Plant-Growth Promoting Microbes Change the Photosynthetic Response to Light Quality in Spinach

Abstract

In this study, the combined effect of plant growth under different light quality and the application of plant-growth-promoting microbes (PGPM) was considered on spinach (Spinacia oleracea L.) to assess the influence of these factors on the photosynthetic performance. To pursue this goal, spinach plants were grown in a growth chamber at two different light quality regimes, full-spectrum white light (W) and red-blue light (RB), with (I) or without (NI) PGPM-based inoculants. Photosynthesis-light response curves (LRC) and photosynthesis-CO2 response curves (CRC) were performed for the four growth conditions (W-NI, RB-NI, W-I, and RB-I). At each step of LRC and CRC, net photosynthesis (PN), stomatal conductance (gs), Ci/Ca ratio, water use efficiency (WUEi), and fluorescence indexes were calculated. Moreover, parameters derived from the fitting of LRC, such as light-saturated net photosynthesis (PNmax), apparent light efficiency (Qpp), and dark respiration (Rd), as well as the Rubisco large subunit amount, were also determined. In not-inoculated plants, the growth under RB- regime improved PN compared to W-light because it increased stomatal conductance and favored the Rubisco synthesis. Furthermore, the RB regime also stimulates the processes of light conversion into chemical energy through chloroplasts, as indicated by the higher values of Qpp and PNmax in RB compared to W plants. On the contrary, in inoculated plants, the PN enhancement was significantly higher in W (30%) than in RB plants (17%), which showed the highest Rubisco content among all treatments. Our results indicate that the plant-growth-promoting microbes alter the photosynthetic response to light quality. This issue must be considered when PGPMs are used to improve plant growth performance in a controlled environment using artificial lighting.

Bacteriophage-mediated biosynthesis of MnO2NPs and MgONPs and their role in the protection of plants from bacterial pathogens

“…The Fv/Fm ratio was approximately between 0.80 and 0.82. It has been reported that the photosynthetic efficacy of plants reduces when they are exposed to stress conditions such as toxicity (Zhao et al, 2007;Santos et al, 2023;Vitale et al, 2023). Hence, the result of the chlorophyll fluorescence revealed that treatment with MgONPs and MnO 2 NPs positively enhanced the chlorophyll fluorescence parameters of Arabidopsis without toxic effects on the plants.…”

Agricultural Jiaosu Enhances the Stress Resistance of Pak Choi (Brassica rapa L. subsp. chinensis) by Recruiting Beneficial Rhizosphere Bacteria and Altering Metabolic Pathways

“…Exogenous reactive oxygen species (ROS) scrubbers, such as paclobutrazol (PP333), brassinosteroids (BR-120), and complex alcohols, can effectively mitigate waterlog damage; however, these measures have some limitations in the field [22]. Several studies have been conducted in recent years to improve plant stress resistance by inoculating beneficial microorganisms (BMs), typically plant-growth-promoting rhizobacteria, in plants [23][24][25]. Additionally, the inoculation of Ochrobactrum cytisi IPA7.2 induces salinity and drought-resistance in plants and helps them recover following stress [26].…”