Mechanistic dissection of plant embryo initiation
Radoeva, T.M. - \ 2016
Wageningen University. Promotor(en): Dolf Weijers, co-promotor(en): Sacco de Vries. - Wageningen : Wageningen University - ISBN 9789462578135 - 183
embryogenesis - embryos - plants - auxins - genes - genomics - arabidopsis - cell suspensions - in vivo experimentation - zygotes - monozygotic twins - embryogenese - embryo's - planten - auxinen - genen - genomica - arabidopsis - celsuspensies - in vivo experimenten - zygoten - monozygote tweelingen
Land plants can reproduce sexually by developing an embryo from a fertilized egg cell, the zygote. After fertilization, the zygote undergoes several rounds of controlled cell divisions to generate a mature embryo. However, embryo formation can also be induced in a variety of other cell types in many plant species. These non-zygotic embryos go through analogous developmental phases and are morphologically similar to the zygotic embryo. Despite its fundamental importance and enormous application potential, the mechanisms that alter cell fate from non-embryonic to embryonic are elusive. In the past decades, a variety of different model systems have been used to identify regulators of embryo induction, but it is unclear if these act in a common network. We recently found that inhibition of auxin response in the extra-embryonic suspensor cells cell-autonomously and predictably triggers a switch towards embryo identity. In my thesis I have used the suspensor-derived embryogenesis as a uniform model system to study the crucial first reprogramming step of embryo initiation process.
Through genome-wide transcriptional profiling upon local (suspensor-specific) auxin response inhibition (Chapter 2) and through testing the ability of fifteen known embryogenesis inducers to promote embryo formation in suspensor cells (Chapter 3), we suggest that suspensor to embryo transformation requires a defined set of genetic regulators. The results obtained in my thesis provide essential tools and basis for further research and are a step forward to understanding the first step of embryo initiation process and to unravel the mystery of totipotency in plants.
Effect of eggshell temperature throughout incubation on broiler hatchling leg bone development
Pol, C.W. van der; Roovert-Reijrink, I.A.M. van; Maatjens, C.M. ; Anker, I. van den; Kemp, B. ; Brand, H. van den - \ 2014
Poultry Science 93 (2014)11. - ISSN 0032-5791 - p. 2878 - 2883.
oxygen concentration - gallus-gallus - growth - chickens - period - embryos - health
Leg problems in broiler chickens may partly be prevented by providing optimal circumstances for skeletal development during incubation. One of the factors demonstrated to affect bone development is eggshell temperature (EST), which provides a reliable reflection of embryo temperature. The present experiment aimed to investigate the effect of EST on development and asymmetry of the femur, tibia, and metatarsus in broiler chicken hatchlings. Eggs were incubated from d 0 until hatch at 1 of 4 EST: low (36.9°C), normal (37.8°C), high (38.6°C), and very high (39.4°C). At hatch, chick quality was determined in terms of chick length, yolk-free body mass, navel score, and organ weights. Tibia, femur, and metatarsus were weighed, their length and width (mediolateral diameter) and depth (craniocaudal diameter) at the middle of the shaft were measured, and their ash content was determined. Relative asymmetry of the leg bones was determined from their relative dimensions. Hatchability, chick quality, and organ development were lower for very high EST compared with all other treatments. Very high EST resulted in lowest tibia and metatarsus lengths (-3.1 to -8.4%) compared with all other treatments, and lower metatarsus weight (-9.1%) and femur length (-4.9%) compared with high EST. Relative asymmetry and ash content did not differ among treatments and no relation between EST and bone parameters was found. To conclude, very high EST resulted in lower bone development, hatchability, and chick quality. Few differences in bone development and chick quality were found between low, normal, and high EST.
