Genetic variation and heterotic effects for seed oil, seed protein and yield attributing traits in upland cotton (ossypium hirsutum L.)

An investigation was carried out to assess the expression of per se performance and heterotic effect for seed oil, seed protein besides various yield attributing characters studied from 28 hybrids involving four adapted varieties as lines and the seven testers in line x tester analysis. A wide range of variability was observed for seed oil content in the parents and their 28 hybrids. The seed oil content in parents ranged from 17.0 to 22.1%, and hybrids varied from 17.7 to 22.9%.The hybrid, MCU 12 x SOCC 11 exhibited significant positive heterotic effect and per se performance for boll weight. The hybrid MCU 5 x SOCC 17 had high per se performance and positive significant heterotic effect for seed protein with seed cotton yield. Two hybrids showed high heterotic effect and per se performance for seed protein content. The hybrid MCU 12 x SOCC 17 exhibited higher per se performance and heterotic effect for seed cotton yield along with seed oil content and MCU 5 x SOCC 17 recorded more seed protein combined with seed cotton yield. Four hybrids revealed greater per se performance and positive heterosis for seed oil content. Of these, Surabhi x TCH 1646 exhibiting highest per se performance, heterotic effect was found to be best for directional selection.Keywords: Cotton, heterosis, seed oil, seed protein, yieldAfrican Journal of Biotechnology Vol. 12(33), pp. 5183-519

An update on conventional and molecular breeding approaches for improving fiber quality traits in cotton - A review

The cultivated Gossypium spp. represents the most important, natural fibre crop in the world. India is the only country cultivating all the four cultivated species of cotton. Among the Gossypium spp., Gossypium hirsutum is the most cultivated species in many countries. Breeding for high cotton yield is still the primary goal of cotton breeding programs, but improving fibre quality has become increasingly important. The enhancement of fibre quality traits like fibre length, strength, and fibre fineness is an essential requirement for the modern textile industry. G. hirsutum is characterized by its high lint yield while Gossypium barbadense has good fibre quality. Through a conventional breeding strategy, introgression of useful alleles for fibre quality from wild species and G. barbadense to G. hirsutum will be the effective way to improve the fibre quality traits. The identification of the stable quantitative trailt loci (QTLs) affecting fiber traits across different generations will be very helpful in molecular marker-assisted selection to improve fiber quality of cotton cultivars. In this review, we present an overview of the genetics and conventional and molecular breeding techniques that have been used to increase the favorable fibre quality traits in cotton.Keywords: Cotton, fibre quality traits, simple sequence repeat (SSR), restricted fragment length polymorphism (RFLP), amplified fragment length polymorphism (AFLP), quantitative trait loci (QTLs)African Journal of Biotechnology, Vol. 13(10), pp. 1097-1108, 5 March, 201

Varietal identification and fingerprinting of Pearl Millet (Pennisetum glaucum L.) varieties and hybrid using morphological descriptors and SSR markers

Pearl Millet (Pennisetum glaucum) is the sixth most important cereal crop in the world. The genomic resources available in Pearl millet can be utilized for fingerprinting and screening of hybrids using SSR markers and will be helpful for the assessment of seed purity. Hence, the present study was focused on fingerprint popular pearl millet varieties and hybrids of Tamil Nadu for varietal identification and hybrid purity test. The varieties used for DNA fingerprinting were CO (Cu) 9, CO 10, Pearl Millet hybrid CO 9 along with the parents, A' line ICMA 93111A and R' line PT 6029-30. The morphological features were recorded to screen the cultivars. The Pearl millet hybrid CO 9 scored the highest value for more than four quantitative characters via., Number of productive tillers (4-6), Leaf blade length (60-68cm), Leaf blade width (4.0-4.5cm), number of nodes (8-10), and 1000 seed weight (13-14g) which is at par and comparable with the composite CO 10  and higher than that of the variety CO (Cu) 9. PCR was performed using 36 SSR primers to find out polymorphism among the varieties. The SSR markers ICMP3021 and PSMP2089 were able to selectively identify CO (Cu) 9 from the other varieties. Whereas, the SSR markers ICMP3018, PSMP2219, and PSMP2220 were used to distinguish CO 10 from the other varieties. Further, the CO10 variety produced additional alleles for all the markers due to its composite nature. Among the thirty-six SSR primers screened, none of them were found suitable to distinguish the TNAU hybrid CO 9 from its parents. The unique DNA fingerprints developed in the present study can be utilized for seed purity testing and varietal identification

