I’ve studied this exact question for majority of crops. Phylogenetic Trees paired with understanding the hybridization barriers is all you need to know to see if crops species are cross compatible.
I am the Phylogenetic Tree Plug, I gotchu on pretty much any Phylogenetic Tree you need for any Crop Species (Phylogenetic trees are basically the family tree of any crop species, it shows you which species are closely related & thus more likely cross-comptaible). Tell me what crop species tree you need here : I'm the Phylogenic Tree Plug, What do you need?
I can also tell you what is likely & not-likely cross-compatible. Ask away!
It’s also important to note that wide hybrids are possible, especially with outside the box methods such as
- Mentor Pollination : Pollen mixing by getting the same ovary pollinated by multiple diverse pollen sources.
- Mentor grafting : Young Hybridized Plants or Seedlings have more flexible/plastid genomes & thus more likely to horizontally transfer genes when grafted. The effect is stronger on wide hybrid seedlings grafted onto a mature plant (You use older plants to mentor hybrid seedlings).
These 2 methods (I learned from Russian Plant Breeder Ivan Michurin) when combined can bypass a lot of hybridization barriers, Mentor Pollination works especially well with Interspecies Squash (Cucurbita spp.) Hybrids. Mentor grafting has been tested on Eggplants & successfully can transfer purple fruit color into white fruited plants.
It’s also important how any plant family/genus evolved it’s hybridization barriers, some plant families often make inter-generic hybrids & others have strong hybridization barriers even within the same family.
There is a trend where plant families that evolved through Polyploidization events (Chromosome doubling) often bypass mis-matching chromosome numbers hybridization barriers. Good examples of this are
- Brassiceae tribe, Intergeneric hybrids can be made between Raphanus x Brassica to make the new hybrid genus ×Brassicoraphanus but the same concept can be expanded to any other species/genus in the Brassiceae tribe. They just simply double chromosome numbers to bypass mis-matching chromosome number hybridization barriers.
- All Claytonia species are cross-comptaible, they give zero fucks about mis-matching chromosome numbers.
- Rose family also has plenty of Intergeneric hybrids, fairly easy to do actually (especially when combined with Mentor Pollination & Mentor Grafting)
- Grass Family is also easily makes intergeneric hybrids
- Cactus Family also makes wide intergeneric hybrids
Good examples of plant familiy/genus where mis-matching chromosome numbers are a real hybridization barrier are
- Alliums like Garlic & Onion, often a mis-matching chromosome number makes plants/offspring sterile. This probably extends to many other plant families of the Asparagales order (except Orchids, those easily do intergeneric hybrids).
- Gourd Family (Cucurbitaceae), Mis-matching chromosome numbers are strong hybridization barriers. think how we got seedless watermelons (best example)!
- Some Solanaceae (Nightshade Family) Plants
- Some Fabaceae (Bean Family) Plants