Effect of Verticillium dahliae on Photosynthesis, Leaf Expansion and Senescence of Field-grown Sunflower
Effect of Verticillium dahliae on Photosynthesis, Leaf Expansion and Senescence of Field-grown Sunflower
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大丽黄萎病对田间向日葵光合作用、展叶和衰老的影响
DOI：
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
V. Pereyra
中科院分区：
文献类型：
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作者：
V. Sadras;F. Quiróz;L. Echarte;A. Escande;V. Pereyra
在已知向日葵(Heliantus annuus L.)在对土壤水分亏缺的响应中，提出黄萎菌对植物叶面积的影响先于对叶片光合作用和气孔导度的影响。为了验证这一假设，我们在田间试验中测量了地上部和叶面积的生长、叶片的光合作用速率、气孔导度和病害症状，其中包括对大丽叶病毒高(Sankol)和低(Dekasol 3900)感病的杂交种。对接种大丽弧菌的植株和对照植株进行了比较。我们还研究了大丽叶病毒对大丽叶病毒中等感病的杂交种桑科尔和多巴的接种和对照植株叶面积、叶展开和衰老关键成分的影响。接种(DAI)后31d，当接种植株的症状轻微(Sankol)或无症状(Dekasol 3900)时，首次检测到由大丽弧菌引起的植物叶面积减少。在整个试验过程中，首次观察到66个DAI叶片光合作用降低；气孔导度和叶片暗呼吸均未受到大丽叶病毒的影响。与对照相比，Dekalb 3900和Sankol的植株叶面积季节历时分别缩短了25%和55%，而叶片的光合速率平均降低了9%。与叶面积持续时间的减少相对应，接种使成熟桑科尔的地上部干物质减少了50%。在这两个实验中，植物叶面积早期减少的主要原因是叶展开较少；随着疾病的发展，不断加剧的衰老也导致植物叶面积减少。结果表明，向日葵对大丽菊的反应类似于植物对土壤水分亏缺的反应：(1)植株叶面积，而不是叶片的光合作用速率，是导致质量增长减少的原因；(2)植株叶面积减少的原因是季节早期叶片膨大减少，老年植株叶片衰老较快。
On the basis of known sunflower (Helianthus annuus L.) responses to soil water deficit, it is proposed that the effect of the fungus Verticillium dahliae Klebahn on plant leaf area precedes and is greater than its effect on leaf photosynthesis and stomatal conductance. To test this hypothesis, we measured shoot and leaf area growth, leaf photosynthetic rate, stomatal conductance and disease symptoms in a field experiment including hybrids of high (Sankol) and low (Dekasol 3900) susceptibility to V. dahliae. Plants inoculated with V. dahliae and controls were compared. We also investigated the effect of V. dahliae on key components of plant leaf area, leaf expansion and senescence, in inoculated and control plants of Sankol and Toba, a hybrid of intermediate susceptibility to V. dahliae. Reduction in plant leaf area caused by V. dahliae was first detected 31 d after inoculation (DAI), when visual symptoms of disease in inoculated plants were slight (Sankol) or absent (Dekasol 3900). Reduction in leaf photosynthesis was first observed 66 DAI; stomatal conductance and leaf dark respiration were both unaffected by V. dahliae during the whole experiment. In comparison with controls, V. dahliae reduced seasonal duration of plant leaf area by 25% in Dekalb 3900 and by 55% in Sankol, whereas the average reduction in leaf photosynthetic rate was 9%. In correspondence with the reduction in leaf area duration, inoculation reduced shoot dry matter of mature Sankol by 50%. In both experiments, less leaf expansion accounted for most of the early reduction in plant leaf area; as the disease progressed, increasing senescence also contributed to reduced plant leaf area. It is concluded that the response of sunflower to V. dahliae resembled the response of the plant to soil water deficit: (1) plant leaf area, rather than leaf photosynthetic rate, accounted for the reduction in growth in mass; and (2) reduced leaf expansion early in the season and faster leaf senescence in older plants accounted for the decrease in plant leaf area.