Abstract
Domesticated crops with high yield and quality are frequently susceptible to pathogen attack, whereas enhancement of disease resistance generally compromises crop yield. The underlying mechanisms of how plant development and disease resistance are coordinately programed remain elusive. Here, we showed that the basic Helix-Loop-Helix (bHLH) transcription factor Cucumis sativus Irregular Vasculature Patterning (CsIVP) was highly expressed in cucumber vascular tissues. Knockdown of CsIVP caused severe vasculature disorganization and abnormal organ morphogenesis. CsIVP directly binds to vascular-related regulators YABBY5 (CsYAB5), BREVIPEDICELLUS (CsBP), and AUXIN/INDOLEACETIC ACIDS4 (CsAUX4) and promotes their expression. Knockdown of CsYAB5 resulted in similar phenotypes as CsIVP-RNA interference (RNAi) plants, including disturbed vascular configuration and abnormal organ morphology. Meanwhile, CsIVP-RNAi plants were more resistant to downy mildew and accumulated more salicylic acid (SA). CsIVP physically interacts with NIM1-INTERACTING1 (CsNIMIN1), a negative regulator in the SA signaling pathway. Thus, CsIVP is a novel vasculature regulator functioning in CsYAB5-mediated organ morphogenesis and SA-mediated downy mildew resistance in cucumber.
Highlights
Crop domestication is a fundamental process promoting agriculture and human societal development
Cucumis sativus Irregular Vasculature Patterning (CsIVP) belongs to the HECATE3 (HEC3) subfamily, which together with the HEC1/2 genes were generated by a HEC duplication prior to the origin of angiosperms; these genes were present in early mosses, lycophytes, and gymnosperms (S1A Fig)
Our results showed that CsIVP substantially enhanced the real-time PCR-based detection of the CsBP, CsAUX4, and CsIVP directly binds to vascularrelated regulators YABBY5 (CsYAB5) promoters after immunoprecipitation (Fig 3E)
Summary
Crop domestication is a fundamental process promoting agriculture and human societal development. Compared with their wild ancestors, cultivated crops have features such as high yield and better quality, largely resulting from increased organ size, improved nutritional quality, synchronous ripening, and reduced dispersibility [1,2]. Due to artificial selection, some stress-resistant traits in wild species were lost during domestication, and many cultivated varieties—with superior agronomic characteristics—are susceptible to disease and abiotic stresses [3]. For disease-resistant genotypes, plants often exhibit reduced yield potential and negative developmental attributes [4]. When plants are infected by pathogens, defense responses frequently occur with a cost of reduction in growth and reproduction [5]. In spite of intensive investigations into the basis of domestication [3,6,7], the underlying mechanism for co-regulation of development and disease resistance remains unclear
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