Junior has been linked with Bartra's former club Barcelona.
"He is a player who has shown that he has a lot of potential, quality and the ability of being in the right place at the right time," said Bartra.
"He is fine at Betis at the moment and I hope we can continue enjoying him here."
Bartra was also asked about his new coach, Rubi.
"He is a very football person; he loves tactics and strategy. On a personal level I can say that he gave me a lot of advice during those years.
"He is one of those coaches that can make the club bigger and he is what Betis are looking for on a philosophical level.
"He is a great coach as he has demonstrated for several seasons and he has experience, while he is a great fit to the club due to his style and philosophy."