Achievements and Perspectives in the Breeding of Temperate Grasses and Legumes

This paper will focus on a historical perspective on cool season forage production, plant breeding methods for cool season forages, major cool season forage selection criteria, some examples of significant achievements, and a future perspective. Topics similar to ours have been discussed at recent previous meeting of this Congress (Humphreys, 1997; Van Wijk et al., 1993); however, we will strive to avoid “plowing the same ground twice”. In an attempt to prevent duplication of content with other sections of this Congress, only limited attention will be given to genetic resource acquisition and conservation. Additionally, alfalfa (Medicago sativa L.), one of the primary temperate forage legumes, will generally not be discussed, since a full paper by Dr. Bouton will be presented in another session

Effects of Selection on Morphological Characteristics in \u3ci\u3eSetaria sphacelata\u3c/i\u3e (Schumach.) Moss

Cattle production in Florida is limited by the lack of available warm-season forages adapted to the cool winters of the region. Setaria (S. sphacelata) has demonstrated green growth during cool conditions in subtropical climates around the world, and has the potential to fill this niche in cattle production in Florida. Four populations were selected in Gainesville and Ona, Florida: two cycles of selection for increased head number, one cycle for increased leaf width and one cycle for grazing tolerance. The objectives of this research were to compare these populations morphologically to determine changes due to selection. Selection for leaf width increased this trait while maintaining other morphological characteristics constant. Selection for head number decreased plant height and increased head number in each cycle, and decreased leaf width and inflorescence length in the second cycle. Selection for grazing regrowth resulted in reduced plant height and inflorescence length. Concern regarding susceptibility of Setaria to chinch bug and possible winter killing in Florida remain to be resolved before this species may be commercialized in Florida

Clovers Around the World: A Symposium in Memory and Honor of Dr. Norman L. Taylor

Trifolium is arguably the largest and most diverse genera of herbaceous forage legumes (Zohary and Heller, 1984). Dr. Norman L. Taylor, Professor Emeritus, Department of Plant and Soil Science, University of Kentucky, deceased, was a pioneer and champion of collection and preservation of Trifolium species throughout his 57-year career. Dr. Taylor was a native of northern Kentucky, born near where this Conference is being held

Temperate/Tropical Transition Zones: A Hotspot for Breeding Forages with Climate Resiliency

Species resiliency to climate change is critical for sustainability of grassland agricultural systems. Transition zones between temperate and tropical climates (between 27 and 31° N and S latitude) with variable annual frost/freeze events have proven to be ideal zones for identification of species with variable climate adaptation. This paper will identify these regions around the globe and show how these regions offer distinct advantages in terms of selection for abiotic and biotic stresses, and thus resiliency to changing climate. Programs located in these regions have the advantage of exposure to alternating extreme warm and cold temperatures, drought and flood conditions, and a multitude of biotic stresses. Examples are presented of successes and constraints in moving cool season species into warmer climates, and tropical species into cooler climates. We present rationale for which direction of species movement (tropical to temperate vs. temperate to tropical) may be more likely to encounter success and why. Specific plant attributes that contribute to climate resiliency will be identified and described. The ability to identify small changes in genetic photoperiod responses in these regions, where daily changes are less than 1.5 m, are illustrated as a further advantage when the objective is development of earlier or later maturity. These regions also provide suitable environments for pests, from both tropical and temperate areas, including diseases, nematodes, and insects, providing desirable field environments for screening and genetic improvement through cycles of recurrent selection. A discussion of reproduction method is included to illustrate the need to accomplish seed production of these species in other zones in order to produce higher yields of high-quality seed

