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Grape rain-shelter cultivation is a widely employed practice in China. At present, the most commonly used rain shelter film materials are polyvinyl chloride (PVC), polyethylene (PE), ethylene-vinyl acetate copolymer (EVA), and polyolefin (PO). Coverlys TF150® is a woven fabric with an internal antifoggy PE coating that has not yet been popularized as a rain shelter film for grapes in China. To investigate the effects of Coverlys TF150® on grapes, we measured the microdomain environment, leaf development, and photosynthetic characteristics of 'Miguang' (Vitis vinifera × V. labrusca) under rain-shelter cultivation and performed transcriptome analysis. The results showed that Coverlys TF150® significantly reduced (p < 0.05) the light intensity, temperature, and humidity compared with PO film, increased the chlorophyll content and leaf thickness (particularly palisade tissue thickness), and increased stomatal density and stomatal opening from 10:00 to 14:00. Coverlys TF150® was observed to improve the maximum efficiency of photosystem II (Fv/Fm), photochemical quenching (qP), the electron transfer rate (ETR), and the actual photochemical efficiency (ΦPSII) from 10:00 to 14:00. Moreover, the net photosynthetic rate (Pn), intercellular CO2 concentration (Ci), stomatal conductance (Gs), and transpiration rate (Tr) of grape leaves significantly increased (p < 0.05) from 10:00 to 14:00. RNA-Seq analysis of the grape leaves at 8:00, 10:00, and 12:00 revealed 1388, 1562, and 1436 differential genes at these points in time, respectively. KEGG enrichment analysis showed the occurrence of protein processing in the endoplasmic reticulum. Plant hormone signal transduction and plant-pathogen interaction were identified as the metabolic pathways with the highest differential gene expression enrichment. The psbA encoding D1 protein was significantly up-regulated in both CO10vsPO10 and CO12vsPO12, while the sHSPs family genes were significantly down-regulated in all time periods, and thus may play an important role in the maintenance of the photosystem II (PSII) activity in grape leaves under Coverlys TF150®. Compared with PO film, the PSI-related gene psaB was up-regulated, indicating the ability of Coverlys TF150® to better maintain PSI activity. Compared with PO film, the abolic acid receptacle-associated gene PYL1 was down-regulated at all time periods under the Coverlys TF150® treatment, while PP2C47 was significantly up-regulated in CO10vsPO10 and CO12vsPO12, inducing stomatal closure. The results reveal that Coverlys TF150® alleviates the stress of high temperature and strong light compared with PO film, improves the photosynthetic capacity of grape leaves, and reduces the midday depression of photosynthesis. [ABSTRACT FROM AUTHOR]

Poplar is an important fast-growing tree, and its photosynthetic capacity directly affects its vegetative growth. Stomatal density is closely related to photosynthetic capacity and growth characteristics in plants. Here, we isolated PagSTOMAGEN from the hybrid poplar (Populus alba × Populus glandulosa) clone 84K and investigated its biological function in vegetative growth. PagSTOMAGEN was expressed predominantly in young tissues and localized in the plasma membrane. Compared with wild-type 84K poplars, PagSTOMAGEN-overexpressing plants displayed an increased plant height, leaf area, internode number, basal diameter, biomass, IAA content, IPR content, and stomatal density. Higher stomatal density improved the net photosynthetic rate, stomatal conductance, intercellular CO2 concentration, and transpiration rate in transgenic poplar. The differential expression of genes related to stomatal development showed a diverged influence of PagSTOMAGEN at different stages of stomatal development. Finally, transcriptomic analysis showed that PagSTOMAGEN affected vegetative growth by affecting the expression of photosynthesis and plant hormone-related genes (such as SAUR75, PQL2, PSBX, ERF1, GNC, GRF5, and ARF11). Taken together, our data indicate that PagSTOMAGEN could positively regulate stomatal density and increase the photosynthetic rate and plant hormone content, thereby promoting vegetative growth in poplar. Our study is of great significance for understanding the relationship between stoma, photosynthesis, and yield breeding in poplar. [ABSTRACT FROM AUTHOR]

