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1.  Coordinated changes in storage proteins during development and germination of elite seeds of Pongamia pinnata, a versatile biodiesel legume 
AoB Plants  2011;2011:plr026.
Seeds of Pongamia pinnata used as feedstock for biodiesel production and the protein-rich residue is fed to farm animals. This paper describes seed development and early germination in terms of phenology, protein and reserve accumulation and utilization. The findings will underpin rapid and successful exploitation of this promising energy and animal feed crop.
Background and aims
The oleaginous legume Pongamia pinnata is a rapidly growing and economically important tree. The seeds are used increasingly as feedstock for biodiesel production, with the protein-rich residue providing valuable supplement to farm animal diets. However, little is known about seed development and the characteristics of germination. We therefore studied morphological, protein and ultrastructural changes during seed maturation and germination using seeds from a tree selected for superior morphological and reproductive characters (candidate plus tree).
Phenology, sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS–PAGE), and scanning and transmission electron microscopy were used to investigate seed development from 90 to 350 days after flowering (DAF), and germination and seedling development from 0 to 45 days after the start of imbibition (DAI) (Stages 0–VII).
Principal results
Seven distinct developmental stages were identified during seed development. Fresh weight, length, breadth and thickness increased from Stage I (90 DAF) to V (270 DAF) and decreased at Stages VI (315 DAF) and VII (350 DAF), when the seeds were fully ripe. Marked changes in total soluble protein content and SDS–PAGE profile were observed in vegetative and reproductive tissues and in the cotyledons of germinating seedlings. Polypeptide fragments of 150–14 kDa were observed during seed maturation and germination. In SDS–PAGE the expression of three main polypeptide bands (50, 18 and 14 kDa) increased from Stage I to Stage V and then almost became the same until Stage VII during seed maturation. During germination the expression of 50 kDa polypeptide decreased and that of 18 and 14 kDa increased from Stage 0 (ungerminated seed) to Stage VI (30 DAI), respectively; however, all three polypeptides (50, 18 and 14 kDa) completely disappeared at Stage VII (45 DAI). Ultrastructural changes during four stages of seed maturation (early immature, 90–135 DAF; late immature, 180–225 DAF; early mature, 225–270 DAF; and late mature, 315–350 DAF) and three stages of germination and seedling development (early 10 DAI to late 45 DAI) localized marked gradients in protein storage reserves.
Increasing the knowledge base for P. pinnata, especially for its seeds, is an essential prerequisite for rapid and successful exploitation of this promising energy and animal feed crop. Our findings contribute to this by establishing key developmental features of the seeds as they form and germinate.
PMCID: PMC3243569  PMID: 22476496
2.  Molecular marker-based characterization in candidate plus trees of Pongamia pinnata, a potential biodiesel legume 
AoB Plants  2010;2010:plq017.
Molecular marker studies provide valid guidelines for collection, characterization and selective cultivation of elite Pongamia germplasm that can be exploited further for its improvement through breeding and marker assisted selection for improved characters and oil yield towards biodiesel production.
Background and aims
Pongamia pinnata, a legume tree, has many traditional uses and is a potential biodiesel plant. Despite its importance and the availability of appropriate molecular genetic tools, the full potential of Pongamia is yet to be realized. The objective of this study was to assess genetic diversity among 10 systematically characterized candidate plus trees (CPTs) of P. pinnata from North Guwahati.
The application and informativeness of polymerase chain reaction-based molecular markers [random amplified polymorphic DNA (RAPD), inter-simple sequence repeat (ISSR) and amplified fragment length polymorphism (AFLP)] to assess the genetic variability and relatedness among 10 CPTs of P. pinnata were investigated.
Principal results
Polymorphism rates of 10.48, 10.08 and 100 % were achieved using 18 RAPD, 12 ISSR and 4 AFLP primer combinations, respectively. Polymorphic information content (PIC) varied in the range 0.33–0.49, 0.18–0.49 and 0.26–0.34 for RAPD, ISSR and AFLP markers, respectively, whereas the corresponding average marker index (MI) values for the above markers were 7.48, 6.69 and 30.75. Based on Nei's gene diversity and Shannon's information index, inter-population diversity (hsp) was highest when compared with intra-population diversity (hpop) and the gene flow (Nm) ranged from a moderate value of 0.607 to a high value of 6.287 for the three DNA markers. Clustering of individuals was not similar when RAPD- and ISSR-derived dendrogram analyses were compared with that of AFLP. The Mantel test cophenetic correlation coefficient was higher for AFLP (r = 0.98) than for ISSR (r = 0.73) and RAPD (r = 0.84). Molecular markers discriminated the individuals efficiently and generated a high similarity in dendrogram topologies derived using unweighted pair-group arithmetic average, although some differences were observed. The three-dimensional scaling by principal coordinate analysis supported the result of clustering.
Comparing the results obtained with the three DNA markers, AFLP indicated higher efficiency for estimating the levels of genetic diversity and proved to be reliable for fingerprinting, mapping and diversity studies in Pongamia in view of their suitability for energy production purposes.
PMCID: PMC2997655  PMID: 22476075

Results 1-2 (2)