Sandra B. Wilson

Container and field evaluation of three native shrubs grown in compost-based media

Three shrubs native to Florida, pineland privet [Forestiera segregata var. pinetorum (Small) M.C. Johnst.], Simpsons stopper [Myrcianthes fragrans (Sw.) McVaugh], and Walters viburnum (Viburnum obovatum Walter), were container grown in a peat- or compost-based medium for 18 weeks. The formulated compost-based medium had lower initial moisture, pH, total porosity, and container capacity; and higher bulk and particle density than the other media. The compost-based medium and unamended compost both had higher levels of N, P, K, Zn, Cu, Mn, and Fe than the peat-based medium. Regardless of species, incorporation of compost in the medium did not affect plant height or shoot dry weight. Although growth indices of Walters viburnum and pineland privet were similar among media, compost-grown Simpsons stopper had 24% greater growth index than plants grown in peat-based media. Root dry weights of Walters viburnum grown in peat or compost-based media were 30 to 50% greater than that of plants grown in unamended compost. Regardless of species, when grown out in the landscape for an additional 32 weeks, initial container medium did not affect subsequent plant height, growth index, stem caliper, or visual quality.

PHOTOSYNTHETIC AND CARBOHYDRATE STATUS OF EASY- AND DIFFICULT-TO-ACCLIMATIZE SEA OATS (UNIOLA PANICULATA L.) GENOTYPES DURING IN VITRO CULTURE AND EX VITRO ACCLIMATIZATION

SummaryThe photosynthetic and carbohydrate status of an easy-to-acclimatize (EK 16-3) and a difficult-to-acclimatize (EK 11-1) genotype of Uniola paniculata L. (sea oats), a native dune species of the southeastern US, were evaluated during in vitro culture and ex vitro acclimatization. Net photosynthetic rate was eight times greater for EK 16-3 than EK 11-1 plantlets after ex vitro transfer. In vitro-produced leaves were morphologically similar to ex vitro-produced leaves and exhibited similar photosynthetic competence. EK 11-1 plantlets exhibited greater transpiration rates at the time of ex vitro transfer than EK 16-3 plantlets. However, the small magnitude of this difference, although significant, indicated that control of water loss was probably not the main cause for poor acclimatization of EK 11-1 plantlets. Carbohydrate analysis in vitro revealed that EK 16-3 plantlets utilized leaf starch reserves more rapidly than EK 11-1 plantlets. Starch utilization correlated with the development of leaves with expanded leaf blades during in vitro rooting in EK 16-3 plantlets. After ex vitro transfer, both genotypes exhibited significant decreases of starch and soluble sugar content in shoots and roots. However, the higher photosynthetic ability of shoots in EK 16-3 resulted in greater accumulation of shoot soluble sugars than EK 11-1 after 2-wk ex vitro culture. After 6-wk in vitro rooting, there were significantly higher chlorophyll and soluble protein contents, ribulose 1,5-bisphosphate carboxylase (rubisco) and phosphoenolpyruvate carboxylase activities in EK 16-3 than EK 11-1 shoots. These differences also correlated with the development of anatomical and morphological leaf features in EK 16-3 similar to those of greenhouse-produced leaves.

Preferential depletion of gut CD4-expressing iNKT cells contributes to systemic immune activation in HIV-1 infection

Chronic inappropriate immune activation is the central defect-driving loss of CD4+ T helper cells and progression to AIDS in persons with HIV-1 infection, but the mechanisms remain controversial. We examined key regulatory invariant receptor natural killer T (iNKT) cells in the gut, the largest reservoir of lymphocytes and a key arena of HIV-1 pathogenesis. In healthy control persons, the anti-inflammatory CD4+ iNKT-cell subset predominated over the pro-inflammatory CD4− iNKT-cell subset in the gut, but not in the blood, compartment. HIV-1 infection resulted in a preferential loss of this anti-inflammatory CD4+ iNKT-cell subset within the gut. The degree of loss of the CD4+ iNKT-cell subset in the gut, but not in the blood, correlated to the systemic immune activation and exhaustion that have been linked to disease progression. These results suggest a potentially important contribution of gut iNKT-cell imbalance in determining the systemic immune activation that is the hallmark of HIV-1 pathogenesis.