Determining genetic variability of traits in backcross populations of sweet corn (Zea mays L. var. Saccharata)

To understand the nature of the traits in breeding programme, knowledge on heritability, genetic advance and genetic variability are inevitable. The paramount aim of the present study was to estimate the heritability, genetic advance and genetic variability of the backcross and selfed population of sweet corn and β-carotene rich inbred combinations viz., USC1-2-3-1× UMI1230β+ and SC1107× UMI1230β+ in order to identify the plants with superior trait combinations. The study involved the recording of fourteen biometrical traits in both the cross combinations which revealed that in backcross and selfed populations, the phenotypic coefficient of variation (PCV) was found to be greater than the genotypic coefficient of variation (GCV) indicating the probable influence of environment in the expression of the traits evaluated. High heritability was recorded for the important trait single plant yield in both the cross combinations of BC2F2 generation. Further, high heritability and high genetic advance as percent of mean was noticed for the traits like plant height, cob length, leaf length and single plant yield under both the cross combinations of BC2F2 generation indicates the governance of additive genes in expression of these traits. Hence, selection for these traits would be effective in developing a genotype with improved yield

Genetic variation of morphological and yield-related traits in backcrossed and selfed population of maize

The number of genes controlling the morphological and yield-related traits and their mode of action plays a vital role in selecting traits and favourable progenies in a segregating population. In this study, we analysed the skewness and kurtosis in the backcrossed and selfed populations of SC11-2×UMI1230β1+. Negative skewness refers to redundant gene activity, positive skewness is connected to complementary gene action. Positive kurtosis suggests the existence of gene activity controlled by a smaller number of genes. Negative kurtosis shows a lack of gene activity and is controlled by a large number of genes. The BC2F2 population of plant height and single plant yield showed positive skewness and platykurtic distribution, suggesting that the genes were governed by complementary gene action and controlled by the large number of genes. This implied need for rigorous selection to achieve a genetic gain in later generations. Cob length and kernel weight showed a duplicate gene action which implied that mild selection can fix these traits and accelerate genetic gain

Quantitative trait loci for thermal time to flowering and photoperiod responsiveness discovered in summer annual-type Brassica napus L

Time of flowering is a key adaptive trait in plants and is conditioned by the interaction of genes and environmental cues including length of photoperiod, ambient temperature and vernalisation. Here we investigated the photoperiod responsiveness of summer annual-types of Brassica napus (rapeseed, canola). A population of 131 doubled haploid lines derived from a cross between European and Australian parents was evaluated for days to flowering, thermal time to flowering (measured in degree-days) and the number of leaf nodes at flowering in a compact and efficient glasshouse-based experiment with replicated short and long day treatments. All three traits were under strong genetic control with heritability estimates ranging from 0.85-0.93. There was a very strong photoperiod effect with flowering in the population accelerated by 765 degree-days in the long day versus short day treatments. However, there was a strong genetic correlation of line effects (0.91) between the long and short day treatments and relatively low genotype x treatment interaction indicating that photoperiod had a similar effect across the population. Bivariate analysis of thermal time to flowering in short and long days revealed three main effect quantitative trait loci (QTLs) that accounted for 57.7% of the variation in the population and no significant interaction QTLs. These results provided insight into the contrasting adaptations of Australian and European varieties. Both parents responded to photoperiod and their alleles shifted the population to earlier flowering under long days. In addition, segregation of QTLs in the population caused wide transgressive segregation in thermal time to flowering. Potential candidate flowering time homologues located near QTLs were identified with the aid of the Brassica rapa reference genome sequence. We discuss how these results will help to guide the breeding of summer annual types of B. napus adapted to new and changing environments. 2014 Nelson et al

Molecular characterization of the invasive fall armyworm, Spodoptera frugiperda (J.E. Smith) feeding on finger millet, Eleusine coracana (L.) Gaertn

