siRNA is mainly involved in RNA interference, using a high specificity way to regular the expression of genes. siRNA can be transported through plants by intercellular and systemic transport or long-distance transport. In this way, exogenous interfering dsRNA can be directly uptake by pest cells or expressed first in plant cells and then delivered to pathogen cells. There are many kinds of existing pine diseases, including root rot caused by Verticicladiella Procera, and Needle rust, owing to Coleosporium asterum. These pine tree illnesses lead to a serious imbalance in the environment.
siRNA in plants
When plants uptake dsRNA and hpRNA, they process them into siRNA and induce RNA interference-mediated pathogen resistance. By intercellular and systemic transport in plants, siRNA can spread through plants. Intercellular transport takes place in plasmodesmata, which are intercellular channels. This channel helps transport siRNA to neighbor cells, while siRNA can transport over a long distance across conducting phloem tissue. The silencing signal can be detected within a few days and is usually prime at leaves rather than roots.
Spray-induced gene silencing is one of the most promising methods so far. Exogenous interfering dsRNA can be directly uptake by pest cells or transferred first to plant cells and then to pathogen cells. Also, dsRNA is capable of systemic transports in plants; besides locally spread dsRNA resistant pathogens, untreated leaves also gained the same ability with treated parts. The mechanism of how dsRNA penetrates from plants into pest cells is not fully understood. The natural pathway is from plant sap into digestive tract cells, where endocytosis may play an important role.
There are many diseases related to pine trees. For example Root rot caused by Verticicladiella Procera will make trees, particularly white pines stunted, decline, yellow, wilt, and die; while Needle rust, owing to Coleosporium asterum. Needled pines develop small, cream-colored, bag-like pustules on the needles. These ruptures and release orange spores that blow to and infect several kinds of flowers where the fungus overwinters. Pines are infected the following summer by spores from them; as for Diplodia tip blight, which is caused by Diplodia. Shoot tips are attacked in spring, and canker forms at the base of the new shoot. Resin oozes from the canker. This often occurs on scattered branches low on the tree at first. Tissue was killed before the needles reached full size. Lower branches are killed in succeeding years. Old cones and dead needles persist on the tree and have small, dark-brown to black structures peppering their surface.
Those who mentioned are only part of the diseases, pine wilt disease is also an example. Though it is only one of them, it doesn’t mean we do not need to care about it. After all, all of them will give the same result-the die of pine trees and the following forest environment imbalance.
 Pine Diseases https://extension.psu.edu/pine-diseases (accessed Oct 19, 2021).
 Morozov, S. Y.; Solovyev, A. G.; Kalinina, N. O.; Taliansky, M. E. Double-Stranded RNAs in Plant Protection against Pathogenic Organisms and Viruses in Agriculture. Acta Naturae 2019, 11 (4), 13–21.