Cloning and functional identification of a Chilo suppressalis‐inducible promoter of rice gene, OsHPL2

Abstract

BACKGROUNDPromoters play a key role in driving insect‐resistant genes during breeding of transgenic plants. In current transgenic procedures for breeding rice resistance to striped stem borer (Chilo suppressalis Walker, SSB), the constitutive promoter is used to drive the insect‐resistant gene. To reduce the burden of constitutive promoters on plant growth, isolation and identification of insect‐inducible promoters are particularly important. However, few promoters are induced specifically by insect feeding.RESULTSWe found rice hydroperoxide lyase gene (OsHPL2) (LOC_Os02g12680) was upregulated after feeding by SSB. We subsequently cloned the promoter of OsHPL2 and analysed its expression pattern using the β‐glucuronidase (GUS) reporter gene. Histochemical assays and quantitative analyses of GUS activity confirmed that P HPL2:GUS was activated by SSB, but did not respond to brown planthopper (Nilaparvata lugens Stål, BPH) infestation, mechanical wounding or phytohormone treatments. A series of 5′ truncated assays were conducted and three positive regulatory regions (−1452 to −1213, −903 to −624, and −376 to −176) induced by SSB infestation were identified. P2R123‐min 35S and P2TR2‐min 35S promoters linked with cry1C of transgenic plants showed the highest levels of Cry1C protein expression and SSB larval mortality.CONCLUSIONWe identified an SSB‐inducible promoter and three positive internal regions. Transgenic rice plants with the OsHPL2 promoter and its positive regions driving cry1C exhibited the expected larvicidal effect on SSB. Our study is the first report of an SSB‐inducible promoter that could be used as a potential resource for breeding insect‐resistant transgenic crops. © 2020 Society of Chemical Industry

Isolation and functional analysis ofOsAOS1 promoter for resistance toNilaparvata lugensStål infestation in rice

“…The inducing ability of OsAOS1 promoter is close to that of the CaMV35S promoter even at 24 h after insect feeding (Figure ). We further investigated that increasing the number of repeats of the regulatory region ( P1R1 ) could significantly enhance the promoter induction function (Figure 5d), indicating that insect inducible promoters have a functional superposition effect, and this phenomenon was also found in our previous research (Li et al, 2020). Erenow, this phenomenon was only found in some bacteria, fungal inducible promoters, and a few tissue‐specific promoters (Bai et al, 2019; Rytter et al, 2014; Sohoni et al, 2014).…”

“…However, research on insect‐inducible promoters is lagging far behind. So far, only a few insect‐inducible promoters have been reported (Hua et al, 2007; Li, Wang, et al, 2020; Siddique et al, 2011).…”

Regulated promoters applied to plant engineering: an insight over promising soybean promoters under biotic stress and their cis-elements

“…Godard et al (2007) showed that the potato proteinase inhibitor II (PinII) promoter was able to drive the woundand insect-inducible GUS expression in Picea glauca (white spruce), Arabidopsis, or tobacco. Li et al (2020) observed that the rice hydroperoxide lyase (OsHPL2) gene promoter was significantly upregulated after herbivory of C. suppressalis, but not after feeding of Nilaparvata lugens, mechanical wounding, abscisic acid, jasmonic acid or salicylic acid treatments. Despite the advantages of inducible promoters over constitutive promoters that have been widely used in the genetic engineering of many plants, the trade-offs between inducibility and strength should be considered for practical biotechnological application.…”

Defense Strategies of Rice in Response to the Attack of the Herbivorous Insect, Chilo suppressalis

“…As early as 2001, researchers found that introducing the spider insecticidal gene, SpI , into rice enhanced its resistance to the SSB and rice leaf roller [ 107 ]. Li et al [ 129 ] found that the promoter of the rice hydroperoxide lyase gene, OsHPL2 , was specifically induced by the SSB, and then optimized to connect with Cry1C and transformed it into rice. Compared with the rice transformed with Cry1C alone, it showed a stronger level of resistance to the SSB.…”