生物谷報道：據(jù)最新出版的Journal of Integrative Plant Biology (《植物學(xué)報》)雜志2007年第七期報道，一直被認(rèn)為是有毒氣體之一的一氧化碳（CO），可以通過一氧化氮（NO）信號來介導(dǎo)，從而誘導(dǎo)油菜的側(cè)根形成。
眾所周知,，根系是植物體的一個重要組成部分，植物體正常生命活動所需要的水分和礦質(zhì)營養(yǎng)物都是由根系從土壤中吸收而來，同時根系對植物體具有機(jī)械支撐作用,。因此根系發(fā)育的好壞直接影響著植物體的生長狀況，因而與農(nóng)業(yè)生產(chǎn)息息相關(guān),。眾所周知,，在種子萌發(fā)后只能形成一條主根，其后產(chǎn)生的不定根的數(shù)目也是有限的,，因此側(cè)根的發(fā)生對于形成龐大的根系不可缺少的,。良好的根系建成是植物健壯生長和抗逆高產(chǎn)的基礎(chǔ)。側(cè)根是植物根系的重要組成部分,，對養(yǎng)分吸收,、錨定植株以及根際共生系統(tǒng)的建立起關(guān)鍵作用。側(cè)根的發(fā)生發(fā)育除了受遺傳因素控制外,，還受環(huán)境因素的影響,，尤其受生長介質(zhì)中各種養(yǎng)分有效性的影響。研究側(cè)根發(fā)生對于提高農(nóng)作物產(chǎn)量,、豐產(chǎn)豐收有著巨大的實踐與理論指導(dǎo)意義,，正因如此，在過去的幾十年里，人們對側(cè)根的發(fā)生進(jìn)行了大量的研究,，迄今這一研究領(lǐng)域仍是國際上的一個研究熱點,。
一直以來，CO僅僅被認(rèn)為是一種有毒有害的氣體,，例如使用化石燃料導(dǎo)致的大氣污染,、引起溫室效應(yīng)及人體煤氣中毒等等。近年來,，一系列動物領(lǐng)域內(nèi)的研究發(fā)現(xiàn)在神經(jīng)傳導(dǎo)和血管收縮方面,，低濃度CO具有與NO類似的功能。其實,，早在上個世紀(jì)50~60年代,，在多種植物的發(fā)育過程中就觀察到低濃度CO釋放的現(xiàn)象，表明植物體釋放CO可能是一個普遍存在的現(xiàn)象,。但由于當(dāng)時條件所限,，一直無法進(jìn)行深入的研究，其生物學(xué)功能也一直不為人們所知,。從上世紀(jì)90年代以來,，尤其在最近，才逐步有報道發(fā)現(xiàn)CO可以參與調(diào)控：植物種子的破休眠與誘導(dǎo)萌發(fā),、不定根的發(fā)生以及各種逆境下農(nóng)作物的抗逆性,，而類似的功能NO都曾有報道。
2006年,，世界知名的《實驗植物學(xué)雜志》（Journal of Experimental Botany）報道發(fā)現(xiàn)NO可以誘導(dǎo)番茄側(cè)根發(fā)生,，這也佐證了我國的Journal of Integrative Plant Biology (《植物學(xué)報》)今年的這一報道。同時,，這一結(jié)果也為揭示植物側(cè)根發(fā)生的意義和機(jī)理提供了更詳細(xì)的證據(jù),，因此在解開植物側(cè)根發(fā)生調(diào)節(jié)規(guī)律之謎的道路上又向前邁出了一步。
報道中指出：低濃度CO供體及氣體都可以明顯地誘導(dǎo)油菜側(cè)根發(fā)生,，并且這一過程具有明顯的CO特異性,。當(dāng)CO被清除后，CO的誘導(dǎo)效應(yīng)即被明顯削弱,。該報道還發(fā)現(xiàn),，CO誘導(dǎo)側(cè)根發(fā)生的效應(yīng)是通過NO信號實現(xiàn)的：將NO清除后,，CO的誘導(dǎo)作用也明顯減弱,。此外，用一種與NO特異性結(jié)合的熒光探針標(biāo)記NO,，觀察發(fā)現(xiàn)CO可以增強(qiáng)NO熒光,，而這些NO恰恰分布于正在發(fā)生的側(cè)根原基上；同樣，將CO清除后,，這一現(xiàn)象也無法觀察到,。這篇文章的模型是：CO可以誘導(dǎo)側(cè)根發(fā)生，并且其誘導(dǎo)作用則是通過NO來實現(xiàn),。
目前,，該研究小組關(guān)于側(cè)根發(fā)生的研究還在繼續(xù)，探討的問題包括：CO與NO之間是如何實現(xiàn)對話的,？在側(cè)根發(fā)生過程中CO或NO是否作為一個基本事件普遍存在,？對這些問題的回答將引導(dǎo)人們提出更加深刻的疑問，直至最終揭示植物側(cè)根發(fā)生調(diào)節(jié)的所有秘密,。
該研究小組還發(fā)現(xiàn),，在其他一些方面，CO也具有明顯的功效,，如可以顯著提高農(nóng)作物各種逆境耐性,，包括干旱、澇害,、鹽漬和重金屬脅迫等,。各種CO作用機(jī)制的剖析，不僅在揭示植物生長發(fā)育和脅迫耐性奧秘方面具有重要的科研價值,，而且可以在運(yùn)用CO優(yōu)化農(nóng)業(yè)生產(chǎn)的過程中發(fā)揮指導(dǎo)作用,。總之,，人們將在對CO隨心所欲的應(yīng)用過程中,，引領(lǐng)現(xiàn)代農(nóng)業(yè)生產(chǎn)進(jìn)入到另一個新時代。（援引人民網(wǎng)）
原始出處:
Journal of Integrative Plant Biology
Volume 49 Issue 7 Page 1070-1079, July 2007
To cite this article: Ze-Yu Cao, Wei Xuan, Zhao-Yang Liu, Xin-Na Li, Nan Zhao, Peng Xu, Zhe Wang, Rong-Zhan Guan, Wen-Biao Shen (2007)
Carbon Monoxide Promotes Lateral Root Formation in Rapeseed
Journal of Integrative Plant Biology 49 (7), 1070–1079.
doi:10.1111/j.1672-9072.2007.00482.x
