Dominance among fruits/sinks and the search for a correlative signal

Abstract

The present problems with hormonal signals transferring dominance effects are reviewed and, as a new hypothesis, it is stated that the sequence of sink development may establish the dominance effect. ‘Primigenic dominance’ (PD) is suggested to describe this kind of correlative inhibition, in which the earlier developed sink inhibits later developed organs. New results show that the polar IAA export of the earlier developed sink inhibits the IAA export of later developed sinks. This ‘autoinhibition’ occurs at ‘junctions’, where auxin streams from various sinks meet. It is suggested that this depressed IAA‐export of the subordinated fruit/sink acts as the signal that leads to inhibited development. This hypothesis avoids some of the problems related with other hypotheses, such as the requirement of a multidirectional signal. Primigenic dominance is a unifying hypothesis, which can be applied to most correlative dominance phenomena in the plant. Primigenic dominance is less complicated than the traditional ‘apical dominance’ (AD) hypothesis, because it does not require secondary messengers.

Baby corn, green corn, and dry corn yield of corn cultivars

“…In addition, the ovaries that produce late-fertilized ovules frequently abort, thus reducing the formation of grain (Carcova et al, 2000;Anderson et al, 2004). Late silk emergence and incomplete kernel set after subapical ears are pollinated may indicate the occurrence of (Cárcova et al, 2000): a dominance mechanism exercised by the apical ear (Pinthus & Belcher, 1994); competition for assimilates between ears (Tollenaar et al, 1992); or the simultaneous occurrence of both processes (Bangerth, 1989). We conclude that baby corn (BC) + green corn (GC) and BC + dry corn (DC) harvesting provided lower baby corn yields than when all ears were harvested as baby corn.…”

Strigolactone Acts Downstream of Auxin to Regulate Bud Outgrowth in Pea and Arabidopsis

“…However, unraveling the action of apically derived auxin has been challenging, mainly because auxin was found to move strictly downward in the vascular cambium of the stem (the polar auxin transport stream) and apparently cannot change direction to move upward to enter axillary buds and branches (Snow, 1937;Hall and Hillman, 1975;Morris, 1977;Morris and Thomas, 1978;Bangerth, 1989;Prasad et al, 1993;Booker et al, 2003). In addition, while apically derived auxin moved downward through live cells (Morris and Thomas, 1978), the inhibiting influence was able to be transmitted upward through dead tissue (Snow, 1929).…”

“…Thus, this "secondary inhibiting influence" of auxin was proposed to act via an inhibiting substance that moved up into buds through the transpiration stream (Snow, 1929(Snow, , 1937. However, despite attempts at identifying the second messenger of auxin action, such a substance was never found (Bangerth, 1989).…”

“…The studies of Sachs (1968Sachs ( , 1969 focused on vascular development; however, Bangerth (1989) showed that auxin (in this case, indole-3-acetic acid [IAA]) export out of a branch was correlated with its ability to repress the outgrowth of other buds or branches. Thus, it was proposed that auxin export may be a requirement of bud outgrowth, and auxin transport from an earlier developed branch might simply inhibit auxin transport from later developed buds.…”

“…Thus, it was proposed that auxin export may be a requirement of bud outgrowth, and auxin transport from an earlier developed branch might simply inhibit auxin transport from later developed buds. This competition was suggested to occur at the junctions where the auxin transport streams meet (Bangerth, 1989).…”