Legume Research

  • Chief EditorJ. S. Sandhu

  • Print ISSN 0250-5371

  • Online ISSN 0976-0571

  • NAAS Rating 6.80

  • SJR 0.391

  • Impact Factor 0.8 (2023)

Frequency :
Monthly (January, February, March, April, May, June, July, August, September, October, November and December)
Indexing Services :
BIOSIS Preview, ISI Citation Index, Biological Abstracts, Elsevier (Scopus and Embase), AGRICOLA, Google Scholar, CrossRef, CAB Abstracting Journals, Chemical Abstracts, Indian Science Abstracts, EBSCO Indexing Services, Index Copernicus
Legume Research, volume 45 issue 8 (august 2022) : 947-951

Effect of F2 Inter se Mating on Quantitative Traits Mean, Range, Variance and Heritability in Dolichos Bean (Lablab purpureus L. Sweet var. Lignosus)

Chandrakant1, S. Ramesh2,*, P.V. Vaijayanthi3, A. Mohan Rao2, M.S. Shivakumar4
1District Agriculture Training Center, Gangavathi-583 235, Karnataka, India.
2Department of Genetics and Plant Breeding, University of Agricultural Sciences, Bangalore-560 065, Karnataka, India.
3Department of Genetics and Plant Breeding, College of Agriculture, Kasargod-671 314, Kerala, India.
4ICAR-Indian Institute of Spices Research, Calicut-673 012, Kerala, India.
  • Submitted24-06-2020|

  • Accepted19-11-2020|

  • First Online 28-01-2021|

  • doi 10.18805/LR-4448

Cite article:- Chandrakant, Ramesh S., Vaijayanthi P.V., Rao Mohan A., Shivakumar M.S. (2022). Effect of F2 Inter se Mating on Quantitative Traits Mean, Range, Variance and Heritability in Dolichos Bean (Lablab purpureus L. Sweet var. Lignosus) . Legume Research. 45(8): 947-951. doi: 10.18805/LR-4448.
Background: Pedigree method of breeding in predominantly self-pollinated crop like dolichos bean enable exploiting only fixable genetic effects as a result of rapid increase in homozygosis. One or a few cycles of inter-mating in F2 generation help create populations with high frequency of desired recombinants which otherwise cannot be realized in later generations. The objective of the present investigation was to assess the impact of inter se mating in F2 population on nine quantitative traits’ (QTs) mean and variability parameters.

Methods: Randomly selected 20 pairs of a single cross-derived F2 plants with flowering synchrony were inter se mated. Progenies derived from 20 paired crosses (designated as BIP F3 progenies) and those (F3) derived from their 40 F2 parents were evaluated for 9 QTs. Statistics such as mean, absolute range (AR) and standardized range (SR), variance (σ2), additive genetic variance (σ2A) and narrow-sense heritability (NS-h2) were estimated. BIP F3 progenies were compared with those of F3 progenies for QTs mean, AR/SR, σ2, σ2A and NS-h2. Significance of differences between BIP F3 progenies and F3 progenies for mean and σ2 were examined using two-sample t test and Levene’s tests, respectively. 

Result: The random mating in F2 population was effective in increasing the means, variances, σ2A and NS-h2 of racemes plant-1, fresh pods node-1, fresh pods plant-1 and fresh pod yield plant-1 in dolichos bean. Considering that random mating followed by selfing is a method of genetic improvement for future breeding rather than for immediate use, our results suggest long-term genetic gain and better prospects of deriving superior pure-lines with desired traits/combination of traits from inter-mated population in dolichos bean.
Dolichos bean var. lignosus is one of the important grain legume crops extensively grown in southern India. It is predominantly a self-pollinated crop (Kukade and Tidke, 2014) with 2n=22 chromosomes (She and Jiang, 2015). It is predominantly grown as a rainfed crop for fresh beans for use as a vegetable. While fresh pods are the harvestable and marketable products, fresh beans are consumable products in dolichos bean (Ramesh and Byregowda, 2016). Pedigree breeding is the most commonly used method for developing improved cultivars in dolichos bean (Ramesh and Byregowda, 2016), as is practiced in other legumes and inbreeding species. However, pedigree method of breeding enable exploiting only fixable genetic effects as a result of rapid increase in homozygosis (Clegg et al., 1972), which further limits opportunities for recombination retaining and/or favoring accumulation of haplotypes harboring genes controlling desirable and undesirable traits (Hanson, 1959; Pederson, 1974; Bos, 1977; Stam, 1977). One or a few cycles of inter-mating in F2 generation results in break-up of linkage blocks and help create populations with high frequency of desired recombinants which otherwise cannot be realized in later generations (Hanson, 1959; Bos, 1977; Stam, 1977; Yunus and Paroda, 1983). Further, complete association of ‘+’ genes (which enhance phenotypic expression) is extremely rare and dispersion (which causes reduction in phenotypic expression) is normal in genotypes particularly those that are from the source material for breeding programmes (Kearsey and Pooni, 1996). The probability of genes being in dispersion phase could be minimized by random mating F2 for few generations before deriving best recombinant inbred lines (RILs) (Stam, 1977). Under these premises, the present investigation was carried out to assess impact of F2 inter se [Bi-parental (BIP)] mating on quantitative traits means and variances, additive genetic variance and heritability.
The basic material for present investigation consisted of F2 population derived from HA 4 × GL 37. The HA 4 is a high yielding photoperiod in-sensitive determinate type released variety, while GL 37 is a photoperiod sensitive in-determinate type local collection being maintained at Zonal Agricultural Research Station (ZARS), University of Agricultural Sciences (UAS), Bengaluru.
 