Temperature and CO2 during the hatching phase. I. Effects on chick quality and organ development
Maatjens, C.M. ; Reijrink, I.A.M. ; Molenaar, R. ; Pol, C.W. van der; Kemp, B. ; Brand, H. van den - \ 2014
Poultry Science 93 (2014)3. - ISSN 0032-5791 - p. 645 - 654.
eggshell temperature - oxygen concentration - broiler-chickens - incubation-temperature - domestic-fowl - ascites - embryos - growth - performance - metabolism
The objective of this study was to investigate the effect of eggshell temperature (EST) and carbon dioxide (CO2) concentration during only the hatching phase on embryonic development and chick quality. Three batches of eggs were incubated at an EST of 37.8°C until d of incubation (E) 19. From E19, embryos were incubated at low (36.7°C), normal (37.8°C), or high (38.9°C) EST and at low (0.2%) or high (1%) CO2 concentration. Organ growth and embryo and chick quality were measured at E19, internal pipping (IP), hatch, and 12 h after hatch. A few interactions between EST and CO2 were found at IP, hatch, and 12 h after hatch, but all of these interactions were temporary and in most cases weak. High EST resulted in a lower relative heart weight compared with low (¿ = 0.05) and normal EST (¿ = 0.06) at IP, compared with low (¿ = 0.11) and normal EST (¿ = 0.08) at hatch, and compared with low (¿ = 0.11) and normal EST (¿ = 0.08) at 12 h after hatch. At hatch, high EST resulted in a lower YFBM compared with low EST (¿ = 0.65). At 12 h after hatch, high EST resulted in a lower relative liver weight compared with low EST (¿ = 0.12). At low EST, greater relative intestinal weight was found compared with normal (¿ = 0.41) and high EST (¿ = 0.37). The effect of CO2 solely was found at 12 h after hatch at which a higher relative heart weight (¿ = 0.05) and a higher relative lung weight (¿ = 0.0542) was found at high CO2 compared with low CO2. High EST during only the hatching phase negatively affected chick development, mainly expressed by the lower relative heart weight at IP, hatch, and 12 h after hatch and lower YFBM at hatch. The resolving effect of CO2 demonstrates that CO2 only seem to have a temporary effect during the hatching phase.
|Control of Pig Reproduction IX
Rodriguez-Martinez, H. ; Soede, N.M. ; Flowers, W.L. - \ 2013
Leicestershire, United Kingdom : Context Products Ltd (Society of Reproduction and Fertility volume 68) - ISBN 9781899043484 - 345
varkens - geslachtelijke voortplanting - gameten - embryo's - kunstmatige inseminatie - embryotransplantatie - zwangerschap - partus - pasgeborenen - biggen - overleving - biotechnologie - metabolomica - eiwitexpressieanalyse - kunstmatige selectie - pigs - sexual reproduction - gametes - embryos - artificial insemination - embryo transfer - pregnancy - parturition - neonates - piglets - survival - biotechnology - metabolomics - proteomics - artificial selection
Rapid BAC selection for tol2-mediated transgenesis in zebrafish
Bussmann, J. ; Schulte-Merker, S. - \ 2011
Development 138 (2011)19. - ISSN 0950-1991 - p. 4327 - 4332.
bacterial artificial chromosomes - fluorescent protein - expression - embryos - gene - integration - circuits - tol2 - mice
The generation of zebrafish transgenic lines that express specific fluorophores in a cell-or tissue-specific manner is an important technique that takes full advantage of the optical clarity of the embryo. Identifying promoter fragments that faithfully recapitulate endogenous expression patterns and levels is often difficult and using large genomic DNA fragments, such as bacterial artificial chromosomes (BACs), makes the process of transgenesis less reliable. Here we provide a detailed protocol that allows for BAC selection and subsequent rapid modification through recombineering in Escherichia coli, resulting in BACs that can be injected into zebrafish embryos and, aided by tol2-mediated transgenesis, reliably yield stable transgenic lines. A number of BACs can be prepared in parallel, and injection of the BACs containing CFP/YFP/RFP or Gal4 cassettes allows for immediate testing of whether a particular BAC will yield the desired result. Furthermore, since injected embryos often show widespread expression, recombineered BACs provide an alternative to two-color in situ hybridizations: BACs injected into embryos of a different transgenic reporter line thus enable in vivo colocalization studies. Using this protocol, we have generated 66 stable lines for 23 different genes, with an average transgenesis rate above 10%. Importantly, we provide evidence that BAC size shows no apparent correlation to the transgenesis rate achieved and that there are no severe position effects.
