Sehar Nawaz

DNA profiling of sugarcane genotypes using randomly amplified polymorphic DNA.

DNA profiles of 40 sugarcane genotypes were constructed with 30 RAPD markers. Sugarcane genotypes of both Saccharum officinarum and S. barberi were included in this study. Multiple alleles were detected from each RAPD; there was a high level of polymorphism. On average, 7.93 alleles were produced per primer, giving a total of 238 alleles. The genetic distances between these genotypes were assessed with the POPGENE DNA sequence analysis software. A dendrogram was constructed from these data; cultivated species of sugarcane formed clusters with S. barberi genotypes. The 40 genotypes were clustered into two main groups; genetic distances ranged from 20.29 to 64.66%. These RAPD fingerprints will help sugarcane breeders to evaluate the efficiency of current conventional breeding methods and will help characterize the genetic pedigree of commercial sugarcane varieties. These data will also be valuable for conservation and utilization of the genetic resources in germplasm collections.

Effect of high temperature on grain filling period, yield, amylose content and activity of starch biosynthesis enzymes in endosperm of basmati rice

BACKGROUND High temperature during grain filling affects yield, starch amylose content and activity of starch biosynthesis enzymes in basmati rice. To investigate the physiological mechanisms underpinning the effects of high temperature on rice grain, basmati rice was grown under two temperature conditions - 32 and 22 °C - during grain filling. RESULTS High temperature decreased the grain filling period from 32 to 26 days, reducing yield by 6%, and caused a reduction in total starch (3.1%) and amylose content (22%). Measurable activities of key enzymes involved in sucrose to starch conversion, sucrose synthase, ADP-glucose pyrophosphorylase, starch phosphorylase and soluble starch synthase in endosperms developed at 32 °C were lower than those at 22 °C compared with similar ripening stage on an endosperm basis. In particular, granule-bound starch synthase (GBSS) activity was significantly lower than corresponding activity in endosperms developing at 22 °C during all developmental stages analyzed. CONCLUSION Results suggest changes in amylose/amylopectin ratio observed in plants grown at 32 °C was attributable to a reduction in activity of GBSS, the sole enzyme responsible for amylose biosynthesis.

Phylogenetic relationships among Saccharum clones in Pakistan revealed by RAPD markers.

Forty sugarcane genotypes (clones), including elite lines, commercial cultivars of Saccharum officinarum and S. barberi clones, were fingerprinted with 30 RAPD markers, using a PCR-based marker assay. The genetic distance for RAPD data was determined according to Nei, and relationships between accessions were graphed in a dendrogram. Genetic distance values ranging from 16.2 to 86.3% were observed among the 40 sugarcane accessions. The lowest genetic distance was found between genotypes US-406 and US-186. These two genotypes differed from each other in only 25 bands with 15 different primers. Genotypes Col-54 and CP-72-2086 were the second most similar group, with a genetic distance of 19.46%. The most dissimilar of all the accessions were CP-77-400 and US-133, with a genetic distance of 86.3%. RAPD fingerprints help sugarcane breeders clarify the genetic pedigree of commercial sugarcane varieties and can be used to evaluate the efficiency of conventional breeding methods.

Molecular characterization of Pakistani wheat cultivars using random markers

The genetic diversity among fifteen varieties of wheat was studied by random amplified polymorphic DNA (RAPD) analysis. By applying 20 RAPD primers, 182 fragments were amplified, out of which 118 were polymorphic (64.84%). The number of fragments amplified per primer ranged from 10 to 24 with an average of 17 fragments per primer. Primer K-17 produced the maximum number of fragments (24) and all the fragments were polymorphic. Range of polymorphism percentage was from as low as 0% (I to 15) to as high as 100% (K-11). The number of fragments produced per wheat genotype varied from 36 to 56 with an average of 47.2 fragments per genotype. The variety Shahkar-95 produced maximum number of fragments (56). Cluster analysis classified fifteen varieties of wheat into two main groups; three varieties were placed in group I and the rest of the varieties were placed in group II. Second group (group II) was further divided into three subgroups; IIA, IIB and IIC. The pair wise similarity values ranged from 54.88 to 82.93% and showed that genotypes Kohinoor-83 and Pak-81 were the closest with highest similarity value (82.93%), while genotypes Kohinoor-83 and Kohistan-97 were most distinct with minimum similarity value (54.88%).

Genetic studies of "noble cane" for identification and exploitation of genetic markers

Forty genotypes (clones) of sugarcane, including elite lines, commercial cultivars of Saccharum officinarum and clones of S. barberi were fingerprinted with 50 SSR markers using a PCR-based marker assay. Neis genetic distances for SSR data were determined and relationships between accessions were portrayed graphically in the form of a dendrogram. Genetic distance values ranging from 0.60 to 1.11 were observed among the 40 sugarcane accessions. The shortest genetic distance of 0.60 was seen between genotypes US-804 and US-130. These two genotypes differed from each other only in 10 bands, with 20 primers. The most dissimilar of the accessions were CP-77-400 and US-133, with a genetic distance of 1.11. SSR fingerprints can help sugarcane breeders to clarify the genetic pedigree of commercial sugarcane varieties and evaluate the efficiency of breeding methods.