Seed Development in Phaseolus vulgaris L. cv Seminole

Abstract

Phaseolus vulgaris L. cv Seminole pods removed from the plant continued their development when incubated in suitable conditions. Seeds continued to grow and develop and pods and seeds passed through an apparently normal developmental sequence to dryness. Seed growth was at the expense of pod dry weight (DW) reserves. Losses of pod DW paralleled DW gains by seeds in detached pods and in pod cylinders containing a seed. The transfer activity was apparent only within the period 10 to 30 days after anthesis (DAA) with maximal activity between 15 to 20 DAA. This period corresponds to maximum pod growth and the attainment of maximal DW. Seeds are in only the early phase of seed growth at this time. No DW transfer was observed at developmental stages beyond 30 to 35 DAA when normal senescence DW losses in pods became evident and seeds were in the later phase of seed fill. Pods or pod cylinders remained green and succulent over the transfer period, later passing through yellowing and drying phases characteristic of normal development. DW transfer was dependent on funicle integrity and was readily detectable in pod cylinders after 7 days incubation. The DW transfer activity may contribute to continuing nutrition of seeds under conditions where the normal assimilate supply to seeds becomes limiting. Defoliation and water stress treatments applied to Phaseolus plants reduced seed yields but allowed persistence of seed maturation processes such that all seeds developing to dryness were capable of germination.Early this century it was suggested that reserves deposited in legume pods might be a source of nutrition for their enclosed developing seeds (7, 23, 30; reviewed in 17). A transfer of reserves of C or N was assumed from observation of losses by pods and gains by seeds. Pfenninger (23) that seeds of Vicia faba continued their development after removal from the plant, and several studies have reported continuing seed growth in detached pods of Pisum sativum (3,14,18,26) and Glycine max (19) cultured in aseptic conditions. In the latter, the potential role of pod tissues in supporting seed growth was not examined directly since contributing nutrition from the culture medium was involved to an unknown extent. Although soybean seeds do continue their maturation in detached pods, their growth is reported to cease upon pod removal (1).More recent studies (27) of the sources of nutrition for developing legume seeds show the greater proportion comes from translocated assimilates of vegetative origin and that fruit reserves provide only a limited supply. Temporary storage of incoming assimilates which may involve conversion to more useful forms has been suggested to account for the remarkable linearity of seed growth in the short term independent of diurnal or day to day fluctuations in supply in soybean (28). This argument is likely to find general application at least in species with relatively fleshy pods (6, 28) and complements other recognized functions ofpods in protecting the developing seeds, and acting as photo...

The activity of SnRK1 is increased in Phaseolus vulgaris seeds in response to a reduced nutrient supply

“…By 20–25 DAF, pods have reached their final size ( Fountain et al, 1989 ), and fruit growth is mainly associated with the active accumulation of storage materials in seeds ( Figure 1A ). In fruits removed from the plant at 20 DAF, seeds can growth at the expense of the nutrients provided for the pod.…”

“…This process is normally associated with leaf senescence, where most of the available nutrients are transported to developing seeds ( Yang et al, 2001b ), but materials accumulated in stems and pods are also important for seed development ( Schiltz et al, 2005 ). Seeds of Phaseolus vulgaris can continue their development at the expense of pod reserves when the fruits are removed from the plant at 15–25 days after flowering (DAF; Fountain et al, 1989 ). SnRK1 has been identified as an important component in the mechanism that allows plants to respond to C and energy deficiencies ( Schluepmann et al, 2012 ).…”

“… Phaseolus vulgaris seeds can grow and develop at the expense of the pod reserves after the fruits have been removed from the plant ( Fountain etal., 1989 ). Because this process involves sensing the reduction of nutrients and the remobilisation of pod reserves, we investigated the effect on sucrose non-fermenting related kinase 1 (SnRK1) activity during this process.…”

From flower to seed: identifying phenological markers and reliable growth functions to model reproductive development in the common bean (Phaseolus vulgarisL.)

“…Moreover, results from depodding experiments showed that, under incubation, pods removed before the maximum length is reached do not persist, while pods harvested after this point produce viable seeds (Fountain et al . ). Very similar synchronization patterns have been reported for determinate and indeterminate bean cultivars (Oliker et al .…”

“…The reproductive developmental patterns of the common bean have been widely studied (Binnie & Clifford , ; Lovett‐Doust & Eaton ; Pechan & Webster ; Fountain et al . ; Muasya et al . ).…”