de Lima J E O, Miranda V S, Hartung J S, Brlansky R H, Coutinho A, Roberto S R, Carlos E F
Agrocitros Citrolima Ltda., Casa Branca, SP 13700, Brazil.
Fundecitrus, Araraquara, SP 14801-970, Brazil.
Plant Dis. 1998 Jan;82(1):94-97. doi: 10.1094/PDIS.1998.82.1.94.
Symptoms of coffee leaf scorch (CLS) appear on young flushes of field plants as large marginal and apical scorched areas on recently mature leaves. Affected leaves drop, shoot growth is stunted, and apical leaves are small and chlorotic. Symptoms may progress to shoot dieback. Only scorched leaves which could not be related to other known agents consistently contained bacteria and bacterial agglomerates when observed with light microscopy. Only plants with these symptoms were positive in enzyme-linked immunosorbent assay (ELISA) tests using antiserum to Xylella fastidiosa Wells et al. The bacterium Xylella fastidiosa Wells et al. was isolated in November 1995 from coffee (Coffea arabica) leaves with scorch symptoms on supplemented periwinkle wilt medium. Colonies were circular, dome-shaped, white, and 0.5 to 1.5 mm in diameter. Two of 10 young coffee seedlings stem-inoculated with a suspension of the isolated X. fastidiosa in January 1996 showed leaf scorch symptoms 3 to 5 months later, contained bacteria in xylem extracts, and reacted positively in ELISA using antiserum to the citrus variegated chlorosis (CVC) strain of X. fastidiosa. ELISA-positive bacteria were reisolated from this plant. None of the symptomless plants, including controls, revealed bacteria on microscopic examinations, ELISA, or isolation attempts. Antisera developed against cultured bacteria from both CLS and CVC plants reacted positively against plant extracts of both diseases in dot immunobinding assays (DIBA). The level of detection was about 5 × 10 bacteria ml for both homologous and heterologous reactions. The polymerase chain reaction amplification products produced by CLS and CVC strains of X. fastidiosa were indistinguishable. Geographical distribution of these strains is not the same. CLS is widespread and usually occurs if coffee is adjacent to CVC-affected citrus. However, CVC does not always occur when citrus is grown adjacent to CLS-affected coffee. The bacteria are closely related, if not identical.
咖啡叶焦枯病（CLS）的症状出现在田间植株的嫩梢上，表现为最近成熟叶片上出现大片边缘和顶端焦枯区域。受影响的叶片会掉落，新梢生长受阻，顶端叶片小且发黄。症状可能发展为新梢枯死。在光学显微镜观察时，只有那些与其他已知病原体无关的焦枯叶片始终含有细菌和细菌聚集体。只有出现这些症状的植株在用针对木质部难养菌（Xylella fastidiosa Wells等人）的抗血清进行酶联免疫吸附测定（ELISA）测试时呈阳性。1995年11月，从有焦枯症状的咖啡（阿拉伯咖啡）叶片中，在添加了长春花萎蔫培养基上分离出了木质部难养菌（Xylella fastidiosa Wells等人）。菌落呈圆形、圆顶状、白色，直径为0.5至1.5毫米。1996年1月，用分离出的木质部难养菌的悬浮液对10株咖啡幼苗进行茎接种，其中2株在3至5个月后出现叶焦枯症状，木质部提取物中含有细菌，在用针对木质部难养菌柑橘杂色黄化病（CVC）菌株的抗血清进行ELISA测试时呈阳性反应。ELISA阳性细菌从该植株中重新分离出来。包括对照在内的无症状植株在显微镜检查、ELISA或分离尝试中均未发现细菌。针对CLS和CVC植株培养细菌产生的抗血清在斑点免疫结合测定（DIBA）中对两种病害的植物提取物均呈阳性反应。同源和异源反应的检测水平均约为5×10个细菌/毫升。木质部难养菌CLS菌株和CVC菌株产生的聚合酶链反应扩增产物无法区分。这些菌株的地理分布不同。CLS广泛分布，通常在咖啡与受CVC影响的柑橘相邻时发生。然而，当柑橘与受CLS影响的咖啡相邻种植时，CVC并不总是出现。这些细菌即使不完全相同，也密切相关。
