title: Rice APOPTOSIS INHIBITOR5 coupled with two DEAD-box adenosine 5'-triphosphate-dependent RNA helicases regulates tapetum degeneration.
abstract: Programmed cell death (PCD) during tapetum degeneration in postmeiotic anthers is critical for the proper development of male gametophytes in flowering plants. Although several genes involved in this process have been identified recently, the molecular mechanism is still poorly understood. Here, we show that knockout of rice (Oryza sativa) APOPTOSIS INHIBITOR5 (API5), which encodes a putative homolog of antiapoptosis protein Api5 in animals, results in delayed degeneration of the tapetum due to inhibition of the tapetal PCD process leading to defects in formation of male gametophytes. Os API5 is a nuclear protein that interacts with two DEAD-box ATP-dependent RNA helicases, API5-INTERACTING PROTEIN1 (AIP1) and AIP2. AIP1 and AIP2 are homologs of yeast (Saccharomyces cerevisiae) Suppressor of Bad Response to Refrigeration1 protein 2 (SUB2p) that have critical roles in transcription elongation and pre-mRNA splicing. Os AIP1 and AIP2 can form dimers and interact directly with the promoter region of CP1, a rice cysteine protease gene. Suppression of Os AIP1/2 leads to down-regulation of CP1, resulting in sterility, which is highly similar to the effects of suppressed expression of Os CP1. Our results uncover a previously unknown pathway for regulating PCD during tapetum degeneration in rice, one that may be conserved among eukaryotic organisms.
authors.affiliation: National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Xingwang
authors.initials: X
authors.lastname: Li
authors.forename: Xinqiang
authors.initials: X
authors.lastname: Gao
authors.forename: Yi
authors.initials: Y
authors.lastname: Wei
authors.forename: Li
authors.initials: L
authors.lastname: Deng
authors.forename: Yidan
authors.initials: Y
authors.lastname: Ouyang
authors.forename: Guoxing
authors.initials: G
authors.lastname: Chen
authors.forename: Xianghua
authors.initials: X
authors.lastname: Li
authors.forename: Qifa
authors.initials: Q
authors.lastname: Zhang
authors.forename: Changyin
authors.initials: C
authors.lastname: Wu
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000595:Amino Acid Sequence; D017209:Apoptosis; D017124:Conserved Sequence / Q000235:genetics; D053487:DEAD-box RNA Helicases / Q000378:metabolism*; D053938:DNA Fragmentation; D035264:Flowers / Q000166:cytology / Q000201:enzymology / Q000378:metabolism* / Q000648:ultrastructure; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D055785:Gene Knockdown Techniques; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D012275:Oryza / Q000166:cytology / Q000201:enzymology* / Q000235:genetics / Q000648:ultrastructure; D010802:Phylogeny; D051479:Plant Infertility / Q000235:genetics; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D000255:Adenosine Triphosphate; D053487:DEAD-box RNA Helicases