NASHVILLE, Tenn. -- The Astros acquired the starting pitching they sought when they made a trade with the Rockies late Tuesday to land right-hander Alex White and a Minor League arm in exchange for reliever Wilton Lopez and a player to be named later.

Less than a week after the Astros tried to send Lopez to the Phillies, they were able to use the arbitration-eligible relief pitcher to acquire White and right-hander Alex Gillingham. White appeared in 23 games (20 starts) for the Rockies last season and was 2-9 with a 5.51 ERA.

White split the season between Colorado and Triple-A Colorado Springs, where he went 3-4 with a 3.71 ERA. He will battle for a spot in the rotation along with Jarred Cosart, Dallas Keuchel and Philip Humber, among others.

"We believe he's a pitcher who's capable of being a big part of our organization, not only for the next year but a long time to come," Astros general manager Jeff Luhnow said.

The trade is the latest in a series of deals made by Luhnow in which he jettisoned a veteran player in exchange for youngsters. Earlier this year, he traded Carlos Lee, J.A. Happ, Brett Myers, Chris Johnson and Wandy Rodriguez, among others.

Lopez has been a workhorse member of the Astros' bullpen the past three years, going 6-3 with a 2.17 ERA last season in 64 games. He also had a career-high 10 saves after assuming the club's closer role following the trade of Myers and ineffectiveness of Francisco Cordero.

He posted the lowest walks-per-nine-innings ratio among all NL relievers (1.09) last season after setting the franchise record in 2010 by issuing only five walks in 67 innings pitched. He began last season by facing 78 batters without issuing a walk.

"Wilton Lopez had been a big part of our organization for the last few years and it's definitely a loss for us from that perspective," Luhnow said. "He was our closer at the end of the year and he was a very effective reliever, but when we look at where we are as an organization and what we have to accomplish, to be able to bring in a starting pitcher like Alex White, who's at the beginning of his Major League career and has a lot of upside. ... It's a guy we believe in Minute Maid Park will be an effective starter for us. We felt this was an opportunity we needed to take advantage of."

The loss of Lopez puts the Astros in search of a closer. Luhnow said the team has internal candidates to fill the spot in Hector Ambriz, Rhiner Cruz and Fernando Rodriguez, as well as Cosart if he doesn't make the rotation. The team has made a list of four or five closers it plans to explore in free agency.

"Right now it's an open competition and we're going to look internally and externally," Luhnow said.

Gillingham, 22, went 6-8 with a complete game and a 3.66 ERA in 19 starts at Class A Asheville of the South Atlantic League last season. An 11th-round Draft pick in 2011 out of the University of Loyola Marymount, Gillingham made his professional debut in 2011 for Rookie League Casper and was the only pitcher in the Pioneer League to toss a perfect game that season.