Development of experimental material
 
To raise F2 population,150 seeds harvested from F1 (HA 4 × GL 37) plants were sown with inter-row spacing of 0.6 m and of 0.3 m between plants within a row at the experimental plots of Department of Genetics and Plant Breeding, UAS, Bengaluru during 2012-13 rabi-summer season. Due to non-germination of a few seeds and mortality of a few seedlings, the F2 population consisted of 132 plants at flowering. Randomly selected 20 pairs of F2 plants with flowering synchrony were inter se mated. Seeds from 20 paired crosses (here after designated as BIPF3 progenies) and selfed seed (F3) from their 40 parents were collected, cleaned, dried and preserved. Twenty BIP F3 and 40 F3 progenies constituted the experimental material for the study.
 
Evaluation of experimental material
 
Seeds of 20 BIP F3 and 40 F3 progenies along with the two parents and three checks (HA 3, HA 4 and Kadle Avare) were sown in Augmented design (Federer, 1961) in five compact blocks at the experimental plots of UAS, Bangalore during 2015 rainy season. Each block consisted of 12 BIP F3 and/or F3 progenies, three checks and two border entries. Each entry in each block was sown in a single row of four meters length with a row spacing of 0.45 m and 0.3 m between plants within a row. Each of BIP F3 and F3 progenies consisted of 18 to 20 plants. Recommended agronomic and plant protection practices were followed to raise a healthy crop.
 
Sampling of plants and data collection
 
The data on eight quantitative traits (QTs) namely, days to flowering, primary branches plant-1, racemes plant-1, nodes raceme-1, fresh pods node-1, fresh pods plant-1, fresh pod yield plant-1 and fresh bean yield plant-1 were recorded on 15 plants (avoiding border plants) of BIP F3 and F3 progenies using the protocol described by Byregowda et al., (2015).
 
Statistical analysis
 
ANOVA was performed following Augmented design (Federer, 1961) using WINDOSTAT 8.5 version. Adjusted trait values of each of the individuals in BIP F3 and F3 progenies were estimated (Federer, 1961). Adjusted means were used for estimating eight QTs means, absolute range (SR), standardized range (SR) (highest trait value-lowest trait value/trait mean), variance, additive genetic variance (σ2A) and narrow-sense heritability (NS-h2). Separate ANOVA were performed to partition total variation in BIP F3 and F3 progenies into sources attributable to ‘between’ and ‘within’ BIP F3 (Kearsey, 1965) and ‘between’ and ‘within’ F3 progeny (van Ooijen, 1989) variances, respectively. The σ2A and NS-h2 of eight QTs in BIP F3 and F3 progenies were estimated using the information from respective ANOVA. The significance of differences in QTs means and variances between BIP F3 and F3 progenies were tested using two-sample ‘t’ test and Levene’s  test (Levene 1960), respectively.
 
