Erickson J E, Stanosz G R, Kruger E L
Department of Forest Ecology and Management, University of Wisconsin-Madison, 1630 Linden Dr, Madison, WI 53706, USA.
Department of Plant Pathology, University of Wisconsin-Madison, 1630 Linden Dr, Madison, WI 53706, USA.
New Phytol. 2004 Feb;161(2):577-583. doi: 10.1046/j.1469-8137.2003.00968.x. Epub 2003 Dec 12.
• In foliage of two hybrid poplars, clone DN-34 (Populus deltoides × P. nigra) and clone NM-6 (P. nigra × P. maximowiczii), we examined relationships between photosynthesis and severity of leaf spot induced by Marssonina brunnea f. sp. brunnea, a common disease of many tree species in the Populus genus with the potential to affect growth. • Gas exchange was measured on asymptomatic and diseased foliage in monoculture stands of each clone. The equation Y = (1 - x) was used to characterize the relationship between relative photosynthesis (Y) and percent leaf spot (x), where β represents the ratio between functional impairment and measured lesion area. • Leaf photosynthesis was strongly and negatively correlated with leaf spot severity in both hybrids, and β-values indicated that photosynthetic impairment extended beyond visibly damaged leaf tissue. However, large differences in β between hybrids indicated differential photosynthetic consequences for a given leaf spot severity. For each hybrid, values of β were positively related to photosynthetic photon flux density incident upon the leaf during gas exchange measurement. • Declines in leaf photosynthesis appeared to result from a disruption of the photosynthetic apparatus by the invading pathogen. However, specific causes for the differential photosynthetic responses of the two hybrids to disease remained elusive.
• 在两个杂交杨树无性系DN-34（美洲黑杨×欧洲黑杨）和NM-6（欧洲黑杨×大青杨）的叶片中，我们研究了光合作用与杨树炭疽病菌（Marssonina brunnea f. sp. brunnea）引起的叶斑病严重程度之间的关系，杨树炭疽病是杨属许多树种的常见病害，有可能影响树木生长。
• 在每个无性系的纯林分中，对无症状和患病叶片进行了气体交换测量。使用方程Y = (1 - x)来表征相对光合作用（Y）与叶斑病百分比（x）之间的关系，其中β表示功能损伤与测量病斑面积的比值。
• 两个杂交杨树无性系的叶片光合作用均与叶斑病严重程度呈强烈负相关，β值表明光合损伤超出了肉眼可见的受损叶组织范围。然而，两个杂交杨树无性系之间β值的巨大差异表明，对于给定的叶斑病严重程度，光合后果存在差异。对于每个杂交杨树无性系，β值与气体交换测量期间入射到叶片上的光合光子通量密度呈正相关。
• 叶片光合作用的下降似乎是由入侵病原体破坏光合机构所致。然而，两个杂交杨树无性系对病害的光合反应差异的具体原因仍不清楚。
