Feature of microsatellites identified by MISA in non redundant EST sequences of <i>Arachis hypogaea</i>.

<p>Feature of microsatellites identified by MISA in non redundant EST sequences of <i>Arachis hypogaea</i>.</p

Novel and Stress Relevant EST Derived SSR Markers Developed and Validated in Peanut

<div><p>With the aim to increase the number of functional markers in resource poor crop like cultivated peanut (<i>Arachis hypogaea</i>), large numbers of available expressed sequence tags (ESTs) in the public databases, were employed for the development of novel EST derived simple sequence repeat (SSR) markers. From 16424 unigenes, 2784 (16.95%) SSRs containing unigenes having 3373 SSR motifs were identified. Of these, 2027 (72.81%) sequences were annotated and 4124 gene ontology terms were assigned. Among different SSR motif-classes, tri-nucleotide repeats (33.86%) were the most abundant followed by di-nucleotide repeats (27.51%) while AG/CT (20.7%) and AAG/CTT (13.25%) were the most abundant repeat-motifs. A total of 2456 EST-SSR novel primer pairs were designed, of which 366 unigenes having relevance to various stresses and other functions, were PCR validated using a set of 11 diverse peanut genotypes. Of these, 340 (92.62%) primer pairs yielded clear and scorable PCR products and 39 (10.66%) primer pairs exhibited polymorphisms. Overall, the number of alleles per marker ranged from 1-12 with an average of 3.77 and the PIC ranged from 0.028 to 0.375 with an average of 0.325. The identified EST-SSRs not only enriched the existing molecular markers kitty, but would also facilitate the targeted research in marker-trait association for various stresses, inter-specific studies and genetic diversity analysis in peanut.</p></div

Regulation of antioxidant mechanisms by AtDREB1A improves soil-moisture deficit stress tolerance in transgenic peanut (Arachis hypogaea L.).

The present study evaluated the soil-moisture deficit stress tolerance of AtDREB1A transgenic peanut lines during reproductive stages using lysimetric system under controlled glasshouse conditions. The antioxidant activities of AtDREB1A transgenic lines were measured by biochemical assays. The transgenic peanut lines recorded significantly lower accumulation of malondialdehyde and hydrogen peroxide than the wild-type. Whereas, specific activity of catalase, guaiacol peroxidase, ascorbate peroxidase, glutathione reductase and ascorbic acid were found to be significantly higher in transgenic lines than in the wild-type line under drought stress. The results showed that the transgenic lines expressed lower oxidative damage than wild-type and could protect themselves from the elevated levels of reactive oxygen species under drought stress. This could be attributed to the regulation of various stress-inducible genes by AtDREB1A transcription factor. Improved photosynthetic and growth parameters were also recorded in transgenic lines over wild-type under drought stress. Improved physio-biochemical mechanisms in transgenic peanut lines might have resulted in improved growth-related traits as significant correlations were observed between physio-biochemical parameters and growth-related traits under drought stress. The potential target genes of AtDREB1A transcription factor in transgenic peanut lines during drought stress were identified, which helped in understanding the molecular mechanisms of DREB-regulated stress responses. The transgenic line D6 reported the best physio-biochemical mechanisms and growth-related parameters under drought stress over other transgenic lines and wild-type, suggesting it may be used to develop high yielding and terminal drought-tolerant peanut varieties

Distribution of most abundant Gene ontology (GO) terms assigned to 2027 annotated SSR containing sequences.

<p>Distribution of most abundant Gene ontology (GO) terms assigned to 2027 annotated SSR containing sequences.</p

Summary and statistics of <i>Arachis hypogaea</i> ESTs assembled by TGICL program at stringency of 50 bp similarity and 95% identity.

<p>Summary and statistics of <i>Arachis hypogaea</i> ESTs assembled by TGICL program at stringency of 50 bp similarity and 95% identity.</p

Classification of EST-SSR according to the motif length.

<p>Classification of EST-SSR according to the motif length.</p

List of polymorphic primer with predicted function based on sequence homology.

<p>List of polymorphic primer with predicted function based on sequence homology.</p

PCR validation of SSRs having functional relevance to various stresses across selected peanut genotypes.

<p>PCR validation of SSRs having functional relevance to various stresses across selected peanut genotypes.</p

Distribution of 3373 EST-SSRs motifs based on MISA script.

<p>Distribution of 3373 EST-SSRs motifs based on MISA script.</p

List of parental genotypes used in current study along with its pedigree.

<p>List of parental genotypes used in current study along with its pedigree.</p