Inheritance of pigeonpea sterility mosaic disease resistance in pigeonpea.

A comprehensive study was conducted using PPSMV resistant (BSMR 736) and susceptible (ICP 8863) genotypes to develop a segregating population and understand the inheritance of PPSMV resistance. The observed segregation was comparable to 13 (susceptible): 3 (resistant). Hence, the inheritance was controlled by two genes, SV1 and SV2, with inhibitory gene interaction.

Molecular mapping of genomic regions harbouring QTLs for root and yield traits in sorghum (Sorghum bicolor L. Moench).

Root system is a vital part of plants for absorbing soil moisture and nutrients and it influences the drought tolerance. Identification of the genomic regions harbouring quantitative trait loci (QTLs) for root and yield traits, and the linked markers can facilitate sorghum improvement through marker-assisted selection (MAS) besides the deeper understanding of the plant response to drought stress. A population of 184 recombinant inbred lines (RILs), derived from E36-1 × SPV570, along with parents were phenotyped for component traits of yield in field and root traits in an above ground rhizotron. High estimates of heritability and genetic advance for all the root traits and for most of the yield traits, presents high scope for improvement of these traits by simple selection. A linkage map constructed with 104 marker loci comprising 50 EST-SSRs, 34 non-genic nuclear SSRs and 20 SNPs, and QTL analysis was performed using composite interval mapping (CIM) approach. A total of eight and 20 QTLs were mapped for root and yield related traits respectively. The QTLs for root volume, root fresh weight and root dry weight were found co-localized on SBI-04, supported by a positive correlation among these traits. Hence, these traits can be improved using the same linked markers. The lack of overlap between the QTLs of component traits of root and yield suggested that these two sets of parameters are independent in their influence and the possibility of combining these two traits might enhance productivity of sorghum under receding moisture condition.

Quantitative RT-PCR analysis of 20 transcription factor genes of MADS, ARF, HAP2, MBF and HB families in moisture stressed shoot and root tissues of sorghum.

Transcription factors (TFs) are an important target in understanding the regulation of plant responses to environmental stress including moisture stress. Members of the same TF family may differ in their response to moisture stress. The expression pattern could vary between shoot and root tissues depending on level of moisture stress. A set of five rarely studied TF families viz., MADS-box (MCM1, AGAMOUS, DEFICIENS and SRF), Auxin Responsive Factor (ARF), Heme Activator Protein 2 (HAP2), Multiprotein Bridging Factor (MBF) and Homeobox (HB) together having 20 members in sorghum, were expression analyzed through quantitative real-time PCR (qRT-PCR) in well watered and moisture stressed shoot and root tissues of sorghum using SYBR Green® to quantify dsDNA synthesis. Fluorescence values were used to calculate PCR efficiency by using LinRegPCR. The PTSb00029.1 and PTSb00033.1 of ARF family and PTSb00174.1 and PTSb00175.1 of HB family recorded 2 to 5, PTSb00221.1 and PTSb00208.1 of MADS family and PTSb00128.1 of HAP2 family recorded 5 to 10 fold up-regulation under moisture stress regimes. The PTSb00128.1, a HAP2 family member, recorded 15 fold up-regulation in mild moisture stressed root tissues. TF genes such as PTSb00218.1, PTSb00220.1, PTSb00031.1, PTSb00032.1, PTSb00034.1 and PTSb00223.1 were found down regulating in both tissues types under moisture stress condition. However, the PTSb00128.1, PTSb00221.1, PTSb00029.1, PTSb00033.1 and PTSb00174.1 TFs were found up-regulating to varied levels in mild and severe moisture stressed root tissues only. Verification of qRT-PCR results was done by in situ hybridization (ISH) of randomly selected two TF genes in shoot and root tissues of sorghum. Taken together, moisture stress triggered up-regulation of more genes in root tissue compared to shoot tissue in sorghum.

Cloning of a Serratia marcescens DNA fragment that induces quinoprotein glucose dehydrogenase-mediated gluconic acid production in Escherichia coli in the presence of stationary phase Serratia marcescens.

Serratia marcescens ER2 was isolated from an endorhizosphere sample based on its high level of mineral phosphate solubilizing (MPS) activity. This phenotype was correlated with expression of the direct oxidation pathway. An ER2 plasmid library constructed in Escherichia coli strain DH5alpha was screened for MPS activity. A recombinant clone DH5alpha (pKG3791) was capable of gluconic acid (GA) production and tricalcium phosphate solubilization but only in the presence of stationary phase ER2 cells. GA production in DH5alpha (pKG3791) was apparently the result of the quinoprotein glucose dehydrogenase activity because AG121 (a Tn5 knockout of gcd) carrying pKG3791 did not produce GA under the same conditions. GA production by DH5alpha (pKG3791) was not observed when ER2 was replaced by another PQQ-producing strain bacterium. These data add to a growing body of evidence that E. coli contains some type of PQQ biosynthesis pathway distinct from those previously characterized in Gram-negative bacteria and that these genes may be induced under appropriate conditions.