A molecular framework for the embryo growth in germinating seeds of Solanum lycocarpum A. St.‐Hil., a nurse plant species

Abstract

We are clarifying how the functional embryo growth occurs in germinating seeds of Solanum lycocarpum A. St.‐Hil., a nurse plant with a central role in forest dynamics in the Cerrado (a biodiversity hotspot). For that, we used classical seed germination measurements (germinability, mean germination time, mean germination rate, coefficient of variation of the germination time, synchronisation index and germination time range) and gene expression of mRNA codifying key proteins/enzymes for the success in the seed–seedling transition (Cyclin, Actin, Small Heat Shock Protein, Glutathione S‐transferase, Malate Dehydrogenase, Alcohol Dehydrogenase). Our findings demonstrate: (a) Although germination kinetics in S. lycocarpum seeds is slower than that in tomato seeds, the fold change of genes codifying key enzymes for the embryo development is similar in germinating seeds of both species. (b) The genes used here are useful, from a technical point of view, for classifying commercial seed samples of the species in relation to physiological quality. More notably, cyclin and malate dehydrogenase genes have a greater expression, both in germination sensu stricto and in immediate post‐germination. (c) A molecular framework for the embryo growth in germinating seeds of S. lycocarpum can be a functional explication for the species to be a nurse plant. Thus, the overlapping of classical and contemporary measurements is especially interesting to those species playing a central role in the environment, such as nurse plants, and may represent a new conservationist paradigm.

What happens when the rain is back? A hypothetical model on how germination and post-germination occur in a species from transient seed banks

“…However, we still know little about what affects this germination-dormancy balance from a molecular point of view. A strategy to fill this gap is to cross classic physiological measurements of the germination ecophysiology with key components of the gene expression involved in embryo growth [8].A limiting factor to perform a crosstalk between gene expression and germination ecophysiology would be that laboratory protocols are not very representative of what happens in the field from an ecological point of view. However, this barrier is being overcome by the idea that detailed laboratory protocols for sampling communities and performing germination experiments can produce significant characters that are as enlightening as those obtained in field experiments.…”

Clues on an intraspecific communication system in early plant establishment: The seed-seedling transition from the point of view of a crosstalk between information theory and gene expression

“…This demonstrates that all seeds in the sample had biological activity in the system. Moreover, the closure of the analysis process was made in resonance with other studies of molecular and physiological aspects of the germination of the species, whose seeds are anhydrobiotic (= orthodox) and non-dormant (Silveira et al , 2019; Souza et al , 2020).…”

“…This species has been used to understand aspects of the seed-environment interface. The germination transcriptome of this native species presents gene expression of actin, cyclin, heat shock protein, glutathione-S-transferase, malate dehydrogenase and alcohol dehydrogenase similar to congener species such as tomato (Silveira et al , 2019; Souza et al , 2020). What draws our attention in this biological model, however, is the fact that the species presents high intra-specific variability among the seeds that compose the sample, which is the basis of the discussion of the information theory (Shannon, 1948; Labouriau, 1983).…”

“…Embryo protrusion assessments were made every 24 hours, from seed contact with water up to 15 days after sowing. The end of the assessments took place 16 days after sowing, due to literature protocols (Silveira et al , 2019) on the species and null protrusion in the last observations. The non-germinated seeds had a viable embryo, detected by staining by solution of 2,3,5-triphenyl tetrazolium chloride solution (TTC at 0.1%) with incubation at 30 °C for 24 hours.…”

“…We tested our hypothesis by means of molecular aspects related to cell growth and protection as well as the energy metabolism of the embryo in germinating seeds. For that, we used nucleotide sequences proved be efficient for our model species (Silveira et al , 2019).…”