Bo-

The prefix bo- is a passivizer that turns verbs into a passive form.

Refgram definition

More on this in the refgram
Morphology: Passivizer prefixes

In the refgram, bo- is shown to turn transitive verbs into new transitive verbs:

cho
___ likes ___

bọcho
___ is liked by ___

Bu bọcho jí kúne.
I'm not liked by the dog.

It doesn't say what bo- does for intransitive or ditransitive verbs.

Semi-official definition

However, Hoemaı has since suggested that it might be better for bo- to move the direct object to the front and delete the old subject entirely.

bọcho
___ is/gets liked.

bọdo
___ is/gets given to ___.

This means we can no longer use bộtua and bộtao as agent tags, and so we must use a new word (like ecı).

Shua múao êcı jí.
The tree falls, caused by me.

Syntax analysis (advanced)

Syntactically, one way of understanding this behavior is by treating bo- as a 𝑣 head. Just like in the case of unaccusative verbs like ruqshua, bo-_𝑣 does not take a specifier (corresponding to the Subject); unlike monotransitive verbs like maı, the “subject” of a bo-X for some ditransitive X is syntactically not a Subject but an Indirect Object (SpecVP). Compare:

do jí súq báq shamu

bọdo súq báq shamu. bo-_𝑣 takes no Spec𝑣P and súq, the first argument or “Subject”, fills IO.

Unofficial definition

An unofficial proposal suggests that bo- always makes intransitive verbs, replacing both the old subject and indirect object by sá.

bọcho
___ is/gets liked (by someone).

bọdo
___ is/gets given (to someone by someone).