Hafeez Ahmad Sadaqat

Effect of osmotic adjustment on root length and dry matter partitioning in sunflower (Helianthus annuus L.) under drought stress

Abstract Field experiments were conducted on sunflower (Helianthus annuus L.) with high- and low-osmotic-adjustment genotypes to ascertain the role of osmotic adjustment (OA) in sustaining achene yield (AY) and its stability under water-deficit conditions. The results indicated that high-osmotic-adjustment (HOA) genotypes were superior in terms of achene yield, root length, dry root weight, root-to-shoot ratio, harvest index (HI), and number of achenes per head under drought stress. The superiority of HOA for AY genotypes was due to efficient translocation of photosynthates to the roots, as indicated by the significant relationship of all root traits with OA and better mobilization of reserves to the developing head by the OA as suggested by a very strong relationship of OA with HI. Among different yield components, OA showed the highest relationship with the number of achenes per head, suggesting that reserves mobilized by OA were utilized to produce a large number of achenes per head. Genotype AMES-10103 belonging to the HOA group showed its superiority over other genotypes under drought stress. Among all traits, HI has shown its promise for selection of high yielding genotypes under drought stress.

Effect of moisture regimes on combining ability variations of seedling traits in sunflower (Helianthus annuus L.)

Seedlings traits provide a reliable and rapid technique for evaluating large numbers of genotypes for abiotic stresses. Experiments on sunflower were carried out under two moisture regimes in controlled conditions to study their modifying effect on phenotypic expression and combining ability of seedling traits such as root length (RL), shoot length (SL), root weight (RW), shoot weight (SW), root-to-shoot ratio (R:S), lateral root number (NLR), lateral root density (LRD), wilting rate index and recovery percent (R%), and their genotypic correlation with achene yield. Variation among breeding lines for relative decrease in the seedling traits under the moisture stress regime indicated their differences in moisture sensitivity. Genetic variation for all seedling traits was low over environments, but high within environments. Moisture regimes modified phenotype, ranking among parents, and combining ability of seedling traits. Relative contribution of specific combining ability to total variation decreased und...

Biodiversity in the sorghum (Sorghum bicolor L. Moench) germplasm of Pakistan.

Sorghum ranks fifth in worldwide economic importance among cereal crops and is one of the most important summer annual grasses of Pakistan. As it is a very diverse crop, sorghum genetic fingerprinting requires an efficient marker system. We estimated genetic divergence among 29 sorghum (Sorghum bicolor) genotypes, including approved varieties and local and exotic lines collected from different ecological regions of Pakistan, using random amplified polymorphic DNA (RAPD) markers. A total of 125 RAPD loci, with an average of 66 loci per genotype, were used to calculate genetic divergence among these genotypes, of which 119 were polymorphic, showing 95% overall polymorphism. Genetic similarity ranged from 0.36 to 0.92, indicating a relatively broad genetic base. RAPD analysis revealed maximum similarity between the Indian III and K-A-113 sorghum genotypes (both exotic lines), while the F-601 and F-606 were observed to be the most diverse genotypes. Mean band frequency revealed by these RAPD primers ranged from 0.17 to 0.56, with an average of 0.36. The data presented here support the findings that RAPDs can be effectively used for studying genetic diversity in sorghum.

Effects of varied water regimes on root length, dry matter partitioning and endogenous plant growth regulators in sunflower (Helianthus annuus L.)

Abstract A field experiment was conducted to quantify the effect of varied water regimes on root length, partitioning of dry matter and plant growth regulators by using sunflower genotypes differing in maturity and drought tolerance. Significant depressing effect of drought stress was evident on traits (i.e., reproductive dry matter, leaf area index and cytokinin concentrations in leaves). However, root/shoot, reproductive/vegetative ratios and Abscisic acid (ABA) concentration were found to increase under drought stress. Drought stress also changed the dry matter accumulation pattern of genotypes. In most cases it reduced the days to reach the maximum peak showing early senescence. ABA was identified as a multi-functional plant growth regulator under drought stress, causing early senescence of plants and translocation of assimilates to the roots and reproductive part while root growth under drought stress was explained by the indole-acetic acid (IAA) concentrations. Maintaining higher cytokinin contents were involved in accumulation of higher reproductive dry matter under drought stress. Although ABA and IAA were both involved in the development of defense responses during the adaptation and survival to drought stress but higher productivity under drought stress was only realized through maintaining higher cytokinin contents.

Estimation of genetic diversity using SSR markers in sunflower.

Microsatellites or simple sequence repeats (SSRs) were used for the estimation of genetic diversity among a group of 40 sunflower lines developed at the research area of Department of Plant Breeding and Genetics, University of Agriculture, Faisalabad. Total numbers of alleles amplified by 22 polymorphic primers were 135 with an average of 6.13 alleles per locus, suggesting that SSR is a powerful technique for assessment of genetic diversity at molecular level. The expected heterozygosity (PIC) ranged from 0.17 to 0.89. The highest PIC value was observed at the locus C1779. The genetic distances ranged from 9% to 37%. The highest genetic distance was observed between the lines L50 and V3. Genetic distances were low showing lesser amount of genetic diversity among the sunflower lines.

Development of a species-specific sequence-characterized amplified region marker for roses.