Seasonal expression of apospory in bahiagrass

This paper was presented at the 22nd International Grassland Congress, Sydney, Australia, 15−19 September 2013. Its publication in Tropical Grasslands – Forrajes Tropicales is the result of a co-publication agreement with the IGC 2013 Organizing Committee. Except for adjustments to the journal’s style and format, the text is essentially the same as that published in: Michalk LD; Millar GD; Badgery WB; Broadfoot KM, eds. 2013. Revitalising Grasslands to Sustain our Communities. Proceedings of the 22nd International Grassland Congress, Sydney, Australia, 2013. New South Wales Department of Primary Industries, Orange, NSW, Australia. p. 258–259.Fil: Rios, Esteban Fernando. University Of Florida; Estados Unidos de América; Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Nordeste. Instituto de Botánica del Nordeste (i); Argentina;Fil: Blount, Ann. University Of Florida; Estados Unidos de América;Fil: Kenworthy, Kevin E.. University Of Florida; Estados Unidos de América;Fil: Acuña, Carlos Alberto. Universidad Nacional del Nordeste; Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Nordeste. Instituto de Botánica del Nordeste (i); Argentina;Fil: Quesenberry, Kenneth H.. University Of Florida; Estados Unidos de América

Seasonal Expression of Apospory in Bahiagrass

Flowering plants can reproduce sexually (outcrossing and/or selfing) and/or asexually. Sexual reproduction implies the successful completion of meiosis and double fertilisation for the formation of both the embryo and the endosperm. In contrast, gametophytic apomixis is an asexual mode of reproduction through seeds that involves parthenogenetic embryo development from a cytologically unreduced egg cell (2n). Apospory is the process by which unreduced gametophytes are formed after a series of mitotic divisions of somatic cells (2n) in the ovary. This occurs independently from the sexual meiotic process; and therefore, both sexual and apomictic pathways may coexist simultaneously. Apospory is inherited in bahiagrass (Paspalum notatum) as a single dominant Mendelian factor with distorted segregation (Martínez et al. 2001), and its degree of expression was reported to vary throughout the flowering season in P. cromyorrhizon, a close relative of bahiagrass (Quarin 1986). Bahiagrass is a perennial warm-season grass widely used for forage and utility turf in the south-eastern US due to its persistence in sandy, infertile soils. Diploid races reproduce sexually and are highly self-incompatible (Acuña et al. 2007), while polyploids are classified as pseudogamous apomicts (pollination is required) (Quarin 1999). Sexual tetraploid genotypes have been experimentally created (Quesenberry and Smith 2003; Quesenberry et al. 2010) and successfully used in crosses (Acuña et al. 2009). Cytoembryological analysis has been used to determine the mode of reproduction in bahiagrass (Martínez et al. 2001; Acuña et al. 2007). At anthesis, sexual plants produce spikelets having only a single Polygonum type meiotic embryo sac (SES), characterised by bearing the egg apparatus close to the micropyla, a large binucleated central cell and a group of antipodal cells at the chalazal end (Figure 1a). Highly apomictic plants produce ovules having single or multiple aposporous embryo sacs (AES), which present the egg apparatus and a central cell with 2 polar nuclei, and no antipodal cells (Figure 1b). Some tetraploid bahiagrass races are also able to produce ovules that have the sexual meiotic megasporocyte together with one or more aposporous sacs (AES+SES), and these plants are classified as facultative apomictic. The objective of this study was to characterise the reproductive mode of 5 wild dwarf bahiagrasses, a highly apomictic hybrid (Acuña et al. 2009) and the cultivar ‘Argentine’ at different times during the flowering season and under different nitrogen (N) fertiliser rates

Evaluation of Limpograss (\u3cem\u3eHemarthria altissima\u3c/em\u3e) Breeding Lines under Different Grazing Managements

