Photoperiod gene control over partitioning between reproductive and vegetative growth

Abstract

The hypothesis tested was that lack of photoperiod gene activity allows inherent partitioning of photosynthate to continued growth of the earliest potential buds, flowers, pods, and seeds (the organs that give rise to the yield). Alternatively, and competitively, photoperiod gene activity causes the photosynthate to be partitioned predominantly toward continued growth of new vegetative organs plus later initiation of more reproductive (yield) organs. This hypothesis was tested by comparing an insensitive and a photoperiod-sensitive bean (Phaseolus vulgaris L.) cultivar and their F1 with F2 segregates of undetermined genotype. Randomly derived homozygous F8 segregates were also compared. The F8 generation included one photoperiod-insensitive and one photoperiod-sensitive genotype in a 1:1 ratio, which verified control by one photoperiod gene. Under long daylength (LD), in addition to early versus late flowering and maturity, the two genotypes expressed opposite levels of 23 other traits that would be changed by competitive partitioning of the photosynthate. In contrast, under short daylength (SD), both genotypes flowered and matured early, and both expressed the levels for all 25 traits that the photoperiod-insensitive genotype expressed in both SD and LD. The photoperiod gene interacted with daylength to control the levels of all three major physiological components of yield: the aerial biomass, harvest index, and days to maturity. Included among the other traits with levels altered by daylength-modulated photoperiod gene activity were: the number of branches, nodes, leaves and leaf area, the rate of yield accumulation, and sink activity.

Growth and phenological development patterns differ between seedling and regrowth lucerne crops (Medicago sativa L.)

“…Long-day plants delay flowering when experiencing day lengths shorter than the Pp crit . A proposed explanatory mechanism is that the activity of genes that reduce sink priority of reproductive organs is triggered at short photoperiods (Wallace et al, 1993). Similar seasonal differences in the metabolic activity of lucerne shoots were identified for dry matter partitioning (Avice et al, 2001;Teixeira et al, 2007b) and canopy expansion (Brown et al, 2005b).…”

Pleiotropic Effects of Flowering Time Genes in the Annual Crucifer Arabidopsis thaliana (Brassicaceae)

“…Flowering time is determined by a shift in the partitioning of resources between reproductive and vegetative growth (Wallace et al, 1993). In Arabidopsis, the apical meristem is dedicated to formation of the inflorescence, in contrast with species with an indeterminate development such as beans (Wallace et al, 1993).…”

“…In Phaseolus vulgaris a single photoperiod gene competition with the surrounding vegetation (Cohen, affected 26 traits, including traits involving resource par-1971). Under such conditions, timing of reproduction will titioning in time, or involving morphological and meribe under stabilizing selection, but with an optimal timing stem development (Wallace et al, 1993). Pleiotropy can that may depend on environmental factors such as rebe an important cause of genetic correlations among source availability and season length.…”

Axillary Meristem Development. Budding Relationships between Networks Controlling Flowering, Branching, and Photoperiod Responsiveness

“…1, A and B), dne, and ppd in pea, dn in sweet pea, and sn in lentil (Lens culinaris; Murfet, 1971;King and Murfet, 1985;Ross and Murfet, 1988;Sarker et al, 1999). The ppd mutant of common bean, a SD species, also shows a similar phenotype (Wallace et al, 1993).…”

“…Perhaps less widely recognized is that, in many species, including temperate LD plants such as Arabidopsis and pea and SD plants such as common bean (Phaseolus vulgaris), photoperiod also affects vegetative shoot architecture (Figs. 1 and 3) and a range of other vegetative and reproductive characteristics (Wallace et al, 1993;Fig. 4).…”