Toxicity of the herbicides bromacil and simazine to the aquatic macrophyte, Vallisneria americana Michx

Vallisneria americana Michx. (tapegrass) is an ecologically important submersed, vascular aquatic plant that provides food and shelter for many aquatic and waterfowl species. This plant often occurs close to land areas where herbicides are used. Nontarget exposure of these plants to herbicides may compromise ecological structure and function. The objective of the present study was to evaluate the suitability of several endpoint measurements for determining no-observable-adverse effect concentrations (NOAECs), lowest-observable-adverse effect concentrations (LOAECs), and median effective concentration values (EC50s) for tapegrass exposed to the herbicides bromacil (0-0.092 mg/L) and simazine (0-0.592 mg/L) following a 13-d single-pulse exposure and 15-d (bromacil) or 14-d (simazine) postexposure periods. The NOAEC/LOAEC/EC50 for fresh weight gains, new leaf production, and total leaf growth after 13-d exposure to bromacil were 0.020/0.036/0.032, 0.036/0.054/0.036, and 0.036/0.054/0.043 mg/L, respectively. The same respective NOAEC/LOAEC/EC50s for simazine were <0.058/0.058/0.067, 0.229/0.344/0.154, and 0.058/0.116/0.081 mg/L. Reductions in quantity and fresh weight of daughter plants produced and stolon fresh weights occurred at bromacil concentrations > or = 77, 0.020, and 0.036 mg/L, respectively; and simazine concentrations > or = 0.344, >0.592, and > or = 0.116 mg/L, respectively. Neither herbicide affected leaf greenness, total chlorophyll concentrations, or carbohydrate allocation. Although toxicity was shown for many endpoints, most EC50 values were greater than aquatic life benchmark values for algae used by the U.S. Environmental Protection Agency (U.S. EPA), but less than for aquatic plants, indicating that V. americana would likely be protected by use of the algal benchmark criteria.

Growth, flowering, and survival of firewheel ( Gaillardia pulchella Foug.) based on seed source and growing location

Home region failed to provide any clear short-term improvement in plant growth, vigor, flowering, quality, or survival of Gaillardia pulchella Foug. (Asteraceae; firewheel) when plants derived from natural populations in east Texas, northeast Florida, central west Florida, central east Florida, and southeast Florida were grown under low-input landscape conditions in northwestern, northern central, or southeastern Florida. During the 22-wk study, adaptability of east Texas plants was similar to that of northeast Florida and southeast Florida plants within the different sites. At the 2 northern sites, plant growth, vigor, and flowering were greater than for plants grown in southeastern Florida. The patterns of biweekly changes in plant vigor, flowering, and quality ratings were similar among plants of all seed sources within a site. Averaged over the entire study, these ratings were equally high for plants of all seed sources except central east Florida plants. Within a site, survival of northeast Florida, southeast Florida, and east Texas plants was equally high (83 to 100%). Also, 100% of central west Florida plants survived at the 2 northern sites, yet no central west Florida plants survived past week 16 in southeastern Florida. Differences in growth, vigor, flowering, quality, and survival were likely related to the loamier soils at the 2 northern sites and (or) flooding June rains in southeastern Florida.

Leaching Potential of Heavy Metals, Nitrogen, and Phosphate from Compost-Amended Media

Leaching potential of nutrients and heavy metals was evaluated from a peat-based medium (containing 70% peat, 20% perlite, and 10% vermiculite) amended with varying proportions (0%, 25%, 50%, 75%, or 100%) of compost (biosolids and yard waste, 1:1 by weight). The compost contained small amounts of Zn, Cu, Pb, and Cd. However, the leachate fractions of Zn, Cu, Pb, and Cd in compost accounted for only 0.19%, 0.23%, 0.05%, and 0.27%, respectively of the total concentrations. Except for Cu, the concentrations of Zn, Pb, and Cd were higher in the leachates of peat-based medium than the compost amended media. The concentrations of Cd and Pb in the first leachate of the peat-based medium exceeded the drinking water standards (USEPA 1989). However, the concentrations of Cd, Cr, Cu, and Pb in all the compost amended media were below the limit of the drinking water standards. The concentrations of total P and PO4-P in leachates increased with increasing proportion of compost in the media. Concentration of NO3-N in the first leachate was high and decreased in the subsequent leachings for all the compost amended media. These results suggested that the biosolids-yard waste compost may be a safe and acceptable replacement or partial replacement to peat-based medium without increased leachability of nutrients and heavy metals.

