Chlorophyll changes, photosynthesis, and ultrastructure of chloroplasts in Albugo candida induced "green islands" on detached Brassica juncea cotyledons

1968 ◽  
Vol 46 (10) ◽  
pp. 1229-1234 ◽  
Author(s):  
Howard Harding ◽  
Paul H. Williams ◽  
Sharon S. McNabola
Keyword(s):  
Chlorophyll Content ◽  
Brassica Juncea ◽  
Photosynthetic Activity ◽  
Photosynthetic Capacity ◽  
Soluble Fraction ◽  
Albugo Candida ◽  
Chlorophylls A And B ◽  
Stroma Lamellae ◽  
Green Island

Brassica juncea cotyledons were detached from the plant 3 days after inoculation with Albugo candida. Changes in chlorophyll content of infected and noninfected tissue were determined over a 4-day period, during which time distinct "green islands" developed. Following incubation with glycine-2-14C in the light, radioactivity was detected in chlorophylls a and b of both infected and noninfected tissue. Both infected and noninfected tissue fixed 14CO2 in the light during the 4 days after detachment. Most of the incorporated activity was in the 70% ethanol-soluble fraction. At 4 days after detachment, "green islands" fixed 5 times more 14CO2 in the light than noninfected tissue while both types of tissue fixed about the same amount in the dark. Photosynthesis per mole of chlorophyll fell at the same rate in "green island" and noninfected tissue. The maintenance of chlorophyll and continued photosynthetic activity in "green islands" paralleled delayed chloroplast breakdown. "Green island" chloroplasts still had intact grana and relatively small osmiophilic globules 96 h after detachment. In noninfected tissue, grana began to break down and osmiophilic globules increased in size 48 h after detachment. At 96 h after detachment, little grana structure remained and chloroplasts contained greatly enlarged osmiophilic globules interspersed with strands of stroma lamellae. Tissue treated with kinetin responded in essentially the same way as "green island" tissue. Chlorophyll content and photosynthetic capacity were maintained and chloroplast breakdown was delayed.

scholarly journals Improvement of the photosynthetic activity of Moldavian dragonhead (Dracocephalum moldavica L.) through foliar application of a nitrophenolate–based biostimulant

2018 ◽  
Vol 10 ◽  
pp. 01009
Author(s):  
Sławomir Kocira ◽  
Agnieszka Sujak ◽  
Tomasz Oniszczuk ◽  
Agnieszka Szparaga ◽  
Mariusz Szymanek ◽  
...  
Keyword(s):  
Chlorophyll Content ◽  
Photosynthetic Activity ◽  
Foliar Application ◽  
Positive Impact ◽  
Abiotic Stress Tolerance ◽  
Photosynthetic Apparatus ◽  
Nutrient Content ◽  
Physiological Processes ◽  
Naturally Occurring ◽  
Reported Study

Application of biostimulants instigates many physiological processes that enhance nutrition efficiency, abiotic stress tolerance, and quality traits of crops, regardless of their nutrient content. One of such preparations is Atonik which contains nitrophenol compounds naturally occurring in plant cells. Several studies have confirmed its beneficial effect on the growth, development, and improved metabolic activity of plants. Therefore, it seems advisable to investigate the effect of Atonik preparation on the photosynthetic activity of Moldavian dragonhead (Dracocephalum moldavica L.). The reported study was carried out in 2014 in Perespa, Poland. Over the growing season, Atonik was foliar-applied at a dose of 0.3 L/ha (0.1%) and 0.6 L/ha (0.2%) by single and double spraying of plants. Chlorophyll content and nitrogen status (N) were estimated by a Chlorophyll Meter SPAD-502 Plus. The foliar application of Atonik was found to improve the efficiency of the photosynthetic apparatus and chlorophyll content in the leaves of Dracocephalum moldavica plants, but the results were dependent on biostimulant concentration and number of its applications, and on the date of measurement. To conclude, Atonik is an environmental-friendly preparation which has a positive impact on the metabolic processes of plants.

scholarly journals Variations of Chlorophyll Content at Abies alba and Nepeta pannonica Species According to Phenophase and Harvesting Area

