Vivian-Smith A, Koltunow A M
Commonwealth Scientific Industrial Research Organization, Plant Industry, Horticulture Research Unit, P.O. Box 350, Glen Osmond, South Australia 5064, Australia.
Plant Physiol. 1999 Oct;121(2):437-51. doi: 10.1104/pp.121.2.437.
In Arabidopsis, seedless silique development or parthenocarpy can be induced by the application of various plant growth regulators (PGRs) to unfertilized pistils. Ecotype-specific responses were observed in the Arabidopsis ecotypes Columbia and Landsberg relative to the type of PGR and level applied. The parthenocarpic response was greatest in ecotype Landsberg, and comparisons of fruit growth and morphology were studied primarily in this ecotype. Gibberellic acid application (10 micromol pistil(-1)) caused development similar to that in pollinated pistils, while benzyladenine (1 micromol pistil(-1)) and naphthylacetic acid (10 micromol pistil(-1)) treatment produced shorter siliques. Naphthylacetic acid primarily modified mesocarp cell expansion. Arabidopsis mutants were employed to examine potential dependencies on gibberellin biosynthesis (ga1-3, ga4-1, and ga5-1) and perception (spy-4 and gai) during parthenocarpic silique development. Emasculated spy-4 pistils were neither obviously parthenocarpic nor deficient in PGR perception. By contrast, emasculated gai mutants did not produce parthenocarpic siliques following gibberellic acid application, but silique development occurred following pollination or application of auxin and cytokinin. Pollinated gai siliques had decreased cell numbers and morphologically resembled auxin-induced parthenocarpic siliques. This shows that a number of independent and possibly redundant pathways can direct hormone-induced parthenocarpy, and that endogenous gibberellins play a role in regulating cell expansion and promoting cell division in carpels.
在拟南芥中，通过对未受精的雌蕊施加各种植物生长调节剂（PGR），可以诱导无籽角果发育或单性结实。相对于PGR的类型和施用水平，在拟南芥生态型哥伦比亚和兰茨贝格中观察到了生态型特异性反应。单性结实反应在兰茨贝格生态型中最为显著，并且主要在该生态型中研究了果实生长和形态的比较。施用赤霉素（10微摩尔/雌蕊）导致的发育与授粉雌蕊相似，而苄基腺嘌呤（1微摩尔/雌蕊）和萘乙酸（10微摩尔/雌蕊）处理产生的角果较短。萘乙酸主要改变了中果皮细胞的扩张。利用拟南芥突变体来研究在单性结实角果发育过程中对赤霉素生物合成（ga1-3、ga4-1和ga5-1）和感知（spy-4和gai）的潜在依赖性。去雄的spy-4雌蕊既没有明显的单性结实，也没有PGR感知缺陷。相比之下，去雄的gai突变体在施用赤霉素后没有产生单性结实角果，但在授粉或施用生长素和细胞分裂素后发生了角果发育。授粉的gai角果细胞数量减少，形态上类似于生长素诱导的单性结实角果。这表明许多独立且可能冗余的途径可以指导激素诱导的单性结实，并且内源性赤霉素在调节心皮细胞扩张和促进细胞分裂中发挥作用。
