The contraction in inverted repeat regions in the complete plastome sequence of Cressa cretica L

Abstract

Plastome studies have been the focus of research in plant molecular evolution and systematics. C. cretica L. (Convolvulaceae) is a halophyte, habitat in the ecologically challenged area with high salinity and drought. The complete physical map of plastome revealed that it is 141,419bp long, circular molecule. It contains typical quadripartite structure of large single copy region (LSC 94,808bp), small single copy region (SSC 32,527bp) separated by a pair of inverted repeat regions (IRs 7042bp). This plastome is compared with the complete plastomes of other members of Convolvulaceae showed notable distinctions. An exceptional shift in IRs to SC regions is experienced in C. cretica led to many genes shift in both SC regions and contraction in IRs. The size of IRs reduced to 2 to 4 times as compared to those of the Convolvulaceae members studied. The shifted IRs regions showed remarkable variation in nucleotides patterns. Further, the shift was from the IR boundaries and in between the IR regions led to segment IRs. It is concluded that the shift in IRs may be the strategic move for adaptation in the harsh environment.