From the looks of things, it’s unofficially bluegrass week at Music City Roots, and the lineup’s a strong, generation-spanning one. Mandolin-playing Jesse McReynolds made up one-half of the influential brother duo Jim & Jesse from just after World War II until Jim passed away in 2002. He’s released a half-dozen albums as a solo act, and the latest happens to be a tribute to The Grateful Dead (the feeling’s mutual, since Jerry apparently dug Jim & Jesse). J.D. Crowe made his most indelible and progressive mark on the banjo from the ’70s on, leading The New South, a band that served as a training ground for the likes of Tony Rice and Ricky Skaggs. Donna Ulisse is the odd woman out, having begun her career as a fine, natural-voiced major-label country singer (think Dolly, not Reba) in the early ’90s before drifting toward bluegrass — first as a songwriter, and now as a singing, writing bandleader.