Some plants Like monocots do have a limited range of genotypes and are prune to callus formation

Abhishek Bhandawat According to De Cleene, Marcel, and Jozef De Ley. "The host range of crown gall." The botanical review 42.4 (1976): 389-466.:

Among angiosperms, 58% of the analyzed dicotyledonous species were susceptible (596 species in total), they belonged to 76% of the studied plant families (84 families in total). On the contrary, among monocotyledons, only 8% of the species studied by the authors, representing 10% of the studied genera, turned out to be susceptible (De Cleene, De Ley, 1976). All of them belonged to the orders Liliales and Arales.

Tumors after artificial inoculation were described for the slime mold Physarum polycephalum Schwein, (Myxophyta, Myxomycetes), champignon Agaricus

campestris L. (Fungi, Basidiomycetes), red algae family Florideae (Rhodophyta), bracken common Pteridium aquilinum (L.) Kuhn (Pteridophyta, Filices)

and moss Pylaisiella selwynii Kindb., (Hypnaceae, Bryophytes).

There are at least 38 pathogen-susceptible species of various families

in the Coniferopsida among gymnosperms. It is determined that in the families Cupressaceae and Taxaceae susceptible species contain less quinic and shikimic acids (De Cleene, De Ley, 1976).

It is important that Lab strains of Agrobacterium represent a very narrow part of the pathogen population, and we have to isolate bacteria virulent to "recalcitrant plants" and develop new lab strains from them.

Acetosyringone, the wound signal hormone helps somehow and to some extent solve this problem but needs a lot of experimenting for the right concentration and cocultivation regimes.