Gene Expression in Cucurbita spp. Root and Crown during Phytophthora capsici Infection

Pedro Gómez,Miguel De Cara-García,Alejandro Ayala-Doñas

doi:10.3390/plants10122718

Pedro Gómez, Miguel De Cara-García + Show 1 more

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https://doi.org/10.3390/plants10122718

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Abstract

Phytophtora capsici causes major diseases in cucurbit crops worldwide. In this study, we inoculated this pathogen into Cucurbita pepo subsp. pepo susceptible MUCU-16 and C. moschata tolerant M63. The gene expression of plant pathogenesis-related proteins chitinase (CpChiIV), lignin-forming peroxidase (CpLPOX), and defensin (CpDEF) and hormone-related enzymes salicylic acid (CpPAL) and ethylene (CpACO) was analyzed for two weeks post-inoculation in root and crown tissues. Differentially expressed genes were found between genotypes, tissues, days post-inoculation, and inoculated/non-inoculated samples. After inoculation, CpPAL and CpChiIV (crown) were downregulated in MUCU-16, while CpLPOX and CpDEF were upregulated in M63. In inoculated samples, higher expression changes were presented on days 10–14 than on day 3 for CpACO, CpLPOX, and CpDEF genes. Overexpression was higher for CpDEF compared to the other tested genes, indicating good suitability as a marker of biotic stress. The overexpression of CpDEF was higher in crown than in roots for both inoculated genotypes. The basal expression of CpPAL and CpDEF was higher in MUCU-16, but after inoculation, CpPAL and CpDEF gene expression were higher in M63. These changes suggest an association between CpDEF upregulation and tolerance, and between CpPAL downregulation and susceptibility.

Highlights

Squashes (Cucurbita spp.) are a heterogeneous genus in terms of cultivable species and morphotypes
The tolerant C. moschata M63 population showed a lower disease severity index (DSI) than the Cucurbita pepo subsp. pepo susceptible MUCU-16 (p = 0.0012; Table 1), both species were damaged by P. capsici
These differences between and non‐inoculated main tissues damaged by the pathogen, root and crown,inoculated in two species, Cucurbita pepo samples were especially observable between days and

Summary

Introduction

Squashes (Cucurbita spp.) are a heterogeneous genus in terms of cultivable species and morphotypes They are distributed worldwide and some have economic significance, such as gourds and pumpkins (Cucurbita moschata and Cucurbita maxima, among others) and zucchini Their production can be severely affected by soil-borne pathogens, such as the oomycete Phytophthora capsici, which causes foliar blight and root, crown (basal stem), and fruit rot in a wide range of cucurbit species [1]. This pathogen, when present in the soil, causes damage to the crown that leads to stem girdling and plant wilting due to the inability to transport nutrients. P. capsici commonly appears in over-irrigated fields and can survive in plant residues or in the soil for long periods as oospores, which allows the fungi to overcome extreme temperatures or desiccation [1,2].

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