Plants (Basel)
September 2024
During the domestication of crops, seed dormancy has been reduced or eliminated to encourage faster and more consistent germination. This alteration makes cultivated crops particularly vulnerable to pre-harvest sprouting, which occurs when mature crops are subjected to adverse environmental conditions, such as excessive rainfall or high humidity. Consequently, some seeds may bypass the normal dormancy period and begin to germinate while still attached to the mother plant before harvest.
View Article and Find Full Text PDFTranscription factors (TFs) regulate gene expression by binding to specific sequences on DNA through their DNA-binding domain (DBD), a universal process. This update conveys information about the diverse roles of TFs, focusing on the NACs (NAM-ATAF-CUC), in regulating target-gene expression and influencing various aspects of plant biology. NAC TFs appeared before the emergence of land plants.
View Article and Find Full Text PDFIn order to adapt to sessile life and terrestrial environments, vascular plants have developed highly sophisticated cells to transport photosynthetic products and developmental signals. Of these, two distinct cell types (i.e.
View Article and Find Full Text PDFBased on prior knowledge and with the support of new methodology, solid progress in the understanding of seed life has taken place over the few last years. This update reflects recent advances in three key traits of seed life (i.e.
View Article and Find Full Text PDFPlants (Basel)
December 2021
To survive in the dry state, orthodox seeds acquire desiccation tolerance. As maturation progresses, the seeds gradually acquire longevity, which is the total timespan during which the dry seeds remain viable. The desiccation-tolerance mechanism(s) allow seeds to remain dry without losing their ability to germinate.
View Article and Find Full Text PDFThe programmed cell death (PCD) occurs when the targeted cells have fulfilled their task or under conditions as oxidative stress generated by ROS species. Thus, plants have to deal with the singlet oxygen O produced in chloroplasts. O is unlikely to act as a primary retrograde signal owing to its high reactivity and short half-life.
View Article and Find Full Text PDFA set of seed dormancy traits is included in this Special Issue. Thus, DELAY OF GERMINATION1 (DOG1) is reviewed in depth. Binding of DOG1 to Protein Phosphatase 2C ABSCISIC ACID (PP2C ABA) Hypersensitive Germination (AHG1) and heme are independent processes, but both are essential for DOG1's function in vivo.
View Article and Find Full Text PDFThe production of viable seeds is a key event in the life cycle of higher plants. Historically, abscisic acid (ABA) and gibberellin (GAs) were considered the main hormones that regulate seed formation. However, auxin has recently emerged as an essential player that modulates, in conjunction with ABA, different cellular processes involved in seed development as well as the induction, regulation and maintenance of primary dormancy (PD).
View Article and Find Full Text PDFDELAY OF GERMINATION-1 (DOG1), is a master regulator of primary dormancy (PD) that acts in concert with ABA to delay germination. The ABA and DOG1 signaling pathways converge since DOG1 requires protein phosphatase 2C (PP2C) to control PD. DOG1 enhances ABA signaling through its binding to PP2C ABA HYPERSENSITIVE GERMINATION (AHG1/AHG3).
View Article and Find Full Text PDFMannans but not endo-β-mannanases are mainly found in the mucilage layer of two Brassicaceae seeds. Nonetheless, mannanase mobilization from inner to outer seed layers cannot be ruled out. The contribution of endo-β-mannanase (MAN) genes to the germination of the wild-type Sisymbrium officinale and cultivated Brassica rapa (Brassicaceae) species has been explored.
View Article and Find Full Text PDFDELAY OF GERMINATION 1 (AtDOG1) was the first gene identified as dormancy-associated, but its physiological role in germination is far from being understood. Here, an orthologue of AtDOG1 in Sisymbrium officinale (SoDOG1; KM009050) is being reported. Phylogenetically, the SoDOG1 gene is included into the dicotyledonous group together with DOG1 from Arabidopsis thaliana (EF028470), Brassica rapa (AC189537), Lepidium papillosum (JX512183, JX512185) and Lepidium sativum (GQ411192).
View Article and Find Full Text PDFThe influence of nitrate upon the germination of Sisymbrium officinale seeds is not entirely controlled by after-ripening (AR), a process clearly influenced by nitrate. Recently, we have reported that nitrate affects sensu-stricto germination of non-AR (AR0) seeds by modifying the expression of crucial genes involved in the metabolism of GA and ABA. In this study, we demonstrate that nitrate affects also the germination of AR seeds because: (i) the AR negatively alters the ABA sensitivity being the seed more ABA-sensible as the AR is farthest from optimal (AR0 and AR20 versus AR7); in the presence of diniconazole (DZ), a competitive inhibitor of ABA 8'-hydroxylase, testa rupture is affected while the endosperm rupture is not.
