role of ampidiploid.pptx
- 2. Role of Amphidiploids Allopolyploidy An allopolyploid resulting due to doubling of chromosome number in sterile hybrid derived from hybridization between two unrelated diploid species is sometimes also called ‘amphidiploid’. Production of triticale from a cross of hexaploid wheat (AABBDD; 2n=42) and diploid rye (RR; 2n=14). The hybrid would have 28 chromosomes which gave rise to octoploid (2n=56=28II) triticale.
- 3. Another amphiploid was derived, as early as 1892, from a sterile hybrid produced from a cross between Anemone sylvestris (2n=16) and A. Multifida (2n=32). This amphiploid had 2n=48 and formed 24 bivalents at meiosis.
- 4. Synthesis of New Genera and Species Allopolyploids originate in nature through interspecific or intergeneric hybridization followed by chromosome doubling. This process has been considered to be a device to generate new species. Since this procedure can be repeated in the laboratory, it has been used for the synthesis of new genera and species.
- 5. Although, a large number of amphiploids (particularly in Triticeae) have been artificially produces, the most important example in this connection is triticale (X tritico secale), which is now used as a commercial crop in several countries, occupying an area of several million hactares.
- 6. Raphano brassica and X brassico raphanus The well known amphidiploid Raphano brassica (2n=36=18II=PRCC) was obtained by Karpechenko (1928), due to spontaneous chromosome doubling of Hybrids between Raphanus sativus (2n=18=9II=RR) and Brassica oleracea (2n=18=9II=CC). Subsequently, it was obtained artificially by several workers and the common name ‘radicale’ was suggested (like ‘triticale’ for X Triticosecale).
- 7. Aritificial synthesis of Raphanobrassica
- 8. For many years, Raphano brassica was only a curiosity and model example of a true allopolyploid or an amphidiploid, but without any practical utility. The improved strains were more vigorous and fertile and also had resistance to club root and powdery mildew, the two important diseases.
- 9. In recent years a number of strains of rapradish (Xbrassicoraphanus, 2n=38=AARR) from the cross B. rapa (syn. B. campestris) X R. sativus have also been synthesized. The initial population of this amphiploid was subjected to breeding, leading to improvement in fertility and nematode resistance.
- 10. Galeopsis tetrahit G.tertahit (2n=32), synthesized from the cross, G. pubescens (2n=16) X G.speciosa (2n=16), was perhaps the first example of an atificially synthesized amphidiploid as a new species. Primula kewensis P.Kewensis (2n=36) was obtained from a 4x branch of a 2x hybrid between P.florifunda (2n=18) and P. verticillata (2n=18). Subsequently. It could be obtained by crossing these two species and doubling the chromosome number in the sterile F1 hybrid.
- 11. Aegilotricum Aegilotricum (2n=56=AABBDDNN) is the name given to an amphiploid derived from the cross Aegilops ventricosa (2n=28=DDNN) X Triticum turgidum (2n=28=AABB), and has been used for the transfer of resistance against the disease ‘eyespot’ from Ae ventricosa to wheat. By repeated crossing of this amphiploid with wheat, new resistant cultivar of wheat, namely ‘Roazon’ was produced. However, Aegilotricum (2n=70=AABBDDDDNN), involving hexaploid wheat in the initial cross, could not be produced.
- 12. Agrotricum Agrotricum was obtained as an amphiploid from a cross Agropyron intermedium (2n=42=E1E1E2E2NN) X Triticum aestivum (2n=42=AABBDD).
- 13. Their vigor and fertility were however low. However, by backcrossing the F1 hybrid with 6x wheat, a partial amphiploid, namely TAF 46, was obtained which had 2n=56 AABBDDXX (where X is a new reconstructed genome having chromosomes from E1, E2 and N genomes.) This partial amphiploid was later used for getting alien addition lines for A. intermedium chromosomes to wheat, which were successfully utilized for transfer of resistance against the rusts to wheat.
- 16. The hexaploid triticales, which are initially produced as amphiploids are called primary triticales. These primary triticales have many drawbacks like shrivelled grains, meiotic instability, poor yield and preharvest sprouting. For further improvement, these primary triticales are regularly intercrossed among themselves with hexaploid triticales. General methods for improvement of these by backcrosses shown in fig.
- 17. It will be seen that the improved triticales can be either recombined triticales or secondary triticales, the latter resulting due to crosses with 6x wheat or 8x triticales. It is these secondary triticales which are being released as cultivars in different parts of the world. It will be seen that in India also in 1982 a cultivar TL 419 was released by Punjab Agricultural Univeristy (PAU), Ludhiana, on a regional basis. After the release of TL 419, even better strains giving yields higher than TL 419 could be produced.
