SEX DETERMINATION

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SEX DETERMINATION
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• Many groups use sex chromosomes to determine sex.
  Mammals have the X and Y chromosomes
• XX female, XY male
• Sex of mammals is determined by the Y chromosome.
  In the absence of Y, gonads become ovaries.
• All other chromosomes are called autosomes
  Thus, humans have 46 chromosomes, 44 autosomes
  plus 2 sex chromosomes.

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X and Y Chromosomes

• The X has many genes on it, just like the
  autosomes. Most of the genes on the X have
  nothing to do with sex.
• The Y has very few genes on it. It consists of
  mostly inactive DNA.
• One gene on the Y is very important SRY. The
  SRY gene is the primary determinant of sex.
• If SRY is present, testes develop in the early
  embryo. The testes secrete the hormone
  testosterone, which causes development as a male.
• If SRY is absent (no Y chromosome), ovaries
  develop instead of testes, and the embryo
  develops into a female.
• The X and Y chromosomes share a common region at
  their tips, the pseudoautosomal region. Crossing
  over in meiosis occurs in this region.

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Sex Chromosomes in Other Organisms

• 1. Sex chromosome composition in birds,
  butterflies, moths and some fish is opposite that
  of mammals, with the male the homogametic sex
  (ZZ) and the female heterogametic (ZW). Z-linked
  genes behave like X-linked genes in mammals, but
  the sexes are reversed.
• 2. In plants, the arrangement of sex organs
  varies
• a. Dioecious species (e.g., ginkgo) have plants
  of separate sexes, one with male parts, the other
  with female.
• b. Monoecious species have male and female parts
  on the same plant.
• i. Perfect flowers have both types of parts in
  the same flower.
• ii. Imperfect flowers (e.g., corn) have male and
  female parts in different flowers on the same
  plant.
• 3. Some dioecious plants have sex chromosomes and
  use an X-chromosome-autosome balance system, but
  many other sex determination systems also occur
  in dioecious plants.

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KONTROL PENAMPILAN SEX
Tipe sex pada tumbuhan
Pada individu bunga
1. Staminat atau Androecious bunga hanya
mempunyai stamen atau benang sari saja, dan
disebut bunga jantan 2. Pistilat atau
Ginoecious bunga hanya mempunyai karpel atau
putik saja dan disebut bunga betina 3.
Hermaprodit atau Sempurna bunga mempunyai stamen
dan karpel 4. Neuter or Agamous bunga tanpa
stamen dan karpel atau organ sex abortive
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Pada individu tumbuhan

• Androecious pada satu tanaman hanya ada bunga
  jantan
• 2. Ginoecious pada satu tanaman hanya ada bunga
  betina
• 3. Monoecious pada satu tanaman terdapat bunga
  jantan dan bunga betina pada bunga yang berbeda
• 4. Hermaprodit pada satu tanaman hanya ada bunga
  hermaprodit
• 5. Andromonoecious Pada satu tanaman terdapat
  bunga jantan dan bunga hermaprodit
• 6. Ginomonoecious pada satu tanaman terdapat
  bunga betina dan bunga hermaprodit
• 7. Trimonoecious pada satu tanaman selain
  terdapat bunga jantan dan bunga betina juga
  terdapat bunga sempurna

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Pada populasi tumbuhan

• Monoecious suatu populasi tumbuhan yang terdiri
  dari hanya tumbuhan monoecious
• 2. Dioecious suatu populasi tumbuhan yang
  terdiri dari hanya tumbuhan androecious dan
  ginoecious
• 3. Hermaprodit Suatu populasi tumbuhan yang
  terdiri dari hanya tumbuhan hermaprodit

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Kromosom sex pada tumbuhan
Silene latifolia
- tumbuhan jantan memiliki kromosom sex
heteromorfik XY (22 kromosom, kromosom sex XY)
- tanaman betina terdapat 22 kromosom dan
kromosom sex XX.
Rumex sub genus acetosa

• rasio (banyaknya kromosom X/banyaknya set
  autosom) sama dengan 1.0 maka terjadi tumbuhan
  ginoecious.
• jika rasionya 0.5 atau lebih kecil maka terjadi
  tumbuhan androecious
• jika antara 0.5 dan 1.0 maka akan dijumpai
  tumbuhan andromonoecious, hermaprodit, atau
  ginomonoecious.

