Host influence on germination and reproduction of the facultative hemi-parasitic weed Rhamphicarpa fistulosa
Host influence on germination and reproduction of the facultative hemi-parasitic weed Rhamphicarpa fistulosa
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寄主对兼性半寄生杂草 Rhamphicarpa fisulosa 萌发和繁殖的影响
DOI：
10.1111/aab.12288
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发表时间：
2016
影响因子：
2.6
通讯作者：
L. Bastiaans
中科院分区：
文献类型：
--
作者：
S. Kabiri;A. Ast;J. Rodenburg;L. Bastiaans
水稻吸血草（Rhamphalipafistulosa）是一种小型寄生杂草，直到最近撒哈拉以南非洲的水稻种植扩展到边缘湿地，这是寄生虫的自然栖息地。与大多数寄生性杂草不同，R. fistulosa是兼性的，这意味着寄生虫能够在没有宿主的情况下完成其生命周期。然而，当不与宿主植物连接时，其生物量和种子产量较低。由于很少有人知道关于寄生虫的发芽生态，我们研究的主要目的是确定有利于发芽的线索。我们假设，首先，作为一个湿地物种，R。fistulosa是由光和高土壤水分刺激。其次，我们假设，如果宿主植物的存在增加其生殖输出，然后从主机存在的发芽刺激效应很可能已经开发。培养皿和盆栽试验结果表明，光照和饱和土壤是种子萌发的必要条件。fistulosa是生长在水位波动环境中的典型物种。盆栽试验中，五个感染水平的R。fistulosa在不存在和存在水稻植物的情况下安装，表明宿主植物的存在导致种子生产率提高3.7倍，平均种子大小增加15%。尽管有这种繁殖优势，但由于独脚金内酯产量的差异而选择的三个水稻品种的盆栽试验表明，无论发育阶段如何，寄主植物的存在都不会影响R.瘘管在后续的研究中，从相同的三个水稻品种和人工发芽刺激剂（GR 24）组成的治疗收集的根分泌物的发芽刺激效果进行了比较，与治疗组成的平原水。在这些处理中，R. fistulosa的种子进行了比较专性寄生Strigahermonthica。S.根分泌物和GR 24的存在能显著促进hermonthica的萌发，而在水中则完全不存在。fistulosa在所有处理中的变化与普通水相似。在萌发阶段的主机识别机制的情况下，通过光和土壤水分的萌发的调节是接近最佳的。我们的发现也可能表明，对于这种兼性寄生植物物种，一个更机会主义的发芽策略是优越的上级。研究结果对R.稻瘟病在水稻栽培中的应用。
Rice Vampireweed, Rhamphicarpa fistulosa, was a minor parasitic weed until recently when rice cultivation in sub-Saharan Africa was expanded into marginal wetlands, that are the parasite's natural habitat. Unlike most of the parasitic weeds, R. fistulosa is facultative, meaning that the parasite is able to complete its life cycle without a host. However, when not connected to a host plant, its biomass and seed production is lower. Because very little is known regarding the germination ecology of the parasite, the main objective of our study was to identify the cues that favour germination. We hypothesised that, first, being a wetland species, germination of R. fistulosa is stimulated by light and high soil moisture. Second, we hypothesised that if host plant presence increases its reproductive output then a germination stimulatory effect from host presence is likely to have developed. A Petri-dish and pot experiment showed that light and completely saturated soils were a requirement for germination, demonstrating that germination requirements of R. fistulosa are typical of species that grow in environments with fluctuating water levels. A pot experiment in which five infestation levels of R. fistulosa were installed in the absence and presence of a rice plant, showed that host plant presence resulted in a 3.7 times higher seed production rate and a 15% larger average seed size. Despite this reproductive advantage, a pot experiment with three rice cultivars, selected because of their difference in strigolactone production, showed that host plant presence, regardless of the development stage, did not influence the emergence rate of R. fistulosa. In a follow-up study, the germination stimulation effect of root exudates collected from the same three rice cultivars and a treatment consisting of an artificial germination stimulant (GR24) was compared with a treatment consisting of plain water. In these treatments, seeds of R. fistulosa were compared with seeds of the obligate parasite Striga hermonthica. Germination of S. hermonthica was strongly advanced by the presence of root exudates and GR24 but was completely absent in water, whereas germination of R. fistulosa in all treatments was similar to that in plain water. The absence of a host recognition mechanism at the germination stage suggests that the regulation of germination through light and soil moisture is near optimal. Our finding might also indicate that for this facultative parasitic plant species, a more opportunistic germination strategy is superior. Implications of the findings for management of R. fistulosa in rice cultivation are discussed.