Impact assessment of F2 BIP mating on QTs dynamics
 
BIP F3 progenies were compared with those of F3 progenies with respect to per se performance (mean), AR/SR, variance, σ2A and NS-h2 of nine QTs.
Analysis of variance
 
Significant differences among the experimental progenies (BIP F3 + F3 progenies) for all the traits, except primary branches plant-1, nodes raceme-1 and fresh bean yield plant-1 (Table 1) supported analysis of variance of BIP F3 and F3 progenies separately. Significant mean squares due to ‘between BIP F3 progenies’ and ‘between F3 progenies’ (Table 2) suggested sufficient variability in F2 population attributable to segregation of genes for which the parents (HA 4 and GL 37) differed. Significant variability between BIP F3 and F3 progenies adequately provided statistical and genetical validity for comparative assessment of BIP F3 and F3 progenies for mean, standardized range, variance, σ2A and NS-h2 of eight QTs.
 

Table 1: Analysis of variance for various quantitative traits in dolichos bean.


 

Table 2: Analysis of variance of F3 and BIP F3 progenies for various quantitative traits in dolichos bean.


 
Impact of BIP mating on QTs mean
 
In F2 population derived from crosses between diverse parents, genes controlling the QTs for which the parents differ would be in significant linkage disequilibrium (LD) (Hanson and Hayman, 1963). Despite the presence of LD between the genes controlling the QTs, means of BIP F3 and F3 progenies is not expected to alter (Kearsey and Pooni, 1996). Also, per se performance of progenies derived from F2 BIP mating compared to those derived from inbreeding is not expected to change unless there exists non-additive gene effects associated with change in LD (Hanson and Hayman, 1963). In the present study, significantly delayed flowering with higher primary branching and raceme producing ability of BIP F3 progenies compared to F3 progenies (Table 3) could be attributed to involvement of non-additive action of genes controlling these traits. Higher means of BIP F3 progenies for days to flowering, number of primary branches and number of racemes compared to those of BIP F3 progenies could also be attributed to breakage of undesirable linkages which otherwise conceal genetic variation accumulation of favorable genes controlling these traits (Hanson, 1959; Bos, 1977; Stam, 1977). The results of present investigation are in conformity with those of Sharma and Kalia (2003) in garden pea and Chand (2000) in blackgram and Kampli et al., (2002), Singh (2004) and Jahagirdar et al., (2005) in chickpea. Contrastingly, F3 progenies manifested higher nodes raceme-1 compared to BIP F3 progenies. Stam (1977) through his extensive theoretical investigation opined that environment variance might also tends to provide selfed progenies, a relative advantage over random mating-derived progenies especially for traits directly related to fitness (such as nodes raceme-1 in the present study) of the individuals. However, BIP F3 progenies were comparable to F3 progenies for fresh pods node-1, fresh pods plant-1, fresh pod yield plant-1and fresh bean yield plant-1. These results could possibly due to inadequacy of one cycle of inter-mating to release genetic variability and/or linkage equilibrium (LE) of genes controlling these traits in F1’s. Thus, per se performance of progenies derived from F2 BIP mating and inbreeding varied with traits in dolichos bean depending on LD/LE of genes controlling traits.
 

Table 3: Estimates of mean and variance of various quantitative traits in BIP F3 and F3 progenies in dolichos bean.


 
Impact of BIP mating on QTs variance
 
Inter-mating F2 individuals derived from diverse parents is expected to decrease and increase genetic variability for traits which are controlled by genes that exist in coupling phase and repulsion phase, respectively (Hanson and Hayman, 1963). While the decrease in genetic variability could be attributed to appearance of individuals with intermediate phenotypes, increase in genetic variability could be attributed to appearance of individuals with extreme phenotypes. In the present investigation, higher genetic variance in BIP F3 than that in F3 progenies (Table 3) suggested predominance of repulsion phase of linkage of genes controlling racemes plant-1 and fresh pods node-1.
       
Increase in QTs variances following F2 inter-mating were also reported by Kampli et al., (2002), Singh (2004), Jahagirdar et al., (2005) in chickpea, Koli and Punia (2012) in aromatic rice and Gauthami et al., (2016) in maize. Hanson (1959) found that with two generations of inbreeding, about 65 per cent of chromosome lengths were left intact (no crossing over), whereas, only about 42 per cent was intact with inter-mating. Thus, F2 BIP mating is expected to offer better opportunities than selfing to prevent early fixation of undesirable genes in homozygous condition in dolichos bean as demonstrated by Meredith and Bridge (1971) in cotton.
       
