Control of Root Parasitic Weeds by Inducing Suicidal Germination

茄病镰刀菌（Fusarium solani，Sud 96）的代谢产物抑制发芽刺激剂GR 24诱导的独脚金（Striga hermonthica）发芽。根据色谱、核磁共振谱和质谱，确定了其有效成分为三烯尖果苷、新茄醇、8-乙酰新茄醇和四乙酰氧基T-2四醇（新茄醇二乙酸酯）。四种单萜类化合物对独脚金种子萌发的抑制活性随羟基乙酰化程度的增加而增加。真菌产生的最丰富的抑制剂8-乙酰新茄醇在24 μM时完全抑制独脚金的萌发。真菌毒素对寄主作物高粱种子萌发无影响，但在相同浓度下，对高粱幼苗的根伸长和芽伸长分别有60%和30%的抑制作用，对蝙蝠葛根培养产生的萌发刺激物进行了分离纯化，经色谱、核磁共振、质谱、紫外和圆二色性光谱鉴定为（+）-独脚金醇。（+）-S的分离量 关于我们 从61培养滤液中计算出trigol约为140 μg。该培养物将使研究发芽刺激物的生物合成成为可能。GR 24处理后12 h从发芽种子中提取的总RNA用于基于PCR的扩增编码ACC合酶和氧化酶活性位点结构域的cDNA片段。对两个编码ACC合酶的cDNA片段（SHACS 1和SHACS 2）和一个编码ACC氧化酶的cDNA片段（SHACO 1）进行了克隆和测序。Southern杂交结果表明，所克隆的基因均为单拷贝;北方杂交结果表明，SHACS 1基因的表达量随时间变化，在GR 24处理后10 h达到高峰，这与种子乙烯释放的规律雅阁。SHACS 2以低水平表达，具有类似的趋势。SHACO 1表现出时间的变化，峰值在15天的条件下，种子对GR 24的反应是最大的。根据这些结果，可以得出结论，ACC氧化酶和ACC合成酶分别响应于条件和萌发刺激。这两种酶协同作用，生物合成乙烯，诱导种子萌发。少

Metabolites of the fungus Fusarium solani (Sud 96) inhibited Striga hermonthica germination induced by the germination stimulant GR24. The, active principles were identified as trichothecenes acuminatin, neosolaniol, 8-acetylneosolaniol and tetraacetoxy T-2 tetraol (neosolaniol diacetate) on the basis of their chromatographic behavior, NMR, and mass spectra. Inhibitory activity of the four trichothecenes against Striga germination increased with acetylation of hydroxyl moieties. 8-Acetylneosolaniol, the most abundant inhibitor produced by the fungus, completely inhibited Striga germination at 24 μM. The fungal toxin did not affect germination of sorghum, a host crop, but retarded root and shoot elongation of the seedlings by 60 % and 30 %, respectively, at the same concentration.Germination stimulant produced by Menispermum dauricum root culture was purified and identified as (+)-strigol on the basis of chromatographic behavior, NMR, MS, UV, and CD spectra. The isolated amount of (+)-s … More trigol was calculated to be about 140 μg from 61 culture filtrate. This culture will make it possible to study biosynthesis of the germination stimulant.Total RNA extracted from germinating seeds 12 h after GR24 treatment was used for PCR-based amplification of cDNA fragments encoding the ACC synthase- and oxidase-active site domains. Two distinct cDNA fragments encoding ACC synthase (SHACS1 and SHACS2) and one encoding ACC oxidase (SHACO1) were cloned and sequenced. Southern hybridization suggested that each of the cloned genes has a single copy in the genome of S.hermonthica.Northern blot analyses showed that expression of SHACS1 exhibited a temporal change, with a peak at 10 h after GR24 treatment, which was in accord with that of ethylene evolution from the seeds. SHACS2 was expressed at a low level with a similar trend. SHACO1 exhibited a temporal change with a peak at 15 days during conditioning, where seed response to GR24 was maximum. Based on these results, it is concluded that ACC oxidase and ACC synthase are responsive to conditioning and germination stimulant, respectively. Both the enzymes act concertedly to biosynthesize ethylene, which induces seed germination. Less