The photosynthetic rate increases under high-N supply, resulting in a large CO2 transport conductance in mesophyll cells. It is less known that water movement is affected by nitrogen supply in leaves. This study investigated whether the expression of aquaporin and water transport were affected by low-N (0.7 mM) and high-N (7 mM) concentrations in the hydroponic culture of four rice varieties: (1) Shanyou 63 (SY63), a hybrid variant of the indica species; (2) Yangdao 6 (YD6), a variant of indica species; (3) Zhendao 11 (ZD11), a hybrid variant of japonica species; and (4) Jiuyou 418 (JY418), another hybrid of the japonica species. Both the photosynthetic and transpiration rate were increased by the high-N supply in the four varieties. The expressions of aquaporins, plasma membrane intrinsic proteins (PIPs), and tonoplast membrane intrinsic protein (TIP) were higher in high-N than low-N leaves, except in SY63. Leaf hydraulic conductance (Kleaf) was lower in high-N than low-N leaves in SY63, while Kleaf increased under high-N supply in the YD6 variant. Negative correlations were observed between the expression of aquaporin and the transpiration rate in different varieties. Moreover, there was a significant negative correlation between transpiration rate and intercellular air space. In conclusion, the change in expression of aquaporins could affect Kleaf and transpiration. A feedback effect of transpiration would regulate aquaporin expression. The present results imply a coordination of gas exchange with leaf hydraulic conductance. [ABSTRACT FROM AUTHOR]

Arabidopsis thaliana SYNAPTOTAGMIN 1 (AtSYT1) was shown to be involved in responses to different environmental and biotic stresses. We investigated gas exchange and chlorophyll a fluorescence in Arabidopsis wild-type (WT, ecotype Col-0) and atsyt1 mutant plants irrigated for 48 h with 150 mM NaCl. We found that salt stress significantly decreases net photosynthetic assimilation, effective photochemical quantum yield of photosystem II (ΦPSII), stomatal conductance and transpiration rate in both genotypes. Salt stress has a more severe impact on atsyt1 plants with increasing effect at higher illumination. Dark respiration, photochemical quenching (qP), non-photochemical quenching and ΦPSII measured at 750 µmol m−2 s−1 photosynthetic photon flux density were significantly affected by salt in both genotypes. However, differences between mutant and WT plants were recorded only for qP and ΦPSII. Decreased photosynthetic efficiency in atsyt1 under salt stress was accompanied by reduced chlorophyll and carotenoid and increased flavonol content in atsyt1 leaves. No differences in the abundance of key proteins participating in photosynthesis (except PsaC and PsbQ) and chlorophyll biosynthesis were found regardless of genotype or salt treatment. Microscopic analysis showed that irrigating plants with salt caused a partial closure of the stomata, and this effect was more pronounced in the mutant than in WT plants. The localization pattern of AtSYT1 was also altered by salt stress. [ABSTRACT FROM AUTHOR]

Photosynthesis is the primary life process in nature, and how to improve photosynthetic capacity under abiotic stresses is crucial to carbon fixation and plant productivity. As a multi-functional tree species, the leaves of Cyclocarya paliurus possess antihypertensive and hypoglycemic activities. However, the regulatory mechanism involved in the photosynthetic process of C. paliurus exposed to salinity has not yet been elucidated. In this study, the photosynthetic characteristics of C. paliurus seedlings, such as photosynthetic rate (Pn), stomatal conductance (Gs), and electron transfer rate (ETR), were investigated under different salt concentrations, while the metabolome and transcriptome analyses were conducted to unravel its molecular regulatory mechanisms. Salt stress not only significantly affected photosynthetic characteristics of C. paliurus seedlings, but also severely modified the abundance of metabolites (such as fumaric acid, sedoheptulose-7-phosphate, d-fructose-1,6-bisphosphate, and 3-phospho-d-glyceroyl phosphate) involved in central carbon metabolism, and the expression of photosynthetic genes. Through the co-expression network analysis, a total of 27 transcription factors (including ERFs, IDD, DOF, MYB, RAP) were identified to regulate photosynthetic genes under salt stress. Our findings preliminarily clarify the molecular regulatory network involved in the photosynthetic process of C. paliurus under salt stress and would drive progress in improving the photosynthetic capacity and productivity of C. paliurus by molecular technology. [ABSTRACT FROM AUTHOR]

