Leaf Age-Dependent Effects of Boron Toxicity in Two Cucumis melo Varieties

Abstract

Boron (B) is an essential nutrient for plant growth and development, exhibiting extremely narrow margins between deficiency and toxicity. B toxicity is devastating for productivity and apparent for a continuously increasing part of agricultural land, under the influence of on-going climate change. In this study, the effects of increased B supply (by using H3BO3) were addressed by examining critical physiological responses of young and mature leaves, which were devoid of toxicity symptoms, in two melon varieties (Armenian cucumbers, cantaloupes). B was primarily translocated through the transpiration stream, and secondarily via the active cell membrane transport system. The B distribution pattern was independent of leaf age, and remained rather unchanged under increased B supply. Armenian cucumbers, exhibiting higher leaf B levels, underwent an enhanced adverse impact on (root and shoot) growth, photosynthetic pigment content, cellular membrane integrity, and also exhibited attenuated antioxidant defense stimulation. Notably, and unlike other abiotic stressors, no evidence of B toxicity-induced systemic reaction was apparent. B toxicity greatly enhanced the transcription of the genes coding for borate influx and efflux channels, an effect that was mostly evident in mature leaves. In conclusion, shoot physiological responses to B toxicity are highly localized. Moreover, the obstruction of the diffusion and the B translocation to the aerial organs under increased B supply is genotype-dependent, governing plant physiological responses.

Differential Triggering of the Phenylpropanoid Biosynthetic Pathway Key Genes Transcription upon Cold Stress and Viral Infection in Tomato Leaves

“…Moreover, low temperature (10 • C for 24 h) greatly induced several genes encoding for 4CL isoenzymes that catalyze the conversion of 4-coumaric acid, caffeic acid, and ferulic acid to their corresponding CoA esters. Hence, it can be deduced that channeling the metabolic flow towards the production of multiple phenylpropanoid metabolites from structural molecules (e.g., lignin) to metabolites with strong antioxidant activity contributes to the plasticity of the metabolic pathway in the ever-changing environmental stimuli [12,13,[40][41][42]. In tomatoes, cold stress (4 • C for 24 h) significantly increased transcription of 4CL genes [43], while the 4CL2 isoenzyme was recently associated with increased flavonoid production and antioxidant activity [44].…”

“…It is well known that the phenylpropanoid biosynthetic pathway is a cross response to several environmental perturbations (reviewed in Šamec et al [11]), and is generally upregulated under either abiotic or biotic stress. In plants facing adverse conditions, the accumulation of phenolic compounds through activation of this pathway has been generally associated with enhanced stress tolerance [12][13][14]. The induced resistance has been related to the wide range of polyphenol functions, principally consisting of reactive oxygen species (ROS) scavenging ability (thus oxidative stress alleviation) and strong antimicrobial activity.…”

Improvement of Plant Responses by Nanobiofertilizer: A Step towards Sustainable Agriculture

“…This has been a major cause of soil and water pollution, soil erosion, nutrient imbalance, lessened agrobiodiversity, decreased soil fertility, and low water holding capacity, and has caused disturbances in natural soil flora and fauna [ 6 ]. The use of excess nutrients is polluting soil, and water scarcity makes the condition worse [ 7 ]. It was reported that a large portion of synthetic nutrients are not absorbed by plants, and instead run off from the fields and become integrated into water resources.…”

Meta-Learning for Few-Shot Plant Disease Detection

“…Abnormal phenotype can be caused by either abiotic or biotic stress. The former is caused, for instance, by lack or excess of nutrients or water [51]. The latter can be caused by fungi, bacteria, and viruses.…”