Gametic Embryogenesis in Triticum: a Study of Some Critical Factors in Haploid (Microspore) Embryogenesis

2006 ◽  
pp. 321-342 ◽  
Author(s):  
L. Cistué ◽  
K. J. Kasha
Keyword(s):  
Microspore Embryogenesis ◽  
Critical Factors ◽  
Gametic Embryogenesis

scholarly journals Microspore embryogenesis in vitro: the role of stresses

2019 ◽  
Vol 23 (1) ◽  
pp. 86-94 ◽  
Author(s):  
T. I. Djatchouk ◽  
O. V. Khomyakova ◽  
V. N. Akinina ◽  
I. A. Kibkalo ◽  
A. V. Pominov
Keyword(s):  
Microspore Culture ◽  
Doubled Haploids ◽  
Embryo Sac ◽  
Microspore Embryogenesis ◽  
Gametic Embryogenesis ◽  
Chemical Pretreatments ◽  
Dh Lines

Gametic embryogenesis is one form of totipotency of plant cells, in which either male or female gametes are induced to form embryoids (sporophytes). Regeneration of haploid plants from embryoids and subsequent chromosome duplication result in doubled haploids and DH-lines. The production of haploids and doubled haploids (DHs) through gametic embryogenesis allows a single-stage development of complete homozygous lines from heterozygous plants. The development of effective haploid protocols to produce homozygous plants has a significant impact on plant breeding, shorting the time and costs required to establish new cultivars. There are several available methods to obtain haploids and DHs-lines, of which anther or isolated microspore culture in vitro are the most effective. Microspore embryogenesis is more commonly applied. This is in part because more male gametophytes are contained in a single anther compared to the single female gametophyte per embryo sac. Microspore embryogenesis is regarded as one of the most striking examples of plant cell totipotency. The switch of cultured microspores from gametophytic to sporophytic mode of development has been induced by stress treatments of various kinds applied to donor plants, inflorescences, buds, anthers or isolated microspores both in vivo and in  vitro. Physical or chemical pretreatments (cold and heat shock, sugar starvation, colchicine, n-butanol, gametocydes) act as a trigger for inducing the sporophytic pathway, preventing the gametophytic pathway development of microspore. The recent investigations have revealed that cold pretreatment during microspore reprogramming acts rather as an anti-stress factor alleviating the real stress caused by nutrient starvation of anthers or microspores isolated from donor plants. Under stress pretreatment a vacuolated and polarized microspore transformed into a depolarized and dedifferentiated cell, which is an obligatory condition for reprogramming their development. We summarize data concerning the role of various stresses in the induction of microspore embryogenesis and possible mechanisms of their action at cellular and molecular levels. Identification of new stresses allows creating efficient protocols of doubled haploid production for end-user application in the breeding of many important crops.

Refining our understanding of the “elephant in the room”

2020 ◽  
Vol 43 ◽  
Author(s):  
Andrew Whiten
Keyword(s):  
Social Cognition ◽  
Cultural Evolution ◽  
Cognitive Abilities ◽  
Critical Factors ◽  
Technological Culture

Abstract The authors do the field of cultural evolution a service by exploring the role of non-social cognition in human cumulative technological culture, truly neglected in comparison with socio-cognitive abilities frequently assumed to be the primary drivers. Some specifics of their delineation of the critical factors are problematic, however. I highlight recent chimpanzee–human comparative findings that should help refine such analyses.

EVALUATION OF MECHANICAL SYSTEMS USED IN PERFUSION

1972 ◽  
Vol 68 (2_Supplb) ◽  
pp. S44-S73 ◽  
Author(s):  
Eugene F. Bernstein
Keyword(s):  
Mechanical Systems ◽  
Organ Perfusion ◽  
Critical Factors ◽  
System 2 ◽  
Common Problems ◽  
Mechanical Components ◽  
Perfusion Experiment ◽  
Selection Of

ABSTRACT Among the critical factors in organ perfusion are (1) the mechanical components of the system, (2) the composition of the perfusate, and (3) the perfusing conditions. In this review, particular consideration is given to the pump, the oxygenator, and cannulas in such systems. Emphasis is placed upon the selection of pertinent equipment for the goals of a particular perfusion experiment, based upon the criteria of adequacy of the perfusion. Common problems in organ perfusion are summarized, and potential solutions to the perfusion problem, involving either biologic or mechanical extracorporeal systems, are suggested.

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