Screening of tomato landraces for drought tolerance based on growth and chlorophyll fluorescence analyses

To investigate the effects of water withholding on 17 tomato (Solanum lycopersicum L.) landraces collected from different climatic zones of Iran and two commercial hybrids, the polyphasic OJIP fluorescence transient, relative water content (RWC), electrolyte leakage (EL) and vegetative growth parameters were analyzed. Duncan’s multiple range test (DMRT) for all the studied parameters and drought factor index (DFI) based on performance index on the absorption basis (PIabs) were used for screening the plants based on their tolerance to drought condition. Result showed that compared to the control plants, vegetative growth parameters, RWC, PIabs, relative maximal variable fluorescence (FM/F0), maximum quantum efficiency of PSII (FV/FM), quantum yield of electron transport (ΦE0) and electron transport flux per reaction center (RC) (ET0/RC) were decreased, whereas, EL, quantum yield of energy dissipation (ΦD0), specific energy fluxes per RC for energy absorption (ABS/RC) and dissipated energy flux (DI0/RC), which are closely related to the incidence of photoinhibition were increased in plants exposed to water withholding. DMRT and DFI screening results clearly categorized the landraces into three groups (tolerant, moderately sensitive and sensitive). Tolerant landraces showed less change for most of the measured parameters compared to sensitive and moderately sensitive landraces. We found that adapted landraces to dry climates had a higher tolerance to drought stress. Principal component analysis (PCA) revealed that FM/F0, FV/FM, ΦE0, ΦD0, PIabs, ABS/RC, ET0/RC and DI0/RC parameters are the most sensitive parameters for detection of impact of drought stress on tomato plants. In conclusion, the eight parameters have the potential to identify the drought injury in tomato seedlings.

Disentangling the photosynthesis performance in japonica rice during natural leaf senescence using OJIP fluorescence transient analysis

Rice undergoes leaf senescence accompanied with grain filling when the plants reach the end of their temporal niche, and a delay in leaf senescence ultimately improves the yield and quality of grain. To estimate the decline in photosynthesis during leaf senescence and to find an efficient and useful tool to identify rice genotypes with a longer duration of active photosynthesis, we examined PSII photosynthetic activity in the flag leaves of japonica rice Shennong265 (SN265) and Beigeng3 (BG3) during leaf senescence using chlorophyll a fluorescence kinetics. The results show that inhibition occurred in the electron transport chains, but the energetic connectivity of PSII units was not affected as dramatically during leaf senescence. PSII reaction centres (RCs) were transformed into ‘silent RCs,’ and the chlorophyll content decreased during leaf senescence. However the size of the ‘economic’ antennae increased. Further, the percentage of variation of the specific energy flux parameters can rationally be used to indicate leaf senescence from the perspective of energy balance. Although the performance indices were more sensitive than other functional and structural JIP-test parameters, they still did not serve as an indicator of crop yield.

Photochemical analysis for selection of stress tolerant plant

This electronic document is a “live” template and already defin This study was carried out to selection of abiotic stress tolerant plant species of sixty-eight plant species at Hantaek Botanical Garden in Korean using photochemical analysis. Many abiotic stresses have led to a decline in agricultural productivity and the disappearance of ecologically important plant species. Chlorophyll a fluorescence is a powerful tool to measure environmental stress response in plants. The polyphasic OJIP fluorescence transient was used to evaluate the behavior of Photosystem II (PSII) and Photosystem I (PSI) during the entire experiment period (from July to August). The photochemical reaction showed higher maximal chlorophyll fluorescence (Fp) intensity under heat and wet stress in forty-one plant species. In twenty seven plant species, chlorophyll fluorescence intensity showed a significant decrease. In wet stress, the fluorescence parameters related with electron transport on PSII and PSI reduced over twenty percent. As a result of the identifying under heat and wet stress, energy dissipation per reaction center (DIo/RC) was heavily affected. It was clearly indicated that the connectivity between photosynthetic PSII and PSI, i.e. electron transport, was far effective in the selection of stress tolerant plants.

Use of O-J-I-P Chlorophyll Fluorescence Transients to Probe Multiple Effects of UV-C Radiation on the Photosynthetic Apparatus of Euglena

Although the kinetic chlorophyll fluorescence signals are rich in information, most of the chlorophyll fluorescence related studies deal only with the quantum yield of primary photochemistry (Fv/Fm). JIP-test based OJIP fluorescence transient analysis is relatively a new technique to investigate the environmental stress responses of photosynthetic organisms. In the present study, the deleterious effects of ultraviolet (UV) radiation on the photosynthetic machinery were probed by the JIP-test in Euglena, one of the most potent organisms for the future space stations. The cells were exposed to a series of UV-C doses and immediately after exposure, survival percentage was determined with Neutral Red staining, and the chlorophyll fluorescence was measured using AquaPen AP-C 100 fluorometer. Resultant OJIP transients were analyzed according to JIP-test, and several functional and structural parameters were derived to explain the PSII behavior. Results indicated that the UV-C induced inhibition of electron transport is severely affected due to higher sensitivity of dark reactions after QA -, represented as ψo, the electron transfer probability, than of the light dependent reactions, represented as φPo, the trapping probability. The performance index (PIABS) of PSII, which is a combination of the indices of three independent parameters, decreased markedly in exponential manner in response to UVC. Results illustrate the advantage of using a number of fluorescent parameters over the use of one parameter, often the Fv/Fm. DOI: http://dx.doi.org/10.3126/ijasbt.v2i4.10510 Int J Appl Sci Biotechnol, Vol. 2(4): 553-558