, endophytes can play a vital role in disease management.

Genus-level evolutionary relationships of FAR proteins reflect the diversity of lifestyles of free-living and parasitic nematodes

“…The silencing of Mj-FAR-1 in tomato hairy roots leads to the expression of a complementary dsRNA and reduced infection, while over-expression of the far gene can increase the infectivity of nematodes [ 25 ]. Jasmonic acid plays an important role in plant responses to biotic and abiotic stress [ 54 , 55 ]. FAR proteins could inhibit the defense reactions of the host plant by obstructing gene expression of jasmonic acid pathway, and therefore play critical roles in the development and infection of plant-parasitic nematodes [ 22 , 24 ].…”

Influence of drought and salt stress on the growth of young Populus nigra ‘Italica’ plants and associated mycorrhizal fungi and non-mycorrhizal fungal endophytes

“…to elevated concentrations of toxic heavy metals in soil and can compete with AM fungi for poplar root colonization under stress conditions (Karliński et al 2010). Endophytes may direct plant metabolism towards the secretion of soluble sugars, amino acids such as proline and polyols, and alkaloids, all of which confer wall elasticity and osmotic adjustment during drought conditions (Mengistu 2020).…”

Heat-killed endophytic bacterium induces robust plant defense responses against important pathogens

“…Samples were collected from the wild plant species G. chinensis (Keng) along the Fu Tuan River (35° 20′ 17″ N, 119° 26 ′8″ E) within 5 km 2 of the coastal region of Rizhao city in Shandong Province, People's Republic of China. G. chinensis (Keng) was identified according to the data on morphological traits from the Flora of China ( http://www.iplant.cn/foc/ ).…”

“…In nature, plants are constantly affected by different biotic and abiotic stresses 1 , 2 . The effects of diseases caused by plant pathogens are among the main limiting factors of crop yields, resulting in losses of 10–30% every year in different important crops 3 .…”