Counteractive Effects of Sugar and Strigolactone on Leaf Senescence of Rice in Darkness

Ikuo Takahashi,Tadao Asami,Kai Jiang

doi:10.3390/agronomy11061044

Ikuo Takahashi, Tadao Asami + Show 1 more

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https://doi.org/10.3390/agronomy11061044

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Abstract

Plant hormones strigolactones (SLs) were recently reported to induce leaf senescence. It was reported that sugar suppresses SL-induced leaf senescence in the dark; however, the mechanism of the crosstalk between SLs and the sugar signal in leaf senescence remains elusive. To understand this mechanism, we studied the effects of glucose (Glc) on various senescence-related parameters in leaves of the rice. We found that sugars alleviated SL-induced leaf senescence under dark conditions, and the co-treatment with Glc suppressed SL-induced hydrogen peroxide generation and membrane deterioration. It also suppressed the expression levels of antioxidant enzyme genes upregulated by SL, suggesting that Glc alleviates SL-induced senescence by inhibiting the oxidative processes. SLs can adapt to nutrient deficiency, a major factor of leaf senescence; therefore, we suggest the possibility that Glc and SL monitor the nutrient status in plants to regulate leaf senescence.

Highlights

Leaf senescence is a major developmental stage of the leaf and is accompanied by multilevel alterations, from the organelle to organ and the organism level
A previous study showed that the application of GR24 accelerated the dark-induced reduction in the chlorophyll content in the leaf of rice SL biosynthesis mutants including d10 mutant, application of GR24 had no significant effect on the chlorophyll content in the leaf of wild-type plants [18]
The leaf segments of d10 mutant treated with GR24 showed a greater reduction in the chlorophyll content than the control leaf segments (Figure 1a,b), but the wild type showed no significant difference on the third day after the treatment (Figure 1a)

Summary

Introduction

Leaf senescence is a major developmental stage of the leaf and is accompanied by multilevel alterations, from the organelle to organ and the organism level. Various endogenous and exogenous factors control leaf senescence [1,2,3]. Unfavorable environmental conditions such as drought, salinity, extreme temperatures, pathogen attack, and soil nutrient limitation influence the senescence rate of leaves. Plant hormones control leaf senescence either positively or negatively [4,5]. Jasmonates, and abscisic acid accelerate this process and, among these, ethylene is considered a key plant hormone in promoting leaf senescence [6,7]. Cytokinins delay leaf senescence [7,8]

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