Early life developmental effects of marine persistent organic pollutants on the sea urchin Psammechinus miliaris
Drs Anselmo, H.M.R. ; Koerting, L. ; Devito, S. ; Berg, J.H.J. van den; Dubbeldam, M. ; Kwadijk, C.J.A.F. ; Murk, A.J. - \ 2011
Ecotoxicology and Environmental Safety 74 (2011)8. - ISSN 0147-6513 - p. 2182 - 2192.
western scheldt estuary - polychlorinated-biphenyls - north-sea - paracentrotus-lividus - aquatic toxicity - sediment - exposure - embryos - pcbs - echinodermata
A new 16-day echinoid early life stage (ELS) bioassay was developed to allow for prolonged observation of possible adverse effects during embryogenesis and larval development of the sea urchin Psammechinus miliaris. Subsequently, the newly developed bioassay was applied to study the effects of key marine persistent organic pollutants (POPs). Mortality, morphological abnormalities and larval development stages were quantified at specific time points during the 16-day experimental period. In contrast to amphibians and fish, P. miliaris early life development was not sensitive to dioxin-like toxicity in the prolonged early life stage test. Triclosan (TCS) levels higher than 500 nM were acutely toxic during embryo development. Morphological abnormalities were induced at concentrations higher than 50 nM hexabromocyclododecane (HBCD) and 1000 nM tetrabromobisphenol A (TBBPA). Larval development was delayed above 25 nM HBCD and 500 nM TBBPA. Heptadecafluorooctane sulfonic acid (PFOS) exposure slightly accelerated larval development at 9 days post-fertilization (dpf). However, the accelerated development was no longer observed at the end of the test period (16 dpf). The newly developed 16-day echinoid ELS bioassay proved to be sensitive to toxic effects of POPs that can be monitored for individual echinoid larvae. The most sensitive and dose related endpoint was the number of developmental penalty points. By manipulation of the housing conditions, the reproductive season could be extended from 3 to 9 months per year and the ELS experiments could be performed in artificial sea water as well.
Local anthropogenic contamination affects the fecundity and reproductive success of an Arctic amphipod
Bach, L. ; Fischer, A. ; Strand, J. - \ 2010
Marine Ecology Progress Series 419 (2010). - ISSN 0171-8630 - p. 121 - 128.
lysianassid amphipods - gammaridean amphipods - marine environments - intersex - bionomics - crustacea - responses - latitude - embryos - sea
This study investigates whether adaptation to life in contaminated Arctic areas carries a cost for the populations in terms of reduced fecundity and reproductive success. The benthic amphipod, Orchomenella pinguis occurs in huge densities in both clean and contaminated sites. O. pinguis was collected at contaminated sites in an open fjord adjacent to Sisimiut, West Greenland, and at clean sites outside the fjord exposed to open waters. The broods of gravid females were analyzed for number of embryos, embryonic developmental stage and number of embryo abnormalities. Further, a sample from 3 of the sites was sexed and analyzed for intersex occurrence. The individuals collected at the most contaminated site had significantly higher fecundity (i.e. reproductive potential), but also higher frequency of embryo aberrations resulting in lower fertility (i.e. actual reproductive success) compared to clean site individuals. These results indicated a cost of living in highly contaminated environments in terms of reduced reproductive success. This study confirms the potential of the benthic amphipod O. pinguis as a bioindicator for assessments of reproductive effects of contaminants in the Arctic marine environment.
