Physiological Integration Increases Sexual Reproductive Performance of the Rhizomatous Grass Hierochloe glabra

Abstract

Clonal plants usually reproduce asexually through vegetative propagation and sexually by producing seeds. Physiological integration, the translocation of essential resources between ramets, usually improves vegetative reproduction. However, how physiological integration affects sexual reproduction has been less studied in clonal grasses. Here, we chose Hierochloe glabra, a major early spring forage of the eastern Eurasian steppe, and conducted a series of field experiments, including sampling reproductive ramets connected by tillering nodes to different numbers of vegetative ramets and 15N leaf labeling of ramet pairs at the seed-filling stage. In the natural populations of H. glabra, vegetative ramets were taller, had more and larger leaves, and greater biomass than reproductive ramets. Except for reproductive ramet biomass, sexual reproductive characteristics significantly increased with an increase in the number and biomass of vegetative ramets connected to tillering nodes. 15N labeling showed that vegetative ramets supplied nutrients to reproductive ramets through tillering nodes. Overall, our results indicate that significant differences in morphological characteristics and biomass allocation underlie resources translocation from vegetative ramets towards reproductive ramets. Physiological integration between different functional ramets can increase sexual reproductive performance, which will be beneficial to population persistence in H. glabra.

Clonal dominant grass Leymus chinensis benefits more from physiological integration in sexual reproduction than its main companions in a meadow

“…Studies have repeatedly revealed that physiological integration between vegetative ramets and vegetative ramets with the same function via a rhizome or stolon has a positive effect on the survival and growth of the ramets ( Evans and Cain, 1995 ; Dong and Alaten, 1999 ; Song et al., 2013 ; Chen et al., 2015 ), but little research has been performed on the effect of physiological integration between vegetative ramets and reproductive ramets with different functions by tillering node connection on sexual reproductive performance. Our previous studies showed that physiological integration between vegetative and reproductive ramets connected by a tillering node increased sexual reproductive characteristics such as inflorescence biomass, floret number, seed number, seed biomass and the seed-setting rate in H. glabra ( Guo et al., 2020b ) and L. chinensis ( Guo et al., 2020c ). In the present study, by severing connections, we found that physiological integration between vegetative ramets and reproductive ramets connected by a tillering node significantly increased the leaf biomass, stem biomass, inflorescence biomass, and ramet biomass of reproductive ramets in L. chinensis , L. secalinus , C. ripidula , C. pseudophragmites and C. epigeios ( Figure 2 ), and these results supported our first hypothesis.…”

Physiological integration between Bermudagrass ramets improves overall salt resistance under heterogeneous salt stress

“…Physiological integration enables plastic responses to heterogeneous environments and is an advantage for the reproduction of clonal plant (Guo et al, 2020;Wang et al, 2020;Xu et al, 2012). Ramets located in favorable conditions can serve as a donor, supporting recipient ramets suffering from stress (Li et al, 2011).…”

“…Physiological integration refers to the transferring and sharing of substances, energy, and signals among sister ramets through their connection by stolon or rhizome (Alpert, 1999). Physiological integration enables plastic responses to heterogeneous environments and is an advantage for the reproduction of clonal plant (Guo et al, 2020; Wang et al, 2020; Xu et al, 2012). Ramets located in favorable conditions can serve as a donor, supporting recipient ramets suffering from stress (Li et al, 2011).…”

Shade Avoidance and Light Foraging of a Clonal Woody Species, Pachysandra terminalis

“…Clonal plants produce their offspring via not only sexual reproduction but also asexual reproduction, in which new individual clones with an identical gene set, called ramets, are generated [ 1 , 2 , 3 , 4 , 5 , 6 ]. Elucidating the mechanism by which clones forage resources in heterogeneous environments is a central issue in clonal plant ecology [ 4 , 5 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ], plant growth modeling [ 23 ], and their application in vegetation management [ 17 , 18 , 19 , 20 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 ]. Additionally, the spatial arrangement of ramets determines the reproductive success of clonal plants; this is because aggregation of ramets that belong to the same genets leads to an increased percentage of geitonogamous self-pollination [ 6 ].…”

“…Most of the previous studies on resource foraging of clonal plants were performed using plants that were grown in pots or trays [ 7 , 8 , 9 , 18 , 19 , 24 , 40 , 42 , 44 , 45 , 46 , 47 ] and/or inside laboratories or greenhouses [ 7 , 8 , 19 , 24 , 45 ] rather than in their natural habitats. Nevertheless, it has been discussed that plants respond to their environment in different ways depending on whether they are grown in pots or in their natural habitats [ 5 , 48 , 49 ]. Plants in natural habitats experience greater fluctuations in their environment compared with plants that grow in pots or in greenhouses [ 32 , 48 ].…”