Maternal control of Pisum sativum embryo development: a role for X8CD1 and X8CD2 genes encoding small cystein-rich proteins
Final Report Abstract
The tissue-specific localization of X8CD1 reveals expression not only in maternal but also in embryonic tissues. The expression patterns overlap partially with that of PsGNS2. On cellular level, X8CD1 localized to plasmodesmata and probably interacts with PsGNS2, containing X8 domain and with itself. In contrast, X8CD2 abundance was low in restricted seed area and expression pattern overlapped with that of PsGNS23; interactions need to be verified. The X8CD1 and X8CD2 genes have been repressed by an anti-sense approaches. Two homozygous lines carrying CaMV35S: X8DC1 antisense and seven for CaMV35S: X8DC2 antisense were established. Gene expression analyses by qRT-PCR confirmed massive reduction of X8DC1 transcripts amounts (up to 80%) and of reduction of X8DC2 mRNA by 20 to 50% in seeds of these plants. Down-regulation of X8DC expression results in reduction of most of the yield-related parameters indicating a probable role of the gene product(s) in seed and pod development. To analyze how altered gene expression networks intersect with gene activities that control embryo growth, the custom made pea Agilent® chip was developed, the genes were annotated and assign to GO categories. Tissue-specific gene expression in transgenic pea seeds with altered X8DC gene(s) expression was analysed in a time-course experiments in comparison to the wild type. A large set of differentially expressed genes (DEGs) was observed in both lines, herewith more DEGs have been observed in cotyledons than in seed coat, at early developmental stages than later and in CaMV35S: X8DC1 antisense, than CaMV35S: X8DC2 antisense lines. The higher transcriptional deregulation in cotyledons can be explained both by repression of the X8DC gene in cotyledons and maternal effect from the transgenic seed coat. The lower extent of transcriptional deregulation during later development demonstrates, that at later development, when endogenous X8DC transcripts are low, RNA antisense repression does not play a notable role anymore and transgenic seeds return to homeostasis. Furthermore, the transgenic phenotype is more prominent in X8DC1 than in X8CD2 repressed seeds. An enrichment of Pd-associated deregulated genes from 8-7% to 14% among all experiments have been observed indicating, that function of plasmodesmata in transgenic seeds is deregulated. A large group of genes involved in biotic stress response was up-regulated in CaMV35S: X8DC1as 10a seeds at 18 DAP. On the contrary, cell cycle and cell division genes were downregulated at the same stage. The similar up-regulation of stress-related genes, especially heat shock proteins, was observed in line CaMV35S: X8DC2as 11c at the same developmental stage. Other biological processes that showed a large proportion of up-regulated genes in CaMV35S: X8DC2as 11c were genes involved in cell wall synthesis and maintenance.
Publications
- Differential transcriptional networks associated with key phases of ingrowth wall construction in trans-differentiating epidermal transfer cells of Vicia faba cotyledons. BMC Plant Biol. 15 (2015) 103
Zhang H M, Wheeler S, Xia X, Radchuk R, Weber H, Offler C E, Patrick J W
(See online at https://doi.org/10.1186/s12870-015-0486-5)