Variances for traits such as days to flowering, primary branches plant-1, nodes raceme-1, fresh pods plant-1, fresh pod yield plant-1 and fresh bean yield plant-1 were comparable between F3 and BIP F3 progenies. While detection of increase/decrease in variance following F2 BIP mating is an indication of repulsion/coupling phase of linkage between genes controlling QTs, failure to detect the same does not rule out the presence of linked loci (Hanson and Hayman 1963; Meredith and Bridge, 1971). Fairly conclusive evidence for the presence of linked loci controlling the inheritance of these QTs could be elicited by comparing the variances between (F1 × P1) and (F2 × P1), (F1 × P2) and (F2 × P2) and between (F1 × F1) and (F2 × F1) (Perkins and Jinks, 1970).
 
Impact of BIP mating on QTs range
 
It is expected that random mating would result in the distribution of genotypic values different from that expected in F2 population. The distribution is less concentrated about the parental and F1 values and thus, higher QTs range is expected (Hanson, 1959). In the present study, a wider standardized range of traits mean values of BIP F3 progenies compared to F3 progenies (Table 4) could be attributed to appearance of extreme phenotypes presumably due to disruption of repulsion phase of linkage (in F1’s) between genes controlling racemes plant-1, fresh pods node-1 and fresh pod yield plant-1. Dutta et al., (1987) have also reported enhanced range in QTs means following F2 inter-mating in groundnut and they attributed it to recombination of genes from upper and lower ends of genotypic values. On the contrary, wider standardized range of QTs means of F3 progenies  compared to BIP F3 progenies could be attributed to appearance of intermediate phenotypes presumably due to breakage of coupling phase of linkage (in F1’s) between genes controlling days to flowering, primary branches plant-1, nodes raceme-1, fresh pods plant-1 and fresh bean yield plant-1.
 

Table 4: Estimates of range, additive genetic variance and narrow-sense heritability for various quantitative traits in dolichos bean.


 
Impact of BIP mating on σ2A and NS-h2 of QTs
 
Additive genetic variances are generally inflated by coupling phase and deflated by repulsion phase consequent to F2 BIP mating (Kearsey and Pooni, 1996). As the QTs are controlled by a large number of genes, very rarely all the ‘plus’ genes will be in complete association (which enhance phenotypic expression) or ‘plus’ and ‘minus’ genes will be in complete dispersion (which causes reduction in phenotypic expression) particularly those that are from the source material for breeding programmes (Kearsey and Pooni, 1996) and thus display coupling/repulsion phase of linkage. However, dispersion does not automatically lead to predominance of repulsion phase as a few gene pairs will be in repulsion phase while others will be in coupling phase. Nevertheless, dispersion of genes between the parents always reduces σ2A. The extent to which reduction in σ2A occurs is more pronounced when ‘plus’ and ‘minus’ genes alternate in the sequence in a haplotype (Kearsey and Pooni, 1996). Higher magnitudes of σ2A and hence NS-h2 in BIP F3 than those in F3 progenies in the present study (Table 4) suggested predominance of coupling phase of linkages of genes (in F1’s) controlling all the traits, except days to flowering and primary branches plant-1 for which they were comparable between BIP F3 and F3 progenies. Kampli et al., (2002), Singh (2004) and Jahagirdar et al., (2005) in chickpea have also reported higher magnitudes of σ2A in BIP F3 than those in F3 progenies. In self-pollinated crops like dolichos bean, selection is generally among pure-lines and hence exploits σ2A and σ2AA epistasis.
Random mating in F2 population was effective in increasing the means, variances, σ2A and NS-h2 of racemes plant-1, fresh pods node-1, fresh pods plant-1 and fresh pod yield plant-1 in dolichos bean. Considering that random mating followed by selfing is a method of genetic improvement for future breeding rather than for immediate use (Hallauer 1984), our results suggest long-term genetic gain and better prospects of deriving superior pure-lines with desired traits/combination of traits from inter-mated population in dolichos bean.

  1. Bos, L. (1977). More arguments against inter-mating F2 plants of a self pollinated crop. Euphytica. 26: 33-46.

  2. Byregowda, M., Gireesh, G., Ramesh, S., Mahadevu, M. and Keerthi, C.M. (2015). Descriptors of dolichos bean (Lablab purpureus L.). Journal of Food Legumes. 28(3): 203-214.

  3. Clegg, M.T. Allard, R.W. and Kahler, A.l. (1972). Is the gene unit of selection? Evidence from two experimental plant populations. Proceedings of National Academy of Sciences (USA). 69: 2474-2478.

  4. Dutta, M. Arunachalam, V. and Bandyopadhyay, A. (1987). Enhanced cross pollination to widen the scope of breeding in groundnut (Arachis hypogaea L.). Theoretical and Applied Genetics.74: 466-470.