DNA fingerprints of four rose species, Rosa centifolia, R. Gruss-an-Teplitz, R. bourboniana, and R. damascena, were developed using RAPD-PCR. We identified a unique polymorphic band in R. centifolia. This 762-bp fragment was produced by the random primer GLI-2. The fragment was eluted and directly cloned in a TA cloning vector, pTZ57R/T. Digestion of the plasmid with EcoRI confirmed the cloning of GLI-2(762) in pTZ57R/T. A second enzyme, PstI, used in combination with EcoRI, gave complete digestion of the plasmid, and the 762-bp fragment was confirmed on the gel. Subsequently, the polymorphic amplicon was sequenced with an AB1 373 DNA sequencer system using the PRISM(TM) Ready Reaction DyeDeoxy(TM) Terminator Cycle Sequencing kit. After sequencing, specific primers (23 bp long) were designed based on the sequence of the flanking regions of the original RAPD fragment. These primers will effectively allow fingerprinting for the identification of R. centifolia species. In essence, we developed an SCAR marker to authenticate the identity of R. centifolia species and to distinguish it from its substitutes. Such techniques are required not only to complement conventional parameters in creating the passport data of commercial and medicinal products of rose, but also for routine quality control in commercial and government rosaries and rose nurseries.

Establishment of efficient in vitro culture protocol for wheat land races of Pakistan

The reliability of the production and presence of disease resistance especially rust has sparked a renewed interest in improving landraces and exploiting these in wheat variety development programs. In vitro culture is a pre-requisite for most of the tools of biotechnology. In this context, three Pakistani wheat ( Triticum aestivum L.) land races viz., LLR-13, LLR-15 and LLR-16, having leaf rust resistance were assessed for in vitro plant regeneration response. Immature embryos were cultured on Murashige and Skoog medium supplemented with 2, 4, 6 and 8 mg/L of 2,4-Dichlorophenoxyacetic acid (2,4-D) for callogenesis and MS + zeatin riboside (1.0 mg/L) medium for regeneration of these calli. All three land races produced callus on all 2,4-D concentrations; higher doses (8 mg/L) being the most effective for callus fresh weight. However, there was a strong carry over effect of 2,4-D on regeneration capacity. Calli induced at 2 mg/L of 2,4-D showed the highest regeneration frequency for LLR-16, LLR-13 and calli of LLR-15 induced on 4mg/L were more regenerative. Overall, LLR-16 produced the maximum regenerants. Rooted plantlets were transferred to glasshouse for further evaluation. Key words: Leaf rust, immature embryos, wheat land races, regeneration, Murashige and Skoog (MS) medium.

Screening of sunflower (Helianthus annus L.) accessions under drought stress conditions, an experimental assay

Drought is the major abiotic stress that limits the crop production at drastic level. Screening of tolerant accessions from available germplasm is the basic step in plant breeding. Sunflower is becoming popular and major oilseed crop in world but unfortunately it is drought sensitive. Screening in field has uncertainties due to the uncontrolled conditions, interaction of biotic and abiotic stresses and variability in environmental factors. Response of the sixty sunflower accessions to drought stress at germination and seedling stage was examined by using polyethylene glycol (PEG-6000) as drought simulator under laboratory. Normal and drought stress treatments i.e. T1= zero (control), T2= -1.33 MPa and T3= -1.62 MPa were developed by dissolving 0, 15 g and 20 g Polyethylene Glycol (PEG-6000) in 100 mL distilled water and a completely randomized design with three replications were used. Promptness, germination, seedling height, fresh weight, dry weight and stress indexes were determined to evaluate the response of sunflower accessions under normal and PEG simulated drought stress treatments. Principal component analysis was used to select the drought tolerant and sensitive accessions. The accessions 017583, A-75, A-79, 017592, G-33, A-48, A-23, G-61, HBRS-1 and 017566 were selected as drought tolerant while, CM-621, 017577, HA-124, HA-133, HA-342 and HA-341 were as drought sensitive. This study may be helpful for the comparison of drought indexes in a controlled experimental assay and for the identification of drought tolerant sunflower cultivars to be used in further breeding programs.

An insight in the genetic control and interrelationship of some quality traits in Brassica napus

A study on three leading lines (KN-256, KN-257, and KN-258) of Brassica napus and an approved variety, Punjab-Sarson, was conducted to gain insight into the genetic control of some quality traits using generation mean analysis. Our results showed that additive gene action predominated in the inheritance of oil content and erucic acid in cross KN-256 x KN-257 and in that of glucosinolates in KN-258 x Punjab-Sarson, indicating that these traits may be improved through selection in early segregating generations. Negative dominance can be exploited through heterosis breeding for the development of lines with low glucosinolates in cross KN-256 x KN-257. Protein content and oleic acid in cross KN-256 x KN-257, and oil content, protein content, and erucic acid in cross KN-258 x Punjab-Sarson depicted non-additive gene action and require further improvement in the later segregating generations. Most of the traits displayed high heritability estimates; glucosinolate content in both the crosses and erucic acid in cross KN- 258 x Punjab-Sarson also displayed high genetic advance, reflecting improvement of the trait in the early segregating generations. All the quality traits were positively correlated with oil content and with one another at both (genotypic and phenotypic) levels in KN-256 x KN-257. Negative correlation was observed between glucosinolate and erucic acid, oleic acid and erucic acid, and linolenic acid and oil content in cross KN-258 x Punjab-Sarson. Thus, gene action changed with the material, and cross KN-258 x Punjab-Sarson carried favorable combinations compared to KN-256 x KN-257.