SELECTION EFFECTS IN RICE AS ASSESSED BY GENETIC ANALYSIS IN SEGREGATING POPULATIONS

Estimation of selection effects on changes of a trait is of vital importance for the success of any plantbreeding program, and helps to select the desirable breeding method. Heritability and genetic advance areimportant selection parameters, and selection success is a reflectance of selection response. To estimate selectioneffects on rice genetic parameters, a research was conducted using 4 different generations (two parents:Neda and Sadri, and two segregating populations: BC1F1 and BC1S1). After development of a backcross population,a single plant (BC1#4) was selected based on its desirable performance, particularly in heading date andseven other morphological traits. BC1F1 population compared to mid-parent performance showed advance forheading date, plant height, tiller number, hundred seed weight, weight of filled seeds per panicle and grainyield per plant, while mean performance of BC1F1 population compared to BC1S1 population showed advanceonly for heading date, plant height, tiller number and grain yield. Prevalence of additive genetic effects incontrolling panicle weight, hundred seed weight, weight of filled seeds per panicle, plant height and headingdate was observed, and in contrast prevalence of non-additive effects in controlling grain yield was observed.High general heritability was observed for most traits, while only heading date and plant height showeda considerable specific heritability (60.7% and 67.5%, respectively), and grain yield showed a relatively lowspecific heritability (37.0%). High expected genetic advance (ΔGe) was obtained for tiller number (49.4%),followed by grain yield (43.5%) and plant height (35.5%), while the highest real genetic advance (ΔGe) wasobtained for heading date (-8.5%) and tiller number (5.4%). High selection success was obtained only forheading date (51.8%). Altogether, the obtained results gave promise for selecting progenies with early maturityand semi-dwarfism in early segregating generations, while they suggested preference of heterosis for improvementof grain yield.

Identification of introgressed rice lines of Binadhan-7×FL-378 under salt stress through SSR markers

Thirty two rice lines of BC1F1 population (Binadhan-7/FL 378) were used to identify introgressed rice lines for salt tolerance using SSR markers at the Plant Breeding and Biotechnology Divisions of Bangladesh Institute of Nuclear Agriculture (BINA), Mymensingh. Seeds of BC1F1 population of Binadhan-7/FL-378 were collected from backcross population of F1 (Binadhan-7/FL 378). Salt tolerant genotype, FL-378 was crossed with high yielding variety, Binadhan-7. Randomly selected 32 BC1F1 progenies along with their two parents (Binadhan-7, FL-378) were genotyped with microsatellite or SSR markers for identification of introgressed rice lines. Parental polymorphism survey was assayed by 8 SSR markers and three polymorphic SSR markers viz., RM296, RM585 and OSR30 were selected to evaluate BC1F1 rice lines for salt tolerance. Primer RM585 indicated 16 lines as introgressed and 16 lines as susceptible in comparison with salt tolerant parent FL-378 and salt susceptible parent Binadhan-7. Primer RM296 identified 13 introgressed, and 19 susceptible lines. Nine introgressed and 23 susceptible lines were identified when BC1F1 lines were evaluated with marker OSR30. Line BC1F1-30, BC1F1-40, BC1F1-2, BC1F1-16 and BC1F1-34 were identified as introgressed in comparison with parent FL-378 (salt tolerant) when RM585 and RM296 markers were used but line BC1F1-1 and BC1F1-3 were identified as introgressed incase of 3 primers (RM585, RM296 and OSR30). Again the lines BC1F1-5, BC1F1-24, BC1F1-26, BC1F1-27, BC1F1-29, BC1F1-31, BC1F1-37 and BC1F1-38 were found susceptible as compared with parent Binadhan-7 when marker RM585, RM296 and OSR30 were used. The polymorphism information content (PIC) values ranged from 0.3290 to 0.3671 with an average of 0.3544. The overall gene diversity of SSR loci for the 32 BC1F1 rice lines along with two parents was 0.4614, ranging from 0.4152 to 0.4844. Positive correlations were found between the genetic diversity and the maximum number of repeats. Among the lines, all the loci were polymorphic and clearly distinct and the cluster analysis (NJ tree and UPGMA) showed nearly similar pattern of variation which could be used for improvement of salt tolerant rice lines of rice through SSR markers. DOI: http://dx.doi.org/10.3329/jbau.v10i2.14680 J. Bangladesh Agril. Univ. 10(2): 185–190, 2012

Identification of introgressed rice lines of Binadhan-7×FL-378 under salt stress through SSR markers

Thirty two rice lines of BC1F1 population (Binadhan-7/FL 378) were used to identify introgressed rice lines for salt tolerance using SSR markers at the Plant Breeding and Biotechnology Divisions of Bangladesh Institute of Nuclear Agriculture (BINA), Mymensingh. Seeds of BC1F1 population of Binadhan-7/FL-378 were collected from backcross population of F1 (Binadhan-7/FL 378). Salt tolerant genotype, FL-378 was crossed with high yielding variety, Binadhan-7. Randomly selected 32 BC1F1 progenies along with their two parents (Binadhan-7, FL-378) were genotyped with microsatellite or SSR markers for identification of introgressed rice lines. Parental polymorphism survey was assayed by 8 SSR markers and three polymorphic SSR markers viz., RM296, RM585 and OSR30 were selected to evaluate BC1F1 rice lines for salt tolerance. Primer RM585 indicated 16 lines as introgressed and 16 lines as susceptible in comparison with salt tolerant parent FL-378 and salt susceptible parent Binadhan-7. Primer RM296 identified 13 introgressed, and 19 susceptible lines. Nine introgressed and 23 susceptible lines were identified when BC1F1 lines were evaluated with marker OSR30. Line BC1F1-30, BC1F1-40, BC1F1-2, BC1F1-16 and BC1F1-34 were identified as introgressed in comparison with parent FL-378 (salt tolerant) when RM585 and RM296 markers were used but line BC1F1-1 and BC1F1-3 were identified as introgressed incase of 3 primers (RM585, RM296 and OSR30). Again the lines BC1F1-5, BC1F1-24, BC1F1-26, BC1F1-27, BC1F1-29, BC1F11F1-37 and BC1F1(PIC) values ranged from 0.3290 to 0.3671 with an average of 0.3544. The overall gene diversity of SSR loci for the 32 BC1F1 rice lines along with two parents was 0.4614, ranging from 0.4152 to 0.4844. Positive correlations were found between the genetic diversity and the maximum number of repeats. Among the lines, all the loci were polymorphic and clearly distinct and the cluster analysis (NJ tree and UPGMA) showed nearly similar pattern of variation which could be used for improvement of salt tolerant rice lines of rice through SSR markers.DOI: http://dx.doi.org/10.3329/jbau.v10i1.12039J. Bangladesh Agril. Univ. 10(1): 49–54, 2012

The inheritance of the red leaf reaction of grain sorghum to sugarcane mosaic virus infection

The hypothesis that the necrotic red leaf and red stripe reactions of grain sorghum to sugar-cane mosaic virus – Johnson grass strain infection are independently inherited was tested. Five F1 and 15 F2 populations and one bc1F1 population were grown under both high (26.6–23.8°C) and low (15.5°) temperature regimes following manual inoculation with the virus. The results were consistent with the hypothesis that the presence of a homozygous recessive allele, termed rlf, conditions the expression of the necrotic red leaf reaction following exposure of plants to low temperatures. Plants express only mosaic symptoms in the presence of the dominant allele RLF and the absence of the N gene. The previously reported N gene and the rlf gene were shown to be independently inherited.