  5. Federer, W.T. (1961). Augmented design with one way elimination of heterogeneity. Biometrics.17: 447-473.

  6. Gauthami, R.B., Gangappa, E., Ramesh, S. and Puttaram, N. (2016). Impact of bipraental mating on grain yield and its component traits and character association in maize (Zea mays L.). Green Farming. 7(6): 1301-1305.

  7. Hallauer, A.R. (1984). Compendium of recurrent selection methods and their application. CRC Critical Reviews on Plant Sciences. 3: 1-33. 

  8. Hanson, W.D. (1959). The breakup of initial linkage blocks under selected mating systems. Genetics. 44: 857-868.

  9. Hanson, W.D. and Hayman, B.I. (1963). Linkage effects on additive genetic variance among homozygous lines arising from the cross between two homozygous parents. Genetics. 48: 755-766.

  10. Jahagirdar, J.E. Katare, N.B. and Sudewad, S.M. (2005). Biparental mating: a tool for creation of genetic variability in chickpea. Indian Journal of Pulses Research. 18(1): 12-13.

  11. Kampli, N. Salimath, P.M. and Kajjidoni, S.T. (2002). Genetic variability created through biparental mating in chickpea (Cicer arietinum L.). Indian Journal of Genetics. 62(2): 128-130.

  12. Kearsey, M.J. (1965). Biometrical analysis of a random mating population: a comparison of five experimental designs. Heredity. 20: 205-235.

  13. Kearsey, M.J. and Pooni, H.S. (1996). The Genetical Analysis of Quantitative Traits, Chapman and Hall, London, UK.

  14. Koli, N.R. and Punia, S.S. (2012). Effect of inter-mating on genetic variability and character association in aromatic rice (Oryza sativa L.). Electronic Journal of Plant Breeding. 3(2): 830-834.

  15. Kukade, S.A. and Tidke, J.A. (2014). Reproductive biology of Dolichos lablab L. (Fabaceae). Indian Journal of Plant Sciences. 3(2): 22-25.

  16. Levene, H. (1960). Robust tests for equality of variances. In: [Olkin et al. (ed.)]. Contributions to Probability and Statistics: Essays in honour of Harold Hotelling, Stanford University Press, Stanford, pp. 278-292.

  17. Meredith, W.R. Jr. and Bridge, R.R. (1971). Breakup of linkage block in cotton G. hirsutum L. Crop Science. 11: 695-698.

  18. Miller, P.A. and Rawlings, J.O. (1967). Breakup of initial linkage blocks through inter-mating in a cotton breeding population. Crop Science. 7: 199-204.

  19. Pederson, D.G. (1974). Arguments against intermating before selection in a self-fertilizing species. Theoretical and Applied Genetics. 45: 157-162.

  20. Perkins, J.M. and Jinks, J.L. (1970). Detection of estimation of genotype-environmental, linkage and epistastic components of variation for a metrical trait. Heredity. 25: 157-177.

  21. Chand, P. (2000). Genetic effects of biparental mating in black gram (Vigna mungo L. Hepper). Annals of Agricultural Research. 21(2): 305-307.

  22. Ramesh, S. and Byregowda, M. (2016). Dolichos bean (Lablab purpureus L. Sweet var. Lignosus) genetics and breeding - present status and future prospects. Mysore Journal of Agricultural Sciences. 50(3): 481-500.

  23. Sharma, A. and Kalia, P. (2003). Studies on biparental progenies in garden pea (Pisum sativum L.). Indian Journal of Genetics. 63(1): 79-80.

  24. She, C. and Jiang, X. (2015). Karyotype analysis of (Lablab purpureus L. Sweet) using flourochrome banding fluorescence in situ hybridization with rDNA probes. Czech Journal of Genetics and Plant Breeding. 51 (3):110-116.

  25. Singh, N. (2004). Generation of genetic variability in chick pea (Cicer arietinum L.) using biparental mating. Indian Journal of Genetics. 64(4): 327-328.

  26. Stam, P. (1977). Selection response under random mating and under selfing in the progeny of a cross of homozygous parents. Euphytica. 262:169-184.

  27. van Ooijen, J.W. (1989). Estimation of additive genotypic variance with the F3 of autogamous crops. Heredity. 63: 73-81.

  28. Yunus, M. and Paroda, R.S. (1983). Extent of genetic variability created through bi-parental mating in wheat. Indian Journal of Genetics. 43: 76-81.

Editorial Board

View all (0)