Chapter 5 Genetic Analysis of Apomixis - cimmyt

More documents

Recommendations

Info

182 Ue5Gro........Meiosis is an almost universal feature ofeukaryotic organisms, suggesting that the keyreguIatory events are conserved a t themolecular level. A search for homologs of themeiotic genes in yeast could proveparticularly useful for the engineering ofapomixis. Indeed, a putative RIMl1 homologfrom rice has recently been isolated bypolymerase chain reaction (peR) Geffersonand Nugroho 1998). The deduced amino acidsequence is 68% similar and 50% identical toyeast RIMl1, with conserved protein kinasesubdomains. Experiments to investigateexpression and function of RIMll in rice areongoing and will reveal whether this geneplays the same regulatory function in plantsand yeast (S. Nugroho and R. Jefferson,personal comm.). However, there are a verylarge number of kinases that are similar toRIMll in the Arabidopsis genome, indicatingthat the identification of the ortholog willrequire a detailed analysis and functionaltests. Similarly, several groups aimed at theisolation of Mei2 homologs (Hirayama et al.1997; 1. Siddiqi, personal comm.; B. Tinland,personal comm.), but the presence of eighthomologous genes in the Arabidopsis genomecomplicates the identification of the functionalhomolog. Despite the conservation of somemeiotic genes between yeast and plants at thesequence level, it should be remE:mbered thatthe molecular aspects of the control of meiosisare not conserved between S. cerevisiae and S.pombe and that the regulatory mechanisms inplants could be completely different.In maize, mutants that influence the"decision" between meiosis and mitosis havealso been identified, but their molecularnature is unknown. In plants homozygous forthe ameiotic 1 (aml) gene, meiosis does notoccur and is replaced by a mitotic division(Palmer 1971). The aml gene appears tocontrol the switch from the mitotic to themeiotic cell cycle and is important for theinitiation of meiotic prophase I (Golubovskayaet aI.1992). In plants homozygous for certainaml alleles, the megasporocyte does not divideat all, whereas in others meiosis is replaced byone or several mitotic division cycles(Golubovskaya et al. 1993, 1997). In absence offirst division (afd) mutants, the first meioticdivision IS replaced by a mitosis(Golubovskaya 1979). This reversion to mitosisof a cell already committed to meiosis showssimilarity to apomixis characterized by arestitution nucleus at meiosis I (TaraxacumandIxeris-type).Several mutants in plants and yeast producetwo unreduced spores reminiscent ofdiplospory. The yeast mutant spo12 (Klapholzand Esposito 1980), the elongatel (ell) mutantof maize (Rhoades 1956; Rhoades andDempsey 1966) and triploid inducer (tri) inbarley (Ahokas 1977; Finch and Bennett 1979)affect the second meiotic division. Thus, theyproduce genetically diverse progeny. Whereasell affects both sexes, tri is specific to the femaleand regular reduced pollen is producedleading to the formation of triploid embryosupon self-fertilization. In Arabidopsis, the dyadmutant produces a dyad of megaspores ratherthan a tetrad (Siddiqi et al. 2000). Based onmicroscopical analysis of chromosomesegregation and the expression of meiosisspecificmarkers, the first meiotic divisionseems to occur normally in dyad mutants butthen m~;osisarrests (Sidd iqi et al. 2000). To myknowledge, dyad is the first Arabidopsis mutantaffecting sporogenesis in a sex-specific manner.Unlike in ell and tri where unreduced viablemegagametophytes are produced, dyadmutants are fully female sterile. Although themegaspores of the dyad sometimes undergoadditional divisions, no functional embryo sacsare formed (Siddiqi et al. 2000). Based on itsgenetic mapping position, dyad may beidentical to the female-specific switchl (swil)gene whose megaspore mother cell undergoes
