Nodulating behaviour of colchicine induced polyploids of Phaseolus aureus Roxb.

Autopolyploidy alters nodule‐level interactions in the legume–rhizobium mutualism

“…caerulea plants. These patterns are consistent with previous work demonstrating that synthetically induced polyploidy directly increased externally measured nodule size in Phaseolus aureus (Kabi and Bhaduri, 1978) studies finding that established natural polyploid plants produced larger nodules than diploids (e.g., Evans and Jones, 1966;Stalker et al, 1994;reviewed by Forrester and Ashman, 2018a). Enlargements in nodule size and the N-fixation zone directly resulting from increases in ploidy may have important consequences for legume-rhizobial interactions because nodule size is positively correlated with rhizobial abundance (Kiers et al, 2003;Heath and Tiffin, 2007;Regus et al, 2015).…”

“…Specifically, polyploid plants that have larger cells or more resources to allocate to the mutualism might host higher quality or a greater quantity of rhizobial symbionts relative to diploids, resulting in increased host benefits obtained (Levin, ; reviewed by Forrester and Ashman, 2018a; Forrester, ). Only a few studies have isolated the direct effects of increased ploidy on the legume–rhizobium mutualism, which found that synthetic neopolyploids produced larger nodules (Kabi and Bhaduri, ) and fixed N at a higher rate (Leps et al., ) than their diploid progenitors. However, no studies have tested whether polyploidy directly alters the internal structure of nodules, which represents the interface of legume–rhizobium interactions.…”

The direct effects of plant polyploidy on the legume–rhizobia mutualism

“…increase in root length and volume; Kulkarni and Borse, 2009) could enhance infection rate by rhizobia, thereby increasing the total number of nodules produced and bacteroids hosted (Fig. 1 I; Nutman, 1967;Kabi and Bhaduri, 1978). Enlarged cell size immediately resulting from polyploidy may increase nodule size and subsequently the number of bacteroids contained within nodules (Fig.…”

“…Although the direct effects of plant polyploidy on the legumerhizobia mutualism remain unresolved, studies evaluating the effects of ancient WGD on the evolution of nodulation suggest that polyploidy may have enhanced key aspects of the mutualism (Cannon et al, 2010;Doyle, 2011;Young et al, 2011;Li et al, 2013). Ancient WGD was not required for the evolution of nodulation, but the genetic material acquired and retained from a WGD event in the Papilionoideae is hypothesized to have led to enhanced and more complex interactions with rhizobia (Cannon et al, Kabi and Bhaduri (1978) Table 1. Continued 2013).…”

“…Nodule number is partially influenced by timing of nodulation, root size and architecture, and autoregulation of nodulation (Nutman, 1967;Diatloff and Ferguson, 1970;Kabi and Bhaduri, 1978;Reid et al, 2011;Thilakarathna et al, 2012). Reduced time to nodulation might occur if polyploidy alters plant signalling molecules that function in mutualism establishment (e.g.…”