الفهرس 
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Abstract
This study was carried out in the laboratories of the Department of Genetics, Faculty of Agriculture, Ain Shams University, Shoubra El-Kheima, Egypt. The field experiments were applied at Giza Agricultural Experiments & Research Station, Food Legumes Research Department, Field Crops Research Institute (FCRI), Agriculture Research Center (ARC), Giza, Egypt during the period from 2008 to 2014. Three years-field experiments were applied at Giza Agricultural Experiments & Research Station, Agricultural Research Station, Giza Governorate, Egypt, during 2008, 2009 and 2010 seasons. Four soybean genotypes; Giza 111, Giza 22, L 127 and L 158 resistant to cotton leaf worm and one susceptible; Dr–101 and their half diallel crosses were sown in randomized complete block design (RCBD) to study soybean genotypes resistance and/or susceptible for cotton leaf worm (Spodopetra littoralis) and detect molecular genetic markers for insect resistance. The results can be summarized as follows:
1. Soybean responses to insect attack
1.1. Soybean – insect damage intensity
- Giza 111, Giza 22, L 127 and L 158 exhibited the minimum cotton leaf worm infestation (1 – 10%), while, Dr – 101 showed the maximum infestation (more than 30%).
- F2 plants gave wide variations of resistance for cotton leaf worm. F2 of hybrids; 4, 5, 7 and 10 (i.e., L 158 x Giza 111, Giza 22 x Giza 111, L 127 x Giza 111 and L 158 x Giza 22) showed minimum cotton leaf worm infestation (1 – 10%), while F2 of hybrids; 1 and 6 (i.e., L 127 x Dr – 101 and L 158 x Dr – 101) gave maximum cotton leaf worm infestation (more than 30%). Moreover, F2 of the other hybrids 2, 3, 8 and 9 (Dr 101 x Giza 111, Dr – 101 x Giza 22, L 158 x L 127 and L 127 x Giza 22) have moderate resistance for this insect (11 – 30%).
1.2.Different mechanisms to counter/offset the effects of insect attack
1.2.1. Direct defense
- Giza 111, L 158 and F2 of hybrids; 4, 5, and 10 have dense pubescence density, while Giza 22, L 127 and F2 of hybrids; 2, 3, 7, 8 and 9 have normal pubescence density. Moreover, Dr – 101 and F2 of hybrids; 1 and 6 showed sparse pubescence density.
1.2.2. Indirect defense
- The resistant genotypes; Giza 111, Giza 22, L 127 and L 158 and F2 of hybrids; 4, 5, 7 and 10 showed high concentration of JA. However, the reverse was true for the susceptible genotypes; Dr – 101, F2 of hybrids; 1 and 6.
2. Performance of soybean yield–related traits
- Giza 111 produced the tallest plants in 2009 season and F2 of hybrid 5 showed the tallest plant in 2010 season, while, Dr–101 was the shortest in 2009 and 2010 seasons.
- F2 plants of hybrids; 4 and 7 showed the highest values of branches number per plant in 2009 and 2010 seasons, while, Dr-101 showed significant less values of branches number per plant than Giza 111 and Giza 22 in 2009 and Giza 111 in 2010 seasons.
- F2 plants of hybrid 4 recorded the highest value for pods number per plant in 2009 and 2010 seasons, while the reverse was true for F2 plants of hybrid 6 as compared with the other soybean genotypes, Giza 111 and Giza 22 recorded high values for this trait when compared with the susceptible parent Dr–101 in 2009 season, while, Giza 111 exhibited only the same results in 2010 season for this trait.
- The number of seeds per plant trait showed nearest results for F2 plants of hybrid 4 in 2009 and 2010 seasons, while the opposite was recorded for F2 plants of hybrid 1 and the susceptible parent Dr–101 in 2009 and 2010 seasons.
- The highest seed yield per plant was found in F2 plants of hybrid 4 in 2009 and 2010 seasons, while, the susceptible parent Dr–101 gave the lowest seed yield per plant in 2009 and 2010 seasons in comparison with the other soybean genotypes.
- Giza 111 had the highest values of 100 seeds weight in 2009 and 2010 seasons, while the reverse was true for the susceptible parent Dr–101 in 2009 and 2010 seasons when compared with the other soybean genotypes. 3. Insect performance responses to soybean genotypes
- Giza 111, Giza 22, L 127, F2 plants of hybrids; 4, 5, 7 and 10 had the lowest percentages of survival, weight of larvae and pupa number after feeding on soybean leaflets, while, the highest percentages were recorded for F2 plants of hybrids; 1 and 6.