F_ s....trty I. Apo"'1s: Maleaolor.d Geoelk Ap,..__, 183mitotic divisions similar to the phenotypedescribed for aml in maize (Motamayor et al.2000). The difference in phenotype may be dueto allelic variation as was observed for aml, inwhich different alleles have quite distinctphenotypes, or to genetic background effects.In the yeast mutant spo13, meiosis I is omittedand a dyad of unreduced spores is formed byan equatorial division (I
Page 2 and 3:
(over illustration:Pictured is an i
Page 4 and 5:
Institut de Recherche pour Ie Devel
Page 6 and 7:
iv33 Outlook33 References35 Appendi
Page 8 and 9:
vi131 Screening Procedures: Advanta
Page 10 and 11:
VIIITables4 Table 1.15 Table 1.29 T
Page 12 and 13:
xAcknowledgmentsWe are grateful to
Page 14 and 15:
xiifood crops such as maize, wheat,
Page 16 and 17:
2 Gary H. T....i.....much food as i
Page 18 and 19:
4 Gary H. Toe"'...breeding: the evo
Page 20 and 21:
6 Gary H. T....it....The potential
Page 22 and 23:
Chapter 2Apomixis and the Managemen
Page 24 and 25:
10M.. Be,th.dcategories n + nand 2n
Page 26 and 27:
12 J.&eo BertIoaodtwo tetraploid sp
Page 28 and 29:
14 JoG.. B.rth""dTable 2.8 Distribu
Page 30 and 31:
16 M......thodhexaploidy through 2n
Page 32 and 33:
18 JI&.. lertIoaodheterozygous cond
Page 34 and 35:
20 JM Iertltaodmarkers to retain th
Page 36 and 37:
22 JoA•• BerthudFurthermore, if
Page 38 and 39:
Chapter 3Classification of Apomicti
Page 40 and 41:
26 (llarIesf.(r••3) The Ixeris-
Page 42 and 43:
simultaneous division of the proxim
Page 44 and 45:
30 (\aries f. Crao.differentiating
Page 46 and 47:
32 CWIts F. C,..haploids from norma
Page 48 and 49:
34 cales F. (,...Campbell, C. S., C
Page 50 and 51:
36 GaOO F. er...media. There may al
Page 52 and 53:
38 (IIarIe,F.e-.The following recip
Page 54 and 55:
40 CWIes F.
Page 56 and 57:
42 C"Ie
Page 58 and 59:
Chapter 4Ultrastructural Analysis o
Page 60 and 61:
46 T.""". N. Naomo•• ..dJ...·P
Page 62 and 63:
(Figure 4.2a,b,c). Their cytoplasm
Page 64 and 65:
50 Tomaro N. Naurnovo ond Jeon-Phil
Page 66 and 67:
Figure 4.2 (cont'd)
Page 68 and 69:
54 Tamara N. Nauma.a and J...-Phaip
Page 70 and 71:
56 Tamara H. Haumaya ...d J...-Phmp
Page 72 and 73:
58 Tamara N. N....... Old JOGO-PUIp
Page 74 and 75:
60 T.mar. N. N••may•••dJ
Page 76 and 77:
62 Tamara N. Nouma.o and Jeon-Phmpp
Page 78 and 79:
Chapter 5Genetic Analysis of Apomix
Page 80 and 81:
66 Robe" T. SherwoodIn mitotic dipl
Page 82 and 83:
68 ••It T. Sllorwoodmegasporoge
Page 84 and 85:
70 Robert T. SherwoodIdentification
Page 86 and 87:
72 R....11 T. SlMrwoodwe postulate
Page 88 and 89:
74 Rob.rt T. Sherwoodin the gametop
Page 90 and 91:
76 Rokrt T. SHtwoodPerhaps the most
Page 92 and 93:
78 Robe" T. S~erwoodEnvironment pla
Page 94 and 95:
80 Robert T. SherwoodBanaglio, E. 1
Page 96 and 97:
82 Robe" 1. Sherwood---. 1989. Apom
Page 98 and 99:
84 Dcaitl ~11i-, lot To...., .od Di
Page 100 and 101:
86 Do.lel Griome/I-, Joe To~ ....,
Page 102 and 103:
88 Oaoitl G
Page 104 and 105:
90 o.lel ~II-, Jo. lob.., aod Diego
Page 106 and 107:
and meiotic or developmental mutant
Page 108 and 109:
94 D..iel Grimallelli-, Jo. Tohme,
Page 110 and 111:
96 10k. G.(o,.,..mechanisms (Figure
Page 112 and 113:
98 Jolo.G.(_explain the existence o
Page 114 and 115:
100 JolI.G.C....parameters affectin
Page 116 and 117:
102 1010. G.(arma.was developed in
Page 118 and 119:
104 J... G.(.....effects), which co
