学术报告 2020年12月11日（星期五）上午10:10 报告人：Prof. Min Ni

题　目： Light signal transduction and regulation of seed development
报告人： Prof. Min Ni，University of Minnesota at Twin Cities, USA
时　间： 2020年12月11日（星期五） 上午10:10-12:00
地　点： 中国农业大学   生命科学研究中心   一层报告厅（线上直播）

腾讯会议直播: https://meeting.tencent.com/l/pi8vMzI1kr3s



Min Ni
Department of Plant and Microbial Biology University of Minnesota at Twin Cities
250 Bioscience Center   1445 Gornter Avenue
St. Paul, MN 55108    612-625-3702 (Office); 612-625-1738 (Fax)

Education
Shandong Agricultural University, China B.S.  1982  Animal Sciences
University of Kentucky, Lexington  M.S,  1987  Crop Sciences
University of Oklahoma, Norman  Ph.D.  1992  Botany
Purdue University, West Lafayette  Postdoc. 1994  Molecular Biology
UC Berkeley     Postdoc. 1998  Molecular Biology

Professional Positions
1998-1999 University of California at Berkeley, CA Assistant specialist
1999-2000 Akkadix Corporation at San Diego, CA Scientist & Project Leader
2000-2006 University of Minnesota Twin Cities, MN Assistant Professor
2006-2012 University of Minnesota Twin Cities, MN Associate Professor
2012-present University of Minnesota Twin Cities, MN Professor

Research Interests:
PIF4 is a critical signaling hub in light, temperature, and hormonal signaling pathways. Its expression peaks in the morning and afternoon. Excess light toward noon damages the photosynthetic apparatus. Upregulation of PIF4 expression by SHB1 and the circadian clock proteins CCA1/LHY under red light represents a desensitization step. After dawn, the highly expressed CCA1 and LHY bring circadian signals to the regulatory region of the PIF4. Recruitment of SHB1 by CCA1 modulates the red light-specific induction of PIF4 expression thus integrating circadian and light signals. As noon approaches and ambient temperature tend to increase, the SHB1-CCA1 interaction sustained PIF4 expression to trigger plant thermomorphogenic responses. Moreover, two WRKY proteins recognize a WRKY-box near the element bound by CCA1 and LHY in the PIF4 promoter and enhance their binding during the day. The two WRKYs also interact indirectly with SHB1 and requires functional CCA1 or LHY for their interaction. SHB1 in turn associates with the regulatory regions of the two WRKY genes and enhances their expression parallel to the PIF4 expression peaks as a forward regulatory loop.
Seed development in Arabidopsis and in some dicots undergoes an initial phase of active endosperm proliferation in the first few days followed by a second phase in which embryo grows at the expense of the endosperm. In many dicots, the embryo grows to full size and the mature seed contains only a single layer of endosperm cells. However, excess endosperm proliferation always enlarges the final mature seeds. IKU2 is a LRR receptor protein kinase and a critical player to elicit a subsequent signaling cascade for endosperm proliferation. It is specifically expressed in the endosperm. Its expression peaks at 2 to 3 Days after Pollination (DAP) and is then repressed at 4 to 5 DAP. Two newly identified transcription factors recruit SHB1 along with a histone modification enzyme to various locus including IKU2 to activate their expression for endosperm proliferation after pollination. To explore how IKU2 expression is repressed at 4 to 5 DAP, we identified two transcription factors that recruit FIS-PRC2 to the IKU2 locus at 4 to 5 DAP for a developmental phase transition.