Comparative transcriptome analysis of the effects of friction and exogenous gibberellin on germination in Abrus cantoniensis

The seeds of Abrus cantoniensis (A. cantonensis) have dormancy characteristics with very low germination under natural conditions. In general, its seed dormancy could be broken by friction or soaking with exogenous gibberellins (GA(3)). To date, the molecular mechanism underlying the effects of GA(3) and friction on its seed germination is unclear. In this study, we tested the effects of different treatments, including soaking in sterile water (G1), friction (G2), soaking in GA(3) (G3), combined treatment of friction, and GA(3) (G4)) on seed germination. Then, we have investigated the seed transcriptome profiles corresponding to the different treatments by RNA sequencing. The results showed that seed germination was significantly increased by combined treatment with friction and GA(3). RNA-Seq analysis generated 84.80 gigabases (Gb) of sequences. 82,996 out of 121,776 unigenes were annotated. Comparative transcriptome analysis observed that 1,130, 1,097, and 708 unigenes were deferentially expressed in G1 vs. G2, G1 vs. G3, and G1 vs. G4 groups, respectively. Additionally, 20 putatively candidate genes related to seed germination, including CYP78A5, Bg7s, GA-20-ox, rd22, MYB4, LEA, CHS, and STH-2, and other potential candidates with abundant expression were identified. Our findings provide first insights into gene expression profiles and physiological response for friction combined with GA(3) on A. cantoniensis seed germination.