دراسة مظهرية وخلوية وجزيئية لعدد من التراكيب الوراثية للرز Oryza sativa L.

Morphological, Cytological and Molecular Study on many Rice ( Oryza sativa L.) Genotypes

Summary
The study included fifteen genotypes of rice (local and introduced) for the study of morphological, cytological and molecular studies using a number of parameters . A field experiment was conducted at the Rice Research Station in Mashkhab governorate of Najaf Governorate and during the (2018) summer season by Randomized Complete Block Design (RCBD), and arrangement three replicates to evaluate the performance of 15 genotypes from the rice crop Oryza sativa L., and to determine the best characteristics as selection indices with grain yield.
A number of traits were studied: number of days from planting to 50% flowering, number of days from planting to maturity, Plant height, Leaf area index, length of panicle, number of branches / panicle, number of panicles / m2, number of grains filled in panicle , sterility percentage, weight of 1000 grains, biological yield, harvest index and grain yield. Using Least Significant Differences ( L.S.D.) p= 0.01.
The results showed that the genotypes significantly affected the studied traits. Gohar genotype gave the highest values for the number of panicles / m 2 and the number of grains in the panicle. On the other hand gave the highest value in the grains yield. The broad – sense heritability in the wide range was high and all the traits entered except for the sterility percentage, which was medium. Results showed that higher genotypic and phenotypic variation were obtained for all plant height, number of panicles / m 2, number of grains in panicles, biological yield and grain yield, so the chances of success of the selection will be the largest of these qualities to the presence of variation great.
Results showed that highest genotypic and phenotypic correlations are positively and significantly between grain yield with harvest index gaving 0.76 and 0.73 followed by the number of grains in the panicles was 0.49 and 0.38 respectively. Conclude from this study that the growing cultivar of the Gohar genotype achieved the highest yield. Harvest index can be adopted as selection indices because that was given the higher genotypic and phenotypic correlation and higher heritability. used as an experimental criterion to improve the cereal yield of the rice crop. As for the cytological study, all genotypes and seedling development were taken in the Petri dishes on filter paper. After 1 to 2 weeks of growth , the developing root tip were removed from the study of total cells number, divided cells number and mitotic index were studied of somatic chromosomes in the meristematic cells of the root tip. Chromosomal aberration and calculation of the percentage of chromosomal abnormalities.
Results showed that the genotypes they were in genetic stability on the level of chromosomal number and in a state of Euploid in all the investigated genotypes. This revealed that the Gohar had a significant increase compared with genotype for it gave the highest total cells number (183.2) , divided cells number (15.20) and mitotic index ( 8.43)% The results also showed a number of chromosomal abnormalities.
As for the molecular study, the use polymerase chain reactions (PCR) based on the marker Simple Sequence Repeat (SSR), The DNA was isolated from fresh leaves of the rice genotypes after 25 days from seedling using Genomic DNA plant kit protocol. Results showed that there were 21 alleles using 4 primers. The range of molecular sizes from 142,947 to 344,366 base pairs (bp). RM171 primer was the highest number of alleles 7 produced while the lowest number of alleles was 4 alleles recorded by RM216 and RM8085 primers.
The Polymorphism information content (PIC), which is the a reflection of allelic diversity and allelic repetition between genotypes ranged value from 0.5198 to 0.8006, As range of genetic diversity values ranged from 0.5711 to 0.8244. RM171 primer produced the highest value of Heterozygote with 0.4000, RM171 primers gave a distinctive genetic fingerprinting of 4 genotypes, under study while the RM8085 did not gave a fingerprint to any genotypes. The lowest genetic distance 0.13279 between Neda and Nemat genotypes, which means that there is a high degree of similarity between these genotypes. Genetic similarity of percent all genotypes ranged between (296470 – 0.86721) depending on the genetic distance that ranging from (0.13279 – 70353) which refers to the large genetic diversity ranged from 29% – 86%. This reveals a high genetic variation between genotypes, making hereditary good sources.
Results also showed that Cluster analysis of two main groups. The first included 12 genotypes, the second included three genotypes. They were not distributed randomly, but its distribution was common ancestor. This is due to the efficiency of the SSR marker in the detection of genetic diversity in rice plant. By using SSR it is possible able to detect of quantitative traits loci that associated drought tolerance and salinity with fertility restorer genes.
Results of the (PCR) test using the RM171 primer determination of the nucleotide sequence (nitrogen bases) generated from PCR-amplified products using the Basic Local Alignment Search Tool (BLAST). From the comparison of the nucleotide sequences analysis obtained from the identified rice genotypes with the nucleotide sequences deposited at the National Center for Biotechnology Information (NCBl), it was revealed that the identified genotypes that all in this study were related to Oryza sativa L. (rice). As found by comparing the nucleotide sequence with the data available at the National Center for Biotechnology Information (NCBI) and showed that the genetic similarity between them, but five of the genotypes, Sumer, Anbar furat, Khazar, Neda, and the Anber Baghdad are not previously, so registered at (NCBI). Therefore; the five identified sequences have been deposited and recorded in GenBank database (NCBI) under the accession numbers: MK419157, MK419158, MK419159, MK419160 and MK419161, respectively .