Role of jasmonate in Lolium perenne compensatory growth and photosynthesis: uncoupling with photosynthesis and differential effects on growth

Abstract

Jasmonate (JA) plays a central role in plant response to wounding and is shown to have crosstalk with gibberellin (GA) and cytokinin (CTK). Nevertheless, a little attempt has been made in connecting JA with tolerant responses and determining its physiological role in such responses. Here, we investigated the possible role of JA in compensatory growth and photosynthesis of Lolium perenne under wounding stress. The results showed that wounding treatment successfully induced compensatory growth and photosynthesis. JA was induced upon wounding, while GA was downregulated. Meanwhile, CTK was upregulated in leaf blade, but downregulated in sheath. In wounded plants, the content of malondialdehyde (MDA) showed little increase, whereas antioxidant enzyme activities showed a statistically insignificant decrease except superoxide dismutase (SOD) in leaf blade and catalase (CAT) in leaf sheath, suggesting alternative antioxidant mechanisms upon wounding. Interestingly, JA treatment induced regrowth in clipped plants, but repressed growth in unclipped plants, and continuous treatment with JA also repressed regrowth in clipped plants, suggesting that the initial JA burst in plants upon wounding can induce growth in L. perenne response to wounding. In addition, JA and its inhibitor induced little changes in photosynthetic yield, displaying that JA was uncoupled from photosynthesis.