Beoordeling van Zaadkwaliteit met behulp van Chlorofyl Fluorescentie Beelden
Jalink, H. - \ 2010
zaadkieming - chlorofyl - embryo's - fluorescentie - zaden - technieken - capsicum - glastuinbouw - seed germination - chlorophyll - embryos - fluorescence - seeds - techniques - capsicum - greenhouse horticulture
Tijdens het kiemingsproces van zaden wordt o.a. chlorofyl gevormd. Dit chlorofyl wordt aangemaakt door het embryo. Het is gebleken dat de toename van chlorofyl een maat is voor het verloop van het kiemingsproces. Dit chlorofyl kan gevoelig worden gemeten met een fluorescentietechniek.
Temperature manipulation during layer chick embryogenesis
Walstra, I. ; Napel, J. ten; Kemp, B. ; Brand, H. van den - \ 2010
Poultry Science 89 (2010)7. - ISSN 0032-5791 - p. 1502 - 1508.
incubation-temperature - thermal manipulations - body-temperature - broiler chicks - muscovy duck - heat-stress - thermoregulation - embryos - hatchability - performance
The current study investigated the effects of temperature manipulation (TM) during late embryogenesis on temperature preference, response to high environmental temperature, behavior, and performance in young layer chicks. Control (CC) embryos (n = 96) were incubated at 37.8°C eggshell temperature throughout incubation. Thermally manipulated embryos (n = 96) were incubated at 37.8°C eggshell temperature throughout incubation and were exposed to 40°C for 4 h/d from embryonic d 14 to 18 (TM chicks). After hatch, chicks from each treatment were divided into 3 subgroups (n = 32 per group) and were subjected to a temperature preference test at d 1, 7, or 33. One day after the temperature preference test, each subgroup was exposed to 1 thermal challenge for 4 h (d 2, 40°C; d 8, 40°C; or d 34, 35°C). Effects of TM on (fearfulness) behavior of chicks were investigated in a tonic immobility test and during home pen observations. Temperature manipulation decreased incubation time with 7 h (P <0.0001) and body temperature at hatch with 0.2°C (P = 0.002). The TM chicks preferred a lower ambient temperature in the temperature preference test (P <0.05) and showed a higher body temperature response than CC chicks to the thermal challenge at d 2 and 8 (P <0.05). No effects of TM on behavior and performance were observed. Because most TM studies are conducted in broilers, this study is the first attempt to unravel the effects of TM during late embryogenesis on posthatch environmental adaptation in layer chicks. The results demonstrated that effects of our TM on postnatal temperature preference and response to high environmental temperatures are only found until d 8 of age. This may suggest 1 of 3 options: a) the timing or the level, or both, of TM and duration were not at the sensitive period of embryogenesis or not sufficient, or both, respectively; b) the level of the postnatal thermal challenge was not strong enough to induce a hyperthermic response; and c) the postnatal effects of TM in layers are limited in time
Telers zijn bestuiving en bevruchting meestal liever kwijt dan rijk : de ontseksualisering van de tuinbouw
Kierkels, T. ; Heuvelink, E. - \ 2010
Onder Glas 7 (2010)1. - p. 12 - 13.
tuinbouw - levenscyclus - chromosomen - bestuiving - bevruchting - spermatozoön - genetische parameters - embryo's - eicellen - vruchtgroenten - sierteelt - glastuinbouw - groenten - horticulture - life cycle - chromosomes - pollination - fertilization - spermatozoa - genetic parameters - embryos - ova - fruit vegetables - ornamental horticulture - greenhouse horticulture - vegetables
Bestuiving en bevruchting zijn natuurlijke processen om nakomelingen te krijgen. In de sierteelt zijn echter steeds minder gewenst, omdat ze de bloemkwaliteit ernstig aantasten. Bevruchting is het samengaan van twee sets chromosomen. De mannelijke zaadcel moet daarvoor de vrouwelijke eicel bereiken. Een gecompliceerd proces dat op veel fronten mis kan gaan. Daarom zoeken veredelaars ook bij vruchtgroenten manieren om het te omzeilen
Embryotemperatuur betere maat voor controleren broedproces
Lourens, A. - \ 2009
V-focus 6 (2009)2. - ISSN 1574-1575 - p. 42 - 43.
