The Role Of MiR169 In Alfalfa Investigated In Response To Fall Dormancy

Alfalfa(Medicago sativa L.)is one of important perennial forage legume and widely cultivated throughout the world,which has high yield and protein.Fall dormancy(FD)is an important indicator evolved in perennial alfalfa plants to the winter freezing survival and biomass production via temporary suspension of growth.During three consecutive productive years(2012~2014),we have identified distinct characteristics of two different FD type alfalfa varieties(WL319,WL903).Each plot was cut about five times each year to evaluate herbage production,plants heights and plant regeneration heights of tested varieties.Mi R169 and its target gene HAP2 showed inverse expression patterns during the fall dormant period of the autumn and different tissue distribution.With short photoperiods and cool temperature,The change trend of mi R168 expression level gradually increased,while HAP2 decreased gradually.Both transcriptome expressed in all the tissues,the expression level was highest in bud.The positive plants were successfully obtained by using Agrobacterium with STTM-mi R169/mi R169 recombinant plasmid infecting cotyledonary node,and were verificated by the analysis of PCR technology and q Real Time PCRtechnology.Compared with non-transgenic plants,mi R169 expression level with transgenic alfalfa plants increased.These results showed that mi R169 and its target gene HAP2 play a significant role of fall dormancy.