近日,，國際植物學著名雜志《植物細胞》The Plant Cell在線刊登了中科院上海生命科學研究院植生生態(tài)所植物分子遺傳國家重點實驗室薛紅衛(wèi)研究組的最新研究成果“轉錄因子MADS29調控水稻種子發(fā)育中母體組織的降解”。
水稻種子是人類重要的食物來源,，其發(fā)育涉及一個復雜的調控網絡,，其中轉錄因子發(fā)揮了關鍵作用。MADS轉錄因子家族成員是植物花器官發(fā)育的重要調控因子,，已有的研究表明,，幾乎所有的水稻MADS基因都在種子中表達，但對MADS家族成員參與水稻種子發(fā)育調控的研究結果仍比較少,。
在這項研究中，研究組基于前期的表達譜研究基礎,，分析得到了一個在水稻生殖發(fā)育階段優(yōu)先表達的轉錄因子MADS29,。細致分析表明，MADS29在花藥,、胚珠和種子中均表達,，且在受精后的母體組織表達量最高。MADS29的反義轉基因植株呈現(xiàn)種子皺縮,、淀粉粒形態(tài)異常,、灌漿速率下降等表型。通過解剖學切片,、末端轉移酶標記實驗和全基因組表達譜芯片分析等,，研究人員證明了MADS29通過調控程序化死亡(PCD)過程促進珠心細胞和珠心突起處的降解。進一步的體外凝膠阻滯實驗顯示,，MADS29能夠通過直接結合程序化死亡相關基因的啟動子區(qū)域而調控其表達,，進而影響胚乳發(fā)育,。
這些結果鑒定了一個參與珠心細胞和珠心突起處降解的調控因子，證實這兩處組織的降解是水稻種子正常灌漿的前提,，并且提示了生長素(IAA)信號在母體組織降解和胚乳發(fā)育中的作用,，有助于進一步了解水稻種子發(fā)育特別是胚乳發(fā)育調控的分子機制。
該項工作得到國家科技部,、農業(yè)部和中國科學院的經費支持,。（生物谷Bioon.com）
doi:10.1105/tpc.111.094854
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The MADS29 Transcription Factor Regulates the Degradation of the Nucellus and the Nucellar Projection during Rice Seed Development
Lin-Lin Yin and Hong-Wei Xue1
The MADS box transcription factors are critical regulators of rice (Oryza sativa) reproductive development. Here, we here report the functional characterization of a rice MADS box family member, MADS29, which is preferentially expressed in the nucellus and the nucellar projection. Suppressed expression of MADS29 resulted in abnormal seed development; the seeds were shrunken, displayed a low grain-filling rate and suppressed starch biosynthesis, and contained abnormal starch granules. Detailed analysis indicated that the abnormal seed development is due to defective programmed cell death (PCD) of the nucellus and nucellar projection, which was confirmed by a TUNEL assay and transcriptome analysis. Further studies showed that expression of MADS29 is induced by auxin and MADS29 protein binds directly to the putative promoter regions of genes that encode a Cys protease and nucleotide binding site–Leu-rich repeat proteins, thereby stimulating the PCD. This study identifies MADS29 as a key regulator of early rice seed development by regulating the PCD of maternal tissues. It provides informative clues to elucidate the regulatory mechanism of maternal tissue degradation after fertilization and to facilitate the studies of endosperm development and seed filling.
