全新形態(tài)性狀（Morphological novelties）的起源是進(jìn)化生物學(xué)研究的熱點(diǎn)之一,。茄科酸漿屬（Physalis）植物具有全新花后結(jié)構(gòu)——“中國燈籠”或膨大花萼癥狀（ICS, inflated calyx syndrome）,，是花萼隨著漿果的生長發(fā)育而迅速膨大的結(jié)果。該創(chuàng)新性狀是如何起源和發(fā)育的呢,？緊密圍繞這一科學(xué)問題,，中科院植物研究所賀超英研究組進(jìn)行了一系列研究，發(fā)現(xiàn)“中國燈籠”的發(fā)育受到授精信號(hào)和植物激素的調(diào)控,，它在茄科的進(jìn)化與MADS-box基因MPF2在花器官中的異位表達(dá)和分子進(jìn)化密切相關(guān),。然而，該創(chuàng)新結(jié)構(gòu)的器官身份決定過程等尚不清楚,。
近期,該研究組發(fā)現(xiàn),，毛酸漿euAP1 MADS-box基因MPF3和MPF2以及它們蛋白產(chǎn)物間的相互作用對(duì)“中國燈籠”的進(jìn)化發(fā)育起重要作用。MPF3與MPF2和一些花部器官特異表達(dá)的MADS-domain蛋白互作,，選擇性地結(jié)合于MPF2啟動(dòng)子中的CArG-box,，調(diào)控MPF2在花部器官中的表達(dá)。當(dāng)MPF3下調(diào)后,，花萼增大并葉化,，但“中國燈籠”變小，花粉中的淀粉積累受阻,，MPF2的表達(dá)在花萼和雄蕊中顯著升高,；當(dāng)MPF2單基因下調(diào)后，花萼身份不變,，“中國燈籠”也變小,，花粉成熟嚴(yán)重受阻，MPF3的表達(dá)則不受影響,；當(dāng)MPF2和MPF3的表達(dá)雙降低后,，可以產(chǎn)生形態(tài)正常的花萼和變小的“中國燈籠”，成熟花粉的比例明顯提高,，但仍約有30%的花粉不能成熟,。
研究結(jié)果顯示，MPF3通過與MPF2的互作和對(duì)MPF2基因的遺傳互作（抑制）來決定花萼身份,、大小和雄性育性,。此外，MPF2和MPF3可以強(qiáng)烈激活PFINV4基因,，它的直系同源基因在水稻等植物中編碼糖分解轉(zhuǎn)運(yùn)途徑中的關(guān)鍵酶,。在進(jìn)化過程中MPF3受到正選擇，序列的歧化改變了其結(jié)合DNA和蛋白質(zhì)的特異性,，進(jìn)而獲得全新的目標(biāo)基因和互作蛋白,，從而使其獲得了在“中國燈籠”發(fā)育和雄性育性決定中的新功能。以上研究結(jié)果進(jìn)一步完善了對(duì)酸漿屬“中國燈籠”進(jìn)化發(fā)育分子機(jī)制和調(diào)控網(wǎng)絡(luò)的認(rèn)識(shí)，并為被子植物中euAP1基因的功能進(jìn)化提供了新證據(jù),。
該研究結(jié)果于6月21日在線發(fā)表在The Plant Cell（Zhao et al. 2013, doi: 10.1105/tpc.113.111757）期刊上。研究組博士研究生趙婧和博士后田穎為該研究論文的并列第一作者,。
該研究得到了中科院“百人計(jì)劃”,、國家自然科學(xué)基金委等項(xiàng)目的資助。（生物谷 Bioon.com）
毛酸漿“中國燈籠”表型及其發(fā)育的調(diào)控網(wǎng)絡(luò)（左）毛酸漿“中國燈籠”表型,。（右）MPF3-相關(guān)的互作調(diào)控網(wǎng)絡(luò),。
生物谷推薦的英文摘要
The Plant Cell doi: http:/?/?dx.?doi.?org/?10.?1105/?tpc.?113.?111757
Jing Zhao, Ying Tiana, Ji-Si Zhang, Man Zhao, Pichang Gong, Simone Riss, Rainer Saedler and Chaoying He
The euAP1 Protein MPF3 Represses MPF2 to Specify Floral Calyx Identity and Displays Crucial Roles in Chinese Lantern Development in Physalis
The Chinese lantern phenotype or inflated calyx syndrome (ICS) is a postfloral morphological novelty in Physalis. Its origin is associated with the heterotopic expression of the MADS box gene 2 from Physalis floridana (MPF2) in floral organs, yet the process underlying its identity remains elusive. Here, we show that MPF3, which is expressed specifically in floral tissues, encodes a core eudicot APETALA1-like (euAP1) MADS-domain protein. MPF3 was primarily localized to the nucleus, and it interacted with MPF2 and some floral MADS-domain proteins to selectively bind the CC-A-rich-GG (CArG) boxes in the MPF2 promoter. Downregulating MPF3 resulted in a dramatic elevation in MPF2 in the calyces and androecium, leading to enlarged and leaf-like floral calyces; however, the postfloral lantern was smaller and deformed. Starch accumulation in pollen was blocked. MPF3 MPF2 double knockdowns showed normal floral calyces and more mature pollen than those found in plants in which either MPF3 or MPF2 was downregulated. Therefore, MPF3 specifies calyx identity and regulates ICS formation and male fertility through interactions with MPF2/MPF2. Furthermore, both genes were found to activate Physalis floridana invertase gene 4 homolog, which encodes an invertase cleaving Suc, a putative key gene in sugar partitioning. The novel role of the MPF3-MPF2 regulatory circuit in male fertility is integral to the origin of ICS. Our results shed light on the evolution and development of ICS in Physalis and on the functional evolution of euAP1s in angiosperms.