Grass pea (Lathyrus sativus) is a leguminous plant of outstanding tolerance to abiotic stress. The aim of the presented study was to describe the mechanism of grass pea (Lathyrus sativus L.) photosynthetic apparatus acclimatisation strategies to salinity stress. The seedlings were cultivated in a hydroponic system in media containing various concentrations of NaCl (0, 50, and 100 mM), imitating none, moderate, and severe salinity, respectively, for three weeks. In order to characterise the function and structure of the photosynthetic apparatus, Chl a fluorescence, gas exchange measurements, proteome analysis, and Fourier-transform infrared spectroscopy (FT-IR) analysis were done inter alia. Significant differences in the response of the leaf and stem photosynthetic apparatus to severe salt stress were observed. Leaves became the place of harmful ion (Na+) accumulation, and the efficiency of their carboxylation decreased sharply. In turn, in stems, the reconstruction of the photosynthetic apparatus (antenna and photosystem complexes) activated alternative electron transport pathways, leading to effective ATP synthesis, which is required for the efficient translocation of Na+ to leaves. These changes enabled efficient stem carboxylation and made them the main source of assimilates. The observed changes indicate the high plasticity of grass pea photosynthetic apparatus, providing an effective mechanism of tolerance to salinity stress. [ABSTRACT FROM AUTHOR]

Impact of photosynthetic and antioxidant capacities on drought tolerance of two closely related forage grasses, Festuca arundinacea and Festuca glaucescens, was deciphered. Within each species, two genotypes distinct in drought tolerance were subjected to a short-term drought, followed by a subsequent re-watering. The studies were focused on: (i) analysis of plant physiological performance, including: water uptake, abscisic acid (ABA) content, membrane integrity, gas exchange, and relative water content in leaf tissue; (ii) analysis of plant photosynthetic capacity (chlorophyll fluorescence; gene expression, protein accumulation, and activity of selected enzymes of the Calvin cycle); and (iii) analysis of plant antioxidant capacity (reactive oxygen species (ROS) generation; gene expression, protein accumulation and activity of selected enzymes). Though, F. arundinacea and F. glaucescens revealed different strategies in water uptake, and partially also in ABA signaling, their physiological reactions to drought and further re-watering, were similar. On the other hand, performance of the Calvin cycle and antioxidant system differed between the analyzed species under drought and re-watering periods. A stable efficiency of the Calvin cycle in F. arundinacea was crucial to maintain a balanced network of ROS/redox signaling, and consequently drought tolerance. The antioxidant capacity influenced mostly tolerance to stress in F. glaucescens. [ABSTRACT FROM AUTHOR]

Light is one of the most important abiotic factors for most plants, which affects almost all growth and development stages. In this study, physiological indicators suggest that the application of exogenous Ca2+ improves photosynthesis and changes phytohormone levels. Under weak light, photosynthetic parameters of the net photosynthetic rate (PN), stomatal conductance (Gs), and transpiration rate (Tr) decreased; the antioxidation systems peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) reduced; the degrees of malondialdehyde (MDA), H2O2, and superoxide anion (O2−) free radical damage increased; while exogenous Ca2+ treatment was significantly improved. RNA-seq analysis indicated that a total of 13,640 differently expressed genes (DEGs) were identified and 97 key DEGs related to hormone, photosynthesis, and calcium regulation were differently transcribed. Gene ontology (GO) terms and Kyoto encyclopedia of genes and genomes (KEGG) pathway analyses, plant hormone signal transduction, photosynthesis, carbon metabolism, and phenylpropanoid biosynthesis were significantly enriched. Additionally, quantitative real-time PCR (qRT-PCR) analysis confirmed some of the key gene functions in response to Ca2+. Overall, these results provide novel insights into the complexity of Ca2+ to relieve injuries under weak light, and they are helpful for potato cultivation under weak light stress. [ABSTRACT FROM AUTHOR]