A screening test for the determination of ethylene sensitivity

Exogenously-Sourced Ethylene Positively Modulates Photosynthesis, Carbohydrate Metabolism, and Antioxidant Defense to Enhance Heat Tolerance in Rice

The effect of exogenously-applied ethylene sourced from ethephon (2-chloroethyl phosphonic acid)was studied on photosynthesis, carbohydrate metabolism, and high-temperature stress tolerance in Taipei-309 and Rasi cultivars of rice (Oryza sativa L.). Heat stress increased the content of H₂O₂ and thiobarbituric acid reactive substances (TBARS)more in Rasi than Taipei-309. Further, a significant decline in sucrose, starch, and carbohydrate metabolism enzyme activity and photosynthesis was also observed in response to heat stress. The application of ethephon reduced H₂O₂ and TBARS content by enhancing the enzymatic antioxidant defense system and improved carbohydrate metabolism, photosynthesis, and growth more conspicuously in Taipei-309 under heat stress. The ethephon application enhanced photosynthesis by up-regulating the psbA and psbB genes of photosystem II in heat-stressed plants. Interestingly, foliar application of ethephoneffectively down-regulated high-temperature-stress-induced elevated ethylene biosynthesis gene expression. Overall, ethephon application optimized ethylene levels under high-temperature stress to regulate the antioxidant enzymatic system and carbohydrate metabolism, reducing the adverse effects on photosynthesis. These findings suggest that ethylene regulates photosynthesis via carbohydrate metabolism and the antioxidant system, thereby influencing high-temperature stress tolerance in rice.

A new approach to suppress methane emissions from rice cropping systems using ethephon

Rice is the main staple food for more than half of the world's population. Yet, rice cultivation is subjected to criticism because of its important role in methane (CH₄) emissions. Although several agronomic practices such as controlled irrigation and conservation tillage have been widely adopted to mitigate CH₄ emissions from rice cultivation, the benefits gained by these practices are highly dependent on site-specific soil and climate conditions, and often offset by yield reduction. The use of plant growth regulating compounds having the potential to increase the crop yield and mitigate CH₄ emissions may be an innovative approach to sustainable agriculture. Ethylene (C₂H₄), a plant growth regulator is known to have a strong inhibitory effect on methanogenesis. However, due to gaseous form and low water solubility, C₂H₄ has not been used to suppress methanogenesis in paddy fields. To develop C₂H₄ as a prospective soil amendment for reducing methane (CH₄) emissions, ethephon (2-Chloroethylphosphonic acid), a precursor of C₂H₄ was tested. We found that ethephon reduced CH₄ formation by 43%, similar to other well known methanogenic inhibitors (2-Bromoethanesulfonate, 2-Chlomoethanesulfonate, 2-Mercaptoethanesulfonate). However, ethephon rapidly hydrolyzed to C₂H₄ and methanogenic activity recuperated completely after C₂H₄ removal. To slow down the release of C₂H₄, ethephon was mixed with bio-degradable polymers such as cellulose acetate and applied to paddy soils. We found that compared with the control, the C₂H₄ release of ethephon slowed down to 90 days, and the CH₄ emissions were reduced by 90%. The application of ethephon at lower concentrations did not significantly alter bacterial communities, their relative abundance, and the abundance of methanotrophs, but it significantly reduced archaeal communities and the relative abundance and expression level of methanogens in paddy soils. Results suggest that cellulose acetate-mixed ethephon has great promise to suppress CH₄ emissions in rice paddies while ensuring sustainable yields.

Ethephon, an organophosphorous, a Fruit and Vegetable Ripener: Has potential hepatotoxic effects?

Introduction:

In the recent years, ethephon, 2-chloroethylphosphonic acid, is one of the most commonly used plant growth regulators. At present, it is being used on fruits, vegetables, and cereals for promoting pre- and post-harvest ripening. The effect of artificial ripening has become questionable because of various health-related issues. This study was conducted to note the morphology of liver after ethephon administration as it is the site where chemicals undergo first pass metabolism and probably will be affected by ethephon. Materials and

Methods:

Adult Wistar albino rats were divided into experimental and control groups (10 each). Ethephon was administered at a dose of 200 mg/kg/day by a gavage tube in the experimental rats for 14 days. The animals were sacrificed within 24 h of the last dose; liver was dissected and processed for light microscopy. Hematoxylin and eosin-stained sections were studied using an image-pro express analyzer. The data obtained from control and experimental groups were statistically analyzed.

Results:

In the experimental rats, the body weight was found to be significantly decreased. The orderly arrangement of hepatocytes was disrupted and was replaced by blood-filled sinusoids. At sites, hepatocytes appeared to be degenerated. Councilman bodies with pyknotic nuclei and inflammatory infiltrations were seen. The population per unit area of the hepatocytes and Kupffer cells was 29.53 ± 10.65 versus 44.18 ± 10.31 and 25.12 ± 4.41versus 13.05 ± 6.5 in experimental and control groups, respectively. The decrease of hepatocytes and increase of Kupffer cells were found to be statistically significant.

Conclusions:

The observations in the liver are probably indicative of degenerative changes associated with ethephon. Hence, we can conclude that this plant growth regulator, Fruit and Vegetable Ripener, has hepatotoxic potential. General awareness and regarding the use of such plant growth regulators is must to reduce the intake.

Enhancing crop yield with the use of N-based fertilizers co-applied with plant hormones or growth regulators

Crop yield, vegetative or reproductive, depends on access to an adequate supply of essential mineral nutrients. At the same time, a crop plant's growth and development, and thus yield, also depend on in situ production of plant hormones. Thus optimizing mineral nutrition and providing supplemental hormones are two mechanisms for gaining appreciable yield increases. Optimizing the mineral nutrient supply is a common and accepted agricultural practice, but the co-application of nitrogen-based fertilizers with plant hormones or plant growth regulators is relatively uncommon. Our review discusses possible uses of plant hormones (gibberellins, auxins, cytokinins, abscisic acid and ethylene) and specific growth regulators (glycine betaine and polyamines) to enhance and optimize crop yield when co-applied with nitrogen-based fertilizers. We conclude that use of growth-active gibberellins, together with a nitrogen-based fertilizer, can result in appreciable and significant additive increases in shoot dry biomass of crops, including forage crops growing under low-temperature conditions. There may also be a potential for use of an auxin or cytokinin, together with a nitrogen-based fertilizer, for obtaining additive increases in dry shoot biomass and/or reproductive yield. Further research, though, is needed to determine the potential of co-application of nitrogen-based fertilizers with abscisic acid, ethylene and other growth regulators.