気中汚染物質に対する植物防御の統合的システムに関する分子生理学的研究
| Project/Area Number |
18F18391
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| Research Category |
Grant-in-Aid for JSPS Fellows
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| Allocation Type | Single-year Grants |
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| Section | 外国 |
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| Review Section |
Basic Section 41050:Environmental agriculture-related
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| Research Institution | Okayama University |
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| Host Researcher |
森 泉 岡山大学, 資源植物科学研究所, 准教授 (40379805)
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| Foreign Research Fellow |
OOI LIA 岡山大学, 資源植物科学研究所, 外国人特別研究員
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| Project Period (FY) |
2018-11-09 – 2021-03-31
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| Project Status |
Granted (Fiscal Year 2020)
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| Budget Amount *help |
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 2020: ¥100,000 (Direct Cost: ¥100,000)
Fiscal Year 2019: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2018: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Keywords | Sulfur dioxide / stomata / abiotic stress / defence mechanism / sulfur oxide |
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| Outline of Annual Research Achievements |
Plants protect themselves from harmful gases through closing stomata and/or detoxification. Sulfur dioxide (SO2) is a harmful gas known to induce stomatal closure. However, the cellular mechanism mediating SO2-induced stomatal closure remains obscure.
To shed lights on the roles of phytohormones in SO2-induced closure, we examined the temporal patterns of nine phytohormones, gibberellin A1, A4, abscisic acid, salicylic acid, jasmonic acid (JA), jasmonoylisoleucine (JA-Ile), indoleacetic acid, zeatin and isopentenyladenine in SO2-treated plants. The contents of JA and JA-Ile continuously increased.
Through comparison of estimated atmospheric concentrations of these gases along the evolution of plants, we propose that this difference is attributed to historical difference in the gas compositions in the atmosphere. Sulfite oxidase (SO) is the key enzyme in SO2 detoxification. Phylogenetic analysis revealed that SO has evolutionally developed dating back at least to green algae. We understand that the detoxification mechanism against SO2 evolved earlier than stomatal defense.
We hypothesized that the action of SO2 inducing stomata is through acidosis. AtClCa is a nitrate/proton antiporter mediating pH stabilization of guard cells. We found that clca mutant guard cells demonstrated stronger resistance to SO2 than guard cells of wild-type plants.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
Our quantitative analysis of nine phytohormones revealed that JA, JA-Ile and IAA contents were changed by SO2 exposure. We scrutinized the involvement of JA and JA-Ile using a JA insensitive mutant, coi1. This work suggested no involvement of JA in SO2-induced stomatal closure. On the other hand, the observation of a transient increment in IAA level where SO2-induced stomatal closure occurred suggests its novel role in inducing stomatal closure.
Hydrogen sulfide (H2S) and nitric oxide (NO) have been suggested to participate in SO2-induced stomatal closure in sweet potato in a past study. We investigated the involvement of H2S and NO in Arabidopsis and found that neither H2S or NO were involved in this process. Our pharmacological study also denied the involvement of reactive oxygen species on SO2-induced stomatal closure, which have been anticipated in a past study.
We also conducted bioinformatics research on the relationship of atmospheric concentration of air pollutants and development of plant defense mechanisms. Our results suggested that guard cell signaling mechanism to ozone and carbon dioxide may be co-established with the acquirement of stomatal apparatus, but SO2 may be far recent. However, SO2 detoxification mechanism of plants had already been developed in algae.
Our hypothesis that SO2 toxicity to guard cells is mediated by acidosis is currently tested by a pH homeostasis mutant, clca. The preliminary study shows a promising result. This will be confirmed in the next 6 months.
Above progresses reasonably fit to the research plan.
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| Strategy for Future Research Activity |
Investigation of the involvement of CLCa in SO2 detoxification and enhancement of SO2 tolerance. Previous studies were conducted using excised Arabidopsis leaves floated on SO2-producing buffer to examine the effects of SO2 on stomatal physiology. Next, SO2 impacts on whole plants will be investigated using gas chamber fumigation approach. Whole plants of wild-types and mutants will be incubated with SO2 gas in a gas chamber. The effects of SO2 on chlorophyll contents and cell viability will be investigated. This study is expected to provide insights on plant resistant mechanisms against SO2 and potential approach to improve SO2 resistance.
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Report
(2 results)
Research Products
(5 results)
