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

Abstract

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. Bean fruits removed from the plant at 20 days after flowering (DAF) demonstrated active remobilisation of nutrients from the pod to the seeds. After 5 days, the pod dry weight was reduced by 50%. The process was characterized by a rapid degradation of starch, with the greatest decrease observed on day 1 after the fruits were removed. The pod nutrients were insufficient for the needs of all the seeds, and only some seeds continued their development. Those seeds exhibited a transient reduction in sucrose levels on day 1 after the fruits were removed. However, the normal level of sucrose was recovered, and the rate of starch synthesis was identical to that of a seed developed under normal conditions. Removing the fruits from the plant had no effect on the activity of SnRK1 in the pods, whereas in the seeds, the activity was increased by 35%. Simultaneously, a large reduction in seed sucrose levels was observed. The increase in SnRK1 activity was observed in both the cotyledon and embryo axes, but it was higher in the cotyledon. At 20–25 DAF, cotyledons actively accumulate storage materials. It is possible that the increase in SnRK1 activity observed in seeds developed in fruits that have been removed from the plant is part of the mechanism required for nutrient remobilisation under conditions of stress.

Phenotypic, Anatomical, and Diel Variation in Sugar Concentration Linked to Cell Wall Invertases in Common Bean Pod Racemes under Water Restriction

“…Walls of long and small pods did not show significant differences in starch concentration between treatments or during the light-dark cycle (Figure 3). These results are consistent with those obtained by [15], in which pods of common bean in the early stages of development showed lower starch concentration than did those in the advanced developmental stage. In contrast, Ref.…”

“…Thus, the physiological responses to drought in the pod wall may be due to the adjustment of metabolism to maintain homeostasis and seed filling. Further studies have demonstrated that the pod wall accumulates starch during the early stages of pod development [15]. For instance, [16] reported that pods accumulate starch in response to drought stress.…”

Thriving under Stress: How Plants Balance Growth and the Stress Response

“…Like their orthologs in fungi and animals, SnRK1s in plants function as the principle regulators of cellular energy homeostasis. SnRK1 activity can be activated by low nutrient stress or energy starvation as a result of prolonged darkness, hypoxia, or chemical inhibition of photosynthesis and can be inhibited by exogenous sucrose or glucose (Ananieva et al, 2008;Baena-Gonza ´lez et al, 2007;Bledsoe et al, 2017;Coello and Martı ´nez-Barajas, 2014;Nunes et al, 2013a). Once activated, SnRK1 kinases globally upregulate catabolic activities and repress anabolic processes (Baena-Gonza ´lez et al, 2007).…”

TOR and SnRK1 signaling pathways in plant response to abiotic stresses: Do they always act according to the “yin-yang” model?

“…In plants, it was suggested that TAP46 acts as an inhibitor of PP2A activity. However, the exact effects on phosphatase modulation [192,193] Summary of studies on TOR and/or SnRK1 pathways associated with abiotic stress responses (direct or indirect evidences). Research works not addressing abiotic stresses were not included in this table.…”