2019 ◽  
Vol 52 (1) ◽  
pp. 74-78
Author(s):  
S. Buhăianu ◽  
Doina Carmen Jităreanu
Keyword(s):  
Chlorophyll Content ◽  
Chlorophyll A ◽  
Photosynthetic Pigments ◽  
Photosynthetic Activity ◽  
Abies Alba ◽  
Chlorophyll B ◽  
Green Color ◽  
Yellow Coloration ◽  
Chlorophyll A And B ◽  
Chlorophyll A Content

Abstract Chlorophylls from plants are photosynthetic pigments. Their quantity offers valuable informations about photosynthetic activity, growing and developing of plants. Photosynthetic pigments decrease quantitatively during senescence process or in stress conditions. The present study has been realized in laboratory conditions with material harvested from spontaneous flora. The purpose of this research was the investigation of variations of chlorophyll content from samples of biological material collected from Nepeta pannonica L. and Abies alba Mill. plants, from Câmpulung Moldovenesc and Cacica areas, Suceava county, Romania. The targeted phenophases were growth and flowering. There were realized acetonic extracts from samples for spectrophotometric determinations. Obtained data were processed to estabilish chlorophyll a and b content. There were observed that at Abies alba species, from both locations, the chlorophyll a content grew during flowering phenophase, while the chlorophyll b content had little variations. At Nepeta pannonica species, the chlorophyll a and b content decreased visibly during the flowering, due to stress. Leaves of plants from this species presented a intense green color in the growing phenophase, while during flowering phenophase they had a purple or yellow coloration. Obtained results revealed a different dynamics of chlorophyll content at studied species.

Expression and relationships of resistance to white rust (Albugo candida) at cotyledonary, seedling, and flowering stages in Brassica juncea germplasm from Australia, China, and India

2007 ◽  
Vol 58 (3) ◽  
pp. 259 ◽  
Author(s):  
C. X. Li ◽  
K. Sivasithamparam ◽  
G. Walton ◽  
P. Salisbury ◽  
W. Burton ◽  
...  
Keyword(s):  
Plant Growth ◽  
Brassica Juncea ◽  
Environmental Conditions ◽  
Host Resistance ◽  
Growth Stages ◽  
Sources Of Resistance ◽  
Albugo Candida ◽  
White Rust ◽  
China And India ◽  
Canola Quality

White rust (Albugo candida) is a highly destructive disease of oilseed Brassicas such as Brassica juncea and B. rapa. Most commercial B. juncea or B. rapa varieties are highly susceptible and yield losses from combined infection of leaves and inflorescences can be up to 20% or 60% in Australia and India, respectively. In Australia, canola-quality B. juncea has been developed to extend oilseed Brassica production into lower rainfall areas, with the first commercial B. juncea canola-quality variety planned for release in 2006. It is essential to identify useful sources of host resistance in B. juncea as breeding and/or selection of material for resistance is the most cost-effective method of delivering control for farmers. Three experiments were undertaken under controlled-environmental conditions to identify the best methods of characterising host resistance and to identify sources of resistance in B. juncea germplasm from Australia, China, and India. Forty-four B. juncea genotypes, viz. 22 from India, 12 from Australia, and 10 from China, were tested. Four Chinese genotypes (CBJ-001, CBJ-002, CBJ-003, CBJ-004) and one Australian genotype (JR049) consistently showed high resistance to A. candida across the different plant growth stages against a pathotype prevailing in Australia. Similarly, the most susceptible genotypes (viz. Indian genotypes RH781, RL1359, RH819) were extremely susceptible irrespective of the plant growth stage. Overall, although disease severity on cotyledons and leaves at the different growth stages was significantly and positively correlated, there was, however, no significant correlation between the number of stagheads and any of the other disease parameters measured. Our study demonstrates that controlled-environmental conditions are suitable for rapid identification of resistant genotypes and that genotypes with high levels of resistance can be reliably identified at the cotyledonary, seedling, or flowering stages.