Evaluation of New Container Media for Aglaonema Production

Mandated processing of waste by‐products in the United States has inspired national interest in addressing the effectiveness of using composted biosolids and yard trimmings to grow containerized plants. Diamond bay Chinese evergreen (Aglaonema ‘Diamond Bay’) was transplanted in containers filled with one of eight formulated media (components added by volume). Medium 1 was a standard mix commonly used in Aglaonema production (5:2:3 peat–vermiculite–perlite); medium 2 was formulated on site to contain peat–bark–stalite–rice hulls–coir (2:2:3:1:2); media 3 and 4 contained 40% biosolid–yard waste compost instead of peat and with or without 20% stalite, respectively; and media 5, 6, 7, and 8 were commercially formulated to contain peat–bark–perlite–rice hulls–coir (4:1.5:2.5:1:1, 4:1.5:2.5:1:1, 4:2:2:1:1, and 3.0:2.5:2:1:1.5, respectively). Physical and chemical properties of the eight media were in ranges 50–65% container water‐holding capacity, 2.9–7.8% air‐filled porosity, 55–80% moisture (w/w), 0.11–0.37 g·cm3 bulk density, 0.34–0.96 g·cm3 particle density, 4.2–7.2 pH, 0.12–4.4 dS·m−1 electrical conductivity (EC), 27.3–54.5 meg/100 g cation exchange capacity (CEC), 17.9–39.0% carbon (C), and 0.22–1.7% nitrogen (N). Medium 4 (40% compost) had 5.5 times more ammoniacal N (NH4‐N) and 1.7 times more nitrate N (NO3‐N) than that of the standard commercial mix. At week 8, plants grown in media 2 and 5 were 8.9% to 9.5% taller than plants grown in medium 1 (commercial standard). At week 16, there were no significant differences in plant heights or growth indices among media. At week 24, there were no significant differences in plant height, growth index, visual quality, shoot dry weight, and root dry weight among media. However, cumulative phosphorus (P) leaching from media 1, 4, and 5 was significantly more than leaching from media 2 and 8. This study suggests that compost may serve as a horticulturally suitable and cost‐effective alternative to peat‐based media for Aglaonema production.

Toxicity of the Norflurazon to the Aquatic Macrophyte Vallisneria americana (Michx.)

Vallisneria americana (Michx.) (common name tapegrass) is a submersed, vascular aquatic plant that reproduces vegetatively and by seed. The objective of this study was to determine the no-observable-effects concentrations (NOECs) and lowest-observable-effects concentrations (LOECs) for tapegrass exposed to the herbicide norflurazon (0–0.1 mg/L) following a 14-d exposure and a postexposure period. The primary symptom of norflurazon toxicity was bleaching of newly emerged leaf blades at concentrations of 0.04 mg/L and higher after 14 d of exposure. Leaf greenness effect levels were 0.04 mg/L (NOEC) and 0.06 mg/L (LOEC). All other endpoints measured resulted in a NOEC greater than 0.1 mg/L following the exposure period. Latent effects were observed 14 d postexposure for new leaf production and fresh weight gains, with a NOEC and LOEC of 0.08 and 0.1 mg/L, respectively. Total leaf growth was the least sensitive endpoint measured. Following the exposure/postexposure periods, significant effects on vegetative reproduction were apparent, with no effects occurring at concentrations up to 0.08 mg/L, but with significant reduction at the 0.1 mg/L treatment level. Root and stolon dry weights were significantly reduced at the 0.1 and 0.08 mg/L treatments, respectively. Total soluble sugars (TSS) and hexose content in shoots was reduced at concentrations of 0.04 mg/L and higher. TSS, hexose, and sucrose contents were higher in roots of plants exposed to 0.1 mg/L. Some recovery was apparent for all treatment concentrations following the postexposure period, indicating that the effects were at least partially reversible. We thank Peter Strimple, Robert Minerva, Ross Loehr, Michael Poult, Ali Poult, Ryan Collins, Laurie Mecca, and Pat Frey for their technical assistance. We also thank Jane Ferguson-Foos for editorial assistance. This is Florida Agricultural Experiment Station Series Publication R-10995.

