德國(guó)科學(xué)家發(fā)現(xiàn)，植物激素茉莉酸不僅可控制油菜花萌芽階段的生長(zhǎng),，還能激發(fā)花蜜生產(chǎn),。該研究對(duì)油菜的高產(chǎn)將產(chǎn)生十分積極的影響，相關(guān)成果發(fā)表在近日美國(guó)《公共科學(xué)圖書館·綜合》雜志網(wǎng)絡(luò)版上,。
很久以來,，人們都不清楚花朵是如何觸發(fā)和控制花蜜生產(chǎn)的。現(xiàn)在,，德國(guó)馬普研究院的博士生拉迪卡·文卡特桑通過研究甘藍(lán)型油菜發(fā)現(xiàn),，是存在于植物體內(nèi)的內(nèi)源生長(zhǎng)調(diào)節(jié)物質(zhì)茉莉酸控制了花朵的生長(zhǎng),，并激發(fā)花蜜的生產(chǎn),。
茉莉酸及其相關(guān)分子是植物組織分子信號(hào)傳導(dǎo)鏈的重要組成成分。它屬于植物激素組中的信號(hào)物質(zhì),，例如當(dāng)毛毛蟲吃植物時(shí)它就會(huì)應(yīng)激合成,。通過產(chǎn)生茉莉酸，植物可刺激合成毒素,，以此來防御病蟲害,。茉莉酸還能控制生產(chǎn)“花外花蜜”。這種特殊的花蜜,，不是由花的組織產(chǎn)生的,，而是由一個(gè)名為“花外蜜腺”的特殊腺體產(chǎn)生的，“花外花蜜”吸引螞蟻,，可間接保護(hù)植物不被食草動(dòng)物蠶食,?；壑泻械奶欠謩t是對(duì)保護(hù)植物的螞蟻的獎(jiǎng)勵(lì)。
不過,，研究人員發(fā)現(xiàn),，在花的早期發(fā)育階段，無論植物有沒有受到食草類動(dòng)物的攻擊,，茉莉酸都會(huì)被合成,，隨即花蜜的生產(chǎn)也會(huì)啟動(dòng)。且茉莉酸在不同的植物組織有不同的功能：在葉片,，它激活植物對(duì)食草動(dòng)物的防御機(jī)制,；而在花朵，它控制花蜜的生產(chǎn),。
茉莉酸和花蜜生產(chǎn)之間的相互聯(lián)系還可通過一種抑制劑實(shí)驗(yàn)得到：當(dāng)用可抑制茉莉酸合成的菲尼酮對(duì)花進(jìn)行處理后,，花蜜生產(chǎn)便會(huì)停止,。當(dāng)用這種抑制劑噴灑還未開放的花蕾時(shí),，花的開放也會(huì)得到抑制，這證實(shí)茉莉酸在花的成長(zhǎng)過程中也起著重要作用,。
研究人員強(qiáng)調(diào),，人類對(duì)激素在花的生長(zhǎng)和花蜜，乃至油菜仔的生產(chǎn)中所起的作用知道得越多,，就越能合理利用這些知識(shí)來保證高產(chǎn),。油菜是全世界10種最重要的農(nóng)作物之一。因此,，加強(qiáng)研究使油菜這一廣泛種植的農(nóng)作物獲得高產(chǎn),，意義十分重大。(生物谷Bioon.com)
生物谷推薦原文出處：
PLoS ONE doi:10.1371/journal.pone.0009265
The Role of Jasmonates in Floral Nectar Secretion
Venkatesan Radhika1, Christian Kost1, Wilhelm Boland1, Martin Heil2*
Plants produce nectar in their flowers as a reward for their pollinators and most of our crops depend on insect pollination, but little is known on the physiological control of nectar secretion. Jasmonates are well-known for their effects on senescence, the development and opening of flowers and on plant defences such as extrafloral nectar. Their role in floral nectar secretion has, however, not been explored so far. We investigated whether jasmonates have an influence on floral nectar secretion in oil-seed rape, Brassica napus. The floral tissues of this plant produced jasmonic acid (JA) endogenously, and JA concentrations peaked shortly before nectar secretion was highest. Exogenous application of JA to flowers induced nectar secretion, which was suppressed by treatment with phenidone, an inhibitor of JA synthesis. This effect could be reversed by additional application of JA. Jasmonoyl-isoleucine and its structural mimic coronalon also increased nectar secretion. Herbivory or addition of JA to the leaves did not have an effect on floral nectar secretion, demonstrating a functional separation of systemic defence signalling from reproductive nectar secretion. Jasmonates, which have been intensively studied in the context of herbivore defences and flower development, have a profound effect on floral nectar secretion and, thus, pollination efficiency in B. napus. Our results link floral nectar secretion to jasmonate signalling and thereby integrate the floral nectar secretion into the complex network of oxylipid-mediated developmental processes of plants.