Carbon Monoxide Promotes Lateral Root Formation in Rapeseed
Supported by the Grant to Innovative Young Scholars of Jiangsu Province in China (BK2004417), the Program for Changjiang Scholars and Innovative Research Team in China (PCSIRT), and by the Student Research Training (SRT) Project of Nanjing Agricultural University (0506B07, KFJJ200501 and JD200502).
*These authors contributed equally to this work. **Authors for correspondence.
Tel (Fax): +86 (0)25 8439 6542;
E-mail: <[email protected] and [email protected]>.
Carbon monoxide (CO), an odorless, tasteless and colorless gas, has recently proved to be an important bioactive or signal molecule in mammalian cells, with its effects mediated mainly by nitric oxide (NO). In the present report, we show that exogenous CO induces lateral root (LR) formation, an NO-dependent process. Administration of the CO donor hematin to rapeseed (Brassica napus L. Yangyou 6) seedlings for 3 days, dose-dependently promoted the total length and number of LRs. These responses were also seen following the application of gaseous CO aqueous solutions of different saturated concentrations. Furthermore, the actions of CO on seedlings were fully reversed when the CO scavenger hemoglobin (Hb) or the CO-specific synthetic inhibitor zinc protoporphyrin-IX (ZnPPIX) were added. Interestingly, depletion of endogenous NO using its specific scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide potassium salt (cPTIO) or the nitric oxide synthase (NOS) inhibitor NG-nitro-l-arginine methyl ester (l-NAME), led to the complete abolition of LR development, illustrating an important role for endogenous NO in the action of CO on LR formation. However, the induction of LR development by 200 μmol/L sodium nitroprusside (SNP), an NO donor, was not affected by the presence or absence of ZnPPIX. Furthermore, using an anatomical approach combined with laser scanning confocal microscopy with the NO-specific fluorophore 4,5-diaminofluorescein diacetate, we observed that both hematin and SNP increased NO release compared with control samples and that the NO signal was mainly distributed in the LR primordia (LRP), especially after 36 h treatment. The LRP were found to have similar morphology in control, SNP- and hematin-treated seedlings. Similarly, the enhancement of the NO signal by CO at 36 h was differentially quenched by the addition of cPTIO, l-NAME, ZnPPIX and Hb. In contrast, the induction of NO caused by SNP was not affected by the application of ZnPPIX. Therefore, we further deduced that CO induces LR formation probably mediated by the NO/NOS pathway and NO may act downstream of CO signaling, which has also been shown to occur in animals.