Photosynthetic Activity of Leaves of Pinus radiata and Nothofagus fusca After 1 Year of Growth at Elevated CO2

1996 ◽  
Vol 23 (5) ◽  
pp. 623 ◽  
Author(s):  
KP Hogan ◽  
D Whitehead ◽  
J Kallarackal ◽  
JG Buwalda ◽  
J Meekings ◽  
...  
Keyword(s):  
Partial Pressure ◽  
Pinus Radiata ◽  
Photosynthetic Activity ◽  
Photosynthetic Capacity ◽  
Radiata Pine ◽  
Rubisco Activity ◽  
Co2 Partial Pressure ◽  
Partial Pressures ◽  
The Difference ◽  
Triose Phosphate Utilisation

Radiata pine (Pinus radiata D.Don) and red beech (Nothofagus fusca (Hook. f.) Oerst.) were grown for over 1 year at elevated (ELEV, 64 Pa) and ambient (AMB, 38 Pa) CO2 partial pressure in open-top chambers. Springtime measurements of overwintering leaves showed that light- and CO2-saturated photosynthetic rates (Amax) of pine leaves were similar for the two treatments (AMB: 6.7 � 1.08 μmol m-2 s-1, mean � 1 s.e.; ELEV: 6.6 � 0.47) but, for beech leaves, Amax was greater for AMB plants (8.8 � 0.90 μmol m-2 s-1) than for ELEV plants (6.10 � 0.71). Summertime measurements of leaves grown that spring showed that for pine, Amax was similar in the two CO2 treatments (AMB 14.9 μmol m-2 s-1 � 0.80; ELEV: 13.5 � 1.9) while, for beech, Amax was higher in AMB plants (21.0 � 1.1) than in ELEV plants (17.2 � 1.9), although the difference was not statistically significant. These results indicate downregulation of photosynthetic capacity of beech but not pine. Vcmax did not differ between treatments within species, suggesting that there was no acclimation of rubisco activity. Triose phosphate utilisation limitation may have contributed to the downregulation of Amax in beech. For pine, photosynthesis at treatment CO2 partial pressures was greater in ELEV plants in both spring and summer. For beech measured at treatment CO2 partial pressures, photosynthesis was greater in ELEV plants in summer, but was similar between treatments in the springtime.

scholarly journals Enhanced Relative Electron Transport Rate Contributes to Increased Photosynthetic Capacity in Autotetraploid Pak Choi

2020 ◽  
Vol 61 (4) ◽  
pp. 761-774 ◽  
Author(s):  
Changwei Zhang ◽  
Huiyu Wang ◽  
Yuanyuan Xu ◽  
Shuning Zhang ◽  
Jianjun Wang ◽  
...  
Keyword(s):  
Electron Transport ◽  
Powdery Mildew Resistance ◽  
Photosynthetic Activity ◽  
Photosynthetic Capacity ◽  
Electron Transport Rate ◽  
Ectopic Expression ◽  
Transport Rate ◽  
Pak Choi ◽  
Relative Electron Transport Rate ◽  
Relative Electron

Abstract Autopolyploids often show growth advantages over their diploid progenitors because of their increased photosynthetic activity; however, the underlying molecular basis of such mechanism remains elusive. In this study, we aimed to characterize autotetraploid pak choi (Brassica rapa ssp. chinensis) at the physiological, cellular and molecular levels. Autotetraploid pak choi has thicker leaves than its diploid counterparts, with relatively larger intercellular spaces and cell size and greater grana thylakoid height. Photosynthetic data showed that the relative electron transport rate (rETR) was markedly higher in autotetraploid than in diploid pak choi. Transcriptomic data revealed that the expressions of genes involved in ‘photosynthesis’ biological process and ‘thylakoids’ cellular component were mainly regulated in autotetraploids. Overall, our findings suggested that the increased rETR in the thylakoids contributed to the increased photosynthetic capacity of autotetraploid leaves. Furthermore, we found that the enhanced rETR is associated with increased BrPetC expression, which is likely altered by histone modification. The ectopic expression of BrPetC in Arabidopsis thaliana led to increased rETR and biomass, which were decreased in BrPetC-silenced pak choi. Autotetraploid pak choi also shows altered hormone levels, which was likely responsible for the increased drought resistance and the impaired powdery mildew resistance of this lineage. Our findings further our understanding on how autotetraploidy provides growth advantages to plants.

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