Mariette Nicolas, Kröner Alexander, Mabon Romain, Montarry Josselin, Marquer Bruno, Corbière Roselyne, Androdias Annabelle, Andrivon Didier
INRA, UMR1349 Institute for Genetics, Environment and Plant Protection, Le Rheu, France.
Front Plant Sci. 2018 Dec 19;9:1841. doi: 10.3389/fpls.2018.01841. eCollection 2018.
The negative relationship between offspring size and number is a classic example of trade-off between life-history traits, reported many times in animal and plant species. Here, we wanted to ascertain whether such a trade-off occurred in the oomycete , and whether it was impacted by biotic and abiotic factors. We thus conducted three infection experiments under controlled conditions and measured the number and the size of sporangia (asexual propagules) produced on potato by different isolates. In all experiments, we observed a negative relationship between sporangia size and number, demonstrating the existence of a trade-off. Moreover, although the potato host cultivar, temperature and host of origin (tomato or potato) all affected sporangia number, sporangia size or both, none of these biotic and abiotic factors did change the trade-off. Therefore, the trade-off between sporangia size and number could maintain the polyphenism for these traits in populations, and favors the coexistence of distinct reproductive strategies within this species. Our results emphasize the relevance to focus on the relationship between offspring size and number in other fungal plant pathogens, as well as to study the impact of offspring size on fitness-linked traits (virulence and disease lesion development) in these organisms.
后代大小与数量之间的负相关关系是生活史特征之间权衡的经典例子，在动植物物种中已被多次报道。在此，我们想确定这种权衡是否发生在卵菌中，以及它是否受到生物和非生物因素的影响。因此，我们在可控条件下进行了三项感染实验，并测量了不同分离株在马铃薯上产生的孢子囊（无性繁殖体）的数量和大小。在所有实验中，我们都观察到孢子囊大小与数量之间存在负相关关系，证明了权衡的存在。此外，尽管马铃薯宿主品种、温度和起源宿主（番茄或马铃薯）都会影响孢子囊数量、孢子囊大小或两者，但这些生物和非生物因素均未改变这种权衡。因此，孢子囊大小与数量之间的权衡可以维持种群中这些性状的多态性，并有利于该物种内不同繁殖策略的共存。我们的研究结果强调关注其他真菌植物病原体中后代大小与数量之间关系的重要性，以及研究后代大小对这些生物体中与适应性相关性状（毒力和病害病斑发展）的影响。