- 18. A New Synthetic Amphiploid (AADDAA) between Gossypium hirsutum and G.arboreum Lays the Foundation for Transferring Resistances to Verticillium and Drought Cross-incompatibility of G. hirsutum (2n = 52, AADD) and G. arboreum (2n = 2x = 26, AA) MSB2K supplemented with 0.5 mgl-1 kinetin and 250 mg-1 casein hydrolysate is an efficient initial medium for rescuing early (3 d after pollination) hybrid embryos Four putative hybrid plants were successfully chromosome-doubled by treatment with 0.1% colchicine for 24 h and become amphiploid, which were confirmed by cytological observation, self-fertilization and backcrossing Resistance at seedling stage indicated that the synthetic amphiploid showed highly resistant to Verticillium and drought.
- 19. The interspecific hybrid plants were preserved and propagated by grafting. The stem apices of vegetative branches from these hybrid plants were immersed in 0.05, 0.10, 0.15 and 0.20% (w/v) colchicine solution for 24, 36 and 48 h and grown in ceramic pots under natural conditions.
- 22. Generation of the amphiploid Generation of the amphiploid obtained by doubling chromosome complements in interspecific F1 hybrids between G. hirsutum and G. arboreum The putative hybrid F1 plants, which were confirmed by cytology, molecular markers and morphological observation, were treated with different concentrations of colchicine for 24, 36 and 48 h. The results show that among 30 plants treated with 0.1% colchicine for 24 h, 22.22% (four out of 18 plants survived, while 12 died) of interspecific hybrid F1 plants exhibited gigantism and had improved fertility, and they set bolls and produced several seeds. To understand why these plants produced seeds, we collected young flower buds from these plants and observed their chromosome associations. The results indicate that the number of univalent significantly decreased while the numbers of bivalents and multivalents greatly increased even if there were too many chromosomes to discriminate, which suggests that these plants were chromosome-doubled and were therefore putative amphiploids, i.e.,hexaploids. Therefore, to further verify the genome components of the putative amphiploids, S1 plants derived from the putative amphiploids by self-pollination were used to identify chromosome numbers by GISH using somatic mitotic cells of the root tips. The results demonstrate that their genome components contained four sets of A genome (red signals) and one set of D subgenome (blue signals) and had a total of 78 chromosomes, i.e., 2n = 6x = AAAADD = 78, which further confirms the
- 23. Screening for drought tolerance
- 24. Screening for verticillium wilt
- 25. S1 progenies derived from the hexaploids self-pollinated were assessed for resistance to VW and drought. The preliminary results demonstrated that S1 has the potential for transferring resistance genes from G. arboreum into G. hirsutum by backcrossing. And these hexaploid plants were also backcrossed with G. hirsutum (TM-1) and have produced enough backcrossing seeds. These backcross progenies will be consecutively backcrossed with G. hirsutum for 4~5 times, which would allows them to develop G. arboreum-introgressed lines with the uniform genetic background of TM-1 by molecular marker-assisted selection. Finally the evaluated lines will be released with resistance to VV and drought tolerance.
- 26. Identifying desirable traits in natural populations Selection of desirable plants in the hotspot location Endemic area Artificial screening
- 27. Cotton useful traits S.No Name Breeding value 1. G.armourianum Resistance to white flies, jassids and bacterial leaf blight 2. G.aridum Resistance to reniform nematode and salinity tolerant 3. G.raimondii Resistance to jassids 4. G.gossypioides Resistance to cotton leaf curl disease 5. G.anomalum Resistance to cotton wilt, angular leaf spot,drought tolerance, high fibre quality. 6. G.sturtianum Resistance to Fusarium wilt 7. G.robinsonii Resistance to Fusarium wilt 8. G.tomentosum Resistance to jassids and thrips
- 28. Redgram Cajanus scarabaeoides: Resistant to wilt, sterility mosaic disease (SMD), phytophthra blight, pod borer, podfly, cyst nematode and possesses combined resistance to diseases and insects, water logging tolerance and high seed protein (>28%). Cajanus platycarpus: Resistant to phytophthora and alternaria blight, salinity tolerance, photoperiod insensitivity, extra early flowering and high seed protein (27-31.6%) Cajanus albicans: Resistant to SMD, alternaria blight, drought and salinity tolerance, high seed protein (>30%). Cajanus sericeus: Resistant to SMD, phytophthora blight and alternaria blight, drought tolerance, high seed protein content (>29%)
- 29. Tomato 2 9 • Charles Rick (1915-2002) who dedicated his life to discover, collect and characterize exotic tomato germplasm • Today >83,000 tomato acc. are stored in seed banks worldwide, ranking 1st among vegetable species collected (FAO 2010) • Main collections in world: Tomato Genetic Resources Center in California (TGRC), USDA2 collection, World Vegetable Center in Taiwan Many tomato disease resistances introgressed from wild species, mostly from Lycopersicon pimpinellifolium Mill • Since 1982 one per year with virtually all disease resistance genes currently in commercial cultivars having been bred from wild genetic resources. • Over 40 resistance genes have been derived from Lycopersicon peruvianum, L. cheesmanii, L. pennellii, and several other wild relatives
