## 1 Introduction  
In recent years, plant disease incidence has been rising gradually with changes in climate, cultivation habits, crop varieties of crops and some human-made factors. During growth and development, plants may will be affected by a variety of diseases, with the degree of damage gradually increasing. Difficulties in disease prevention and control are increasing instead of decreasing, which seriously threatens food security and farmers' ability to increase both yield and income [1, 2]. At the beginning of the 21 st century, rice stripe leaf blight broke out in a large area of involving Jiangsu and Henan provinces [3], having a great negative impact that resulted in heavy losses to local rice growers. In southwestern Europe, a region known for its grape cultivation, a disease caused by phytoplasma called _Fluorescence force_ is widespread and is a major cause of annual economic losses [4]. Potato virus disease generally reduces potato production by 20-50%, and more than 80% in severe cases, resulting in smaller tubers [5]. During the tomato planting process, late blight, early blight, gray mold and leaf mold occur frequently, which intensifies the use of chemical pesticides and seriously hinders development of \"green\" agriculture and rural areas [6].  
Silicon (Si) is the second most abundant element in the earth's crust. Due to its role in promoting plant growth and development, it has received extensive attention from researchers. It acts as a beneficial element and increasing Si fertilizer applications improve fruit quality. In addition, it enhances plant photosynthetic potentials [7]. Studies have shown that Si can effectively alleviate abiotic stresses [8], including drought [9],radiation [10], salinity [11] and heavy metal-induced toxicity [12]. In addition, Si can effectively enhance the resistance levels of different plants to pests and pathogens [13]. Thus, Si plays very important roles in ameliorating plant resistance to biotic and abiotic stresses.  
A large number of data showed that Si improves plant resistance to a variety of diseases, such as blast [14] and sheath blight [15] in rice, powdery mildew in wheat and other crops [16; 17], as well as tomato bacterial wilt [18]; Si is taken up by roots in the form of orthosilicic acid [Si(OH)\({}_{4}\)], an uncharged monomeric molecule, when the solution pH is less than 9. Three types of Si uptake in higher plants have been proposed: active, passive and rejective. However, the silica content varies greatly among different plant species. The Si content in the leaf sheaths of rice can reach 20%; those of graminaceous plants, such as barley and wheat, can reach approximately 2-4%, but the Si contents in most legumes and other dicotyledons are less than 1%.  
[PERSON] et al. [19] found and cloned the first Si transporter gene _Lsi1_ in rice and proved that the _Lsi1_ gene functions to transport silicic acid into root cells. The Si content in rice is significantly reduced after the _Lsi1_ gene is deleted, and the yield and disease resistance of rice are also significantly reduced. In recent years, homologous genes have been found in barley [20], maize [21], pumpkin [22], horsetail [23], wheat [24], soybean [25], cucumber [26] and tomato [27]. The discovery of Si transporter genes provided direct molecular evidence for studying Si functions, which a provide molecular basis for Si transport and uptake, and this enhances our understanding of the molecular mechanism responsible for disease resistance in plants. In this review, research progress on Si, Si transporters and their beneficial roles in disease resistance are summarized, and existing issues in the field are discussed to provide effective directions and methods for using Si to increase disease resistance in plants.