Quantifying benefits of kinship dependent variation in
allelopathy
Plants produce a wide variety of allelopathic compounds which can have
negative effects on con-specific plants or negative effects on
hetero-specific plants, the former also being called autotoxicity.
Autotoxicity has been documented in a wide variety of plants and is
thought as a mechanism to avoid local intraspecific competition and thus
ensure a greater spatial and temporal seed dispersal (Singh, Batish, &
Kohli, 1999). It is also well documented in several crops including rice
(Singh et al., 1999) and is believed as an important cause of yield
reductions in continuous mono-cropping (i.e., growing the same crop on a
field year after year, Chi et al., 2013). Xu et al.’s finding of reduced
allelopathic activities in rice plants only interacting with
closely-related-cultivar neighbours may suggest this reduction to
reflect a kinship-selected cooperative strategy avoiding auto-toxic
effects on kin. However, this raises the question why the highest
allelopathic activities were found in plants interacting with neighbours
of the same cultivar (i.e., the treatment with the greatest degree of
neighbour relatedness).Recent research has shown for wheat that plants
may produce allelochemicals in response to exudates produced by
neighbours, particularly loliolide and jasmonic acid (Kong et al.,
2018). It is possible that such signalling also occurs in rice and that
it differs between cultivars, independently of relatedness, and that the
two focal cultivars in Xu et al. (2021) may have happened to be active
producers of such signalling compounds. Clearly, more research is needed
to better understand the possible connection between kin recognition and
allopathy.