Changes in levels of foliar carbohydrates and myo-inositol before premature leaf senescence of Populus nigra induced by a mixture of O3 and SO2

1996 ◽  
Vol 74 (6) ◽  
pp. 965-970 ◽  
Author(s):  
R. C. Fialho ◽  
J. Bücker

Specimens of Populus nigra L. cv. Loenen exhibit premature leaf senescence when exposed for a few weeks to realistic air pollution. In this study, the changes in levels of foliar carbohydrates and myo-inositol (MI) due to 30 ± 1 nL/L O3 + 12 ± 1 nL/L SO2 from the onset of exposure to the occurrence of premature abscission is presented. Petioles and laminae of the 12 oldest leaves were separately analysed on days 0, 4, 8, 12, 16, 20, 22, and 32 of continuous exposure, which was performed in open-top chambers (OTC). On days 8 to 12, clearly prior to yellowing (starting on day 22), total nonstructural carbohydrates (TNC; starch + raffinose + sucrose + glucose + fructose + MI) in the fumigated laminae exceeded that in controls by about 30%. This increase was due to higher amounts of different soluble forms, while starch remained unaltered. From day 20 onwards, the level of TNC in the fumigated laminae progressively fell below that in controls. This decrease was due to a progressive decline in starch, which had started on day 16 and was dominating, although glucose and raffinose increased significantly. In the petioles, starch, sucrose, and glucose decreased because of fumigation with the occurrence of leaf yellowing, while raffinose increased. In contrast, MI in the petioles progressively accumulated directly on exposure until leaf yellowing occurred. The results are discussed in terms of the "general adaption syndrome" of H. Selye (1936. Nature (London), 138: 32). The marked MI response in petioles is concluded to be an early indication of phytorelevant O3 + SO2 pollution. Keywords: air pollution, carbohydrates, myo-inositol, pigments, Populus nigra L., senescence, stress.

Plants ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 415 ◽  
Author(s):  
Xiaoming Gao ◽  
Xinru Wu ◽  
Guanshan Liu ◽  
Zenglin Zhang ◽  
Jiangtao Chao ◽  
...  

As the last stage of plant development, leaf senescence has a great impact on plant’s life cycle. Genetic manipulation of leaf senescence has been used as an efficient approach in improving the yield and quality of crop plants. Here we describe an ethyl methane sulfonate (EMS) mutagenesis induced premature leaf senescence mutant yellow leaf 1 (yl1) in common tobacco (Nicotiana tabacum L.). The yl1 plants displayed early leaf yellowing. Physiological parameters and marker genes expression indicated that the yl1 phenotype was caused by premature leaf senescence. Genetic analyses indicated that the yl1 phenotype was controlled by a single recessive gene that was subsequently mapped to a specific interval of tobacco linkage group 11 using simple sequence repeat (SSR) markers. Exogenous plant hormone treatments of leaves showed that the yl1 mutant was more sensitive to ethylene and jasmonic acid than the wild type. No similar tobacco premature leaf senescence mutants have been reported. This study laid a foundation for finding the gene controlling the mutation phenotype and revealing the molecular regulation mechanism of tobacco leaf senescence in the next stage.


2021 ◽  
Vol 22 (8) ◽  
pp. 3936
Author(s):  
Ahmed G. Gad ◽  
Habiba ◽  
Xiangzi Zheng ◽  
Ying Miao

Leaf senescence, as an integral part of the final development stage for plants, primarily remobilizes nutrients from the sources to the sinks in response to different stressors. The premature senescence of leaves is a critical challenge that causes significant economic losses in terms of crop yields. Although low light causes losses of up to 50% and affects rice yield and quality, its regulatory mechanisms remain poorly elucidated. Darkness-mediated premature leaf senescence is a well-studied stressor. It initiates the expression of senescence-associated genes (SAGs), which have been implicated in chlorophyll breakdown and degradation. The molecular and biochemical regulatory mechanisms of premature leaf senescence show significant levels of redundant biomass in complex pathways. Thus, clarifying the regulatory mechanisms of low-light/dark-induced senescence may be conducive to developing strategies for rice crop improvement. This review describes the recent molecular regulatory mechanisms associated with low-light response and dark-induced senescence (DIS), and their effects on plastid signaling and photosynthesis-mediated processes, chloroplast and protein degradation, as well as hormonal and transcriptional regulation in rice.


