Structural and functional disorder in the photosynthetic apparatus of radish plants under magnesium deficiency

Abstract

Magnesium (Mg) is one of the significant macronutrients which is involved in the structural stabilisation of plant tissues and many enzymes such as PSII. The latter efficiency and performance were analysed, using chlorophyll (Chl) a fluorescence induction kinetics and microscopic images, to detect the changes in structure and function of photosynthetic apparatus of radish plants grown under Mg deficiency (Mgdef). Plants grown under Mgdef showed less PSII connectivity and fewer active primary electron acceptors (QA) oxidizing reaction centres than control plants. Confocal and electron microscopy analyses showed an increased amount of starch in chloroplasts, and 3,3ʹ-diaminobenzidine (DAB)-uptake method revealed higher H2O2 accumulation under Mgdef. Prominent changes in the Chl a fluorescence parameters such as dissipated energy flux per reaction centre (DIo/RC), relative variable fluorescence at 150 μs (Vl), and the sum of the partial driving forces for the events involved in OJIP fluorescence rise (DFabs) were observed under Mg deficiency. The latter also significantly affected some other parameters such as dissipated energy fluxes per cross-section (DIo/CSo), performance index for energy conservation from photons absorbed by PSII antenna until the reduction of PSI acceptors (PItotal), and relative variable fluorescence at 300 μs (Vk). This work emphasises the use of chlorophyll fluorescence in combination with microscopic and statistical analyses to diagnose the effects of nutrients deficiency stress on plants at an early stage of its development as demonstrated for the example of Mgdef. Due to the short growth period and simple cultivation conditions of radish plant we recommend it as a new standard (model) plant to study nutrients deficiency and changes in plant photosynthetic efficiency under stress conditions.

Special issue in honour of Prof. Reto J. Strasser - Structural and functional response of photosynthetic apparatus of radish plants to iron deficiency

“…Polyethylene pellets (PE), made from a synthetic resin, were used as root growth medium. Comparing to other growth substrates, it is characterized by a very low ion absorption capacity (innovative method by Cetner et al 2017, Samborska et al 2018. Radish seeds were germinated for 7 d and after that sprouts were moved into plastic multi-pot trays (48 seedlings per tray: 24 of 'Fluo HF1' and 24 of 'Suntella F1' cultivars) filled with PE.…”

“…During the recovery phase, while J and I peak disappeared, the peaks around K, H, and G were still visible on the differential curve after the addition of Fe, which indicated, among others, the slower recovery of PSI-end acceptors pool size. The detailed analyses of the shape of Chl a fluorescence combined with PCA analysis are very sensitive tools for early detection of environmental stress (Allakhverdiev 2011Cetner et al 2017, Samborska et al 2018). The PCA analysis and inspection of the Table 1 of temporal changes in ChlF parameters during controlstress-recovery sequence provided additional insight into the reaction of photosynthetic apparatus to iron deficiency in radish.…”

“…Chlorophyll (Chl) a fluorescence is a quick, reliable tool for in vivo assessment of bioenergetic status of plants (Baker 2008, Cetner et al 2017, Kalaji et al 2017a, Samborska et al 2018Bąba et al 2019). The changes in fluorescence signals are related, directly or indirectly, to various stages of photosynthetic light reactions: photolysis of water, reduction of photosynthetic machinery components, electron transport, generation of the pH gradient across thylakoid membranes, and ATP synthesis (Goltsev et al 2016, Kalaji et al 2017a.…”

Special issue in honour of Prof. Reto J. Strasser - Photosynthetic efficiency of two Platanus orientalis L. ecotypes exposed to moderately high temperature - JIP-test analysis

“…'Turnover number' N shows how many times QA is reduced from time 0 to tFM (Tsimilli-Michael and Strasser 2013, Kalaji et al 2017, Samborska et al 2018. In most of the leaves from both ecotypes, N had higher values after the treatment which corresponds to bigger PQ pool.…”

Special issue in honour of Prof. Reto J. Strasser - Analysis of K- and L-band appearance in OJIPs in Antarctic lichens in low and high temperature

“…The OJIP ChlF transients have been commonly used for studies of plant responses to a great variety of abiotic stressors (for reviews, see Kalaji et al 2016, Stirbet et al 2018. The studies include e.g., high light stress (Oukarroum and Strasser 2004), nitrogen deficiency (Cetner et al 2017, Samborska et al 2018, salinity (Dąbrowski et al 2016), water deficit, drought stress (Kiani et al 2008, Czyczyło-Mysza et al 2011, Wang et al 2012, Jedmowski et al 2014, Rapacz et al 2019, action of herbicides (Lazár et al 1997a(Lazár et al , 1998, and waterlogging (Bertholdsson et al 2015). The studies focused on temperature effects on OJIP shape and derived parameters have addressed both low (e.g., Fracheboud et al 1999, Rapacz et al 2015, Husičková et al 2019 and high (Pastenes andHorton 1996, Azam et al 2015) temperature.…”