The most important PGR for induction somatic embryos are cytokinins e.g., benzyladenine (BA) and thidiazuron (TDZ) and auxins e.g., indole butyric acid (IBA) and naphthalene acetic acid (NAA).

Dear @Reza Ghahremani

Different plant species, such as C. canephora, A. thaliana, and Musa spp. responded successfully to the Somatic Embryogenesis induction using different explants, conditions, and concentrations of PGR. The details can be accessed at:

https://www.frontiersin.org/articles/10.3389/fpls.2019.00077/full

https://link.springer.com/article/10.1007/BF00234290

https://link.springer.com/article/10.1186/s13007-020-00655-9

https://www.sciencedirect.com/science/article/pii/B9780128022214000066

https://www.mdpi.com/2223-7747/8/6/144

According to my experiences, different plants require different type of PGRs (maybe a combination of certain PGRs) so it is difficult to determine a PGR that work for all species. For example, cytokinin plays a major part in tobacco somatic embryogenesis, on the other hand, auxin contributes more in oil palm.

Reza Ghahremani

Somatic embryogenesis in various species is regulated in a specific way, in response to exogenous stimuli produced by the use of plant growth regulators or certain stress conditions. The induction of SE in vitro can be accomplished through two pathways. For indirect somatic embryogenesis, we use 2,4-D, which will produce non-embryogenic calli sometimes and they can be converted into embryogenic calli by the application of cytokinins alone or in combination with auxins. In the case of direct somatic embryogenesis, it is uncertain to predict the type of PGR. Some species like Euphorbia respond even in BAP alone, Hybanthus in BAP and IAA, etc.

In general, 2,4-dichlorophenoxyacetic acid (PGR) is the most important plant growth regulator for initiation of somatic embryogenesis in melon species. The young leaf explants were excised from in vivo grown plants and used for induction of embryogenesis and organogenesis.

https://www.ncbi.nlm.nih.gov › pmc

High efficient somatic embryogenesis development from leaf cultures of ...

In most species studied in which growth regulators are needed for induction of somatic embryogenesis, auxins and cytokinins are key factors determining the embryogenic response.

https://www.sciencedirect.com › topics

Somatic Embryogenesis - an overview | ScienceDirect Topics

https://passel2.unl.edu/view/lesson/a2f44b5b9a27/10,kindly check this link.

https://www.jstor.org/stable/20461690,kindly check this link.

Dear respected Arbind K. Choudhary,

I appreciate you for your valuable comments.

Dear Chris Darmawan,

I appreciate you for your response.

Dear M. Manokari,

Thanks for your reply.

Dear Faraed Salman,

I like to appreciate for your concideration.

In most species studied in which growth regulators are needed for induction of somatic embryogenesis, auxins and cytokinins are key factors determining the embryogenic response. In general, 2,4-dichlorophenoxyacetic acid (PGR) is the most important plant growth regulator for initiation of somatic embryogenesis

Dear respected Prof. Kourosh Vahdati,

I appreciate you for your valuable comments.

In most plant specie, 2,4-D is the most frequently used for somatic embryogenesis. It can also be used for callus induction with other auxins or CKKs. BAP, TDZ and a combination of these CKKs with small amount of NAA could give good results.

Dear Bekele Abebie,

I like to appreciate for your concideration.

it depends on genotype as well. High concentration of cytokinin may induce SE on particular genotype or not.

I agree with Bekele Abebie's comments. PGR types and concentrations will depend on the plant species.

Cytokinen and giberrelic acid for higher chances of succes in somatic hybridization.

Yes, it is true that SEs induction depends on the genotype of plant and the use of PGRs but use of TDZ is always useful to induce SEs in all almost all plants.

The most commonly used PGR is 2,4-D but TDZ has also given good results in some perennial species like mango in SEs.

After callus induction, increasing of sucrose concentration in media also induces somatic embryogenesis..

We used BA, BAP, TDZ and a combination of BA/BAP with small amount of NAA for orchid direct somatic embryogenesis. Interestingly, we obtained this kind of embryo recently without PGRs and just with modified media.

The use of TDZ for dicots and the use of 2,4-D for monocots generally work for induction of somatic embryos.

TDZ in very little amounts... in higher amounts with monocots we experienced negligible shoot elongation. plus do not screwcap jars, instead use cotton plugs.. aeration is important.. you can as well try with higher temperature shifts in day time incubation periods.

TDZ and BAP in 1:2 ratio worked for Capsicum.