Expressed sequence tags (ESTs) and single nucleotide polymorphisms (SNPs): Emerging molecular marker tools for improving agronomic traits in plant biotechnology

Expressed Sequence Tags (ESTs) and Single Nucleotide Polymorphisms (SNPs) are providing in depth knowledge in plant biology, breeding and biotechnology. The emergence of many novel molecular marker techniques are changing and accelerating the process of producing mutations in plant molecular biology research. This coupled with the availability of cheap sequencing techniques and access to a complete genome sequence has been shown to complement traditional marker -based approaches. Expressed Sequence Tags (ESTs) have provided an important source for the study of Single Nucleotide Polymorphisms (SNPs) in plants. SNP markers have become popular, partly because of their high density within the genome and also their ease with which they are characterized. This review also focuses on some methods used in genotyping SNPs

Growth, seed development and genetic analysis in wild type and Def mutant of Pisum sativum L

<p>Abstract</p> <p>Background</p> <p>The <it>def </it>mutant pea (<it>Pisum sativum </it>L) showed non-abscission of seeds from the funicule. Here we present data on seed development and growth pattern and their relationship in predicting this particular trait in wild type and mutant lines as well as the inheritance pattern of the <it>def </it>allele in F₂and F₃populations.</p> <p>Findings</p> <p>Pod length and seed fresh weight increase with fruit maturity and this may affect the abscission event in pea seeds. However, the seed position in either the distal and proximal ends of the pod did not show any difference. The growth factors of seed fresh weight (FW), width of funicles (WFN), seed width (SW) and seed height (SH) were highly correlated and their relationships were determined in both wild type and <it>def </it>mutant peas. The coefficient of determination <it>R</it>²values for the relationship between WFN and FW, SW and SH and their various interactions were higher for the <it>def </it>dwarf type. Stepwise multiple regression analysis showed that variation of WFN was associated with SH and SW. Pearson's chi square analysis revealed that the inheritance and segregation of the <it>Def </it>locus in 3:1 ratio was significant in two F₂populations. Structural analysis of the F3 population was used to confirm the inheritance status of the <it>Def </it>locus in F₂heterozygote plants.</p> <p>Conclusions</p> <p>This study investigated the inheritance of the presence or absence of the <it>Def </it>allele, controlling the presence of an abscission zone (AZ) or an abscission-less zone (ALZ) forming in wild type and mutant lines respectively. The single major gene (<it>Def</it>) controlling this phenotype was monogenic and <it>def </it>mutants were characterized and controlled by the homozygous recessive <it>def </it>allele that showed no palisade layers in the hilum region of the seed coat.</p

Primary and secondary abscission in Pisum sativum and Euphorbia pulcherrima –how do they compare and how do they differ?

ABSTRACTAbscission is a highly regulated and coordinated developmental process in plants. It is important to understand the processes leading up to the event, in order to better control abscission in crop plants. This has the potential to reduce yield losses in the field and increase the ornamental value of flowers and potted plants. A reliable method of abscission induction in poinsettia (Euphorbia pulcherrima) flowers has been established to study the process in a comprehensive manner. By correctly decapitating buds of the third order, abscission can be induced in one week. AFLP differential display (DD) was used to search for genes regulating abscission. Through validation using qRT-PCR, more information of the genes involved during induced secondary abscission have been obtained. A study using two mutants of pea (Pisum sativum) in the def (Developmental funiculus) gene have been performed and compared these with wild type peas (tall and dwarf in both cases). The def mutant results in a deformed, abscission-less zone instead of normal primary abscission at the funiculus. RNA in situ hybridization studies using gene sequences from the poinsettia differential display, resulted in six genes differentially expressed for abscission specific genes in both poinsettia and pea. Two of these genes are associated with gene up- or down-regulation during the first two days after decapitation in poinsettia. Present and previous results in poinsettia (biochemically and gene expressions), enables a more detailed division of the secondary abscission phases in poinsettia than what has previously been described from primary abscission in Arabidopsis.This study compares the inducible secondary abscission in poinsettia and the non-abscising mutants/wild types in pea demonstrating primary abscission zones. The results may have wide implications on the understanding of abscission, since pea and poinsettia have been separated for 94-98 million years in evolution, hence any genes or processes in common are bound to be widespread in the plant kingdom