pluimveehouderij - pluimvee - embryo's - broeden - eieren - poultry farming - poultry - embryos - incubation - eggs
De embryotemperatuur in de broedeieren is een betere maat voor het controleren van het broedproces dan de machinetemperatuur. Variaties in de embryotemperatuur kunnen namelijk een groot effect hebben op de uiteindelijke resultaten. Dat blijkt uit het promotieonderzoek van ASG-onderzoeker Sander Lourens. De eischaaltemperatuur blijkt een goede graadmeter te zijn voor het bepalen van de embryotemperatuur
Embryo temperature during incubation: practice and theory
Lourens, A. - \ 2008
Wageningen University. Promotor(en): Bas Kemp, co-promotor(en): Henry van den Brand; R. Meijerhof. - S.l. : S.n. - ISBN 9789085852582 - 131
kuikens - embryo's - temperatuur - broeden - embryonale ontwikkeling - warmteproductie - warmteverlies - eierschaal - incubators - pluimveehouderij - chicks - embryos - temperature - incubation - embryonic development - heat production - heat loss - egg shell - incubators - poultry farming
(Key words: incubation, embryo temperature, embryonic development, heat production, heat loss)
Until recently, all incubator studies were performed using a constant machine temperature (MT). But it is embryo temperature (ET) that is of importance to the embryo, and not MT. In practice, MT is often measured at one location within the incubator, while ET can vary between eggs within an incubator. Furthermore, ET is the result of the balance between heat production (HP) and heat loss, and if HP or heat loss is affected it may have consequences for ET. Aim of this dissertation was to identify the causes of variable ET and to describe the consequences of variable ET on embryonic development, hatchability, HP and chick quality. Because the direct measurement of ET is destructive, it was chosen in this dissertation to use eggshell temperature (EST) measurements as a reflection of ET.
Long term deviations of 1.1ºC away from a constant EST of 37.8ºC decreased embryonic growth, development, hatchability, and the ability of young chicks to maintain high body temperatures after hatching, especially under cold stress. HP was considered to be positively related to embryonic development, because when more energy is used for growth, HP during incubation will increase and chicks will subsequently hatch with a larger yolk free body and with a lower amount of energy left over in the residual yolk. Within the EST zone of 1.0ºC below and above 37.8ºC it was observed that HP increased linearly with short term EST increments, and the response of the embryos to EST variations was identical in young, mid term and late term embryos. Maximizing HP based on metabolic responses to EST fluctuations will therefore increase EST above the studied EST zone, leading to decreased embryonic growth and increased embryonic mortality. High EST increases the demand for oxygen, so oxygen availability was expected to limit HP and embryonic growth more at higher EST profiles than at EST of 37.8ºC. However, despite the fact that HP at day 18 was highest for the combination of high EST with high oxygen concentration, embryonic development did not show the same relationship. At EST above 37.8ºC, the amount of energy utilized from the egg content remained the same, but the efficiency of energy transfer (EYFB) between egg and embryo decreased. Factors as egg size, breed, and oxygen availability affected HP through changes in energy utilization, and had no effect on EYFB.
In this thesis, the importance was shown to measure and control ET during incubation and not MT. Factors were identified that affect ET through changes in HP and heat loss. When ET is controlled and maintained at a constant level of 37.8ºC, embryonic development may be improved by measures that increase energy utilization through increments in gas exchange, which will increase HP.