2020 ◽  
Vol 35 (4) ◽  
pp. 379-399
Author(s):  
Seyed M. Karimi ◽  
Ali Maziyaki ◽  
Samaneh Ahmadian Moghadam ◽  
Mahtab Jafarkhani ◽  
Hamid Zarei ◽  
...  

AbstractStudies that assess the connection between the prevalence of chronic diseases and continuous exposure to air pollution are scarce in developing countries, mainly due to data limitations. Largely overcoming data limitations, this study aimed to investigate the association between the likelihood of reporting a set of chronic diseases (diabetes, cancer, stroke and myocardial infarction, asthma, and hypertension) and continuous exposure to carbon monoxide (CO), nitrogen dioxide (NO2), ozone (O3), and coarse particulate matter (PM10). Using the estimated associations, the disease burden and economic costs of continuous exposure to air pollutants were also approximated. A 2011 Health Equity Assessment and Response Tool survey from Tehran, Iran, was used in the main analyses. A sample of 67,049 individuals who had not changed their place of residence for at least 2 years before the survey and reported all relevant socioeconomic information was selected. The individuals were assigned with the average monthly air pollutant levels of the nearest of 16 air quality monitors during the 2 years leading to the survey. Both single- and multi-pollutant analyses were conducted. The country’s annual household surveys from 2002 to 2011 were used to calculate the associated economic losses. The single-pollutant analysis showed that a one-unit increase in monthly CO (ppm), NO2 (ppb), O3 (ppb), and PM10 (μg/m3) during the 2 years was associated with 751 [confidence interval (CI): 512–990], 18 (CI: 12–24), 46 (CI: −27–120), and 24 (CI: 13–35) more reported chronic diseases in 100,000, respectively. The disease-specific analyses showed that a unit change in average monthly CO was associated with 329, 321, 232, and 129 more reported cases of diabetes, hypertension, stroke and myocardial infarction, and asthma in 100,000, respectively. The measured associations were greater in samples with older individuals. Also, a unit change in average monthly O3 was associated with 21 (in 100,000) more reported cases of asthma. The multi-pollutant analyses confirmed the results from single-pollutant analyses. The supplementary analyses showed that a one-unit decrease in monthly CO level could have been associated with about 208 (CI: 147–275) years of life gained or 15.195 (CI: 10.296–20.094) thousand US dollars (USD) in life-time labor market income gained per 100,000 30-plus-year-old Tehranis.


1989 ◽  
Vol 19 (6) ◽  
pp. 773-782 ◽  
Author(s):  
Michel A. Campagna ◽  
Hank A. Margolis

Black spruce seedlings (Piceamariana Mill.) were exposed to either elevated (1000 ppm) or ambient (340 ppm) atmospheric CO2 levels at different stages of seedling development over a winter greenhouse production cycle. Seedlings germinated in early February and were placed in CO2 chambers for either 3 or 6 weeks during March, April, May, or August. Total seedling biomass increased under high CO2 conditions for the March, April, and May stages of development, but showed no significant response in August. The greater part of the CO2 response occurred during the second 3 weeks of exposure in March and April but during the first 3 weeks of exposure in May. In September, those seedlings exposed to CO2 in April and May had 30 and 14%, respectively, greater biomass than control seedlings, but seedlings from the other stages of development no longer had significant differences remaining from the CO2 treatment. This suggests that it could be very efficient to give a short well-timed CO2 pulse at the beginning of the production cycle in hopes of producing a size difference that is maintained throughout the remainder of the greenhouse production cycle under ambient levels of CO2. Short-term exposure to elevated CO2 also increased the ratio of shoot dry weight to total height for the March, April, and May stages of development. The ratio of total nonstructural carbohydrates to free amino acids was negatively correlated (r2 = 0.98) with the allocation of new growth between shoots and roots as measured by the allocation coefficient, k (milligrams shoot growth per milligrams root growth). As seedlings developed along their seasonal growth cycle, ratios of total nonstructural carbohydrates to free amino acids increased and the values for k decreased. The effect of CO2 enrichment on these two factors is discussed. Monitoring total nonstructural carbohydrate and free amino acid concentrations in foliage could have potential as a method to predict the percentage of carbon allocated to root systems of entire forest stands as well as of individual tree seedlings.


