HrCYP90B1 modulating brassinosteroid biosynthesis in sea buckthorn (Hippophae rhamnoides L.) against fruit fly (Rhagoletis batava obseuriosa Kol.) infection

Abstract

Sea buckthorn is an important ecological and economic tree species, and its berries have been severely damaged by sea buckthorn fruit fly, Rhagoletis batava obseuriosa Kol. (Diptera: Tephritidae) (RBO). Brassinosteroid (BR) is widely involved in stress tolerance of plant. However, limited knowledge exists regarding the molecular mechanisms underlying insect resistance. Here, we found that BR content was much higher in sea buckthorn fruits with RBO infection than non-infection, and the damage rates of fruit with BR treatment were significantly lower than that of non-treatment. It indicated that BR could enhance RBO resistance in sea buckthorn. Several BR biosynthesis related genes HrCYPs (CYP85A1/85A2/90A1/90B1/90C1/90D1/92A6/724B/734A1) were obtained and identified based on transcriptome analysis, of which the most up-regulated gene in fruits was HrCYP90B1 under RBO and mechanical damage. Overexpression of HrCYP90B1 in Arabidopsis thaliana showed BR and salicylic acid (SA) content was significantly increased, the substrate campesterol (CR) of HrCYP90B1 content decreased. Further studies revealed that silencing HrCYP90B1 by virus-induced gene silencing (VIGS) resulted in decrease of BR, SA and defense-related enzymes contents, increase of CR content. Silencing HrCYP90B1 also caused suppression of SA and activation of jasmonic acid (JA) pathways, enabling enhanced of RBO susceptibility and more damage of fruits. Taken together, we obtained evidence that HrCYP90B1 was a positive regulator in RBO-resistance improvement in sea buckthorn, which will provide comprehensive insights into the tree defense system of sea buckthorn to pest infection.

Lignans dramatically enhance the resistance of Fraxinus velutina Torr. by adjusting the dominant bacterium group of Agrilus planipennis Fairmaire

“…VIGS is widely used in crop plant genetics for gene knockdown due to its ease of use and the short time required to generate phenotypes, but there are few studies on the woody plant. 32,46,47 Here, we successfully targeted the FvPLR1 gene along with the specific VIGS vector systems in velvet ash. The VIGS-treated plants had decreased FvPLR1 gene expression and lignan content, which ultimately inhibited the lignan synthesis.…”

“…The virus-induced gene silencing (VIGS) experiments were performed according to our previous reports with minor modifications. 32 The Agrobacterium tumefaciens harboring tobacco rattle virus (TRV) vectors were prepared according to Fradin's description (Fig. S2).…”

HrTPS12 gene dramatically enhanced insect resistance of sea buckthorn to infection by fruit fly (Rhagoletis batava obseuriosa Kol.)

“…S4a,b). 19 For tested plant materials, RBO resistant and sensitive sea buckthorn leaves/fruits were abbreviated as RL/RF and SL/SF, respectively.…”

“…The HrTPS12 silencing in RBO-resistant sea buckthorn induced by virus was carried out according to our previous study with minor modifications. 19 The silencing vector TRV: HrTPS12 and positive control vector TRV: HrPDS (phytoene desaturase) were successfully constructed. The constructed vectors were then transformed into GV3101 plasmid with electroporation transformation.…”

“…In the early stage of our lab, VIGS technology has been used in woody plants, Hippophae rhamnoides, and Fraxinus velutina and has been successfully conducted in gene insect-resist analysis. 19,57 We used a VIGS protocol to obtain the silencing HrTPS12 sea buckthorn. Our results indicated that the (E)-⊎-ocimene released from sea buckthorn leaves with VIGS silencing HrTPS12 was notably lower than those control leaves.…”