Institut des Sciences Végétales, C.N.R.S., Allée de la Terrasse, 91198 Gif sur Yvette, France.
Plant Physiol. 1991 Jun;96(2):459-66. doi: 10.1104/pp.96.2.459.
When auxin was omitted during either the preparation or the culture of tobacco mesophyll protoplasts, as well as during both periods, synthesis of beta-glucanase was spontaneously induced. In contrast, when protoplasts were prepared and cultured in the presence of 16 micromolar 1-naphthaleneacetic acid (optimal concentration for protoplast division), the expression of beta-glucanase was maintained close to the minimal level observed in tobacco leaves. This inhibitory effect was only promoted by active auxins (1-naphthaleneacetic acid, 2,4-dichlorophenoxyacetic acid, 2,4,5-trichlorophenoxyacetic acid, and 3-indoleacetic acid) but not by inactive auxin analogs. Tobacco protoplasts responded to exogenous elicitors from the cell wall of Phytophthora megasperma glycinea (Pmg) by accumulating beta-glucanase in the presence of 16 micromolar 1-naphthaleneacetic acid. At higher auxin concentrations, the elicitor-induced beta-glucanase synthesis was inhibited. Naphthaleneacetic acid concentration (3 x 10(-5) molar) required to inhibit by 50% the expression of this defense reaction triggered by a near-optimal elicitor concentration was about 100 times higher than that sufficient to inhibit by 50% the spontaneous expression in nonelicited protoplasts. This is the first demonstration of an auxin-fungal elicitor interaction in the control of a defined defense reaction. The above observations were extended to soybean cell protoplasts. The Pmg elicitor-induced stimulation of the synthesis of pathogenesis related P17 polypeptides and of a 39-kilodalton peptide immunologically related to tobacco beta-glucanase was only observed when the spontaneous accumulation of these proteins was inhibited in auxin-treated protoplasts.
当在烟草叶肉原生质体的制备或培养过程中以及两个阶段都缺失生长素时，β-葡聚糖酶的合成会自发诱导。相比之下，当原生质体在 16 微摩尔 1-萘乙酸（原生质体分裂的最佳浓度）存在的条件下制备和培养时，β-葡聚糖酶的表达保持在烟草叶片中观察到的最低水平附近。这种抑制作用仅被活性生长素（1-萘乙酸、2,4-二氯苯氧乙酸、2,4,5-三氯苯氧乙酸和 3-吲哚乙酸）促进，而不被非活性生长素类似物促进。烟草原生质体对来自大豆疫霉菌细胞壁的外源诱导剂作出反应，在 16 微摩尔 1-萘乙酸存在的情况下积累β-葡聚糖酶。在较高的生长素浓度下，诱导的β-葡聚糖酶合成被抑制。抑制由近最佳诱导剂浓度触发的这种防御反应表达的 50%所需的萘乙酸浓度（3 x 10(-5)摩尔）比抑制非诱导原生质体中自发表达的 50%所需的浓度高约 100 倍。这是生长素-真菌诱导剂相互作用控制特定防御反应的首次证明。上述观察结果扩展到大豆细胞原生质体。只有在生长素处理的原生质体中抑制这些蛋白质的自发积累时，大豆疫霉菌诱导剂才会诱导与发病相关的 P17 多肽和与烟草β-葡聚糖酶免疫相关的 39 千道尔顿肽的合成。
