Asexual reproduction is a type of reproduction that does not involve the fusion of gametes or change in the number of chromosomes. The offspring that arise by asexual reproduction from either unicellular or multicellular organisms inherit the full set of genes of their single parent and thus the newly created individual is genetically and physically similar to the parent or an exact clone of the parent. Asexual reproduction is the primary form of reproduction for single-celled organisms such as archaea and bacteria. Many eukaryotic organisms including plants, animals, and fungi can also reproduce asexually. In vertebrates, the most common form of asexual reproduction is parthenogenesis, which is typically used as an alternative to sexual reproduction in times when reproductive opportunities are limited. Komodo dragons and some monitor lizards can also reproduce asexually.
In botany, apomixis is asexual reproduction without fertilization. Its etymology is Greek for "away from" + "mixing". This definition notably does not mention meiosis. Thus "normal asexual reproduction" of plants, such as propagation from cuttings or leaves, has never been considered to be apomixis, but replacement of the seed by a plantlet or replacement of the flower by bulbils were categorized as types of apomixis. Apomictically produced offspring are genetically identical to the parent plant.
Vegetative reproduction is any form of asexual reproduction occurring in plants in which a new plant grows from a fragment or cutting of the parent plant or specialized reproductive structures, which are sometimes called vegetative propagules.
Hieracium , known by the common name hawkweed and classically as hierakion, is a genus of flowering plant in the family Asteraceae, and closely related to dandelion (Taraxacum), chicory (Cichorium), prickly lettuce (Lactuca) and sow thistle (Sonchus), which are part of the tribe Cichorieae. Hawkweeds, with their 10,000+ recorded species and subspecies, do their part to make Asteraceae the second largest family of flowering plants. Some botanists group all these species or subspecies into approximately 800 accepted species, while others prefer to accept several thousand species. Since most hawkweeds reproduce exclusively asexually by means of seeds that are genetically identical to their mother plant, clones or populations that consist of genetically identical plants are formed and some botanists prefer to accept these clones as good species whereas others try to group them into a few hundred more broadly defined species. What is here treated as the single genus Hieracium is now treated by most European experts as two different genera, Hieracium and Pilosella, with species such as Hieracium pilosella, Hieracium floribundum and Hieracium aurantiacum referred to the latter genus. Many members of the genus Pilosella reproduce both by stolons and by seeds, whereas true Hieracium species reproduce only by seeds. In Pilosella, many individual plants are capable of forming both normal sexual and asexual (apomictic) seeds, whereas individual plants of Hieracium only produce one kind of seeds. Another difference is that all species of Pilosella have leaves with smooth (entire) margins whereas most species of Hieracium have distinctly dentate to deeply cut or divided leaves.
A dry roadside dotted with small, ¾ inch red orange flowers, interspersed with very similar yellow ones, and often the white of daisies, is a good sign that you are in Hawkweed country.
The cowpea is an annual herbaceous legume from the genus Vigna. Its tolerance for sandy soil and low rainfall have made it an important crop in the semiarid regions across Africa and Asia. It requires very few inputs, as the plant's root nodules are able to fix atmospheric nitrogen, making it a valuable crop for resource-poor farmers and well-suited to intercropping with other crops. The whole plant is used as forage for animals, with its use as cattle feed likely responsible for its name.
Crepis, commonly known in some parts of the world as hawksbeard or hawk's-beard, is a genus of annual and perennial flowering plants of the family Asteraceae superficially resembling the dandelion, the most conspicuous difference being that Crepis usually has branching scapes with multiple heads. The genus name Crepis derives from the Greek krepis, meaning "slipper" or "sandal", possibly in reference to the shape of the fruit.
Adrienne Elizabeth Clarke is Professor Emeritus of Botany at the University of Melbourne, where she ran the Plant Cell Biology Research Centre from 1982–1999. She is a former chairman of the Commonwealth Scientific and Industrial Research Organisation, former Lieutenant Governor of Victoria (1997–2000) and former Chancellor of La Trobe University (2011–2017).
Plant reproduction is the production of new offspring in plants, which can be accomplished by sexual or asexual reproduction. Sexual reproduction produces offspring by the fusion of gametes, resulting in offspring genetically different from either parent. Asexual reproduction produces new individuals without the fusion of gametes, resulting in clonal plants that are genetically identical to the parent plant and each other, unless mutations occur.
Nucellar embryony is a form of seed reproduction that occurs in certain plant species, including many citrus varieties. Nucellar embryony is a type of apomixis, where eventually nucellar embryos from the nucellus tissue of the ovule are formed, independent of meiosis and sexual reproduction. During the development of seeds in plants that possess this genetic trait, the nucellus tissue which surrounds the megagametophyte can produce nucellar cells, also termed initial cells. These additional embryos (polyembryony) are genetically identical to the parent plant, rendering them as clones. By contrast, zygotic seedlings are sexually produced and inherit genetic material from both parents. Most angiosperms reproduce sexually through double fertilization. Different from nucellar embryony, double fertilization occurs via the syngamy of sperm and egg cells, producing a triploid endosperm and a diploid zygotic embryo. In nucellar embryony, embryos are formed asexually from the nucellus tissue. Zygotic and nucellar embryos can occur in the same seed (monoembryony), and a zygotic embryo can divide to produce multiple embryos. The nucellar embryonic initial cells form, divide, and expand. Once the zygotic embryo becomes dominant, the initial cells stop dividing and expanding. Following this stage, the zygotic embryo continues to develop and the initial cells continue to develop as well, forming nucellar embryos. The nucellar embryos generally end up outcompeting the zygotic embryo, rending the zygotic embryo dormant. The polyembryonic seed is then formed by the many adventitious embryos within the ovule. The nucellar embryos produced via apomixis inherit its mother's genetics, making them desirable for citrus propagation, research, and breeding.
