Boron (B) is an essential microelement for plants, and its deficiency can lead to impaired development and function. Around 50% of arable land in the world is acidic, and low pH in the soil solution decreases availability of several essential mineral elements, including B, magnesium (Mg), calcium (Ca), and potassium (K). Plants take up soil B in the form of boric acid (H₃BO₃) in acidic soil or tetrahydroxy borate [B(OH)₄]^- at neutral or alkaline pH. Boron can participate directly or indirectly in plant metabolism, including in the synthesis of the cell wall and plasma membrane, in carbohydrate and protein metabolism, and in the formation of ribonucleic acid (RNA). In addition, B interacts with other nutrients such as Ca, nitrogen (N), phosphorus (P), K, and zinc (Zn). In this review, we discuss the mechanisms of B uptake, translocation, and accumulation and its interactions with other elements, and how it contributes to the adaptation of plants to different environmental conditions. We also discuss potential B-mediated networks at the physiological and molecular levels involved in plant growth and development.

Aluminum (Al) toxicity is one of the major factors that limit the growth and production of crops in acid soils. Highbush blueberry (Vaccinium corymbosumL.) cultivars differing in resistance to Al toxicity regarding root growth and photosynthetic performance were used. In this study, we compared the physiological and metabolic strategies to cope with Al toxicity among the highbush blueberry cultivars [two new ones (Camellia and Cargo) and three established ones (Brigitta (Al-resistant), Star and Duke)]. Aluminum concentration in roots and leaves increased in all cultivars after 24 and 48 h of exposure to Al, but less so in roots of cultivar Camellia and leaves of cultivar Cargo. These two cultivars displayed minor effects of Al exposure in terms of photosynthetic activity in comparison with the established cultivars. Furthermore, Cargo did not vary fluorescence parameters, whereas Camellia exhibited a decrease in effective quantum yield (ΦPSII) and electron transport rate (ETR) and a change in non-photochemical quenching (NPQ) and maximum quantum yield (Fv/Fm) under Al after 48 h. The Al treatment increased total phenols in leaves of Brigitta, Cargo, and Camellia, whereas antioxidant activity increased in Star and Cargo after 48 h. Aluminum exposure decreased malate concentration in roots of all cultivars, but no change was noted in fumarate concentration. The antioxidant activity correlated with photosynthetic performance and the total phenol concentration in the leaves of new cultivars exposed to Al, suggesting enhanced resistance in the short-term experiment. The principal component analysis separated the new from the established cultivars. In conclusion, the new cultivars appear to be more Al-resistant than the established ones, with Star being most Al-sensitive. Regarding the Al-resistance mechanisms of the new cultivars, it is suggested that Camellia could have a root Al-exclusion mechanism under Al toxicity. This mechanism could be explained by low Al concentration in roots, suggesting that this cultivar could exude organic acid, allowing to chelate Al in the rhizosphere. Nonetheless, further researches are needed to confirm this assumption.

Salicylic acid (SA) has been shown to ameliorate drought stress. However, physiological and biochemical mechanisms involved in drought stress tolerance induced by SA in plants have not been well understood. Thus, this study aimed to study the role of SA application on enzymatic and non-enzymatic antioxidants, photosynthetic performance, and plant growth in A. chilensis plants subjected to moderate drought stress. One-year-old A. chilensis plants were subjected to 100% and 60% of field capacity. When plants reached moderate drought stress (average of stem water potential of −1.0 MPa, considered as moderate drought stress), a single SA application was performed on plants. Then, physiological and biochemical features were determined at different times during 14 days. Our study showed that SA application increased 13.5% plant growth and recovered 41.9% A_N and 40.7% g_s in drought-stressed plants on day 3 compared to drought-stressed plants without SA application. Interestingly, SOD and APX activities were increased 85% and 60%, respectively, in drought-stressed SA-treated plants on day 3. Likewise, SA improved 30% total phenolic content and 60% antioxidant capacity in drought-stressed A. chilensis plants. Our study provides insight into the SA mechanism to tolerate moderate drought stress in A. chilensis plants.