Page 120 and 121:
106 J.hG.eforseveral thousand to a
Page 122 and 123:
108 Jelo.G.(_large linkage group in
Page 124 and 125:
11 0 Joh. G.(orma.---. 1997. Asynch
Page 126 and 127:
112 a... A. 8icUeI1993). Before the
Page 128 and 129:
114 ROil A. 8idlooll(Sherwood et al
Page 130 and 131:
116 R... A. IkbeIlinduced mutation
Page 132 and 133:
118 Ron A. Mlltllstudies of apomixi
Page 134 and 135:
120 I... A. BkbollLeblanc, 0., M.D.
Page 136 and 137:
122 Olivier L.bla.,.ncI A.d,ea M.nu
Page 138 and 139:
124 Olivier lt~1ao< aod Aock.. Mau"
Page 140 and 141:
126 OIlrier Ltblaooc ood AocI...Mo,
Page 142 and 143:
128 or..Ie, leblal( allll Aodrea Ma
Page 144 and 145:
130 Ofjyier LH......AodrH Mom","Mar
Page 146 and 147: 132 Olivier leblaoc and Aldr.. Mall
Page 148 and 149: 134 OIivie' I
Page 150 and 151: 136 or..io. u.~100< awd Aod.... M.n
Page 152 and 153: 138 udda lorge. do Val. aod Joh W.
Page 154 and 155: 140 Ca
Page 156 and 157: 142 C«ida Jorge. do Va" aod Jah W.
Page 158 and 159: 144 (..iIda 80rges cit Va" DOd Ja~.
Page 160 and 161: 146 Cacido ....... Vole..J.b W. MIe
Page 162 and 163: 148 Ca
Page 164 and 165: 150 (adlda Borge. da VaNe and Joh.
Page 166 and 167: 152 Ccdda Borge. do v..... J.h W. M
Page 168 and 169: 154 Yve< 5
Page 170 and 171: 156 rn. s.mdaosearch for an opitimu
Page 172 and 173: 158 Yv•• Savid..unreduced polar
Page 174 and 175: 160 Yves SoviclaoBashawet al. (1970
Page 176 and 177: 162 hOI Scrvidao211 = 56 chromosome
Page 178 and 179: 164 r.., SaYid..Transfer of Gene(s)
Page 180 and 181: 166 rves Sqyldaounanswered. However
Page 182 and 183: Chapter 12From Sexuality to Apomixi
Page 184 and 185: 170 lie. Gros..iklalSgametes and em
Page 186 and 187: 172 Uti Gro....1aosGunning 1990). T
Page 188 and 189: 174 UeIGr.........embryogenesis, wh
Page 190 and 191: 176 U.IGm..lln.apomictic pathway wi
Page 192 and 193: 178 IJeIGr.........development with
Page 194 and 195: 180 Ud Gr....lIoo,(Rhoades and Demp
Page 198 and 199: 184 Uel Gn...lIDo,To date, the phen
Page 200 and 201: 186 Uei Gr....lIa..do not display p
Page 202 and 203: 188 UtI GrOSllilaot.development of
Page 204 and 205: 190 Ud e;,....1Ia..Arabidopsis, unp
Page 206 and 207: 192 Ueli Gro".llae,system to identi
Page 208 and 209: 194 UeI Gm..ikIonsystem developed b
Page 210 and 211: 196 Ud Gro...ild...concentrate our
Page 212 and 213: 198 lleIG
Page 214 and 215: 200 UtlG09".ila,ndescribed that are
Page 216 and 217: 202 UeIGfo...ll...Two additional po
Page 218 and 219: 204 Uel G.....ilcmDiboll, A.G., and
Page 220 and 221: 206 UeRG'....ild...--.1974. Reprodu
Page 222 and 223: 208 Uel GtO,,"ikIa..MIodzik, M., Y.
Page 224 and 225: 21 0 Ud Gromild.1S--.1982. Nature e
Page 226 and 227: Chapter 13Induction of Apomixis inS
Page 228 and 229: 214 Uta Praebll aod Rod ScottCrosse
Page 230 and 231: 216 Uta Praektlt.. Rod Scana minori
Page 232 and 233: 21 8 Uta P...ke~ .d Rod S
Page 234 and 235: 220 Ura P"",k.h .d Rod ScottStubby
Page 236 and 237: 222 Uta Praekelt Old Rod S,ollelong
Page 238 and 239: 224 Uta P...kek .d Rad Scaliresulti
Page 240 and 241: 226 Uta P,..kelt ..dRod S
Page 242 and 243: 228 Uta P..utt aod Rod 5
Page 244 and 245: 230 1\omas Dresselhaus, Joh. G. (IJ
Page 246 and 247:
progression or inhibition of develo
Page 248 and 249:
234 T1lo.... Dr......... Jo~. G. (.
Page 250 and 251:
236 TIoo.... D........., J.~. G. (a
Page 252 and 253:
238 T1tonoas Dr......... Joino G. '
Page 254 and 255:
240 no- P,ossdlaos, Jo. G.'-.... Y.
Page 256 and 257:
242 1110""" 0,........, M. G. c,.._
show all

Chapter 5 Genetic Analysis of Apomixis - cimmyt

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?