Induction, Identification, and Characterization of Tetraploids in Japanese Privet (Ligustrum japonicum)

A number of privet species (Ligustrum spp.) that are important to the nursery and landscape industry have escaped cultivation and become invasive or weedy in the United States and other countries. Induced tetraploids in these species may produce new selections or cultivars with reduced or eliminated invasive potential. Applying drops of semisolid agar containing 0.1% to 0.3% colchicine and 0.2% dimethyl sulfoxide (DMSO) to newly emerged seedlings of japanese privet (Ligustrum japonicum Thunb.) resulted in 15.6% to 22.6% tetraploid induction. The nuclear DNA content of tetraploids was 5.31 pg/2C, 101.9% higher than that of diploids. Compared with diploid plants, tetraploids were more compact, with an average of 31.0% shorter plant height and 33.1% smaller canopy width. Tetraploids had 29.2% thicker internodes, and their leaves were 39.5% larger and 33.8% thicker, resulting in 42.1% to 24.1% greater fresh or dry leaf weights (per leaf) in tetraploids compared with diploids. Without indole-3-butyric acid (IBA) treatment, cuttings from tetraploids showed 28% lower rooting than diploids. IBA treatments improved the rooting of tetraploid cuttings, resulting in 65% rooting success. These results indicate that tetraploids can be readily induced in japanese privet and induced tetraploids show significant changes in plant growth and size, shoot growth, leaf morphology, and rooting of cuttings. The modified tetraploid induction method and the induced tetraploids are expected to be useful for producing new selections or cultivars with reduced invasive potential in japanese and other privets. Exotic plant invasions are considered one of the main causes of the degradation of ecosystems and the loss of biodiversity globally (Theoharides and Dukes, 2007). Ornamental horticulture has been recognized as the main source of plant invaders (Bell et al., 2003; Niemiera and Von Holle, 2009; Reichard andWhite, 2001; Rejm anek, 2014). The economic impacts of invasive plant species in the United States are estimated at nearly

Effects of Medium Sugar on Growth and Carbohydrate Status of Sweetpotato and Tomato Plantlets in Vitro