Arabidopsis SOMATIC EMBRYOGENESIS RECEPTOR KINASE Proteins Serve Brassinosteroid-Dependent and -Independent Signaling Pathways
Albrecht, C. ; Russinova, E.T. ; Kemmerling, B. ; Kwaaitaal, M.A.C.J. ; Vries, S.C. de - \ 2008
Plant Physiology 148 (2008)1. - ISSN 0032-0889 - p. 611 - 619.
leucine-rich repeat - gene family - thaliana - bak1 - bri1 - sequence - embryos - erecta - anther - plants
The Arabidopsis (Arabidopsis thaliana) SOMATIC EMBRYOGENESIS RECEPTOR KINASE (SERK) genes belong to a small family of five plant receptor kinases that are involved in at least five different signaling pathways. One member of this family, BRASSINOSTEROID INSENSITIVE1 (BRI1)-ASSOCIATED KINASE1 (BAK1), also known as SERK3, is the coreceptor of the brassinolide (BR)-perceiving receptor BRI1, a function that is BR dependent and partially redundant with SERK1. BAK1 (SERK3) alone controls plant innate immunity, is also the coreceptor of the flagellin receptor FLS2, and, together with SERK4, can mediate cell death control, all three in a BR-independent fashion. SERK1 and SERK2 are essential for male microsporogenesis, again independent from BR. SERK5 does not appear to have any function under the conditions tested. Here, we show that the different SERK members are only redundant in pairs, whereas higher order mutant combinations only show additive phenotypes. Surprisingly, SERK members that are redundant within one are not redundant in another pathway. We also show that this evolution of functional pairs occurred by a change in protein function and not by differences in spatial expression. We propose that, in plants, closely related receptor kinases have a minimal homo- or heterodimeric configuration to achieve specificity.
AtSERK1 expression precedes and coincides with early somatic embryogenesis in Arabidopsis thaliana
Salaj, J. ; Recklinghausen, I.R. von; Hecht, V. ; Vries, S.C. de; Schel, J.H.N. ; Lammeren, A.A.M. van - \ 2008
Plant Physiology and Biochemistry 46 (2008)7. - ISSN 0981-9428 - p. 709 - 714.
arabinogalactan proteins - developmental pathway - tissue cultures - callus-cultures - cell - gene - embryos - carrot - plants - methacrylate
The Arabidopsis thaliana primordia timing (pt) mutant was transformed with an AtSERK1::GUS construct. Liquid cultures of this line were used to study the relationship between somatic embryogenesis and the expression of SOMATIC EMBRYOGENESIS RECEPTOR-LIKE KINASE (AtSERK1) as a marker for cells competent to form embryos. In order to search for the expression of AtSERK1::GUS during early stages of somatic embryogenesis, histochemical as well as immunochemical approaches were used for the detection of ß-glucuronidase (GUS). Four sites of AtSERK1 expression were found in the embryogenic cultures: in embryogenic callus, where primary somatic embryos developed; in the basal parts of primary somatic embryos; in the outer layers of cotyledons of primary somatic embryos where secondary embryos were formed; and in provascular and vascular strands of developing somatic embryos. The in vitro expression of AtSERK1::GUS coincides with embryogenic development up to the heart-shaped stage. Prior to the expression in embryos, AtSERK1 was expressed in single cells and small cell clusters, indicating that AtSERK1 indeed marks embryogenic competence. Its expression in (pro)
Mechanism of endocarp-imposed constraints of germination of Lannea microcarpa seeds
Neya, O. ; Hoekstra, F.A. ; Golovina, E.A. - \ 2008
Seed Science Research 18 (2008)01. - ISSN 0960-2585 - p. 13 - 24.
