Foliar Application of Spermidine Alleviates Waterlogging-Induced Damages to Maize Seedlings by Enhancing Antioxidative Capacity, Modulating Polyamines and Ethylene Biosynthesis

Deciphering Physio-Biochemical Basis of Tolerance Mechanism for Sesame (Sesamum indicum L.) Genotypes under Waterlogging Stress at Early Vegetative Stage

Waterlogging represents a substantial agricultural concern, inducing harmful impacts on crop development and productivity. In the present study, 142 diverse sesame genotypes were examined during the early vegetative phase to assess their response under waterlogging conditions. Based on the severity of symptoms observed, 2 genotypes were classified as highly tolerant, 66 as moderately tolerant, 69 as susceptible, and 5 as highly susceptible. Subsequent investigation focused on four genotypes, i.e., two highly tolerant (JLT-8 and GP-70) and two highly susceptible (R-III-F6 and EC-335003). These genotypes were subjected to incremental stress periods (0 h, 24 h, 48 h, 72 h, and 96 h) to elucidate the biochemical basis of tolerance mechanisms. Each experiment was conducted as a randomized split-plot design with three replications, and the statistical significance of the treatment differences was determined using the one-way analysis of variance (ANOVA) followed by the Fisher least significant difference (LSD) test at p ≤ 0.05. The influence of waterlogging stress on morphological growth was detrimental for both tolerant and susceptible genotypes, with more severe consequences observed in the latter. Although adventitious roots were observed in both sets of genotypes above flooding levels, the tolerant genotypes exhibited a more rapid and vigorous development of these roots after 48 h of stress exposure. Tolerant genotypes displayed higher tolerance coefficients compared to susceptible genotypes. Furthermore, tolerant genotypes maintained elevated antioxidant potential, thereby minimizing oxidative stress. Conversely, susceptible genotypes exhibited higher accumulation of hydrogen peroxide (H2O2) and malondialdehyde content. Photosynthetic efficiency was reduced in all genotypes after 24 h of stress treatment, with a particularly drastic reduction in susceptible genotypes compared to their tolerant counterparts. Tolerant genotypes exhibited significantly higher activities of anaerobic metabolism enzymes, enabling prolonged survival under waterlogging conditions. Increase in proline content was observed in all the genotypes indicating the cellular osmotic balance adjustments in response to stress exposure. Consequently, the robust antioxidant potential and efficient anaerobic metabolism observed in the tolerant genotypes served as key mechanisms enabling their resilience to short-term waterlogging exposure. These findings underscore the promising potential of specific sesame genotypes in enhancing crop resilience against waterlogging stress, offering valuable insights for agricultural practices and breeding programs.

Uncovering the synergistic interplay of melatonin and spermidine in the alleviation of nematode stress in Solanum lycopersicum

Worldwide, biotic stress severely degrades agricultural output and increases the risk of starvation. Root-knot nematodes (Meloidogyne incognita) are one of the important endoparasites that adversely affect the growth and development in plants, thus affecting their productivity. Contrarily, humans employ a number of unfriendly techniques, such as chemical applications, to manage biotic stressors. Use of Plant Growth Regulators is an environmentally safe alternative method against chemical pesticides that can be used to defend plants from biotic stressors. Melatonin and polyamines have been broadly found in multiple physiological processes and in diverse biotic and abiotic stresses faced by plants. In the contemporaneous study, we conducted an in vitro experiment which disclosed that pretreated seeds with melatonin and spermidine (a polyamine), decreased root galls in afflicted plants and uplifted the growth of Solanum lycopersicum seedlings. According to our findings, tomato plants' photosynthetic efficiency dropped and reactive oxygen species levels dramatically rose after nematode inoculation. On the other hand, melatonin and spermidine decreased oxidative stress by scavenging hydrogen peroxide and decreased malonaldehyde. The present work investigated improvement in growth characteristics, photosynthetic pigments, antioxidative enzymes and non-antioxidative enzymes in PGR treated tomato seedlings even during the nematode stress. Confocal studies evaluated nuclear damage within root apices and intensity of blue colour was directly proportional to nuclear damage. The findings of the present investigation support the use of plant growth regulators, melatonin and spermidine as seed priming agent to manage nematode stress in plants.