Kin Recognition in an Herbicide-Resistant Barnyardgrass (Echinochloa crus-galli L.) Biotype

Abstract

Despite increasing evidence of kin recognition in natural and crop plants, there is a lack of knowledge of kin recognition in herbicide-resistant weeds that are escalating in cropping systems. Here, we identified a penoxsulam-resistant barnyardgrass biotype with the ability for kin recognition from two biotypes of penoxsulam-susceptible barnyardgrass and normal barnyardgrass at different levels of relatedness. When grown with closely related penoxsulam-susceptible barnyardgrass, penoxsulam-resistant barnyardgrass reduced root growth and distribution, lowering belowground competition, and advanced flowering and increased seed production, enhancing reproductive effectiveness. However, such kin recognition responses were not occurred in the presence of distantly related normal barnyardgrass. Root segregation, soil activated carbon amendment, and root exudates incubation indicated chemically-mediated kin recognition among barnyardgrass biotypes. Interestingly, penoxsulam-resistant barnyardgrass significantly reduced a putative signaling (–)-loliolide production in the presence of closely related biotype but increased production when growing with distantly related biotype and more distantly related interspecific allelopathic rice cultivar. Importantly, genetically identical penoxsulam-resistant and -susceptible barnyardgrass biotypes synergistically interact to influence the action of allelopathic rice cultivar. Therefore, kin recognition in plants could also occur at the herbicide-resistant barnyardgrass biotype level, and intraspecific kin recognition may facilitate cooperation between genetically related biotypes to compete with interspecific rice, offering many potential implications and applications in paddy systems.

Chemically Mediated Plant–Plant Interactions: Allelopathy and Allelobiosis

“…Plants can distinguish their conspecific neighbors based on their genetic relatedness (i.e., kin recognition) and adjust their ‘behavior’ accordingly (i.e., kin discrimination) [ 150 ]. Such kin recognition and kin discrimination have been observed in individuals [ 151 ], populations, biotypes [ 122 , 152 ], and cultivar levels [ 87 ]. Kin recognition and kin discrimination allow behaviors toward kin groups.…”

“…Subsequent studies have shown that many plants are able to differentiate relatives from unrelated plants from the same population. Such kin recognition occurs in various types of plant species, ranging either from gymnosperms to angiosperms, or from wild species to crop plants [ 87 , 122 , 152 , 155 , 156 ]. The ability to detect relatedness would allow plants to discriminate closely from distantly related neighbors and optimize response strategies for the composition of their local neighborhood [ 6 , 150 , 157 , 158 ].…”

“…Induce allelopathy [119] Participate in plant neighbor detection [23] Salicylic acid Participate in plant neighbor detection and allelopathy [16] Allantoin Participate in kin recognition in rice [87] Activate stress response [120] (-)-Loliolide Participate in plant neighbor detection [23] Induce defense responses [121] Mediate plant kin recognition [122] Modulate flowering time [123] Modify the rhizosphere microbial community [124] Root-microbe signals…”

Phytochemical Cue for the Fitness Costs of Herbicide-Resistant Weeds

“…Although the fitness cost of resistance and its mechanisms in herbicide-resistant weeds have been investigated and interpreted from molecular, physiological, and biochemical perspectives [17,22,[25][26][27][28], few studies, to our knowledge, involve phytochemical cues. In fact, phytochemicals, either endogenous hormones or exogenous signals and allelochemicals, play vital roles in plant growth, defense, and reproduction [29][30][31][32]. In particular, phytochemical signals can regulate the tradeoff between growth and defense and aboveground and belowground performance, and thus alter plant fitness [33].…”

Plant Signaling, Behavior and Communication

“…Accordingly, Midzi et al [ 16 ] highlight the ecological relevance of such interactions under various environmental stresses and the growing understanding of the mechanisms involved and the significance of VOC-mediated inter-plant interactions under both biotic and abiotic stresses. As an interesting example of inter-plant interactions, Le Ding et al [ 17 ] show that intraspecific kin recognition may facilitate cooperation between genetically related biotypes to compete with interspecific rice, offering many potential implications and applications in paddy systems.…”