Over-Expression of Chorismate Mutase Enhances the Accumulation of Salicylic Acid, Lignin, and Antioxidants in Response to the White-Backed Planthopper in Rice Plants

Abstract

The white-backed planthopper (WBPH) is a serious pest of rice crop and causes sever yield loss each year, especially in Asian countries. In this study, we used chorismate mutase (CM) transgenic line to examine the defense mechanism of rice plants against WBPH. The survival rate of WBPHs, infestation rate of plants, lignin biosynthesis, transcriptional regulation of related genes, salicylic acid (SA) accumulation and signaling and antioxidants regulation were investigated. The WBPH population decreased by 67% in OxCM-t, and the plant infestation rate was 3.5-fold higher in wild-type plants compared with transgenic plants. A substantial increase in lignin was found in the transgenic line (742%) and wild-type (417%) plants. Additionally, CM, phenylalanine ammonia lyase (PAL), chalcone synthase (CHS), and chalcone isomerase (CHI) showed significant increases in their relative expression level in the transgenic line. Salicylic acid was significantly enhanced in the transgenic line compared with WBPH infestation. SA can activate pathogenesis related proteins-1 (PR1), PR2, antioxidants, and the expression of their related genes: superoxide dismutase (SOD) and catalase (CAT). WBPH infestation reduced the chlorophyll contents of both transgenic and wild-type plants, but the reduction was great in wild-type than transgenic plants. The sugar content was only significantly increased in the transgenic line, indicating that sugars are not heavily involved in WBPH stress. Phenylalanine, proline, aspartic acid, and total amino acids were increased in the transgenic line and reduced in the wild-type plants. Taken together, all the results suggest that overexpression of CM gene regulates the defense mechanisms and enhances the rice toward WBPH stress.

Overexpression of a Cinnamyl Alcohol Dehydrogenase-Coding Gene, GsCAD1, from Wild Soybean Enhances Resistance to Soybean Mosaic Virus

“…Many studies have reported that lignin, acting as the first physical barrier, can withstand the expending of pathogens [ 32 , 37 , 38 , 39 ]. There is also a report on the co-regulation of pathogenic bacteria resistance with SA [ 59 ]. Our results are consistent with these studies and further confirm that lignin may act as the first physical line of defense against SMV, then SA can activate several plant defense responses, which together constrain either or both the amplification and intercellular movement of SMV.…”

The Role of Exogenous Gibberellic Acid and Methyl Jasmonate against White-Backed Planthopper (Sogatella furcifera) Stress in Rice (Oryza sativa L.)

“…Histochemical staining with DAB and trypan indicates that H 2 O 2 accumulation was reduced in GA-treated plants and a lower amount of cell death was visualized in GA-treated plants. Previous studies suggested that high H 2 O 2 accumulation and cell death were seen in WBPH-infested plants [ 7 ]. Our study suggests that giving exogenous GA treatment to WBPH-infested plants can reduce these effects, which is in line with previous reports that applying exogenous GA can reduce the intracellular ROS under stress conditions [ 35 ].…”

“…The water was changed daily. After three days of soaking, the pre-germinated seeds were transferred to soil and kept in the dark for three days until successful growth was observed, as published previously [ 7 ], and the seedlings were kept in the greenhouse for further experimentation.…”

“…The host plants also produce different types of hormones, which result in defense responses to different stresses. In response to biotic stress, plants mainly produce salicylic acid (SA), jasmonate (JA), ethylene (ET), and gibberellic acid (GA) to overcome the effects of biotic stress [ 7 , 8 ]. Gibberellic acid (GA) and methyl jasmonate (MeJA) are plant-growth-promoting hormones that play a regulatory role in plant growth and development; besides growth, both play a key role in stress tolerance.…”

Genome and Transcriptome-Wide Analysis of OsWRKY and OsNAC Gene Families in Oryza sativa and Their Response to White-Backed Planthopper Infestation

“…Approximately 25% of global rice production is lost annually due to damage caused by pest assaults [ 4 ]. The white-backed planthopper (WBPH) is a serious insect pest that damages plants through cellsap-sucking and viral transmissions, and causes severe losses in yield each year, especially in Asian countries [ 5 , 6 ].…”