View Article and Find Full Text PDFNon-symbiotic hemoglobins (nsHbs), ancestors of symbiotic-Hbs, are hexacoordinated dimeric proteins, for which the crystal structure is well described. According to the extent of hexacoordination, nsHbs are classified as belonging to class-1 (nsHbs1) or class-2 (nsHbs2). The nsHbs1 show weak hexacoordination, moderate rates of O(2)-binding, very small rates of O(2) dissociation, and a remarkably high affinity for O(2), all suggesting a function involving O(2) scavenging.
View Article and Find Full Text PDFWe have here demonstrated for the first time that nitrate not only accelerates testa rupture of non- AR seeds but also modifies expression pattern of the cell-wall remodeling proteins (mannanases; SoMAN6 and SoMAN7) and key genes belonging to metabolism and signaling of ABA (SoNCED6, SoNCED9, SoCYP707A2 and SoABI5) and GAs (SoGA3ox, SoGA20ox, SoGA2ox and SoRGL2). These results were obtained during Sisymbrium officinale seed imbibition in the absence of endosperm rupture. Exogenous ABA induced a notable inhibition of testa rupture in both absence and presence of nitrate being this effect sharply reversed by GA(4+7).
View Article and Find Full Text PDFThe softening and degradation of the cell wall (CW), often mannan enriched, is involved in several processes during development of higher plants, such as meristematic growth, fruit ripening, programmed cell death, and endosperm rupture upon germination. Mannans are also the predominant hemicellulosic CW polymers in many genera of green algae. The endosperm CWs of dry seeds often contain mannan polymers, sometimes in the form of galactomannans (Gal-mannans).
View Article and Find Full Text PDFPlant Signal Behav
January 2011
The endo-β-mannanase (MAN) family is represented in the Arabidopsis genome by eight members, all with canonical signal peptides and only half of them being expressed in germinating seeds. The transcripts of these genes were localized in the radicle and micropylar endosperm (ME) before radicle protrusion and this expression disappears as soon as the endosperm is broken by the emerging radicle tip. However, only three of these MAN genes, AtMAN5, AtMAN7 and especially AtMAN6 influence the germination time (t50) as assessed by the analysis of the corresponding knock-out lines.
View Article and Find Full Text PDFMannans are hemicellulosic polysaccharides in the plant primary cell wall (CW). Mature seeds, specially their endosperm cells, have CWs rich in mannan-based polymers that confer a strong mechanical resistance for the radicle protrusion upon germination. The rupture of the seed coat and endosperm are two sequential events during the germination of Arabidopsis thaliana.
View Article and Find Full Text PDFThe rupture of the seed coat and that of the endosperm were found to be two sequential events in the germination of Sisymbrium officinale L. seeds, and radicle protrusion did not occur exactly in the micropylar area but in the neighboring zone. The germination patterns were similar both in the presence of gibberellins (GA(4+7)) and in presence of ethrel.
View Article and Find Full Text PDFThe seed is an important organ of higher plants regarding plant survival and species dispersion. The transition between seed dormancy and germination represents a critical stage in the plant life cycle and it is an important ecological and commercial trait. A dynamic balance of synthesis and catabolism of two antagonistic hormones, abscisic acid (ABA) and giberellins (GAs), controls the equilibrium between seed dormancy and germination.
View Article and Find Full Text PDFAfter-ripening (AR) in Sisymbrium officinale seeds altered SoACS7, SoACO2, SoGA20ox2, SoGA3ox2, and SoGA2ox6 gene expression. Except for SoGA20ox2 expression, which sharply diminished, the expression of the other genes rose during development, particularly that of SoACS7. In contrast, only the SoACO2 and SoGA2ox6 transcripts increased with seed desiccation; the others decreased.
View Article and Find Full Text PDFEthylene (ET) is a notable signaling molecule in higher plants. In the year 1993 the ET receptor gene, ETR1, was identified; this ETR1 receptor protein being the first plant hormone receptor to be isolated. It is striking that there are six ET receptors in tomato instead of five in Arabidopsis, the two best-known signaling-model systems.
View Article and Find Full Text PDFThe flower opening of damson plum (Prunus insititia L.) was accompanied by an increase in the content of free-polyamines (PA) in the sepals, petals and sex organs, the ovary being most active in accumulating spermine (Spm). The fertilization process and senescence brought on a decline in ovarian Spm, but stimulated putrescine (Put) and spermidine (Spd) content in the sepals.
View Article and Find Full Text PDFIn a previous report from the present authors, it was shown that the 1-aminocyclopropane-1-carboxylate (ACC) oxidation may play a crucial role during zygotic embryogenesis of turnip tops seeds. The present study was performed to elucidate the contribution of the silique-wall and seeds in ethylene production during this developmental process. ACC content in the silique wall is only higher than in seeds during the middle phases of zygotic embryogenesis.
View Article and Find Full Text PDFDuring zygotic embryogenesis of turnip-tops (Brassica rapa L. cv. Rapa), the polygalacturonase activity (PG; EC 3.
View Article and Find Full Text PDFThe mature silique of turnip-tops (Brassica rapa L. cv. Rapa) contains seeds that are heterogeneous in colour.
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