Characterisation of wheat germplasm for slow rust resistance against Puccinia striiformis

Thirty-seven wheat germplasm were screened under artificial epiphytotic conditions against stripe rust of wheat at University Research Farm, Chatha, during Rabi, 2013–2014 and 2014–2015. On the basis of final rust severity (FRS), AURPC (Area Under Rust Progress Curve) and CI (Coefficient of Infection), 8 genotypes ((DWR 16, HD2281, VL616, K65, UP2121, HD2329, HD2307 and Lal Bahadur) exhibited partial resistance against the disease. PCR profiles revealed co-dominant pattern with distinct fragment of 150 bp in 14 germplasm, showing the presence of Yr18 gene and 229 bp band in 16 germplasm exhibited absence of Yr18.     

Molecular characterization of a bean α-amylase inhibitor that inhibits the α-amylase of the Mexican bean weevil Zabrotes subfasciatus

Cultivated varieties of the common bean (Phaseolus vulgaris L.) contain an α-amylase inhibitor (αAI-1) that inhibits porcine pancreatic α-amylase (PPA; EC 3.2.1.1) and the amylases of certain seed weevils, but not that of the Mexican bean weevil, Zabrotes subfasciatus. A variant of αAI-1, called αAI-2, is found in certain arcelin-containing wild accessions of the common bean. The variant αAI-2 inhibits Z. subfasciatus α-amylase (ZSA), but not PPA. We purified αAI-2 and studied its interaction with ZSA. The formation of the αAI-2-ZSA complex is time-dependent and occurs maximally at pH 5.0 or below. When a previously isolated cDNA assumed to encode αAI-2 was expressed in transgenic tobacco seeds, the seeds contained inhibitory activity toward ZSA but not toward PPA, confirming that the cDNA encodes αAI-2. The inhibitors αAI-1 and αAI-2 share 78% sequence identity at the amino acid level and they differ in an important region that is part of the site where the enzyme binds the inhibitor. The swap of a tripeptide in this region was not sufficient to change the specificity of the two inhibitors towards their respective enzymes. The three-dimensional structure of the αAI-1/PPA complex has just been solved and we recently obtained the derived amino acid sequence of ZSA. This additional information allows us to discuss the results described here in the framework of the amino acid residues of both proteins involved in the formation of the enzyme-inhibitor complex and to pinpoint the amino acids responsible for the specificity of the interaction. Received: 14 April 1997 / Accepted: 10 May 1997     

Scholaricine,an alkaloid from alstonia scholaris

A new alkaloid, scholaricine, has been isolated to which structure 2 (demethylscholarine) has been assigned.