Dehors Jérémy, Mareck Alain, Kiefer-Meyer Marie-Christine, Menu-Bouaouiche Laurence, Lehner Arnaud, Mollet Jean-Claude
Normandie Univ, UNIROUEN, Laboratoire de Glycobiologie et Matrice Extracellulaire Végétale, Rouen, France.
Front Plant Sci. 2019 Apr 18;10:441. doi: 10.3389/fpls.2019.00441. eCollection 2019.
During evolution of land plants, the first colonizing species presented leafy-dominant gametophytes, found in non-vascular plants (bryophytes). Today, bryophytes include liverworts, mosses, and hornworts. In the first seedless vascular plants (lycophytes), the sporophytic stage of life started to be predominant. In the seed producing plants, gymnosperms and angiosperms , the gametophytic stage is restricted to reproduction. In mosses and ferns, the haploid spores germinate and form a protonema, which develops into a leafy gametophyte producing rhizoids for anchorage, water and nutrient uptakes. The basal gymnosperms (cycads and ) reproduce by zooidogamy. Their pollen grains develop a multi-branched pollen tube that penetrates the nucellus and releases flagellated sperm cells that swim to the egg cell. The pollen grain of other gymnosperms (conifers and gnetophytes) as well as angiosperms germinates and produces a pollen tube that directly delivers the sperm cells to the ovule (siphonogamy). These different gametophytes, which are short or long-lived structures, share a common tip-growing mode of cell expansion. Tip-growth requires a massive cell wall deposition to promote cell elongation, but also a tight spatial and temporal control of the cell wall remodeling in order to modulate the mechanical properties of the cell wall. The growth rate of these cells is very variable depending on the structure and the species, ranging from very slow (protonemata, rhizoids, and some gymnosperm pollen tubes), to a slow to fast-growth in other gymnosperms and angiosperms. In addition, the structural diversity of the female counterparts in angiosperms (dry, semi-dry wet stigmas, short long, solid hollow styles) will impact the speed and efficiency of sperm delivery. As the evolution and diversity of the cell wall polysaccharides accompanied the diversification of cell wall structural proteins and remodeling enzymes, this review focuses on our current knowledge on the biochemistry, the distribution and remodeling of the main cell wall polymers (including cellulose, hemicelluloses, pectins, callose, arabinogalactan-proteins and extensins), during the tip-expansion of gametophytes from bryophytes, pteridophytes (lycophytes and monilophytes), gymnosperms and the monocot and eudicot angiosperms.
在陆地植物的进化过程中，最早的拓殖物种呈现出以叶为主的配子体，见于非维管植物（苔藓植物）。如今，苔藓植物包括地钱、苔藓和角苔。在最早的无籽维管植物（石松类植物）中，生活史的孢子体阶段开始占主导地位。在种子植物，即裸子植物和被子植物中，配子体阶段仅限于繁殖过程。在苔藓和蕨类植物中，单倍体孢子萌发并形成原丝体，原丝体发育成带叶的配子体，配子体产生假根用于固定、吸收水分和养分。基部裸子植物（苏铁类植物等）通过游动精子受精进行繁殖。它们的花粉粒发育出多分支的花粉管，花粉管穿透珠心并释放出具鞭毛的精子细胞，精子细胞游向卵细胞。其他裸子植物（针叶树和买麻藤类植物）以及被子植物的花粉粒萌发并产生花粉管，直接将精子细胞输送到胚珠（管受精）。这些不同的配子体，无论是短期还是长期存在的结构，都具有共同的顶端生长细胞扩展模式。顶端生长需要大量的细胞壁沉积以促进细胞伸长，但也需要对细胞壁重塑进行严格的空间和时间控制，以调节细胞壁的机械性能。这些细胞的生长速度因结构和物种而异，范围从非常缓慢（原丝体、假根和一些裸子植物花粉管）到其他裸子植物和被子植物中的缓慢到快速生长。此外，被子植物中雌性对应结构的结构多样性（干燥、半干燥、湿润柱头，短、长，实心、空心花柱）会影响精子输送的速度和效率。随着细胞壁多糖的进化和多样性伴随着细胞壁结构蛋白和重塑酶的多样化，本综述聚焦于我们目前对苔藓植物、蕨类植物（石松类植物和蕨类植物）、裸子植物以及单子叶和双子叶被子植物配子体顶端扩展过程中主要细胞壁聚合物（包括纤维素、半纤维素、果胶、胼胝质、阿拉伯半乳聚糖蛋白和伸展蛋白）的生物化学、分布和重塑的认识。
