http://www.ejbiotechnology.info/index.php/ejbiotechnology/article/view/v13n1-4/1082
http://scialert.net/fulltext/?doi=ajps.2009.276.284
ABA has a distinct role in zygotic embryo development, i.e. during normal seed development. A peak of ABA in developing seeds is observed at the time of maturation when the seed starts to lose water and dry (desiccation). No other plant part has such high desiccation tolerance than seed. Seeds can be dried to 8 - 12 % moisture content in many orthodox species and they are still alive and ABA is known to give desiccation tolerance to the seed/embryo.
Researchers mimic this phenomenon when they want to mature the somatic embryos which are actually artificial. A short exposure to ABA during the maturation period (torpedo stage in many species) sometimes coupled with a short desiccation step, helps produce somatic embryos with good germination capacity and storability. As somatic embryos do not have the genetic programming present in zygotic embryos to produce ABA at the right time, we have to add ABA exogenously to get the same effect. It has been shown that when the ABA exposure time and rate is optimised, one can dry the somatic embryos to the levels found in true seeds. ABA enhances the storage of reserves in the somatic embryo and prevents precocious germination of embryos when they are produced without appropriate control of the process using growth regulators. Cells of somatic embryos that get ABA treatment are more cytoplasmic and smaller than in embryos growing on media without control. The latter have elongated distorted cells with large vacuoles. Therefore in many somatic embryo induction protocols, ABA plays an important role, particularly during maturation.
Somatic embryo (SE) are bipolar structures having a radicle and a plumule. The radicular end is always oriented towards the centre of callus or cell mass, while the plumule end sticks our of cell mass. In many somatic embryos, radicle is suppressed so that they often do not produce roots. In such cases, roots have to be regenerated from the shoots produced by germinating embryos. Somatic embryos often show abnormal developmental features. Such abnormalities are generally overcome by the presence of ABA. all in all ABA has a role in maturation of SEs.
Thanks four your answers.
ABA usually used for maturation in somatic embryos, but there are little reports that said ABA have positive effect on induction of somatic embryogenesis. the role of ABA on maturation in clearly but whats the reason of induction role?
Hi Shirin,
The attached research paper suggested that ABA acts as a signal substance which render 'some substances' (they don't know) from 'shoot apices' downwards from hypocotyl to activate the induction of one form of somatic embryogenesis (SE) in carrots in this case. When the 'shoot apices' were chopped off, there was no more SE induction effect.
Some anatomical studies proved that ABA stimulates epidermis formation in prosomatic embryos.
- Badges
- Science topic
- Similar topics
- Biological Science
- Botany
- Plant Biology
- Plant Biotechnology