Fos M, Nuez F, García-Martínez J L
Departamento de Biología Vegetal, Universidad Politécnica de Valencia, 46022-Valencia, Spain.
Plant Physiol. 2000 Feb;122(2):471-80. doi: 10.1104/pp.122.2.471.
We investigated the role of gibberellins (GAs) in the effect of pat-2, a recessive mutation that induces facultative parthenocarpic fruit development in tomato (Lycopersicon esculentum Mill.) using near-isogenic lines with two different genetic backgrounds. Unpollinated wild-type Madrigal (MA/wt) and Cuarenteno (CU/wt) ovaries degenerated, but GA(3) application induced parthenocarpic fruit growth. On the contrary, parthenocarpic growth of MA/pat-2 and CU/pat-2 fruits, which occurs in the absence of pollination and hormone application, was not affected by GA(3). Pollinated MA/wt and parthenocarpic MA/pat-2 ovary development was negated by paclobutrazol, and this inhibitory effect was counteracted by GA(3). The main GAs of the early-13-hydroxylation pathway (GA(1), GA(3), GA(8), GA(19), GA(20), GA(29), GA(44), GA(53), and, tentatively, GA(81)) and two GAs of the non-13-hydroxylation pathway (GA(9) and GA(34)) were identified in MA/wt ovaries by gas chromatography-selected ion monitoring. GAs were quantified in unpollinated ovaries at flower bud, pre-anthesis, and anthesis. In unpollinated MA/pat-2 and CU/pat-2 ovaries, the GA(20) content was much higher (up to 160 times higher) and the GA(19) content was lower than in the corresponding non-parthenocarpic ovaries. The application of an inhibitor of 2-oxoglutarate-dependent dioxygenases suggested that GA(20) is not active per se. The pat-2 mutation may increase GA 20-oxidase activity in unpollinated ovaries, leading to a higher synthesis of GA(20), the precursor of an active GA.
我们利用具有两种不同遗传背景的近等基因系，研究了赤霉素（GAs）在pat - 2（一种隐性突变，可诱导番茄（Lycopersicon esculentum Mill.）兼性单性结实果实发育）效应中的作用。未授粉的野生型马德里加尔（MA/wt）和夸伦特诺（CU/wt）子房会退化，但施用GA(3)可诱导单性结实果实生长。相反，MA/pat - 2和CU/pat - 2果实的单性结实生长在未授粉且未施用激素的情况下发生，不受GA(3)影响。多效唑使授粉的MA/wt和单性结实的MA/pat - 2子房发育受到抑制，而GA(3)可抵消这种抑制作用。通过气相色谱 - 选择离子监测，在MA/wt子房中鉴定出了13 - 羟基化途径的主要赤霉素（GA(1)、GA(3)、GA(8)、GA(19)、GA(20)、GA(29)、GA(44)、GA(53)，以及暂定的GA(81)）和非13 - 羟基化途径的两种赤霉素（GA(9)和GA(34)）。在花芽期、开花前和开花期对未授粉子房中的赤霉素进行了定量分析。在未授粉的MA/pat - 2和CU/pat - 2子房中，GA(20)含量比相应的非单性结实子房高得多（高达160倍），而GA(19)含量则较低。施用2 - 酮戊二酸依赖性双加氧酶抑制剂表明GA(20)本身没有活性。pat - 2突变可能会增加未授粉子房中GA 20 - 氧化酶的活性，导致活性GA的前体GA(20)合成增加。