rhus species anacardiaceae - physical dormancy - ftir microspectroscopy - desiccation tolerance - ethylene - spectroscopy - metabolism - embryos - sativa
Lannea microcarpa, a multipurpose tree species from the dry African savanna, sheds seeds that often display inhibition of germination. The underlying mechanism was investigated using seeds processed from fully matured fruits collected from natural stands in Burkina Faso. Germination of fresh seeds was variable (16¿28%), while they did not germinate after drying and rehydration. Mechanical scarification of the endocarp at the proximal end of the seeds increased germination to 83¿94%. Scarification on the distal end led to delayed radicle emergence through the produced hole in c. 40% of the seeds. The endocarp was permeable to water and respiratory gases. Increased water content in scarified seeds was associated with radicle extension during germination. Intact and scarified non-germinated seeds displayed a moderate rate of respiration with respiratory quotient (RQ) values of c. 1. Respiration increased and RQ decreased to c. 0.7 with radicle emergence. Ethylene evolution peaked in both intact and scarified seeds at the beginning of incubation and then decreased to low values. Inhibition of ethylene production by 1¿5 mM 2-amino-ethoxyvinylglycine (AVG) caused only a partial decrease of germination of the scarified seeds. Intact non-germinated seeds gradually lost viability during incubation at 30°C, but could be rescued by delayed scarification before day 15 of incubation. It is concluded that radicle emergence in dry L. microcarpa seeds is inhibited only mechanically. The mechanical properties of the endocarp are attributed to irreversible structural changes of the lignin¿hemicellulose complex, which occur during drying.
|Nog even verder broeden
Brand, H. van den; Klein Swormink, B. - \ 2007
De Pluimveehouderij 37 (2007)32. - ISSN 0166-8250 - p. 14 - 15.
pluimveehouderij - pluimvee - eieren - embryo's - embryonale ontwikkeling - broedeieren - poultry farming - poultry - eggs - embryos - embryonic development - hatching eggs
Wageningen UR deed onderzoek naar het onder water bewaren van broedeieren. In de eerste fase van ontwikkeling verloopt de embryonale ontwikkeling erg goed, maar in de tweede fase moet die voorsprong weer worden prijs gegeven
Functional genomics of microspore embryogenesis
Hosp, J. ; Faria Maraschin, S. de; Touraev, A. ; Boutilier, K.A. - \ 2007
Euphytica 158 (2007)3. - ISSN 0014-2336 - p. 275 - 285.
wheat triticum-aestivum - brassica-napus l - pollen embryogenesis - cell-death - barley androgenesis - arabidopsis pollen - messenger-rna - abscisic-acid - in-vitro - embryos
Isolated plant microspores, when stressed and cultured in vitro, can be diverted from their normal gametophytic pathway towards sporophytic development, with the formation of haploid embryos and ultimately doubled-haploid plants. This process is called androgenesis or microspore embryogenesis, and is widely used in plant breeding programmes to generate homozygous lines for breeding purposes. Protocols for the induction of microspore embryogenesis and the subsequent regeneration of doubled haploid (DH) plants have been successfully developed for more than 200 species. These practical advances stand in stark contrast to our knowledge of the underlying molecular genetic mechanism controlling this process. The majority of information regarding the genetic and molecular control of the developmental switch from gametophytic to sporophytic development has been garnered from four intensely studied (crop) plants comprising two dicotyledonous species, rapeseed (Brassica napus) and tobacco (Nicotiana tabacum), and two monocotyledonous species, wheat (Triticum aestivum) and barley (Hordeum vulgare). In these species the efficiency of microspore embryogenesis is very high and reproducible, making them suitable models for molecular studies. In the past, molecular studies on microspore embryogenesis have focussed mainly on the identification of genes that are differentially expressed during this developmental transition and/or early in embryo development, and have identified a number of genes whose expression marks or predicts the developmental fate of stressed microspores. More recently, functional genomics approaches have been used to obtain a broad overview of the molecular processes that take place during the establishment of microspore embryogenesis. In this review we summarise accumulated molecular data obtained in rapeseed, tobacco, wheat and barley on embryogenic induction of microspores and define common aspects involved in the androgenic switch
The potential of cryopreservation and reproductive technologies for animal genetic resources conservation strategies
Hiemstra, S.J. ; Lende, T. van der; Woelders, H. - \ 2006
In: The Role of Biotechnology in Exploring and Protecting Agricultural Genetic Resources / Ruane, J., Sonnino, A., Rome : FAO - ISBN 9789251054802 - p. 45 - 60.
