Chromium (Cr) contamination poses food safety and environmental challenges, yet the early-stage physiological and molecular responses to Cr(III) stress remain unclear. Citrus and tomato are economically important crops representing woody and herbaceous species, making them valuable models for studying heavy metal toxicity in plants. This study investigates the impact of Cr (III) exposure on citrus and tomato seedlings, with a focus on physiological phenotypes and transcriptional response. Citrus seed germination declines with increasing Cr(III) concentrations, while low Cr(III) levels promote tomato germination, with inhibition occurring above 1 g/L. Under hydroponic conditions, Cr (III) severely hampers root and leaf growth in both citrus and tomato plants, accompanied by decreased net photosynthetic rate. Using a GFP-based confocal microscopy system, we observed reduced fluorescence intensity within three days of Cr(III) exposure (100 mg/L and 500 mg/L), indicating early cellular damage. Biochemical assays revealed oxidative stress, marked by increased H2O2, malondialdehyde (MDA), and antioxidant enzyme activity. Additionally, low Cr (III) concentrations could result in the death of various microorganisms, including Escherichia coli, Agrobacterium rhizogenes, and Agrobacterium tumefaciens. Transcriptomic analysis identified differentially expressed genes related to MAPK signaling pathway and Plant hormone signal transduction pathway. Transcription of many transcription factors, such as bHLH, WRKY, and MYB, also underwent significant changes.

Drought is one of the main abiotic stresses affecting plant growth and development. Reduced plant yield and quality are primarily caused by the reductions in photosynthesis, mineral uptake, metabolic disorders, damages from the increased production of reactive oxygen species, and many other disruptions. Plants utilize drought resistance mechanisms as a defense strategy, and the systems' activation is dependent upon several factors, including plant genotype, onthogenesis phase, drought intensity and duration, and the season in which the drought occurs. Impatiens walleriana is a worldwide popular flowering plant recognized for its vibrant flower colors, and is an indispensable plant in pots, gardens and other public areas. It prefers well-draining, moisturized soil, and does not perform well in overly dry or waterlogged conditions. Consequently, inadequate water supply is a common problem for this plant during production, transportation, and market placement, which has a substantial impact on plant performance overall. This review article outlines certain features of morphological, physiological, and molecular alterations induced by drought in ornamental, drought-sensitive plant species I. walleriana, as well as research carried out to date with the aim to improve the drought tolerance. Stress proteins aquaporins and dehydrins, whose molecular structure was described for the first time in this plant species, are highlighted specifically for their role in drought stress. Furthermore, the effective improvement of drought tolerance in I. walleriana by exogenous application of Plant Growth Regulators and Plant Growth-Promoting Bacteria is discussed in detail. Finally, this review can provide valuable insights for improving plant resilience and productivity in the face of water scarcity, which is critical for sustainable agriculture and horticulture.