Whereas this harpin was expressed without a signal peptide, the authors ascribed the necrotic phenotype to leakage of intracellularly accumulated HrpZPss from the E. cichoracearum-penetrated plant cells, allowing the protein to access the plant cell exterior where it normally acts, thus activating plant defense mechanisms.
Jasmonic acid (JA) and salicylic acid (SA) play an important role in activating plant defensive responses against insect pests.
These elicitors are important components of signal transduction cascades activating plant's defence response against pathogen attack and often result in increased metabolite accumulation.
As was the case for genes from the AP2 family, which have been identified previously in the gene network activating plant freezing tolerance in Arabidopsis[ 61] and Triticum aestivum[ 62].
It was found, at early stages (7 and 45 days old) in greenhouse, that H. seropedicae in mixture with HS from vermicompost activated plant metabolic processes such as enhancement of plasma membrane H+-ATPase activity, alteration of both sugar and N metabolism and increase of net photosynthesis.
The ancient Egyptians figured out that light could activate plant-derived drugs.
Thus, the genes that activate plant defense responses are unlikely to be a good strategy to increase disease resistance.
Production of auxins, an important hormone that activates plant cells division, is widespread among plant growth promoting bacteria and M. oryzae CBMB20 is no exception to this.
Besides, according to Balakrishnan et al. (2010), compost at moderate doses can activate plant growth via its positive effect on leaf expansion.
However, accompanied by the release of inorganic nitrogen that becomes soil nutrients, this accelerated soil decomposition rate might activate plant productivity.
The extract could activate plant antioxidant defense system that comprises various enzymatic antioxidants that mainly caused a reduction of ROS content (Bharanidharan et al. 2013; Guedes et al. 2013).
