Changes in in vivo protein complements in drying leaves of the desiccation-tolerant grass Sporobolus stapfianus and the desiccation-sensitive grass Sporobolus pyramidalis

Protein synthesis in vivo was studied with two-dimensional SDS-PAGE of extracts of leaves on intact drying plants of Sporobolus stapfianus (a desiccation-tolerant grass) and S. pyramidalis (a desiccation-sensitive species). Protein complements were also studied in dried, detached leaves of S. stapfianus (detached leaves are also desiccation-sensitive). Extensive changes in in vivo proteins were observed in S. stapfianus plants drying intact: 25 novel proteins, 10 proteins augmented, 13 proteins decreased and 7 proteins disappeared. Two main phases could be distinguished in leaves as plants dry. In the first phase (85-51% relative water content (RWC) range), 10 novel proteins appeared and 2 proteins increased in content. In the second phase (37-3.5% RWC), 15 novel proteins appeared and 2 proteins increased in content. Some changes in protein patterns were also observed in desiccation-sensitive leaves, i.e. in (a) S. stapfianus leaves drying detached and in (b) drying S. pyramidalis leaves attached. These changes were fewer than those in desiccation-tolerant leaves, i.e. in (c) S. stapfianus leaves drying on intact plants; that is, (a) and (b) differed from each other and from (c), which indicates that there is no common injury-related pattern of protein change. These results are consistent with the view that changes in protein complements accompany the induction of desiccation tolerance in drying plants of S. stapfianus.