Rice OsHOL1 and OsHOL2 proteins have S-adenosyl-L-methionine-dependent methyltransferase activities toward iodide ions

Takekawa, Yuko; Nakamura, Tatsuo

doi:10.5511/plantbiotechnology.12.0207a

Cited by 7 publications

(10 citation statements)

References 23 publications

(28 reference statements)

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“…The RT-qPCR analysis we performed showed that the transcription levels of OsHOL1 and OsHOL2 were quite different, and that OsHOL1 was the most expressed of the two genes, with a particularly high transcription rate in leaves. Our results agreed with the data reported in previous studies 28 , and also with those present in the Rice Expression Profile Database 39 , which show a sustained OsHOL1 expression in leaves and a low transcription of OsHOL2 , without preferential locations in the plant (Fig. S8 ).…”

Section: Discussionsupporting

confidence: 93%

“…The two genes of rice identified as homologous of AtHOL1 22 , OsHOL1 and OsHOL2 28 , belong to different chromosomes. OsHOL1 ( Os03g62670 ) is located on chromosome 3 and organized into seven exons and six introns, which can be alternatively spliced in three predicted different isoforms (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Homologous of these enzymes are widespread in the plant kingdom, including dicots, monocots, and unicellular algae 27 . In Oryza sativa , two genes were identified, OsHOL1 and OsHOL2 , which show, respectively, a 51% and a 57% similarity with Arabidopsis HOL1 28 . In in vitro studies, recombinant OsHOL proteins showed SAM-dependent methyltransferase activities towards halide and thiocyanate ions, with the highest effects exerted with iodide, suggesting a major involvement in the metabolism of iodine 28 .…”

Section: Introductionmentioning

confidence: 99%

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Targeted knockout of the gene OsHOL1 removes methyl iodide emissions from rice plants

Carlessi

Mariotti

Giaume

et al. 2021

Sci Rep

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Iodine deficiency represents a public health problem worldwide. To increase the amount of iodine in the diet, biofortification strategies of plants have been tried. They rely on the exogenous administration of iodine to increase its absorption and accumulation. However, iodine is not stable in plants and can be volatilized as methyl iodide through the action of specific methyltransferases encoded by the HARMLESS TO OZONE LAYER (HOL) genes. The release of methyl iodide in the atmosphere represents a threat for the environment due to its ozone depletion potential. Rice paddies are among the strongest producers of methyl iodide. Thus, the agronomic approach of iodine biofortification is not appropriate for this crop, leading to further increases of iodine emissions. In this work, we used the genome editing CRISPR/Cas9 technology to knockout the rice HOL genes and investigate their function. OsHOL1 resulted a major player in methyl iodide production, since its knockout abolished the process. Moreover, its overexpression reinforced it. Conversely, knockout of OsHOL2 did not produce effects. Our experiments helped elucidating the function of the rice HOL genes, providing tools to develop new rice varieties with reduced iodine emissions and thus more suitable for biofortification programs without further impacting on the environment.

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Section: Discussionsupporting

confidence: 93%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Targeted knockout of the gene OsHOL1 removes methyl iodide emissions from rice plants

Carlessi

Mariotti

Giaume

et al. 2021

Sci Rep

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“…The affinity of these methyl-halide transferase enzymes to iodine is much greater than that observed in other halogens or ions such as thiocyanate (Takekawa and Nakamura, 2012). Volatilization can be faster as iodine increases its concentration in the substrate (Itoh et al, 2009), and occurs in all organs; in rice, the iodine foliar concentration decreases exponentially with a half-life of 14 days (Nakamura et al, 1986).…”

Section: Iodine Applications In Agricultural Cropsmentioning

confidence: 89%

“…Once absorbed, transported, and accumulated in different plant organs, iodine is not stable; plants volatilize iodine as methyl iodide (CH 3 I) using the enzymes halide ion methyltransferase (HMT) and halide/thiol methyltransferase (HTMT), with methyl transferase activity dependent on S-adenosylmethionine (SAM; Redeker et al, 2004 ; Itoh et al, 2009 ). The affinity of these methyl-halide transferase enzymes to iodine is much greater than that observed in other halogens or ions such as thiocyanate (Takekawa and Nakamura, 2012 ). Volatilization can be faster as iodine increases its concentration in the substrate (Itoh et al, 2009 ), and occurs in all organs; in rice, the iodine foliar concentration decreases exponentially with a half-life of 14 days (Nakamura et al, 1986 ).…”

Section: Iodine Applications In Agricultural Cropsmentioning

confidence: 89%

Use of Iodine to Biofortify and Promote Growth and Stress Tolerance in Crops

et al. 2016

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Iodine is not considered essential for land plants; however, in some aquatic plants, iodine plays a critical role in antioxidant metabolism. In humans, iodine is essential for the metabolism of the thyroid and for the development of cognitive abilities, and it is associated with lower risks of developing certain types of cancer. Therefore, great efforts are made to ensure the proper intake of iodine to the population, for example, the iodization of table salt. In the same way, as an alternative, the use of different iodine fertilization techniques to biofortify crops is considered an adequate iodine supply method. Hence, biofortification with iodine is an active area of research, with highly relevant results. The agricultural application of iodine to enhance growth, environmental adaptation, and stress tolerance in plants has not been well explored, although it may lead to the increased use of this element in agricultural practice and thus contribute to the biofortification of crops. This review systematically presents the results published on the application of iodine in agriculture, considering different environmental conditions and farming systems in various species and varying concentrations of the element, its chemical forms, and its application method. Some studies report beneficial effects of iodine, including better growth, and changes in the tolerance to stress and antioxidant capacity, while other studies report that the applications of iodine cause no response or even have adverse effects. We suggested different assumptions that attempt to explain these conflicting results, considering the possible interaction of iodine with other trace elements, as well as the different physicochemical and biogeochemical conditions that give rise to the distinct availability and the volatilization of the element.

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Metabolic Engineering of Essential Micronutrients in Plants to Ensure Food Security

Chakraborty¹,

Roychoudhury²

2023

Plants as Bioreactors for Industrial Molecules

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Rice OsHOL1 and OsHOL2 proteins have S-adenosyl-L-methionine-dependent methyltransferase activities toward iodide ions

Cited by 7 publications

References 23 publications

Targeted knockout of the gene OsHOL1 removes methyl iodide emissions from rice plants

Targeted knockout of the gene OsHOL1 removes methyl iodide emissions from rice plants

Use of Iodine to Biofortify and Promote Growth and Stress Tolerance in Crops

Metabolic Engineering of Essential Micronutrients in Plants to Ensure Food Security

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