Callose is a plant polysaccharide. Its production is due to the glucan synthase-like gene (GLS) in various places within a plant. It is produced to act as a temporary cell wall in response to stimuli such as stress or damage. Callose is composed of glucose residues linked together through β-1,3-linkages, and is termed a β-glucan. It is thought to be manufactured at the cell wall by callose synthases and is degraded by β-1,3-glucanases. Callose is very important for the permeability of plasmodesmata (Pd) in plants; the plant's permeability is regulated by plasmodesmata callose (PDC). PDC is made by callose synthases and broken down by β-1,3-glucanases (BGs). The amount of callose that is built up at the plasmodesmatal neck, which is brought about by the interference of callose synthases (CalSs) and β-1,3-glucanases, determines the conductivity of the plasmodesmata.
Carl Emil Hansen Ostenfeld was a Danish systematic botanist. He graduated from the University of Copenhagen under professor Eugenius Warming. He was a keeper at the Botanical Museum 1900–1918, when he became professor of botany at the Royal Veterinary and Agricultural University. In 1923, by the early retirement of Raunkiær's, Ostenfeld became professor of botany at the University of Copenhagen and director of the Copenhagen Botanical Garden, both positions held until his death in 1931. He was a member of the Royal Danish Academy of Sciences and Letters and served on the board of directors of the Carlsberg Foundation.
Nagendra Kumar Singh is an Indian agricultural scientist. He is presently a National Professor Dr. B.P. Pal Chair and JC Bose National Fellow at ICAR-National Institute for Plant Biotechnology, Indian Agricultural Research Institute, New Delhi. He was born in a small village Rajapur in the Mau District of Uttar Pradesh, India. He is known for his research in the area of plant genomics, genetics, molecular breeding and biotechnology, particularly for his contribution in the decoding of rice, tomato, wheat, pigeon pea, jute and mango genomes and understanding of wheat seed storage proteins and their effect on wheat quality. He has made significant advances in comparative analysis of rice and wheat genomes and mapping of genes for yield, salt tolerance and basmati quality traits in rice. He is one of the highest cited agricultural scientists from India for the last five years.
Rajeev Kumar Varshney is an Indian agricultural scientist, specializing in genomics, genetics, molecular breeding and capacity building in developing countries. Varshney is currently serving as Director, Western Australian State Agricultural Biotechnology Center; Director, Centre for Crop & Food Innovation; and International Chair in Agriculture & Food Security with the Food Futures Institute at Murdoch University, Australia since Feb 2022. Before joining Murdoch University, Australia he served International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), a global agriculture R&D institute, for more than 16 years in different scientific and research leadership roles including Research Program Director for three global research programs– Grain Legumes, Genetic Gains and Accelerated Crop Improvement Program. He has the onus of establishing and nurturing the Center of Excellence in Genomics & Systems Biology (CEGSB), a globally recognized center for genomics research at ICRISAT that made impacts on improving agriculture and development of human resources in several countries including India, China, Kenya, Ethiopia, Tanzania, Nigeria, Ghana, Mali, Senegal, Burkina Faso, etc. Varshney holds Adjunct/Honorary/Visiting Professor positions at 10 academic institutions in Australia, China, Ghana, Hong Kong and India, including The University of Western Australia, University of Queensland, West Africa Centre for Crop Improvement, University of Hyderabad, Chaudhary Charan Singh University and Professor Jayashankar Telangana State Agricultural University.
Lloyd Thomas Evans AO FRS FAA was a New Zealand plant physiologist who made his career in Australia.
Guranda Gvaladze was a notable Georgian botanist, one of the founders of Plant Embryology in Georgia, Academician of the Abkhazian Regional Academy of Sciences (1997), Doctor of Biological Sciences (1974), Professor (1991). Her father Evgen Gvaladze (1900-1937) was a notable Lawyer and Publicist, one of the leaders of the National-Liberation Movement of Georgia of 1921–1937.
Rana Ellen Munns is an Australian botanist whose primary research has been to determine the traits that underpin salinity tolerance and adaptation to drought in crop plants. Rana was born in Sydney Australia and attended the University of Sydney, receiving her undergraduate degree in Biochemistry in 1966. She completed her Ph.D. in 1972 to begin a lifelong course of research on salt tolerance of plants first as a Research Fellow at the University of Western Australia and later at CSIRO Plant Industry in Canberra. In the early 1990s, she found that sodium exclusion was an important trait associated with the salt tolerance in wheat using a seedling stage assay. This work culminated in understanding wheat grain yield in saline soils in terms of genetic components that could be improved by an ancestral transporter gene. This research eventually led to a cultivar of wheat that yielded 25% more on saline soils that in farmers' fields and is used by over thirty wheat seed companies globally.
Felix Dapare Dakora, is a Ghanaian plant biologist investigating biological nitrogen fixation at the Tshwane University of Technology in South Africa. He currently serves as President of The African Academy of Sciences for the 2017–2023 terms. Dakora was awarded the UNESCO-Equatorial Guinea International Prize for Research in the Life Sciences and the African Union Kwame Nkrumah Scientific Award. Dakora is a Fellow of the Academy of Science of South Africa.
Jennifer Lee Stauber is an Australian ecotoxicologist and chief research scientist at the CSIRO Land and Water.
Leslie A. Weston FAA, is a plant biologist, who was awarded a Fellow of the Australian Academy of Science in 2023, for her work on weed suppressing ground covers and pest management. She is a professor at Charles Sturt University, at Wagga Wagga, and researches botany, agronomy, weed control and horticulture.