genetische bronnen van diersoorten - cryopreservering - vee - vissen - kunstmatige inseminatie - voortplanting - technologie - conservering - embryo's - embryokloneren - spermaconservering - genetische diversiteit - ex-situ conservering - animal genetic resources - cryopreservation - livestock - fishes - artificial insemination - reproduction - technology - conservation - embryos - embryo cloning - semen preservation - genetic diversity - ex situ conservation
This chapter focuses on ex situ conservation. An overview of the state of the art cryopreservation and reproductive technology for farm animals and fish is followed by a discussion on the implications of ex situ conservation strategies. Ex situ conservation of genetic material from livestock and fish through cryopreservation is an important strategy to conserve genetic diversity in these species. Conservation strategies benefit from advances in cryopreservation and reproductive technologies. Choice of genetic material type to be preserved for different species depends highly on objectives, technical feasibility (e.g. collection, cryopreservation), costs and practical circumstances
Use of the SSLP-based method for detection of rare apomictic events in a sexual AtSERK1 transgenic Arabidopsis population
Kantama, L. ; Lambert, J.M. ; Hu, H. ; Jong, H. de; Vries, S.C. de; Russinova, E. - \ 2006
Sexual Plant Reproduction 19 (2006)2. - ISSN 0934-0882 - p. 73 - 82.
polycomb group gene - poa-pratensis l - somatic embryogenesis - apomixis - expression - fertilization - seeds - embryos - growth - strategies
Here we present a screening method to evaluate the potential of genes to transfer aspects of apomixis into sexual crop plants. Based on the assumption that an apomictic progeny is an exact genetic replica of the mother plant we employed a set of single sequence length polymorphism (SSLP) markers to identify individuals displaying heterozygosity fixation in segregating sexual populations as an indication of rare apomictic events. Here we present the results of such a study using the Arabidopsis thaliana SOMATIC EMBRYOGENESIS RECEPTOR KINASE 1 (AtSERK1) gene expressed under the control of the AtLTP1 promoter in sexual Arabidopsis plants. In one of the three tested F2 transgenic populations expressing the AtLTP1::AtSERK1 construct we observed two plants with heterozygosity maintenance for the full set of SSLP markers indicating a possible clonal inheritance. However, as their offspring revealed a close to binomial segregation for a number of heterozygous loci, it was concluded that these two putative apomictic plants either lost their clonal ability in the next generation or resulted from incidental recombination events displaying the genotype of the parent
PCIB an antiauxin enhances microspore embryogenisis in microspore culture of Brassica juncea
Agarwal, P.K. ; Agarwal, P. ; Custers, J.B.M. ; Liu, C.M. ; Bhojwani, S.S. - \ 2006
Plant Cell, Tissue and Organ Culture: an international journal on in vitro culture of higher plants 86 (2006)2. - ISSN 0167-6857 - p. 201 - 210.
doubled haploid plants - immediate colchicine treatment - napus cv topas - oilseed rape - desiccation tolerance - efficient production - anther cultures - heat-shock - embryos - induction
An efficient protocol to improve microspore embryogenesis is established in an important oleiferous crop, Brassica juncea (Indian mustard). Colchicine was used for enhancing microspore embryogenesis and also to obtain doubled haploid embryos. Colchicine at high concentrations (>10 mg l¿1), for 24 h, proved convenient for direct recovery of diploid embryos. Higher temperature treatment and an antiauxin PCIB (p-chlorophenoxyisobutyric acid) enhanced microspore embryogenesis significantly as compared to colchicine. An increase in temperature from 32°C to 35°C proved very efficient in increasing embryogenesis by 10-fold. The highest embryogenesis rate was obtained when PCIB was added at 35°C in the culture after 1 day of culture initiation. 20 ¿M PCIB could enhance microspore embryogenesis by 5-fold. Different abnormal shapes of embryos like lemon, banana, flask and fused cotyledons were observed. Both normal and fused cotyledonous embryos showed normal germination when transferred on the B5 basal medium