Boron, Iron, Manganese, and Zinc Allocation in Above- and Below-ground Components of HLB-affected Grapefruit Trees

Proceedings of the Florida State Horticultural Society · 2026-04-10

A new use of Agrobacterium plant growth regulator genes for plant bioengineering

Frontiers in Plant Science · 2026-03-16

Delivery of biomolecules into plant vascular tissues remains a barrier to managing diseases caused by insect vector-borne pathogens and to modifying phenotypes of established perennial crops. Inspired by the vascularized growth of crown galls induced by Agrobacterium tumefaciens , we repurposed the bacterium’s plant growth regulator (PGR) genes to engineer autonomously dividing, transgene-expressing plant cell structures termed symbionts. A plant transformation vector (pSYM) incorporating the IaaM, IaaH, Ipt and gene5 cassette from A. tumefaciens strain C58 together with a gene of interest on the same transfer DNA was delivered to stems of herbaceous and woody dicots using disarmed A. tumefaciens strain EHA105. Symbiont morphology, vascular differentiation, transgene expression, molecular mobility and protein secretion were evaluated using microscopy, fluorescent reporters, dye tracing, RNA silencing assays and mass spectrometry-based proteomics. pSym inoculation reproducibly generated symbionts across diverse host plant species that were vascularly integrated into their host plants and transgene expression ranging from heterogeneous niches to more uniform patterns. Small molecules moved between symbionts and host vascular tissues, whereas larger proteins exhibited more restricted mobility. Post-transcriptional gene silencing signals moved freely throughout the symbiont and slightly into adjacent stem tissue. Under tested field and greenhouse conditions in potato and tomato, respectively, gall or symbiont formation had no negative impacts on plant growth or tuber and fruit yield. In vitro , symbiont cultures abundantly secreted recombinant protein into surrounding media. Together, these results establish symbionts as a modular, plant bioengineering platform capable of producing and potentially delivering biomolecules without modifying the host plant genome, providing a foundation for vascular-targeted therapeutics and phenotype modulation in crops.

Adaptation and Early Establishment of Olive Trees (Olea europaea L.) under the Humid Subtropical Climate of the Southeastern United States

HortScience · 2025-07-21

Olive cultivation in the southeastern United States is challenging due to the warm and humid subtropical climate of the region. This study examined the impact of cultivar selection, transplant strategy, and environmental conditions on the adaptability and early establishment of olive trees in Florida. Two research orchards were established at two different locations (Citra and Jay), featuring three cultivars (Arbequina, Arbosana, and Koroneiki) transplanted at two sizes (large and small). Shoot and root growth were monitored over 2 years (Jul 2017 to May 2019) to assess transplant stress, tree establishment, and environmental adaptation. Small transplants exhibited higher growth rates than large ones, with differences in tree height and trunk cross-sectional area diminishing over time. Large transplants experienced greater transplant stress, as evidenced by a significant reduction in number of primary branches. Severe winter temperatures at Jay caused damage to ‘Arbosana’ and ‘Koroneiki’ trees, leading to high mortality rates and poor post-winter recovery growth. In contrast, ‘Arbequina’ demonstrated greater tolerance to both transplant stress and cold damage, maintaining stable vegetative growth. Root growth was primarily influenced by environmental factors rather than cultivar selection or transplant size. Total root length declined from 4 to 9 months after transplant (MAP), but it remained stable from 9 to 20 MAP. Most roots were concentrated within 20- to 40-cm soil depth, likely due to irrigation. These findings highlight the complex interactions among cultivar, transplant size, and environmental conditions. In addition, our results suggest ‘Arbequina’ has potential for commercial cultivation in the region. Further research is needed to assess long-term effects on productivity and resilience.