Euphytica ◽  
2018 ◽  
Vol 214 (10) ◽  
Author(s):  
Junyang Huang ◽  
Meng Yan ◽  
Xiaoyan Zhu ◽  
Ting Zhang ◽  
WenQiang Shen ◽  
...  

1994 ◽  
Vol 47 (6) ◽  
pp. 481 ◽  
Author(s):  
John R. Lacey ◽  
Kathrin M. Olson-Rutz ◽  
Marshall R. Haferkamp ◽  
Gregory A. Kennett

2016 ◽  
Vol 15 (9) ◽  
pp. 1944-1954 ◽  
Author(s):  
Zhong-xian LIU ◽  
Yu CUI ◽  
Zhong-wei WANG ◽  
Yuan-hua XIE ◽  
Xian-chun SANG ◽  
...  

2020 ◽  
Vol 19 (9) ◽  
pp. 2150-2164
Author(s):  
Mao-di ZHU ◽  
Xin-long CHEN ◽  
Xiao-yan ZHU ◽  
Ya-di XING ◽  
Dan DU ◽  
...  

2019 ◽  
Vol 61 (3) ◽  
pp. 644-658 ◽  
Author(s):  
Zewen Wen ◽  
Yuanyuan Mei ◽  
Jie Zhou ◽  
Yanjiao Cui ◽  
Dan Wang ◽  
...  

Abstract The involvement of SMALL AUXIN-UP RNA (SAUR) proteins in leaf senescence has been more and more acknowledged, but the detailed mechanisms remain unclear. In the present study, we performed yeast two-hybrid assays and identified SAUR49 as an interactor of SENESCENCE SUPPRESSED PROTEIN PHOSPHATASE (SSPP), which is a PP2C protein phosphatase that negatively regulates Arabidopsis leaf senescence by suppressing the leucine-rich repeat receptor-like protein kinase SENESCENCE-ASSOCIATED RECEPTOR-LIKE KINASE (SARK), as reported previously by our group. The interaction between SAUR49 and SSPP was further confirmed in planta. Functional characterization revealed that SAUR49 is a positive regulator of leaf senescence. The accumulation level of SAUR49 protein increased during natural leaf senescence in Arabidopsis. The transcript level of SAUR49 was upregulated during SARK-induced premature leaf senescence but downregulated during SSPP-mediated delayed leaf senescence. Overexpression of SAUR49 significantly accelerated both natural and dark-induced leaf senescence in Arabidopsis. More importantly, SAUR49 overexpression completely reversed SSPP-induced delayed leaf senescence. In addition, overexpression of SAUR49 reversed the decreased plasma membrane H+-ATPase activity mediated by SSPP. Taken together, the results showed that SAUR49 functions in accelerating the leaf senescence process via the activation of SARK-mediated leaf senescence signaling by suppressing SSPP. We further identified four other SSPP-interacting SAURs, SAUR30, SAUR39, SAUR41 and SAUR72, that may act redundantly with SAUR49 in regulating leaf senescence. All these observations indicated that certain members of the SAUR family may serve as an important hub that integrates various hormonal and environmental signals with senescence signals in Arabidopsis.


Sign in / Sign up

Export Citation Format

Share Document