Genetically, the maize fall armyworm (FAW, Spodoptera frugiperda J.E. Smith) consists of two strains viz., corn (C) strain mainly feeding on maize, sorghum, cotton, pulses, etc., and rice (R) strain feeding on rice crop and other grasses. The present study was carried out to identify the strains of FAW collected from finger millet crop at three different locations viz., Morappur (Dharmapuri district), Vridhachalam (Cuddalore district) and Salem (Salem district) of Tamil Nadu, India. PCR–RFLP profile of mitochondrial cytochrome oxidase I fragment exhibited the presence of both ‘C’ and ‘R’ strains of FAW feeding on finger millet. Out of ten samples, 6, 8 and 8 samples assumed ‘R’ strain identity, whereas, 4, 2 and 2 samples assumed ‘C’ strain identity in the locations of Morappur, Vridhachalam and Salem, respectively. Sequence analyses of mtCOI region of FAW feeding on finger millet showed nucleotide variations in eight positions. The molecular identity of S. frugiperda was ranged from 98 to 100% with previously deposited sequences in the NCBI GenBank database

Understanding genetic diversity in drought-adaptive hybrid parental lines in pearl millet.

Information on genetic diversity and population structure is helpful to strategize enhancing the genetic base of hybrid parental lines in breeding programs. The present study determined the population structure and genetic diversity of 109 pearl millet hybrid parental lines, known for their better adaptation and performance in drought-prone environments, using 16,472 single nucleotide polymorphic (SNP) markers generated from GBS (genotyping-by-sequencing) platforms. The SNPs were distributed uniformly across the pearl millet genome and showed considerable genetic diversity (0.337), expected heterozygosity (0.334), and observed heterozygosity (0.031). Most of the pairs of lines (78.36%) had Identity-by-State (IBS) based genetic distances of more than 0.3, indicating a significant amount of genetic diversity among the parental lines. Bayesian model-based population stratification, neighbor-joining phylogenetic analysis, and principal coordinate analysis (PCoA) differentiated all hybrid parental lines into two clear-cut major groups, one each for seed parents (B-lines) and pollinators (R-lines). Majority of parental lines sharing common parentages were found grouped in the same cluster. Analysis of molecular variance (AMOVA) revealed 7% of the variation among subpopulations, and 93% of the variation was attributable to within sub-populations. Chromosome 3 had the highest number of LD regions. Genomic LD decay distance was 0.69 Mb and varied across the different chromosomes. Genetic diversity based on 11 agro-morphological and grain quality traits also suggested that the majority of the B- and R-lines were grouped into two major clusters with few overlaps. In addition, the combined analysis of phenotypic and genotypic data showed similarities in the population grouping patterns. The present study revealed the uniqueness of most of the inbred lines, which can be a valuable source of new alleles and help breeders to utilize these inbred lines for the development of hybrids in drought-prone environments

Induced Mutagenesis Enhances Lodging Resistance and Photosynthetic Efficiency of Kodomillet (Paspalum Scrobiculatum)

The present research was focused in the development of photosynthetically efficient (PhE) and non-lodging mutants by utilizing ethyl methane sulphonate (EMS) and gamma radiation in the kodomillet variety CO 3, prone to lodging. Striking variations in a number of anatomical characteristics of leaf anatomy for PhE and culm thickness for lodging resistance was recorded in M2 (second mutant) generation. The identified mutants were subjected to transcriptomic studies to understand their molecular basis. Expression profiling was undertaken for pyruvate phosphate dikinase (PPDK), Nicotinamide Adenine Dinucleotide Phosphate Hydrogen—(NADPH) and NADP-dependent malate dehydrogenase (NADP-MDH) in the mutants CO 3-100-7-12 (photosynthetically efficient) and in CO 3-200-13-4 (less efficient). For lodging trait, two mutants CO 3-100-18-22 (lodged) and CO 3-300-7-4 (non-lodged) were selected for expression profiling using genes GA2ox6 and Rht-B. The studies confirmed the expression of PPDK increased 30-fold, NADP-ME2 ~1-fold and NADP-MDH10 was also highly expressed in the mutant CO 3-100-7-12. These expression profiles suggest that kodomillet uses an NADP-malic enzyme subtype C4 photosynthetic system. The expression of Rht-B was significantly up regulated in CO 3-300-7-4. The study highlights the differential expression patterns of the same gene in different lines at different time points of stress as well as non-stress conditions. This infers that the mutation has some effect on their expression; otherwise the expression levels will be unaltered. Enhancement in grain yield could be best achieved by developing a phenotype with high PhE and culm with thick sclerenchyma cells