ABSTRACT
The negative impacts of climate change on native forest ecosystems have created challenging conditions for the sustainability of natural forest regeneration. These challenges arise primarily from abiotic stresses that affect the early stages of forest tree development. While there is extensive evidence on the diversity of juvenile microbial symbioses in agricultural and fruit crops, there is a notable lack of reports on native forest plants. This review aims to summarize the critical studies conducted on the diversity of juvenile plant-microbe interactions in forest plants and to highlight the main benefits of beneficial microorganisms in overcoming environmental stresses such as drought, high and low temperatures, metal(loid) toxicity, nutrient deficiency, and salinity. The reviewed studies have consistently demonstrated the positive effects of juvenile plant-microbiota interactions and have highlighted the potential beneficial attributes to improve plantlet development. In addition, this review discusses the beneficial attributes of managing juvenile plant-microbiota symbiosis in the context of native forest restoration, including its impact on plant responses to phytopathogens, promotion of nutrient uptake, facilitation of seedling adaptation, resource exchange through shared hyphal networks, stimulation of native soil microbial communities, and modulation of gene and protein expression to enhance adaptation to adverse environmental conditions.
ABSTRACT
Salicylic acid (SA) application is a promising agronomic tool. However, studies under field conditions are required, to confirm the potential benefits of SA. Thus, SA application was evaluated under field conditions for its effect on abscisic acid levels, antioxidant related-parameters, fruit quality, and yield in Aristotelia chilensis subjected to different levels of irrigation. During two growing seasons, three-year-old plants under field conditions were subjected to full irrigation (FI: 100% of reference evapotranspiration (ETo), and deficit irrigation (DI: 60% ETo). During each growth season, a single application of 0.5 mM SA was performed at fruit color change by spraying fruits and leaves of both irrigation treatments. The results showed that DI plants experienced moderate water stress (-1.3 MPa), which increased ABA levels and oxidative stress in the leaves. The SA application facilitated the recovery of all physiological parameters under the DI condition, increasing fruit fresh weight by 44%, with a 27% increase in fruit dry weight, a 1 mm increase in equatorial diameter, a 27% improvement in yield per plant and a 27% increase in total yield, with lesser oxidative stress and tissue ABA levels in leaves. Also, SA application significantly increased (by about 10%) the values of fruit trait variables such as soluble solids, total phenols, and antioxidant activity, with the exceptions of titratable acidity and total anthocyanins, which did not vary. The results demonstrated that SA application might be used as an agronomic strategy to improve fruit yield and quality, representing a saving of 40% regarding water use.
ABSTRACT
Nanoparticles (NPs) of titanium dioxide (TiO2) alter photosynthetic and biochemical parameters in Solanum lycopersicum L., possibly due to their photocatalytic properties given by energy absorption in the UV-A range; however, the joint effects TiO2 NPs and UV-A radiation are not well understood. This work evaluates the combined responses of TiO2 NPs and UV-A radiation at the physiological and molecular levels in S. lycopersicum. In a split growth chamber, the presence (UV-A +) and absence (UV-A -) of UV-A were combined with 0 (water as a control), and 1000 and 2000 mg L-1 of TiO2 NPs applied at sowing. At the end of exposure (day 30 after sowing), the photosynthetic performance was determined, and biochemical and molecular parameters were evaluated in leaf tissues. Better photochemical performance in UV-A + than UV-A - in control plants was observed, but these effects decreased in 1000 and 2000 mg TiO2 L-1, similar to net CO2 assimilation. A clear increase in photosynthetic pigment levels was recorded under UV-A + compared to UV-A - that was positively correlated with photosynthetic parameters. A concomitant increase in total phenols was observed on adding TiO2 in UV-A - conditions, while a decreasing trend in lipid peroxidation was observed for the same treatments. There was an increase in psbB gene expression under TiO2/UV-A + treatments, and a reduced expression of rbcS and rbcL under UV-A - . These results suggest that the reduction in photosynthetic performance on applying high doses of TiO2 NPs is probably due to biochemical limitation, while UV-A achieves the same result via the photochemical component.
ABSTRACT
The crop Vitis vinifera (L.) is of great economic importance as Chile is one of the main wine-producing countries, reaching a vineyard area of 145,000 ha. This vine crop is usually very sensitive to local condition changes and agronomic practices; therefore, strategies to counteract the expected future decrease in water level for agricultural irrigation, temperature increase, extreme water stress (abiotic stress), as well as increase in pathogenic diseases (biotic stress) related to climate change will be of vital importance for this crop. Studies carried out in recent years have suggested that arbuscular mycorrhizal fungi (AMF) can provide key ecosystem services to host plants, such as water uptake implementation and enhanced absorption of nutrients such as P and N, which are key factors for improving the nutritional status of the vine. AMF use in viticulture will contribute also to sustainable agronomic management and bioprotection against pathogens. Here we will present (1) the current status of grapevines in Chile, (2) the main problems in grapevines related to water stress and associated with climate change, (3) the importance of AMF to face water stress and pathogens, and (4) the application of AMF as a biotechnological and sustainable tool in vineyards.
