The MYB80 Transcription Factor Is Required for Pollen Development and the Regulation of Tapetal Programmed Cell Death inArabidopsis thaliana   

Abstract

Arabidopsis thaliana MYB80 (formerly MYB103) is expressed in the tapetum and microspores between anther developmental stages 6 and 10. MYB80 encodes a MYB transcription factor that is essential for tapetal and pollen development. Using microarray analysis of anther mRNA, we identified 404 genes differentially expressed in the myb80 mutant. Employing the glucocorticoid receptor system, the expression of 79 genes was changed when MYB80 function was restored in the myb80 mutant following induction by dexamethasone. Thirty-two genes were analyzed using chromatin immunoprecipitation, and three were identified as direct targets of MYB80. The genes encode a glyoxal oxidase (GLOX1), a pectin methylesterase (VANGUARD1), and an A1 aspartic protease (UNDEAD). All three genes are expressed in the tapetum and microspores. Electrophoretic mobility shift assays confirmed that MYB80 binds to all three target promoters, with the preferential binding site containing the CCAACC motif. TUNEL assays showed that when UNDEAD expression was silenced using small interfering RNA, premature tapetal and pollen programmed cell death occurred, resembling the myb80 mutant phenotype. UNDEAD possesses a mitochondrial targeting signal and may hydrolyze an apoptosis-inducing protein(s) in mitochondria. The timing of tapetal programmed cell death is critical for pollen development, and the MYB80/UNDEAD system may regulate that timing.

A Rice Ca2+ Binding Protein Is Required for Tapetum Function and Pollen Formation

“…Either premature or delayed tapetal degradation frequently causes reduced male sterility (Balk and Leaver, 2001;Ku et al, 2003;Lee et al, 2004;Jung et al, 2005;Luo et al, 2006;Kawanabe et al, 2006;Li et al, 2006;Oshino et al, 2007;Li et al, 2011;Aya et al,2009;Tan et al, 2012;Niu et al,2013;Ji et al, 2013;Fu et al, 2014;Ko et al, 2014;. We observed a persistent and partially expanded tapetal layer in osdex1 until stage 11.…”

EAT1 promotes tapetal cell death by regulating aspartic proteases during male reproductive development in rice

“…Moreover, even though OsAP25, OsAP37, PCS1 and UNDEAD belong to the C-group of aspartic proteases 43,44 , OsAP25 and OsAP37 can promote cell death (Fig. 6b-e) whereas UNDEAD and PCS1 have anti-PCD functions 31,32 , suggesting diversified roles of aspartic proteases in plant PCD.…”

“…In addition, aspartic protease is implicated in plant development and cell death. Arabidopsis UNDEAD, which encodes an A1 aspartic protease, suppresses tapetal PCD; knockdown of UNDEAD causes premature tapetal PCD 31 . Another Arabidopsis aspartic protease, PROMOTION OF CELL SURVIVAL1 (PCS1), has an anti-cell death role in embryonic and reproductive development 32 .…”

The Rice Basic Helix-Loop-Helix Transcription Factor TDR INTERACTING PROTEIN2 Is a Central Switch in Early Anther Development

“…Premature or retarded tapetal degeneration frequently causes male sterility (N. Li et al, 2007;Zhang et al, 2007;Shi et al, 2009;Phan et al, 2011). Genetic investigations discovered several transcription factors involved in rice tapetal degeneration, such as GAMYB (Kaneko et al, 2004;Liu et al, 2010), TDR (N. , EAT1 (Niu et al, 2013), and Os-API5 (X.…”