Root morphological and anatomical responses of olive tree cultivars ‘Oliana’ and ‘Lecciana’ under salinity stress

Scientia Horticulturae · 2025-03-01 · 6 citations

• ‘Oliana’ and ‘Lecciana’ are two novel, understudied olive tree cultivars gaining interest for cultivation in coastal, saline prone, areas. • For both cultivars, salinity stress induced a decrease in plant height, trunk diameter, and negatively affected root morphological traits. • K/Na ratio was significantly lower in both cultivars under salinity treatment compared to the control and translocation factors confirmed that Na translocation from roots to leaves was lower as well. • Microscopy analysis revealed that root apoplastic barriers developed near to the root tip in both the cultivars under salinity stress. • ‘Oliana’ and ‘Lecciana’ cultivars can be considered cultivars tolerant to salinity under the tested conditions. Olive trees ( Olea europaea ) exhibit a moderate to high salinity tolerance, varying by cultivar. Interest in cultivating olive trees is growing in coastal areas, which are characterized by poorly drained soil and low-quality brackish groundwater, leading to salt accumulation in the root zone. The rising salinity levels in these areas present a significant challenge for crop cultivation; therefore, evaluating new salt-tolerant cultivars is necessary. Various studies demonstrated the salinity tolerance of olive cultivars, but there is little information available for the novel cultivars ‘Oliana’ and ‘Lecciana’. For this study, eight-month-old plants ( n = 9) were assigned to a completely randomized experimental design and grown in pots using a sand medium under greenhouse conditions, treated with varying salt concentrations (0 mM - control, 50 mM, and 100 mM NaCl), and half-strength Hoagland solution was applied to meet their nutrient requirements. Height and trunk diameter were measured at three different time points (15, 30, and 45 days). At the same three time points, cohorts of plants were destructively sampled to study the root morphological traits, sodium (Na) and potassium contents, and root anatomical measurements. Both cultivars demonstrated a decrease in plant height, trunk diameter, and negative effects on root morphological traits under salinity treatments; moreover, translocation factors confirmed that the translocation of Na from roots to leaves was lower in both the cultivars. Microscopy analysis revealed that root apoplastic barriers developed near to the root tip in both the cultivars under salinity stress. Results indicate that both ‘Oliana’ and ‘Lecciana’ cultivars can be considered cultivars tolerant to salinity under the tested conditions.

Synergistic Effects of Polystyrene Nanoplastics and Cadmium on the Metabolic Processes and Their Accumulation in Hydroponically Grown Lettuce (<i>Lactuca sativa</i>)

Journal of Agricultural and Food Chemistry · 2025-06-24 · 6 citations

Plastic contamination in agricultural systems is an emerging concern. While current research suggests low direct toxicity, the consequences from interactions between nanoplastics and copresent contaminants are poorly understood. In this study, the synergistic effects of cadmium (Cd) and polystyrene nanoplastics (PS NP) on the growth and physiological responses of hydroponically grown Lactuca sativa (lettuce) were examined. Coexposure significantly increased the accumulation of Cd and PS NP by 61 and 67% in lettuce shoots compared with single-contaminant exposure. Metabolomic analysis showed that joint exposure induced an increase in glutathione and flavonoid-like compounds, suggesting an energy-intensive oxidative stress response. In addition, coexposure appeared to promote adventitious root formation, as evidenced by an increased abundance of metabolites linked to nitric oxide signaling. These findings suggest that the projected increase in PS NP in agricultural environments could exacerbate Cd uptake in food crops, potentially increasing human dietary exposure to heavy metals.

Use of Cover Crops in Florida’s Citrus Industry: History and Resurgence, Current Practices, Challenges, and Opportunities

