Sorensen A, Guerineau F, Canales-Holzeis C, Dickinson H G, Scott R J
Max Plank Institute, Carl von Linne Weg 10, D-50829, Cologne, Germany.
Plant J. 2002 Mar;29(5):581-94. doi: 10.1046/j.0960-7412.2001.01240.x.
Few Arabidopsis mutants defective in early male or female germline development have been reported. A novel extinction screen has been devised which permits the identification of mutants deficient in the earliest stages of anther development. Using mutagenized plants carrying GUS reporter constructs driven by tapetal-specific promoters originally derived from Brassica genes, a wide spectrum of mutants have been identified in Arabidopsis, ranging from those defective in archesporial cell differentiation to others expressed later in development. Crosses between these lines and known anther development mutants have enabled the identification of lines carrying mutations in genes expressed during very early anther formation. Initial characterization reveals these early mutants fall into two classes, gne (GUS-negative) 1-like, and gne2-like. Members of the gne1 mutant class initiate all four layers of the anther wall and an appropriate number of sporogenous cells; however, as development proceeds the tapetal and middle-layer cells enlarge, eventually crushing the sporogenous cells. The gne2 class anthers are disrupted at an earlier stage, with the middle and tapetal layers failing to form, and an excess of sporogenous cells developing until the germline aborts late in meiosis II. Analysis of these mutants has already raised questions about the accuracy of current models of angiosperm anther development.
鲜有关于拟南芥早期雄配子或雌配子体发育缺陷突变体的报道。人们设计了一种新的筛选方法，可用于鉴定花药发育早期阶段存在缺陷的突变体。利用携带由最初源自芸苔属基因的绒毡层特异性启动子驱动的GUS报告构建体的诱变植物，在拟南芥中鉴定出了广泛的突变体，从孢原细胞分化缺陷的突变体到发育后期表达的其他突变体。这些品系与已知的花药发育突变体之间的杂交，使得鉴定出在花药形成非常早期表达的基因突变体品系成为可能。初步鉴定表明，这些早期突变体分为两类，即gne（GUS阴性）1样和gne2样。gne1突变体类的成员起始花药壁的所有四层以及适量的造孢细胞；然而，随着发育的进行，绒毡层和中层细胞增大，最终挤压造孢细胞。gne2类花药在更早阶段就受到破坏，中层和绒毡层无法形成，并且过量的造孢细胞发育，直到生殖系在减数分裂II后期终止。对这些突变体的分析已经对当前被子植物花药发育模型的准确性提出了质疑。
