Project description:Sacred lotus (Nelumbo nucifera) belongs to Nelumbonaceae family. Its seeds are widely consumed in Asia countries as snacks or even medicine. Besides the market values, lotus seed also plays crucial roles in lotus life cycle. Consequently, it is essential to gain a comprehensive understanding on the development of lotus seed. During its development, lotus seed undergoes cell division, expansion, reserve accumulation, desiccation and maturation phases. We observed the morphological and biochemical changes of lotus seed from 10 to 25 days after pollination (DAP) which was corresponding to the reserve synthesis and accumulation phase. The volume of the seed expanded until 20 DAP with the color of the seed coat changing from yellow-green to dark green and gradually faded again. Starch and protein rapidly accumulated from 15 to 20 DAP. To further reveal the metabolism adaptation, primary metabolites and proteins profiles were obtained from the mass spectrometry based platforms. Metabolites and enzymes involved in sugar metabolism, glycolysis, TCA cycle and amino acids metabolism schematized on their biosynthetic pathways. Both metabolic and proteomic profiles indicated more active metabolism from 10 to 15 DAP than after 20 DAP. The results provide a frame of reference for the evaluation of primary metabolism during lotus seed development.
Project description:Lotus is an aquatic plant that is sensitive to water loss, but its seeds are longevous after seed embryo dehydration and maturation. The great difference between the responses of vegetative organs and seeds to dehydration is related to the special protective mechanism in embryos. In this study, tandem mass tags (TMT)-labeled proteomics and parallel reaction monitoring (PRM) technologies were used to obtain novel insights into the physiological regulatory networks during lotus seed dehydration process. Totally, 60,266 secondary spectra and 32,093 unique peptides were detected. A total of 5,477 reliable proteins and 815 differentially expressed proteins (DEPs) were identified based on TMT data; of these, 582 DEPs were continuously down-regulated and 228 proteins were significantly up-regulated during the whole dehydration process. Bioinformatics and protein-protein interaction network analyses indicated that carbohydrate metabolism (including glycolysis/gluconeogenesis, galactose, starch and sucrose metabolism, pentose phosphate pathway, and cell wall organization), protein processing in ER, DNA repair, and antioxidative events had positive responses to lotus embryo dehydration. On the contrary, energy metabolism (metabolic pathway, photosynthesis, pyruvate metabolism, fatty acid biosynthesis) and secondary metabolism (terpenoid backbone, steroid, flavonoid biosynthesis) gradually become static status during lotus embryo water loss and maturation. Furthermore, non-enzymatic antioxidants and pentose phosphate pathway play major roles in antioxidant protection during dehydration process in lotus embryo; ABA signaling and the accumulation of oligosaccharides, late embryogenesis abundant proteins, and heat shock proteins may be the key factors to ensure the continuous dehydration and storage tolerance of lotus seed embryo. Stress physiology detection showed that H2O2 was the main ROS component inducing oxidative stress damage, and glutathione and vitamin E acted as the major antioxidant to maintain the REDOX balance of lotus embryo during the dehydration process. These results provide new insights to reveal the physiological regulatory networks of the protective mechanism of embryo dehydration in lotus.
Project description:•Cutin and suberin are lipid polyesters deposited in specific apoplastic compartments. Their fundamental roles in plant biology include controlling the movement of gases, water and solutes, and conferring pathogen resistance. Both cutin and suberin have been shown to be present in the Arabidopsis seed coat where they regulate seed dormancy and longevity. •In this study, we use accelerated and natural aging seed assays, glutathione redox potential measures, optical and transmission electron microscopy and gas chromatography-mass spectrometry to demonstrate that increasing the accumulation of lipid polyesters in the seed coat is the mechanism by which the AtHB25 transcription factor regulates seed permeability and longevity. •Chromatin immunoprecipitation during seed maturation revealed that the lipid polyester biosynthetic gene LACS2 (long-chain acyl-CoA synthetase 2) is a direct AtHB25 binding target. Gene transfer of this transcription factor to wheat and tomato demonstrates the importance of apoplastic lipid polyesters for the maintenance of seed viability. •Our work establishes AtHB25 as a trans-species regulator of seed longevity and has identified the deposition of apoplastic lipid barriers as a key parameter to improve seed longevity in multiple plant species.
Project description:Lotus japonicus is a perennial legume with a small diploid genome that has been adopted as a model species for legume genetics and genomics. With the genome sequence as a backdrop (Sato et al. 2008), we have generated a gene expression atlas that provides a global view of gene expression in all major organ systems of this species, including nodule and seed development.