- 30. • Bemisia tabaci is one of the most threatening pests in in Solanaceous crops such as tomato and pepper • Pesticide application is often not effective and hazardous • The exploitation of plant natural defenses that are present in wild relatives of tomato, may offer a solution. • Screened 46 accessions of tomato and related wild species 3 methods of screening; (1)a free-choice test in a screen-house (Indonesia), (2) a no-choice test with clip-on cages in a greenhouse and (3) a leaf disc test in a climate-room • Antibiosis resulting in low adult survival was the major component for resistance in tomato • Whitefly non-preference and resistance were associated with the presence of type IV trichomes 3 0
- 31. Important genes in wheat found in related species System-wide Genetic Resources Program (123 996)
- 32. The Genus Oryza : Broadening the Gene Pool of Rice— Exploitation of Diversity of the Wild Species Germplasm 24 Paul et al (2014) Genetics and Genomics of Rice
- 33. Genus oryza: 12 representative species IRRI Rice Gene Bank and The National Institute of Genetics’ Oryza base, combined, maintain >4,000 acc. of wild Oryza species and 1,500 cultivated O . glaberrima acc. 3 3
- 34. 3 4
- 35. 3 5
- 36. 3 6
- 37. Potato late blight resistance • Best resistance source for potato late blight are Solanum demissum and S. stoloniferum. • Currently 40% of the total area of the most popular potato cultivars in US have S. demissum in their ancestry (National Potato Council 2003), • Along with these wild relatives, S. chacoense, S. acaule, S. vernei and S. spegazzinii have provided resistance to several viruses and pests 3 7
- 38. 3 8
- 39. Wild Cicer species with resistance to various biotic and abiotic stresses 3 9
- 40. Yield improvement 4 0 • In backcross progeny derived from crosses of two indica rice varieties (IR64 and IR55423-01) with O . glaberrima: 1. Two new QTLs for grain yield per plant ( ypp2 . 1 and ypp4 . 2 ) 2. In IR55423-01 × O . glaberrima , 11 new QTLs for biomass identified • Alleles associated with the yield-related traits, such as spikelet number, grain weight, and panicle length, were identified in this O . rufipogon accession using a BIL population derived from a cross with Zhenshan 97B
- 41. 4 1 Contd… • Rice cultivar NSICRc112 released in the Philippines in 2002 from Oryza sativa and O. longistaminata (Brar 2005) • Synthetic hexaploid (SH) wheats; cross between durum wheat and the wild relative Aegilops tauschii that has undergone artificial chromosome doubling (hexaploid) • These lines are then back-crossed to elite bread wheat cultivars, to produce wheats with superior quality, disease resistance and yield. • In 2003, ‘Chuanmai 42’, cross between an SH and a local cultivar, released in China, producing 20–35% higher yields (CIMMYT 2004). • Pyramiding of three independent yield-promoting genomic regions introduced from Solanum pennellii, has led to hybrids with a 50% increased yield over a leading variety (Gur and Zamir 2004)
- 42. High yielding ILs (IL50-7) derived from BC3F2-F8 of cross KMR3 x O. rufipogon (major yield QTL yld2.1), control KMR3 Aim: Comparing global gene expression of flag leaf and young panicle of IL50-7 with those of recurrent parent KMR3. Such a comparison would lead to discovery of novel yield-related genes/alleles from wild rice 4 2
- 43. ; Four crosses, ILC 482 (C. arietinum) x ILWC 179 (C. echinospermum) ILC 482 x ILWC 124 (C. reticulatum) and their reciprocals F1 F2 Selected 22 F7 lines International Center for Agricultural Research in the Dry Areas (ICARDA), Syria, from 195 83 7-95
- 44. • In India Mulbery (Morus) is represented by four species i.e., M.indica L., M.alba L., M.laevigata and M.serrata • Central Silk Board developed improved mulberry varieties through conventional, polyploid and backcross breeding. • Though varieties have more leaf yield/ quality aspects but in long term this may not be suitable for specific condition. To bring greater diversity into the breeding pools, it requires introduction of unadapted and productive exotic or wild species • M. serrata: possess several agronomically important traits such as higher leaf thickness, greater leaf moisture content, moisture retention and resistance to abiotic and biotic stresses (drought and frost) • M. laevigata: bigger leaf size, higher leaf thickness, moisture retention, resistance to biotic and abiotic stress (drought, saline and frost) • They have scope for introgression breeding between wild and cultivated species 4 4
- 45. • IARI released ‘BG1103’ a drought and temperature tolerance chickpea variety derived from Cicer reticulatum, is a leading cultivar (40% more yield) in Northern India • Oryza rufipogon genes have been exploited for tolerance to high acidic-sulfate content soil in Vietnam • O. longistaminata genes for drought tolerance in cultivars of Philippines, allowing the spread of rice production to previously unusable lands Introgression for Tolerance to Abiotic Stresses 4 5
- 46. 4 6