Opposite function of hstore each function

Each function returns key/value pairs from hstore type.
Is there any opposite function that returns hstore type from key/value rows?

I know hstore (text[], text[]) can construct it. Is there any other choice?

I have a table with ID & Description columns and want to return hstore type
(ID1=>Desc1,ID2=>Desc2,....) that matches a query condition.
>From top of my head, this is the only query I can think of

SELECT hstore ((SELECT array(SELECT CAST(ID as TEXT) FROM T1 WHERE ....)),
(SELECT array(SELECT Description FROM T1 WHERE ...)))

But I don't want to run the same where condition twice.

If I can construct a single array (K1, V1, K2, V2, ...) from key/value
rows, then I can use hstore(text[]) function.

Of course, I can create a stored function that loops through the rows and
construct it, that's the last resort and I don't like that approach.

Any idea?

Thank you,
Choon Park