Rapid In Vitro Multiplication of Non-Runnering \u3cem\u3eFragaria vesca\u3c/em\u3e Genotypes from Seedling Shoot Axillary Bud Explants

Fragaria vesca L. has become a model species for genomic studies relevant to important crop plant species in the Rosaceae family, but generating large numbers of plants from non-runner-producing genotypes is slow. To develop a protocol for the rapid generation of plants, leaf explants were compared to single axillary bud shoot explants, both from in vitro-grown Fragaria vesca seedlings, as sources of shoots for new plant production in response to benzyladenine (BA) or thidiazuron (TDZ) combined with indolebutyric acid (IBA) on Murashige and Skoog’s Basal Salt (MS) medium. BA at 2.0 and 4.0 mg L−1 and TDZ at 1.5 mg L−1 promoted the greatest number of shoots produced per shoot explant. There were no IBA effects or IBA interactions with BA or TDZ. Significant interactions between BA and IBA, but not TDZ and IBA, occurred in leaf explant callus formation and % explants with callus at 6 and 9 weeks of culture and on shoots per leaf explant at 9 weeks. TDZ treatments produced uniformly high levels of callus but low numbers of shoots. The treatment generating the most shoot production was BA at 4.0 mg L−1 plus IBA at 0.50 mg L−1. After 9 weeks of culture, leaf explants of the non-runner-producing genotype Baron Solemacher had generated 4.6 shoots per explant with the best treatment, while axillary bud explants had generated 30.8 shoots with the best treatment. Thus, in vitro culture of shoot axillary bud explants can generate high numbers of clonal shoots from a single seedling plant in vitro

The Regulation of Plant Vegetative Phase Transition and Rejuvenation: miRNAs, a Key Regulator

In contrast to animals, adult organs in plants are not formed during embryogenesis but generated from meristematic cells as plants advance through development. Plant development involves a succession of different phenotypic stages and the transition between these stages is termed phase transition. Phase transitions need to be tightly regulated and coordinated to ensure they occur under optimal seasonal, environmental conditions. Polycarpic perennials transition through vegetative stages and the mature, reproductive stage many times during their lifecycles and, in both perennial and annual species, environmental factors and culturing methods can reverse the otherwise unidirectional vector of plant development. Epigenetic factors regulating gene expression in response to internal cues and external (environmental) stimuli influencing the plant’s phenotype and development have been shown to control phase transitions. How developmental and environmental cues interact to epigenetically alter gene expression and influence these transitions is not well understood, and understanding this interaction is important considering the current climate change scenarios, since epigenetic maladaptation could have catastrophic consequences for perennial plants in natural and agricultural ecosystems. Here, we review studies focusing on the epigenetic regulators of the vegetative phase change and highlight how these mechanisms might act in exogenously induced plant rejuvenation and regrowth following stress

Near-Infrared Spectroscopy Used to Predict Soybean Seed Germination and Vigour

Rapid, non-destructive methods for measuring seed germination and vigour are valuable. Standard germination and seed vigour were determined using 81 soybean seed lots. From these data, seed lots were separated into high and low germinating seed lots as well as high, medium and low vigour seed lots. Near-infrared spectra (950–1650 nm) were collected for training and validation samples for each seed category and used to create partial least squares (PLS) prediction models. For both germination and vigour, qualitative models provided better discrimination of high and low performing seed lots compared with quantitative models. The qualitative germination prediction models correctly identified low and high germination seed lots with an accuracy between 85.7 and 89.7%. For seed vigour, qualitative predictions for the 3-category (low, medium and high vigour) models could not adequately separate high and medium vigour seeds. However, the 2-category (low, medium plus high vigour) prediction models could correctly identify low vigour seed lots between 80 and 100% and the medium plus high vigour seed lots between 96.3 and 96.6%. To our knowledge, the current study is the first to provide near-infrared spectroscopy (NIRS)-based predictive models using agronomically meaningful cut-offs for standard germination and vigour on a commercial scale using over 80 seed lots

A Laboratory Exercise in Physiological Seed Dormancy Using Eastern Redbud

A laboratory exercise is presented that demonstrates the impact of seed coverings and hormones on seed dormancy and release in seeds with endogenous, physiological dormancy. The materials and methods are simple and inexpensive and can be accomplished as an on-campus laboratory or as a distance education exercise. The execution of the laboratory is rapid (approximate to 1 hour), and the results are obtained in 2 weeks. The exercise generates an opportunity for the discussion of a complex subject that involves the interaction of two tissue types within the seed (the embryo vs. the seed coverings) and nicely illustrates their role in seed dormancy maintenance

A Laboratory Exercise in Physiological Seed Dormancy Using Eastern Redbud

A laboratory exercise is presented that demonstrates the impact of seed coverings and hormones on seed dormancy and release in seeds with endogenous, physiological dormancy. The materials and methods are simple and inexpensive and can be accomplished as an on-campus laboratory or as a distance education exercise. The execution of the laboratory is rapid (approximate to 1 hour), and the results are obtained in 2 weeks. The exercise generates an opportunity for the discussion of a complex subject that involves the interaction of two tissue types within the seed (the embryo vs. the seed coverings) and nicely illustrates their role in seed dormancy maintenance

The Regulation of Plant Vegetative Phase Transition and Rejuvenation: miRNAs, a Key Regulator

In contrast to animals, adult organs in plants are not formed during embryogenesis but generated from meristematic cells as plants advance through development. Plant development involves a succession of different phenotypic stages and the transition between these stages is termed phase transition. Phase transitions need to be tightly regulated and coordinated to ensure they occur under optimal seasonal, environmental conditions. Polycarpic perennials transition through vegetative stages and the mature, reproductive stage many times during their lifecycles and, in both perennial and annual species, environmental factors and culturing methods can reverse the otherwise unidirectional vector of plant development. Epigenetic factors regulating gene expression in response to internal cues and external (environmental) stimuli influencing the plant’s phenotype and development have been shown to control phase transitions. How developmental and environmental cues interact to epigenetically alter gene expression and influence these transitions is not well understood, and understanding this interaction is important considering the current climate change scenarios, since epigenetic maladaptation could have catastrophic consequences for perennial plants in natural and agricultural ecosystems. Here, we review studies focusing on the epigenetic regulators of the vegetative phase change and highlight how these mechanisms might act in exogenously induced plant rejuvenation and regrowth following stress