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来源|科学网博客
麻省大学阿姆赫斯特分校的Alice Cheung和Hen-Ming Wu与中国的Qui-Jia Qu和Hongya Gu在模式植物拟南芥中的工作提高了对植物繁殖的基本了解。 研究人员将这两个新的受体命名为Buddha Paper Seal1和2(BUPS1 / 2)。 他们的论文还鉴定了几种称为快速碱化因子(RALF)4,19和34的小肽作为它们的配体 - 调节受体功能的分子。
此外,作者描述了如何将BUPS1 / 2和第二对称为ANXUR1和2(ANX1 / 2),RALF4和19的相关受体全部在花粉管中表达并且为雄性生育所需要,相互作用以获得它们的工作完成。
Cheung说:“我们的论文描述了植物繁殖中男性和女性相互作用网络的一个重要阐述,涉及这个过程的分子必须密切合作来协调和支持雌雄互动事件,在这个过程中,花粉管生长在内部雌蕊常常在距离管子直径数百或数千倍的距离处将精子传递到目标卵细胞,花粉管在整个行程中必须保持完整,但必须在恰当的时间和地点爆发到达释放精子受精的目标,破裂过早或未能破裂,对繁殖造成破坏。“
两个研究小组发现受体和RALF4和19需要在生长过程中保持花粉管的完整性。 他们还表明,从女性表达的RALF34促进了爆裂过程,以及一些已知的和其他尚未确定的因素。 他们展示了这些分子如何相互作用,说明了男性和女性之间产生种子的“有趣的沟通机制”。
In flowering plants, fertilization requires complex cell-to-cell communication events between the pollen tube and the female reproductive tissues, which are controlled by extracellular signaling molecules interacting with receptors at the pollen tube surface. We found that two such receptors in Arabidopsis, BUPS1 and BUPS2, and their peptide ligands, RALF4 and RALF19, are pollen tube–expressed and are required to maintain pollen tube integrity. BUPS1 and BUPS2 interact with receptors ANXUR1 and ANXUR2 via their ectodomains, and both sets of receptors bind RALF4 and RALF19. These receptor-ligand interactions are in competition with the female-derived ligand RALF34, which induces pollen tube bursting at nanomolar concentrations. We propose that RALF34 replaces RALF4 and RALF19 at the interface of pollen tube–female gametophyte contact, thereby deregulating BUPS-ANXUR signaling and in turn leading to pollen tube rupture and sperm release.
UMass Amherst plant molecular biologist Alice Cheung says the male plant's pollen tube transports sperm to female target cells. She and colleagues identify two new receptors essential to this communication and other molecules whos..
Read more at: https://phys.org/news/2017-12-pair-receptors-essential-male-female.html#jCp
Two groups of plant molecular biologists, at the University of Massachusetts Amherst and Peking University, China, have long studied how pollen tubes and pistils, the male and female parts of flowers, communicate to achieve fertilization in plants. Today they report in a Science early release paper that they have identified a pair of receptors essential to these communications as well as molecules that modulate the receptors' activity.
The work, in the model plant Arabidopsis, advances basic understanding of plant reproduction, say Alice Cheung and Hen-Ming Wu at UMass Amherst, with Li-Jia Qu and Hongya Gu in China. The researchers named the two new receptors Buddha Paper Seal 1 and 2 (BUPS1/2). Their paper also identifies several small peptides known as Rapid Alkalinization Factors (RALF) 4, 19 and 34 as their ligands - molecules that modulate the receptors' functions.
Further, the authors describe how BUPS1/2 and a second pair of related receptors called ANXUR 1 and 2 (ANX1/2), and RALF 4 and 19, all expressed in the pollen tube and required for male fertility, interact together to get their jobs done.
Cheung says, "Our paper describes an important elaboration of the male and female interaction network in plant reproduction. Molecules involved in the process have to work intimately together to orchestrate and support the male-female interactive events. In this process the pollen tube grows inside the pistil, often over distances hundreds or thousands of times greater than the tube s diameter, to deliver sperm to the target egg cell. The pollen tube must remain intact throughout this journey, but then must burst open at exactly the right time and place when it arrives at the target to release sperm for fertilization. Bursting too soon or failing to burst when it should are both devastating to reproduction."
The two research teams found that the receptors and RALF4 and 19 are required to maintain pollen tube integrity during the growth process. They also show that RALF34, expressed from the female, facilitates the bursting process, along with some known and other not yet identified factors. They demonstrate how these molecules interact with each other, illustrating an "intriguing communication mechanism" between male and female to produce seeds, Cheung says.
She adds, "In showing how receptors and their ligands work together to ensure reproductive success, our work illuminates one of the most mysterious processes in biology."
The plant reproduction research community has a tradition of naming important genes from ancient mythology, the biologist says. For example, a gene her group also works on, FERONIA, is named after the Roman goddess of fertility. The researchers named the new factors Buddha paper seal 1 and 2 after a Chinese tale about a naughty monkey held under a rock for 400 years by a charmed paper seal. When a kindly monk passing by broke the seal, the monkey burst out, which is what the scientists were reminded of when they saw how the pollen tube explodes to release sperm and enable fertilization.
This work continues the Cheung-Wu group's many years of plant reproduction research, especially on FERONIA, a receptor related to BUPSs and ANXURs that plays a major role in controlling plant female fertility in development and in coping with environmental stresses.
"It's actually very interesting," says Cheung. "The pollen tube transports sperm to female target cells. FERONIA is waiting there for the pollen tube to arrive. BUPSs, ANXURs, RALF 4 and 10 in the pollen tube make sure the tube does not burst too early, but wait until it gets to the target female cell. There the tube bursts abruptly, an action controlled by FERONIA and in part mediated by a different set of RALFs, releasing sperm at the right time and place."
The team used a combination of reverse genetics, biochemical and biophysical approaches for this work, in collaboration not only with the Chinese group, but also involved investigators from Brazil, Germany, the United States and Mexico. Cheung says the U.S. National Science Foundation's Research Coordination Network in Integrative Pollen Biology, of which she is the principle investigator, provided the catalyst and forum that stimulated these international interactions.
She adds, "I want to emphasize this work as a collaboration. We and the Peking University group, close colleagues with common interests, worked in parallel on some of the topics in this paper without knowing about each other's efforts. In a discussion one day we found out that we had common results, but each group had also generated unique observations and developed distinct insights, so we decided to merge our efforts and publish jointly."
She adds, "In my mind, this sort of collaboration is probably the best kind of scientific interaction. As scientists, we value our own independence and creativity. Even with common results, our thinking could diverge, leading each team to further investigate in different directions, getting to end points that complement each other. This collaboration is not a matter of different expertise, but a matter of common interest and curiosity that took us in different directions that eventually came back together in a complete story."
Read more at: https://phys.org/news/2017-12-pair-receptors-essential-male-female.html#jCp
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