Department of Plant Pathology, Cornell University, Ithaca, New York 14853.
Proc Natl Acad Sci U S A. 1980 Apr;77(4):2046-9. doi: 10.1073/pnas.77.4.2046.
Plant cells react to localized stress by forming wall appositions outside their protoplasts on the inner surface of their cellulose walls. For many years it has been inferred that appositions elicited by encroaching fungi, termed "papillae," may subsequently also deter them and thus represent a disease-resistance mechanism. Recently, it has been shown that preformed, oversized papillae, experimentally produced in coleoptile cells of compatible barley, Hordeum vulgare, can completely prevent direct entry of Erysiphe graminis f. sp. hordei that ordinarily penetrates and causes disease. To discover how these papillae may function, acoustic microscopy was used to contrast their in vivo elastic properties with those of ineffective normal papillae and contiguous cell wall. Raster and line scans showed intense acoustic activity at sites of preformed papillae; scans in selected focal planes identified this activity with the papillae, not with subtending cell wall. Minimal acoustic activity was found in normal papillae. It is suggested that some wall appositions could serve in disease resistance as viscoelastic barriers to mechanical forces exerted by the special penetration structures of advancing pathogenic fungi.
植物细胞通过在其质体外层的纤维素壁的内表面上形成细胞壁附著来对局部应力作出反应。多年来，人们推断，由侵入真菌引起的细胞壁附著（称为“乳突”）可能随后也会阻止真菌的侵入，因此代表了一种抗病机制。最近，已经表明，在相容大麦（Hordeum vulgare）的 coleoptile 细胞中实验产生的预先形成的过大乳突可以完全阻止通常穿透并引起疾病的禾柄锈菌（Erysiphe graminis f. sp. hordei）的直接进入。为了发现这些乳突可能如何发挥作用，使用声显微镜将其体内弹性特性与无效的正常乳突和相邻细胞壁的弹性特性进行对比。光栅和线扫描显示，在预先形成的乳突部位有强烈的声活动；在选定的焦点平面上进行的扫描将该活动与乳突而不是与支撑细胞壁相关联。在正常乳突中发现了最小的声活动。有人提出，一些细胞壁附著物可以作为抵抗病害的粘性弹性屏障，抵抗前进的致病真菌的特殊穿透结构施加的机械力。