35 billion (Pimentel et al., 2005). To help mitigate this huge impact and meet the nursery and landscape industry’s need for plant materials, horticulturists have been searching for cultivars with reduced invasive potential (Knox and Wilson, 2006; Trueblood et al., 2010; Wilson and Mecca, 2003; Wilson et al., 2004, 2012). Multiple ornamental breeding programs in the United States have initiated breeding projects to develop new cultivars with reduced or eliminated invasive potential in major invasive ornamental shrubs or trees (Anderson, 2007; Czarnecki et al., 2012; Freyre et al., 2012; Leonhardt and Shi, 2009; Olsen, 2007; Phillips et al., 2015; Ranney et al., 2007, 2010; Thammina et al., 2011; Vining et al., 2012). Developing genetic tools and generating germplasm resources that can be used for this objective have become essential and important for current and future ornamental plant breeding (Anderson, 2007; Li et al., 2004; Olsen, 2007; Thammina et al., 2011; Vining et al., 2012). Several species of Ligustrum L. (privet) are commonly used as ornamentals in many parts of the world (Dirr, 1998; Wilson et al., 2014). In the landscape, these plants are valued for their evergreen leaves, white flowers, adaptability to a range of landscape conditions, tolerance to pruning, resistance to diseases, and wide availability (Dirr, 1998). Some Ligustrum species have escaped cultivation and become naturalized in natural areas (Munger, 2003). For example, 16 countries report naturalization of chinese privet (Ligustrum sinense Lour.) (Morris et al.; 2002; Munger, 2003). In the United States, chinese privet has escaped in 20 states and is considered invasive in many states (FLEPPC, 2015; Munger, 2003). Glossy privet (Ligustrum lucidum W.T. Aiton) has escaped cultivation in 10 states in the United States (Munger, 2003; Wilson et al., 2014) and is also a weed in Australia (Panetta, 2000), New Zealand (Miller and Henzell, 2000), and Argentina (Hoyos et al., 2010). Japanese privet (L. japonicum Thunb.) is native to Japan and eastern Asia and was introduced to the United States from Japan and Korea in 1845 as an ornamental landscape plant (Munger, 2003; Wilson et al., 2014). Since then, this species has been widely used in the landscape in the southeastern, southern, and western United States. It has escaped cultivation and become naturalized in 12 southeastern states in the United States (Munger, 2003). Japanese privet commonly forms dense thickets in the field or forest understories, shading and displacing many native species. Once established, it is difficult to eradicate. The invasiveness of many ornamentals is attributed to a number of factors including prolific production of viable seeds. Thus, making plants sterile or seedless can reduce, even eliminate, their invasive potential (Anderson, 2007; Ranney, 2004, 2006). Several genetic tools have been used to reduce seed production, viability, and/or germination, including natural mutations, artificial mutagenesis, interspecific hybridization, ploidy manipulation (Czarnecki et al., 2012; Freyre et al., 2012; Trueblood et al., 2010), endosperm culture (Thammina et al., 2011), and transgenics (Li et al., 2004; Vining et al., 2012). So far, ploidy manipulation has resulted in considerable success and yielded multiple sterile, noninvasive cultivars or breeding lines in several important ornamental plants, such as HORTSCIENCE VOL. 51(11) NOVEMBER 2016 1371 Hypericum androsaemum L. (Trueblood et al., 2010), Lantana camara L. (Czarnecki et al., 2012), and Ruellia simplex Wright (Freyre et al., 2012). The key step in ploidy manipulation is chromosome doubling and induction of stable tetraploids, which are the gateway to obtain other ploidy levels (triploids, pentaploids, hexaploids, octoploids, etc.) through interploid crosses. Several antimitotic agents have been used to inhibit the separation of chromosomes at the anaphase of cell division and achieve chromosome doubling in ornamental plants (Contreras, 2012; Contreras et al., 2010; Nadler et al., 2012; Vining et al., 2012). Colchicine has been one of the widely used agents to induce tetraploids in numerous ornamental plants (Abdoli et al., 2013; Henny et al., 2009; Lehrer et al., 2008; Leonhardt and Shi, 2009). Several types of plant tissues or organs, such as seeds, seedlings, axillary buds or shoot tips, embryos, and cultured cells or tissues, have been used as the target for colchicine treatment with various rates of successful tetraploid induction and mixoploidy (Habbard et al., 2016; Henny et al., 2009; Jones et al., 2007; Lehrer et al., 2008; Leonhardt and Shi, 2009; Vining et al., 2012). The availability of an effective and efficient chromosome doubling and tetraploid induction protocol is critical for successful ploidy manipulation and development of sterile, noninvasive cultivars in invasive ornamental plants. Our literature searches and quick surveys of privet cultivars indicated a lack of tetraploids in glossy, chinese, and japanese privet. Preliminary work on treating axillary buds of privet plants with colchicine resulted in few solid tetraploids. Thus, the main objectives of this study were to use japanese privet as a model to evaluate the effectiveness and efficiency of the semisolid agar method for induction of stable tetraploids in privet and to characterize the effects of chromosome doubling and tetraploidy on shoot growth and leaf morphology. Materials and Methods Plant materials.Open-pollinated seedswere collected from mature shrubs of L. japonicum ‘Texanum’ grown at the University of Florida (UF) North Florida Research and Education Center, Quincy, FL, in Feb. 2010 and shipped to the UF Gulf Coast Research and Education Center (GCREC), Wimauma, FL. Dry seeds were sown onto a commercial potting mix (Metro Mix 200; Sun Gro Horticulture, Agawam, MA) in plastic containers (15 cm in diameter) in Feb. 2011. Seeds were covered with a layer of horticultural grade vermiculite ( 1 cm thick) and germinated in a growth room at 24 C with 16 h of light (120 to 150 mmol·m·s) and 8 h of dark. About 5weeks after sowing, seedlings emerged with fully expanded cotyledons. Induction, identification, and confirmation of tetraploids. The semisolid agar method of Jones et al. (2007) was used with some modifications. Colchicine was applied to the growing points of newly emerged seedlings at the cotyledonary stage to induce tetraploids. A 1% colchicine stock solution was made by dissolving colchicine power (Sigma-Aldrich, St. Louis, MO) in water. The colchicine stock solution was added to melted semisolid agar containing one-fourth-strength Murashige and Skoog (MS) basal salts, 0.55%agar, andDMSO (Sigma-Aldrich; final concentration 0.2%) to a final concentration. Three colchicine concentrations were used: 0.1%, 0.2%, and 0.3%. The colchicine-containing agar solution was kept at 40 C and then 30 mL were pipetted onto the growing point of each privet seedling. Treated seedlings were placed in a high humidity ( 100% relative humidity) growth chamber at 24 C in dark to minimize colchicine degradation by light. Control seedlings received semisolid agar without colchicine. All treatments were repeated during three consecutive days. After treatment, seedlings were grown in a greenhouse, and fertigated with 50 to 100 ppm nitrogen as needed. Seedlings were kept in community containers until they produced shoots with several true leaves and later transplanted individually into new containers (10 to 15 cm in diameter). Seedlings were grown in these containers for 1 year, and then transplanted into ground beds at the UF’s GCREC in Mar. 2013. All transplanted plants were grown in full sun, irrigated through drip tapes, and fertilized with 15 g of 15N–3.9P–12K controlled-release fertilizer (Osmocote; Scotts, Marysville, OH). To identify tetraploids, multiple fully expanded young leaveswere collected from each plant, and each leaf was analyzed separat