生物谷報(bào)道：美國(guó)加州大學(xué)圣地亞哥分校的生物學(xué)家在植物中發(fā)現(xiàn)了一種異乎尋常的基因,。當(dāng)這個(gè)基因的突變同時(shí)存在于雌性和雄性生殖細(xì)胞中時(shí),，就會(huì)干擾授精過(guò)程。這項(xiàng)研究的結(jié)果發(fā)表在最新一期的《現(xiàn)代生物學(xué)》雜志上,。他們發(fā)現(xiàn)由于該基因的獨(dú)特性質(zhì),，使植物因雙方“一致”的突變而達(dá)到“節(jié)欲”的作用。
研究人員解釋說(shuō),，雖然人們對(duì)植物中抑制受精過(guò)程的突變已經(jīng)有所了解,，但是通常這些突變都是由于雌性生殖細(xì)胞中一種突變或雄性生殖細(xì)胞中的一種突變所導(dǎo)致的。
但是,，這種被命名為“雙方一致節(jié)欲”的基因中,，在僅雌性攜帶這種突變時(shí)仍然能夠正常進(jìn)行受精，而當(dāng)只有雄性攜帶這種突變時(shí)也一樣能夠進(jìn)行正常的受精,。但是,，當(dāng)雌雄生殖細(xì)胞雙方同時(shí)攜帶這種基因時(shí)，受精過(guò)程被完全阻斷,。
研究人員表示,，這個(gè)控制植物受精的新基因的發(fā)現(xiàn)可能對(duì)植物育種專(zhuān)家和保育專(zhuān)家具有重要應(yīng)用價(jià)值。
在研究這種突變?yōu)楹螘?huì)導(dǎo)致受精的中斷時(shí),，研究人員在模式植物擬南芥中發(fā)現(xiàn),，在植物受精過(guò)程中，當(dāng)花粉管接近雌性卵細(xì)胞時(shí),，花粉管不會(huì)破裂,。因此，在突變植物中,，精細(xì)胞不能從花粉管中突圍出來(lái)到達(dá)卵細(xì)胞。
這種怪辟的“雙方一致節(jié)欲”基因是目前確定出的第一個(gè)同時(shí)對(duì)植物雄性和雌性生殖細(xì)胞起到關(guān)鍵作用的基因,，它對(duì)精子細(xì)胞相卵細(xì)胞傳遞至關(guān)重要,。
研究人員發(fā)現(xiàn),，這種基因負(fù)責(zé)編碼一種叫做peroxin的蛋白質(zhì),，這種蛋白質(zhì)能靶向細(xì)胞內(nèi)的過(guò)氧物酶體的細(xì)胞器,。在細(xì)胞中，過(guò)氧物酶體（peroxisomes,，生物谷注）的主要功能是代謝脂肪酸，保護(hù)細(xì)胞不受有毒自由基的侵害,，并且能夠產(chǎn)生出各種信號(hào)分子,。
該研究組的發(fā)現(xiàn)正式，過(guò)氧物酶體在雄性精子載體和雌性卵細(xì)胞之間的對(duì)話(huà)中起到一種意料之外的關(guān)鍵作用,。研究還暗示出,，雌性或雄性生殖細(xì)胞中過(guò)氧物酶體中產(chǎn)生的擴(kuò)散性的信號(hào)能夠使雌雄交流得以進(jìn)行。這種來(lái)自雌性或雄性生殖細(xì)胞的過(guò)氧物酶體信號(hào)足以啟動(dòng)花粉管的破裂,。
研究人員表示,，接下來(lái)的一個(gè)有趣的問(wèn)題就是，這種能導(dǎo)致花粉管破裂的來(lái)源于過(guò)氧物酶體的信號(hào)到底是些什么物質(zhì),。
原始出處：
Current Biology
The Peroxin Loss-of-Function Mutation abstinence by mutual consent Disrupts Male-Female Gametophyte Recognition
Aurélien Boisson-Dernier,1, Sabine Frietsch,1,2,3 Tae-Houn Kim,1,2 Marie B. Dizon,1 and Julian I. Schroeder1,
1 Division of Biological Sciences, Cell and Developmental Biology Section and Center for Molecular Genetics, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0116
Corresponding author
Aurélien Boisson-Dernier
[email protected]
Corresponding author
Julian I. Schroeder
[email protected]
In eukaryotes, fertilization relies on complex and specialized mechanisms that achieve the precise delivery of the male gamete to the female gamete and their subsequent union [1, 2, 3, 4]. In flowering plants, the haploid male gametophyte or pollen tube (PT) [5] carries two nonmotile sperm cells to the female gametophyte (FG) or embryo sac [6] during a long assisted journey through the maternal tissues [7, 8, 9, 10]. In Arabidopsis, typically one PT reaches one of the two synergids of the FG (Figure 1A), where it terminates its growth and delivers the sperm cells, a poorly understood process called pollen-tube reception. Here, we report the isolation and characterization of the Arabidopsis mutant abstinence by mutual consent (amc). Interestingly, pollen-tube reception is impaired only when an amc pollen tube reaches an amc female gametophyte, resulting in pollen-tube overgrowth and completely preventing sperm discharge and the development of homozygous mutants. Moreover, we show that AMC is strongly and transiently expressed in both male and female gametophytes during fertilization and that AMC functions in gametophytes as a peroxin essential for protein import into peroxisomes. These findings show that peroxisomes play an unexpected key role in gametophyte recognition and implicate a diffusible signal emanating from either gametophyte that is required for pollen-tube discharge.