Limpograss (Hemarthria altissima (Poir.) Stapf et C.E. Hubb.) is a stoloniferous, warm-season perennial grass from South Africa. It is frequently used to extend the grazing season in poorly drained soils of subtropical regions (Quesenberry et al. 2004). The cold tolerance of limpograss allows it to grow at temperatures below which other commonly used warm-season grasses (e.g. bermudagrass) remain productive. Use of limpograss has helped to reduce forage shortfall during winter, therefore, reducing feeding costs. In the past 30 years, the area planted to limpograss in Florida, USA has grown faster than that of any other forage grass species. It is estimated that over 0.2 million ha are planted to limpograss (Quesenberry et al. 2004). Recent University of Florida research with limpograss has focused on developing new hybrids which incorporate the persistence of the most widely used cultivar ‘Floralta’ with the digestibility of ‘Bigalta’. Preliminary clipping and grazing trials evaluated 50 breeding lines and identified 5 lines (designated 1, 4F, 10, 32 and 34) with superior performance. With an overall program goal of identifying the best limpograsses for cultivar release, the specific objective of this experiment was to investigate the forage productivity and sward canopy characteristics of these 5 breeding lines, compared to Floralta, in response to different grazing management strategies

Photoperiod Response in Pensacola Bahiagrass

Photoperiod response has been found to influence the growth and development of \u3ePensacola\u27 derived bahiagrass (Paspalum notatum Flugge var. saure Parodi). Four selection cycles [\u3ePensacola= (Cycle 0), Cycle 4, \u3eTifton 9\u27 (Cycle 9) and Cycle 23] resulting from recurrent restricted phenotypic selection (RRPS) of spaced-plants, were field grown in 1999 and 2000, to study photoperiod sensitivity among genotypes. Two day-length treatments were imposed on the field grown plants. One treatment, used only natural light. The second treatment imposed an extended day-length treatment using Quartz-halogen lamps, installed in the field during the fall and winter, to extend day-length to15 hours. The top growth of individual plants was harvested three times during the fall and winter seasons and stolon spread was measured in mid February, 2000. Top growth was increased by the extended day-length treatment for Pensacola and RRPS Cycle 4 in all three harvest dates. Top growth of Tifton 9 was unaffected by the extended light for the September harvest, but increased in the late October and late January harvests. RRPS Cycle 23 plants grown under natural light, out-yielded the plants grown under extended light treatment, for the first two harvests. There were no differences in yields of RRPS Cycle 23 plants from extended or natural light from the January harvest. The later cycles, Tifton 9 and RRPS Cycle 23, were less sensitive to day-length, than RRPS Cycles 0 and 4. Extended daylength, for all cycles, dramatically reduced stolon spread by nearly half that of the plants grown under natural light. Results from this experiment demonstrate a high sensitivity in growth and development of Pensacola-derived bahiagrass to day-length

Minimal information for studies of extracellular vesicles 2018 (MISEV2018):a position statement of the International Society for Extracellular Vesicles and update of the MISEV2014 guidelines

The last decade has seen a sharp increase in the number of scientific publications describing physiological and pathological functions of extracellular vesicles (EVs), a collective term covering various subtypes of cell-released, membranous structures, called exosomes, microvesicles, microparticles, ectosomes, oncosomes, apoptotic bodies, and many other names. However, specific issues arise when working with these entities, whose size and amount often make them difficult to obtain as relatively pure preparations, and to characterize properly. The International Society for Extracellular Vesicles (ISEV) proposed Minimal Information for Studies of Extracellular Vesicles (“MISEV”) guidelines for the field in 2014. We now update these “MISEV2014” guidelines based on evolution of the collective knowledge in the last four years. An important point to consider is that ascribing a specific function to EVs in general, or to subtypes of EVs, requires reporting of specific information beyond mere description of function in a crude, potentially contaminated, and heterogeneous preparation. For example, claims that exosomes are endowed with exquisite and specific activities remain difficult to support experimentally, given our still limited knowledge of their specific molecular machineries of biogenesis and release, as compared with other biophysically similar EVs. The MISEV2018 guidelines include tables and outlines of suggested protocols and steps to follow to document specific EV-associated functional activities. Finally, a checklist is provided with summaries of key points