Welcome to Acta Prataculturae Sinica ! Today is Share:

Acta Prataculturae Sinica ›› 2024, Vol. 33 ›› Issue (10): 135-146.DOI: 10.11686/cyxb2023426

Previous Articles    

Exogenous melatonin mediates the antioxidant system and phenylpropanoid metabolism to induce resistance to leaf spot disease in oat

Zheng WANG(), Xin LI, Jian-gui ZHANG, Ji-kuan CHAI, Gui-qin ZHAO, Kui-ju NIU()   

  1. College of Pratacultural Science,Gansu Agricultural University,Key Laboratory of Grassland Ecosystem,Ministry of Education,Lanzhou 730070,China
  • Received:2023-11-14 Revised:2024-01-18 Online:2024-10-20 Published:2024-07-15
  • Contact: Kui-ju NIU

Abstract:

The aim of this work was to determine how exogenous melatonin affects the resistance of oat (Avena sativa) to leaf spot disease caused by the pathogen Drechslera avenae. Seedlings of the oat cultivar ‘Molasses’ were subjected to foliar spraying with melatonin (0, 10, 100, 250, 500, and 1000 μmol·L-1) followed by inoculation with the pathogen. At 9 days after inoculation, the disease index was calculated, and physiological indicators and the transcript levels of genes related to the antioxidant system and phenylpropanoid metabolism were determined. The results showed that leaf spot disease significantly inhibited oat plant growth, but the disease index was significantly decreased when melatonin was applied. The degree to which the disease index was decreased differed depending on the melatonin concentration. The in vitro induction efficiency of the pathogen, the activities of catalase and phenylalanine ammonia lyase, and the transcript level of the gene encoding ascorbate peroxidase were highest in the 100 μmol·L-1 melatonin treatment, and were 50.72%, 80.32%, 3.88%, and 148.00% higher than their respective values in the control. The lowest superoxide anion production rate and malondialdehyde content were in the 250 μmol·L-1 melatonin treatment, and were 28.27% and 86.62% lower than their respective values in the control. Compared with the control, in the 250 μmol·L-1 melatonin treatment, the activities of superoxide dismutase, peroxidase, ascorbate peroxidase, cinnamic acid-4-hydroxylase, and 4-coumaric acid∶CoA ligase were increased by 128.23%, 137.14%, 74.00%, 52.65%, and 26.73%, respectively; the contents of lignin, total phenols, and flavonoids were increased by 1.40%, 10.33%, and 13.70%, respectively, and the transcript levels of genes encoding superoxide dismutase, peroxidase, catalase, phenylalanine ammonia lyase, 4-coumaric acid∶CoA ligase, and cinnamic acid-4-hydroxylase were increased by 352.56%, 80.32%, 65.71%, 26.65%, 52.65%, and 20.11%, respectively. Seedlings treated with 500 μmol·L-1 melatonin showed the lowest hydrogen peroxide content (75.45% lower than that in the control) and the highest chlorophyll content (81.35% higher than that in the control). According to the above results, the best concentration of melatonin for inducing resistance to leaf spot in oat plants is 250 μmol·L-1. The results of this study demonstrate a new approach for the control of leaf spot disease in oat.

Key words: oat, melatonin, induced disease resistance, leaf spot