HortTechnology · 2024-08-29 · 11 citations

Cover crops have a long and significant history in Florida’s citrus industry. During the late 1800s and early 1900s, they were widely used to enhance soil quality, boost fertility, and manage pests; therefore, they served as a critical agricultural tool before the widespread adoption of synthetic fertilizers. However, during the middle of the 20th century, a decline in the use of cover crops occurred as synthetic fertilizers and chemical pest control methods became more prevalent. Despite this decline, a resurgence of interest in cover crops has occurred among Florida’s citrus growers. This renewed interest is driven by the urgent need to increase soil fertility while reducing inputs, particularly in the context of managing citrus groves affected by citrus greening [huanglongbing (HLB)], which is a devastating disease that threatens the viability of the citrus industry. Citrus greening has created a growing interest in the use of management practices that can help mitigate the increasing cost of inputs needed to manage the disease. This literature review delves into the historical use of cover crops in Florida’s citrus industry and highlights their early adoption and subsequent decline. Additionally, it examines current cover crop management practices and focuses on key components such as seed selection, planting techniques, and termination methods. Finally, this review discusses the challenges and limitations associated with integrating cover crops into modern citrus production systems.

Impact of polystyrene nanoplastics on physiology, nutrient uptake, and root system architecture of aeroponically grown citrus plants

NanoImpact · 2024-11-29 · 16 citations

Nutrient uptake, growth, and physiology of Chinese cabbage (Brassica rapa L. ssp. pekinensis) varieties under NaCl stress

Soil & Environment · 2024-06-01 · 6 citations

Soil salinity and poor-quality irrigation water in Florida, USA, have become major issues for agricultural crops. Since Florida is one of the major producers of cabbage in the country, soil salinization may significantly impact this industry. Chinese cabbage varieties are very popular in the farming community of Florida and are widely cultivated. In the present study, four Chinese cabbage varieties (‘Bilko’, ‘Red Dragon’, ‘Rubicon’, and ‘Minuet’) were tested for their tolerance, agronomic, physiological, and nutritional responses to irrigation with 0, 100, and 200 mM NaCl solutions. The results showed that NaCl irrigation has decreased the growth of the tested plants, with ‘Bilko’ being the most tolerant one, showing higher production in both control and salt stress conditions. Although NaCl stress has increased electrolyte leakage in plant leaves, it has no significant effect on proline contents, and chlorophyll contents tend to increase with salinity stress, highlighting the physiological responses of all tested varieties. Among nutritional contents, there were no significant differences, but a few treatment groups showed a significant increase and decrease in nutrient contents. The higher NaCl treatments have caused a higher accumulation of Na and Cl elements in plants, making it a major factor for the decrease in plant growth.

Soil Organic Matter Influences Citrus Growth, Nutrient Uptake, and Root System Architecture

HortScience · 2024-11-13 · 7 citations

Florida citrus production faces multiple challenges, including low nutrient retention, low soil organic matter (SOM) and, more importantly, the devastating impacts of citrus greening, which is a bacterial disease that impacts root growth and nutrient uptake. Growers are exploring management practices to improve SOM and hoping to enhance tree health, nutrient uptake, and yield. Despite these efforts, research of the effects of SOM on citrus root systems and nutrient absorption remains limited, particularly that defining a target SOM range for optimal production. This study investigated the influence of varying SOM levels on citrus tree root system architecture, biomass, and nutrient uptake. This experiment was conducted in a greenhouse where 1-year-old ‘US-942’ rootstocks were assigned to a completely randomized experimental design and exposed to one of six experimental treatments with differing levels of SOM as the growing media [0% (control), 1%, 2%, 3%, 5%, or &gt;10% (100% compost)]. Each pot was considered an experimental unit and replicated six times ( n = 6), for a total of 36 seedlings. The results indicated that although root biomass did not change significantly, lower SOM levels resulted in longer roots with greater surface area and volume, likely because of increased soil exploration for nitrogen. Higher SOM treatments, however, showed improved leaf nutrient content, with increased nitrogen, phosphorus, and potassium uptake. In conclusion, the results of this study indicate that 3% SOM may be ideal for citrus because it positively impacted both root system architecture and nutrient uptake, which are both of primary concern because of citrus greening. Further research is necessary to establish critical SOM thresholds and evaluate the effects under field conditions and in combination with different irrigation and fertilizer regimes.

Influences of cerium oxide nanoparticles and salinity on common bean (Phaseolus vulgaris) growth, physiology, and root system architectural and anatomical traits

NanoImpact · 2024-10-01 · 4 citations