Pectin methylesterase (PME) controls the methylesterification status of pectins and thereby determines the biophysical properties of plant cell walls, which are important for tissue growth and weakening processes. We demonstrate here that tissue-specific and spatiotemporal alterations in cell wall pectin methylesterification occur during the germination of garden cress (Lepidium sativum). These cell wall changes are associated with characteristic expression patterns of PME genes and resultant enzyme activities in the key seed compartments CAP (micropylar endosperm) and RAD (radicle plus lower hypocotyl). Transcriptome and quantitative real-time reverse transcription-polymerase chain reaction analysis as well as PME enzyme activity measurements of separated seed compartments, including CAP and RAD, revealed distinct phases during germination. These were associated with hormonal and compartment-specific regulation of PME group 1, PME group 2, and PME inhibitor transcript expression and total PME activity. The regulatory patterns indicated a role for PME activity in testa rupture (TR). Consistent with a role for cell wall pectin methylesterification in TR, treatment of seeds with PME resulted in enhanced testa permeability and promoted TR. Mathematical modeling of transcript expression changes in germinating garden cress and Arabidopsis (Arabidopsis thaliana) seeds suggested that group 2 PMEs make a major contribution to the overall PME activity rather than acting as PME inhibitors. It is concluded that regulated changes in the degree of pectin methylesterification through CAP- and RAD-specific PME and PME inhibitor expression play a crucial role during Brassicaceae seed germination.

• MeSH
• endosperm enzymologie   fyziologie   MeSH
• hypokotyl enzymologie   fyziologie   MeSH
• karboxylesterhydrolasy biosyntéza   genetika   fyziologie   MeSH
• klíčení genetika   fyziologie   MeSH
• kvantitativní polymerázová řetězová reakce MeSH
• Lepidium sativum enzymologie   genetika   fyziologie   MeSH
• regulace genové exprese u rostlin genetika   fyziologie   MeSH
• rostlinné proteiny genetika   fyziologie   MeSH
• semena rostlinná enzymologie   fyziologie   MeSH
• stanovení celkové genové exprese MeSH
• Publikační typ
• časopisecké články MeSH

Seed germination is an important life-cycle transition because it determines subsequent plant survival and reproductive success. To detect optimal spatiotemporal conditions for germination, seeds act as sophisticated environmental sensors integrating information such as ambient temperature. Here we show that the delay of germination 1 (DOG1) gene, known for providing dormancy adaptation to distinct environments, determines the optimal temperature for seed germination. By reciprocal gene-swapping experiments between Brassicaceae species we show that the DOG1-mediated dormancy mechanism is conserved. Biomechanical analyses show that this mechanism regulates the material properties of the endosperm, a seed tissue layer acting as germination barrier to control coat dormancy. We found that DOG1 inhibits the expression of gibberellin (GA)-regulated genes encoding cell-wall remodeling proteins in a temperature-dependent manner. Furthermore we demonstrate that DOG1 causes temperature-dependent alterations in the seed GA metabolism. These alterations in hormone metabolism are brought about by the temperature-dependent differential expression of genes encoding key enzymes of the GA biosynthetic pathway. These effects of DOG1 lead to a temperature-dependent control of endosperm weakening and determine the optimal temperature for germination. The conserved DOG1-mediated coat-dormancy mechanism provides a highly adaptable temperature-sensing mechanism to control the timing of germination.

• MeSH
• Arabidopsis genetika   růst a vývoj   fyziologie   MeSH
• biomechanika MeSH
• diploidie MeSH
• geneticky modifikované rostliny MeSH
• gibereliny metabolismus   MeSH
• klíčení genetika   fyziologie   MeSH
• konzervovaná sekvence MeSH
• Lepidium sativum genetika   růst a vývoj   fyziologie   MeSH
• molekulární sekvence - údaje MeSH
• mutace MeSH
• proteiny huseníčku genetika   MeSH
• regulace genové exprese u rostlin MeSH
• rostlinné geny MeSH
• semena rostlinná růst a vývoj   MeSH
• teplota MeSH
• vegetační klid genetika   fyziologie   MeSH
• vývojová regulace genové exprese MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH