LAUSR

Abstract Drought can induce shifts in plant species or functional group abundances, which may favor coexisting subordinate species at the expense of previous dominants. Within-generation and transgenerational phenotypic plasticity can be important mechanisms to shape species responses to drought. Although a handful of studies have already investigated transgenerational plasticity in the context of drought, they provided variable results, and usually focused on species that currently dominate communities. We performed pot experiments with Secale sylvestre, a typical subordinate species in semiarid grasslands of Central Hungary. We tested if this annual grass shows reduced growth or reproduction in response to drought, and whether drought in the maternal environment affects offspring performance. For both maternal and offspring generations, plant height, shoot biomass, flowering onset, and seed number showed no within-generation plasticity in response to drought, and drought only decreased the seed mass of mother plants. In contrast, we found strong transgenerational effects on the overall performance of progenies, which changed with offspring age. At an early life stage, shoots were shorter for the offspring of drought-treated mothers than for the progenies of control mothers. This difference turned in the opposite direction later, and tiller number was also greater for the offspring of drought-treated mothers. Furthermore, the offspring of drought-treated mothers had over two-times higher adult shoot biomass and seed production compared to the offspring of control mothers. These beneficial transgenerational effects may help S. sylvestre to gain dominance in sand grasslands following dry years that decrease the abundance of perennial grasses, a vegetation change often observed in these grasslands after droughts. Our study provides the first evidence for positive transgenerational plasticity in response to drought for a subordinate species, which may be adaptive when the suppression of dominant species in the offspring environment is predictable from drought in the maternal environment.