open access publication

Article, 2024

Sodium Tetraborate Induces Systemic Resistance in Watermelon against Stagonosporopsis cucurbitacearum

AGRONOMY-BASEL, ISSN 2073-4395, 2073-4395, Volume 14, 5, 10.3390/agronomy14050979

Contributors

Nga, Nguyen Thi Thu 0000-0003-4994-2747 [1] [2] de Neergaard, Eigil [1] Shetty, Hunthrike Shekar [3] Thuy, Tran Thi Thu [2] Van Kim, Pham [2] Jorgensen, HJ 0000-0002-5902-6550 (Corresponding author) [1]

Affiliations

  1. [1] Univ Copenhagen, Copenhagen Plant Sci Ctr, Dept Plant & Environm Sci, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark
  2. [NORA names: KU University of Copenhagen; University; Denmark; Europe, EU; Nordic; OECD];
  3. [2] Can Tho Univ, Coll Agr, Dept Plant Protect, Can Tho City 90000, Vietnam
  4. [NORA names: Vietnam; Asia, South];
  5. [3] Univ Mysore, Dept Studies Biotechnol, Mysore 570006, Karnataka, India
  6. [NORA names: India; Asia, South]

Abstract

Imbibing watermelon seeds in 1 mM sodium tetraborate (Na2B4O7) for 24 h systemically protected plants against foliar infection by Stagonosporopsis cucurbitacearum in detached leaves and under greenhouse conditions. The treatment resulted in both a reduction in the overall percentage of leaf infection as well as in the size of lesions. Studies of the mechanisms by which Na2B4O7 protected watermelon showed that there was no direct effect on the S. cucurbitacearum mycelium growth in vitro. On the other hand, plants raised from seeds primed with Na2B4O7 showed a higher frequency of fluorescent epidermal cells compared to the plants treated with water. This indicates that a higher number of cells expressed the hypersensitive response after Na2B4O7 priming. In addition, there was an increase in peroxidase activity and an enhanced accumulation of a 45 kDa acidic peroxidase isoform during the early stages of infection in plants treated with Na2B4O7 compared to plants treated with water and this was positively correlated to the reduction of leaf infection caused by the pathogen. These results indicate that Na2B4O7 is able to induce systemic resistance in watermelon against S. cucurbitacearum by activating the hypersensitive reaction at penetration sites, increasing peroxidase activity and altering the peroxidase isozyme profile. Although each individual response may only have had a minor effect, their combined effects had a reducing effect on the disease.

Keywords

borax, gummy stem blight, hypersensitive response, induced resistance, microscopy, peroxidase activity, peroxidase isozymes

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