Aluminum (Al) toxicity and phosphorus (P) deficiency are widely recognized as major constraints to agricultural productivity in acidic soils. Under this scenario, the development of ryegrass plants with enhanced P use efficiency and Al resistance is a promising approach by which to maintain pasture production. In this study, we assessed the contribution of growth traits, P efficiency, organic acid anion (OA) exudation, and the expression of Al-responsive genes in improving tolerance to concurrent low-P and Al stress in ryegrass (Lolium perenne L.). Ryegrass plants were hydroponically grown under optimal (0.1 mM) or low-P (0.01 mM) conditions for 21 days, and further supplied with Al (0 and 0.2 mM) for 3 h, 24 h and 7 days. Accordingly, higher Al accumulation in the roots and lower Al translocation to the shoots were found in ryegrass exposed to both stresses. Aluminum toxicity and P limitation did not change the OA exudation pattern exhibited by roots. However, an improvement in the root growth traits and P accumulation was found, suggesting an enhancement in Al tolerance and P efficiency under combined Al and low-P stress. Al-responsive genes were highly upregulated by Al stress and P limitation, and also closely related to P utilization efficiency. Overall, our results provide evidence of the specific strategies used by ryegrass to co-adapt to multiple stresses in acid soils.

Improving plant ability to acquire and efficiently utilize phosphorus (P) is a promising approach for developing sustainable pasture production. This study aimed to identify ryegrass cultivars with contrasting P use efficiency, and to assess their associated biochemical and molecular responses. Nine ryegrass cultivars were hydroponically grown under optimal (0.1 mM) or P-deficient (0.01 mM) conditions, and P uptake, dry biomass, phosphorus acquisition efficiency (PAE) and phosphorus utilization efficiency (PUE) were evaluated. Accordingly, two cultivars with high PAE but low PUE (Ansa and Stellar), and two cultivars with low PAE and high PUE (24Seven and Extreme) were selected to analyze the activity and gene expression of acid phosphatases (APases), as well as the transcript levels of P transporters. Our results showed that ryegrass cultivars with high PAE were mainly influenced by root-related responses, including the expression of genes codifying for the P transporter LpPHT1;4, purple acid phosphatase LpPAP1 and APase activity. Moreover, the traits that contributed greatly to enhanced PUE were the expression of LpPHT1;1/4 and LpPHO1;2, and the APase activity in shoots. These outcomes could be useful to evaluate and develop cultivars with high P-use efficiency, thus contributing to improve the management of P in grassland systems.

While soil responses to organic and inorganic phosphorus (P) fertilizers have been widely studied, plant physiological and molecular responses remain insufficiently characterized. Such an understanding is necessary to develop sustainable P fertilization strategies that enhance plant performance in soils with P limitations. This study investigated the impact of poultry manure (PM) and its combination with phytase enzyme on molecular plant responses involved in P use efficiency (PUE) of ryegrass plants growing on a P-deficient Andisol. A greenhouse experiment under controlled conditions was performed to evaluate soil properties, plant biomass, P uptake, plant performance, and the expression of P transporters under the following P treatments: P deficiency (PD), mineral fertilizers (F), PM alone, and PM combined with phytase. The combination of PM and phytase enhanced soil P availability by 60% and increased soil P enzyme activities 2.6-fold, facilitating the mineralization of organic P. This resulted in a 63% increase in shoot P concentration and a 35% enhancement in shoot biomass. Additionally, oxidative stress markers decreased, with lipid peroxidation in roots reduced up to five-fold, while antioxidant activity increased 1.6-fold. Molecular analysis revealed that the expression of the P transporter gene LpPHT1;4 was upregulated 9.3-fold, indicating an improved capacity for P acquisition and utilization. These findings suggest that phytase-mediated hydrolysis of organic P and the activation of plant P transporters are key mechanisms driving enhanced P uptake and efficiency in P-deficient soils.

Phytomelatonin is a versatile compound with important roles in plants, spanning from promoting germination and plant growth to defending against abiotic and biotic stresses. Its natural origin as biostimulator aligns with sustainable agricultural practices that aim to reduce reliance on synthetic agrochemicals while supporting crop productivity. As research progresses and reveals its full potential across various sectors of agriculture and food production systems, phytomelatonin emerges as a promising candidate for integrated crop management, with the goal of achieving more resilient and sustainable food systems worldwide. More agronomic data will be essential to decide whether the use of (phyto)melatonin can be a clear advance in the improvement of crops and their production. This paper presents the possible improvements and challenges to be faced in order to elucidate whether the cost/benefit balance in the use of melatonin in crops will be environmentally and economically sustainable.