Differential activation of sporamin expression in response to abiotic mechanical wounding and biotic herbivore attack in the sweet potato

Kumar, Rajendran Senthil; Lin, I Winnie; Chen, Mei-Ju; Chen, Chien‐Yu; Yeh, Kai‐Wun

doi:10.1186/1471-2229-14-112

Cited by 35 publications

(33 citation statements)

References 81 publications

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“…Our previous work demonstrated that sporamin is induced by herbivory (Rajendran et al ., ). Sporamin, which has trypsin inhibitory activity (TPI), confers insect resistance on sweet potato (Yeh et al ., ,b).…”

Section: Resultsmentioning

confidence: 97%

Sweet potato NAC transcription factor, IbNAC1, upregulates sporamin gene expression by binding the SWRE motif against mechanical wounding and herbivore attack

et al. 2016

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SUMMARYSporamin is a tuberous storage protein with trypsin inhibitory activity in sweet potato (Ipomoea batatas Lam.), which accounts for 85% of the soluble protein in tubers. It is constitutively expressed in tuberous roots but is expressed in leaves only after wounding. Thus far, its wound-inducible signal transduction mechanisms remain unclear. In the present work, a 53-bp DNA region, sporamin wound-response ciselement (SWRE), was identified in the sporamin promoter and was determined to be responsible for the wounding response. Using yeast one-hybrid screening, a NAC domain protein, IbNAC1, that specifically bound to the 5 0 -TACAATATC-3 0 sequence in SWRE was isolated from a cDNA library from wounded leaves.IbNAC1 was constitutively expressed in root tissues and was induced earlier than sporamin following the wounding of leaves. Transgenic sweet potato plants overexpressing IbNAC1 had greatly increased sporamin expression, increased trypsin inhibitory activity, and elevated resistance against Spodoptera litura. We further demonstrated that IbNAC1 has multiple biological functions in the jasmonic acid (JA) response, including the inhibition of root formation, accumulation of anthocyanin, regulation of aging processes, reduction of abiotic tolerance, and overproduction of reactive oxygen species (ROS). Thus, IbNAC1 is a core transcription factor that reprograms the transcriptional response to wounding via the JA-mediated pathway in sweet potato.

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Section: Resultsmentioning

confidence: 97%

Sweet potato NAC transcription factor, IbNAC1, upregulates sporamin gene expression by binding the SWRE motif against mechanical wounding and herbivore attack

et al. 2016

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“…Therefore, our wounding transcriptomic datasets [32] were carefully surveyed, and five bHLH transcription factors, namely IbbHLHa , b , c , d and e , were screened out. Subsequently, the gene expression pattern was monitored by qRT-PCR under a wounding time-course analysis.…”

Section: Resultsmentioning

confidence: 99%

The Sweet Potato NAC-Domain Transcription Factor IbNAC1 Is Dynamically Coordinated by the Activator IbbHLH3 and the Repressor IbbHLH4 to Reprogram the Defense Mechanism against Wounding

Chen

Kuo

et al. 2016

PLoS Genet

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IbNAC1 is known to activate the defense system by reprogramming a genetic network against herbivory in sweet potato. This regulatory activity elevates plant defense potential but relatively weakens plants by IbNAC1-mediated JA response. The mechanism controlling IbNAC1 expression to balance plant vitality and survival remains unclear. In this study, a wound-responsive G-box cis-element in the IbNAC1 promoter from -1484 to -1479 bp was identified. From a screen of wound-activated transcriptomic data, one transcriptional activator, IbbHLH3, and one repressor, IbbHLH4, were selected that bind to and activate or repress, respectively, the G-box motif in the IbNAC1 promoter to modulate the IbNAC1-mediated response. In the early wound response, the IbbHLH3-IbbHLH3 protein complex binds to the G-box motif to activate IbNAC1 expression. Thus, an elegant defense network is activated against wounding stress. Until the late stages of wounding, IbbHLH4 interacts with IbbHLH3, and the IbbHLH3-IbbHLH4 heterodimer competes with the IbbHLH3-IbbHLH3 complex to bind the G-box and suppress IbNAC1 expression and timely terminates the defense network. Moreover, the JAZs and IbEIL1 proteins interact with IbbHLH3 to repress the transactivation function of IbbHLH3 in non-wounded condition, but their transcription is immediately inhibited upon early wounding. Our work provides a genetic model that accurately switches the regulatory mechanism of IbNAC1 expression to adjust wounding physiology and represents a delicate defense regulatory network in plants.

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“…The measurement of plant biochemical variation in response to insect herbivory previously faced substantial limitations that have hindered the progress of the field. In particular, current practice in many labs is to use a single ecotype to measure differences between experimental treatments and to pool tissue from multiple leaves and individuals to obtain sufficient sample mass (War et al., ; Rajendran et al., ; Ferrieri et al., ). However, this approach has precluded the study of variation within and between individuals, which is what is relevant for real‐world interactions (Whitham, ; Winn, ; Bolnick et al., ).…”

Section: Discussionmentioning

confidence: 99%

A high‐throughput method of analyzing multiple plant defensive compounds in minimized sample mass

et al. 2019

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Premise of the StudyCurrent methods for quantifying herbivore‐induced alterations in plant biochemistry are often unusable by researchers due to practical constraints. We present a cost‐effective, high‐throughput protocol to quantify multiple biochemical responses from small plant tissue samples using spectrophotometric techniques.Methods and ResultsUsing Solanum lycopersicum and Medicago polymorpha leaves pre‐ and post‐herbivory, we demonstrate that our protocol quantifies common plant defense responses: peroxidase production, polyphenol oxidase production, reactive oxygen species production, total protein production, and trypsin‐like protease inhibition activity.ConclusionsCurrent protocols can require 500 mg of tissue, but our assays detect activity in less than 10 mg. Our protocol takes two people 6 h to run any of the assays on 300 samples in triplicate, or all of the assays on 20 samples. Our protocol enables researchers to plan complex experiments that compare local versus systemic plant responses, quantify environmental and genetic variation, and measure population‐level variation.

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Differential activation of sporamin expression in response to abiotic mechanical wounding and biotic herbivore attack in the sweet potato

Cited by 35 publications

References 81 publications

Sweet potato NAC transcription factor, IbNAC1, upregulates sporamin gene expression by binding the SWRE motif against mechanical wounding and herbivore attack

Sweet potato NAC transcription factor, IbNAC1, upregulates sporamin gene expression by binding the SWRE motif against mechanical wounding and herbivore attack

The Sweet Potato NAC-Domain Transcription Factor IbNAC1 Is Dynamically Coordinated by the Activator IbbHLH3 and the Repressor IbbHLH4 to Reprogram the Defense Mechanism against Wounding

A high‐throughput method of analyzing multiple plant defensive compounds in minimized sample mass

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