애기장대에서의 SAG12 유전자 과발현이 관다발조직 발달과 식물 전체의 바이오매스에 미치는 영향

Abstract

The plant vasculature spreading all over the plant organs plays essential roles in plant development. Recently, many efforts have been made to figure out related mechanisms of vascular development and thus get bulk of biomass for biofuels by modifying those mechanisms. Among vascular tissues, development of xylem is notable as the majority of plant biomass derives from xylem. Here, we identified SAG12 as a candidate for modulator of plant biomass. Overexpression of cysteine protease SAG12 which has not yet been verified about its exact function affects plant vascular development. In F27818 FOX line which overexpressing SAG12, inflorescence stemdiameter and number of vascular cells were increased and transcriptional level of several vascular marker genes was induced. Indeed, overexpression of SAG12 makes plant biomass increased. Consistent with those results, plant hormone responsive genes related to giberrelin or auxin which is involved in the development of procambial cell and xylem were induced. As altered expression level of SAG12 does not affect senescence progression, we focused on role as a protease in vasculature rather than a senescence facilitator. We discovered that the expression level of PCD- and SCW- related genes concerning xylem development was increased in SAG12 overexpressing line. These results proposed the possibilities that SAG12 might be partially involved in programmed cell death for secondary cell wall formation as protease and modulation of SAG12 could be useful tool to increase biomass.