Comparative Analysis of Primary Photosynthetic Reactions Assessed by OJIP Kinetics in Three Brassica Crops after Drought and Recovery

Abstract

Plant drought tolerance depends on adaptations of the photosynthetic apparatus to changing environments triggered by water deficit. The seedlings of three Brassica crops differing in drought sensitivity, Brassica oleracea L. var. capitata—white cabbage, Brassica oleracea L. var. acephala—kale, and Brassica rapa L. var. pekinensis—Chinese cabbage, were exposed to drought by withholding water. Detailed insight into the photosynthetic machinery was carried out when the seedling reached a relative water content of about 45% and after re-watering by analyzing the OJIP kinetics. The key objective of this study was to find reliable parameters for distinguishing drought−tolerant and drought-sensitive varieties before permanent structural and functional changes in the photosynthetic apparatus occur. According to our findings, an increase in the total performance index (PItotal) and structure–function index (SFI), positive L and K bands, total driving forces (DDF), and drought resistance index (DRI) suggest drought tolerance. At the same time, susceptible varieties can be distinguished based on negative L and K bands, PItotal, SFI, and the density of reaction centers (RC/CS0). Kale proved to be the most tolerant, Chinese cabbage was moderately susceptible, and white cabbage showed high sensitivity to the investigated drought stress. The genetic variation revealed among the selected Brassica crops could be used in breeding programs and high-precision crop management.

Photosynthetic response of Chlamydomonas reinhardtii and Chlamydomonas sp. 1710 to zinc toxicity

“…Strikingly, although 5 mg/L slightly increased the ABS/RC and DIo/RC of C. reinhardtii , the TRo/RC remained largely unchanged ( Figure 6E ). This was consistent with previous studies ( Liu et al, 2021 ; Antunović Dunić et al, 2023 ), indicating that the energy dissipation process offsets excess energy and effectively protected the photosystem complex. However, the TRo/RC of C. reinhardtii increased from 1.3 to 1.53 when Zn concentration increased from 0 to 30 mg/L ( Figure 6E ), showing that the energy dissipation was insufficient.…”

“…1710 immediately increased at 24 h ( Figure 4D ), whereas Y(NO) and UQF(rel) were maintained ( Figures 4B , F ). The results of C. reinhardtii aligned with previous studies, indicating increased unregulated energy dissipation under abiotic stress ( Antunović Dunić et al, 2023 ; Pluciński et al, 2023 ). In contrast, Chlamydomonas sp.…”

“…1710, 300 and 600 mg/L were more closely correlated with the aforementioned parameters ( Figure 8B ). Consistent with previous studies, these parameters were identified as the main indicators of severe Zn stress ( Almeida et al, 2021 ; Antunović Dunić et al, 2023 ).…”

Improving strawberry plant resilience to salinity and alkalinity through the use of diverse spectra of supplemental lighting

“…Our research indicates that salinity, alkalinity, and their combined effects contribute to reduced electron absorption and trapping within the electron transport chain. This leads to an elevated ABS/RC and TR 0 /RC across all stress conditions, primarily attributable to the loss of active reaction centers [ 37 ]. The water-splitting complex (OEC) is a crucial and sensitive part of the electron transport chain of the photosynthetic apparatus [ 38 ].…”

A non-invasive method to predict drought survival in Arabidopsis using quantum yield under light conditions

“…In this sense, the measurement of photosynthetic parameters related to chlorophyll a uorescence has been employed to estimate the impact of drought on photosynthesis in a non-invasive way. From these parameters, the most commonly used are 1) quantum yield (QY), which can be estimated under dark (maximum QY or Fv/Fm) and light conditions (operational QY or Fv'/Fm'); 2) rapid polyphasic chlorophyll a uorescence transient (OJIP), and 3) non-photochemical quenching (NPQ) [27][28][29][30][31]. Speci cally, QY represents the e ciency of photosystem II to employ the absorbed photon energy in photochemistry [32,33], and the maximum QY, also called Fv/Fm, has been previously applied to monitor the viability of plants after severe drought to determine the time of death [28].…”