4. Molecular genetic studies
4.1. SDS–protein markers
- The results of SDS–protein PAGE revealed the presence of 17 bands with molecular weight ranging from 242.22 to 14.41 KDa.
- Bands 13 and 14 with MW of 55 and 40 KDa, respectively, were present in the resistant parents Giza 111, Giza 22, L 158 and L 127, while were absent in the susceptible parent Dr – 101 The two bands exhibited the same trend for the F2 plants of hybrids included the susceptible parent; Dr–101.
- The SDS–protein results showed a clear cut molecular markers for monitoring soybean resistance against the cotton leaf worm ’Spodopetra littoralis (Boisd.)’
4.2.Inter simple sequence repeats (ISSRs-PCR)
- Fifteen ISSRs primers were used with the 15 soybean genotypes (parents and F2 plants) to get molecular markers for resistant genotypes to cotton leaf worm infestation.
- Primer HB08 pattern resulted in six fragments at molecular sizes (MS) ranged from 280 to 800 bp with three polymorphic fragments (50.0%) with no detected marker.
- Primer HB09 pattern showed nine fragments with MS ranged from 200 to 910 bp, eight polymorphic fragments (88.8%) appeared with no detected marker.
- Primer HB10 pattern detected eight fragments with MS ranged from 250 to 810 bp, five polymorphic fragments (62.5%) were present with no detected marker.
- Primer HB11 pattern resulted in 11 fragments with MS from 130 to 990 bp with 81.8% polymorphism (9 fragments). Two fragments at MS of 990 and 130 bp, were present in the resistant genotypes; parents, F1 and the resistant F2 genotypes, they could be considered as positive markers for cotton leaf worm resistance.
- Primer HB12 pattern resulted in five fragments with MS ranged from 490 to 1060 bp with four polymorphic fragments (80.0%). Fragment 5 at MS of 490 bp was present in resistant genotypes, it could be considered as a positive marker for cotton leaf worm resistance. Primer HB13 pattern showed eight fragments with MS ranged from 250 to 960 bp. Six polymorphic fragments (75.0%) appeared with no ISSRs markers.
- Primer HB14 pattern exhibited 12 fragments with MS ranged from 270 to 870 bp and seven polymorphic fragments (58.3%). Fragment 8 at MS of 380 bp was present in the resistant genotypes, and could be considered as a positive marker for cotton leaf worm resistance.
- Primer HB15 pattern resulted in 10 fragments with MS ranged from 170 to 920 bp and nine polymorphic fragments (90.0%). Fragment 8 at MS of 770 bp was present in the resistant parents, F1 and most of resistant F2 genotypes, and could be considered a positive marker for cotton leaf worm resistance.
- Primer 814 pattern resulted in seven fragments with MS ranged from 310 to 930 bp. Five polymorphic fragments (71.4%) with no markers were observed.
- Primer 844A pattern showed 11 fragments with MS ranged from 250 to 930 bp. Six polymorphic fragments (54.5%) with no markers were detected.
- Primer 844B pattern resulted in nine fragments with MS ranged from 110 to 820 bp. Three polymorphic fragments (33.3%) with no markers were observed.
- Primer 17898A pattern resulted in 12 fragments with MS ranged from 170 to 910 bp. Nine polymorphic fragments (75.0%) with no markers were observed.
- Primer 17898B pattern resulted in seven fragments with MS ranged from 150 to 570 bp. Two polymorphic fragments (28.5%) with no markers were detected.
- Primer 17899A pattern resulted in 10 fragments with MS ranged from 350 to 950 bp. Six polymorphic fragments (60.0%) with no markers were present.Primer 17899B pattern showed 10 fragments with MS ranged from 310 to 1070 bp. Nine polymorphic fragments (90.0%) appeared with no markers.
- The specific molecular markers for the 15 soybean genotypes generated based on ISSRs–PCR analysis are five ISSR–PCR markers out of the 135 bands (about 3.7%) were found to be useful as specific positive markers for resistant genotypes.
As a general conclusion, Soybean experiments can detect the resistant genotypes for cotton leaf worm through breeding programs, some mechanisms to counter/offset the effects of insect attack and molecular markers–assisted selection (protein and ISSRs).