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Tanaman dioecious asparagus (Asparagus
officinalis). - Yang jantan memiliki kromosom
sex heteromorfik. - YY dijumpai hidup dan
fertil.
Cannabis sativa - tipe sex heterogametik XY
monoecious - homogametik XX menampilkan
ginoecious. Alel resesif pada kromosom X
mengurangi kemampuan menjadi betina -tanaman
XXm menampilkan tipe sex dari ginoecious sampai
ke monoecious -tanaman XmXm menjadi tanaman
jantan dengan morfologi bunga seperti bunga
betina
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Gen Mendelian Yang Mengontrol Tipe Seks
Penampilan seks pada ketimun
Genotipe Fenotipe
M_F_ M_ff mmF_ mmff Ginoesious Monoesious Hermaprodit Andromonoesious
Penampilan seks pada melon
Genotipe Fenotipe
A_G_ A_gg aaG_ aagg Monoesious Ginomonoesious Andromonoesious Hermaprodit
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Penentuan sex secara molekuler
Dengan menggunakan teknik PCR (Polymerase Chain
Reaction) dimana fragment DNA dapat diamplifikasi
secara in vitro, identifikasi sex pada tanaman
dapat dilakukan
PCR tanaman Salix viminalis
PCR Silene latifolia. (no 5-8 tanaman
jantan)
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The search for sex-specific markers in
Leucadendron Applications of ISSR and
suppression subtractive hybridisation
All species Leucadendron are dioecious
Karyotyping could not identify sex
chromosomes
RAPD
25 RAPD primers could not identify sex-specific
markers for 12 Leucadendron species
ISSR
37 primers and 8 combined primers failed to find
sex-specific fragment
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Plants with heteromorphic sex chromosomes
Silene latifolia, 64 RAPD primers identified 4
male-specific markers Canabis sativa, 15 RAPD
primers found 2 male-specific markers
SCAR marker
Silene latifolia
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No heteromorphic sex chromosomes
Ginko biloba, 1200 RAPD primers detected 1
male-linked band Pistacia vera, 1000 primers, 1
sex marker found P. atlantica, 472 primers, 1 sex
marker identified
Leucadendron?
45 ISSR primers could not identify sex-specific
fragments
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Male substracted library
Differential screening of male substraction
(B) Probed with ?
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Insert no Approxsize (bp)a Clear readable sequence Accession no Gene(s) Organism Sequence identity E-value
2 3 11 17 30 101 197 204 220 240 354 356 362 600 710 500 470 450 1000 620 510 680 510 620 620 650 220 725 272 463 252 321 617 321 680 503 639 639 662 AJ627251 AY586361 AJ428413 Z00044554304 AY582139 U63020 AJ428413 BAA22288 AJ428413 AJ970307 AJ428413 AJ428413 AJ428413 cpDNA 23S rRNA cpDNA NADH dehydrogenase subunit F cpDNA rpoC2 cpDNA rrn23 cpDNA psaB cpDNA D1 protein (psbA) cpDNA petB and petD polyprotein (mat_peptides) cpDNA ycf6-psbM intergenic spacer cpDNA16S rRNA and tRNA Ile cpDNA 23S rRNA and tRNA Ala cpDNA 23S rRNA and tRNA Ala cpDNA tRNA Ile and tRNA Ala Nymphaea alba Fagus grandifolia Calycanthus fertilis var. ferax Nicotiana tabacum Panax ginseng Magnolia pyramidata Calycanthus fertilis var. ferax Oryza australiensis Calycanthus fertilis var. ferax Cucumis sativus Calycanthus fertilis var. ferax Calycanthus fertilis var. ferax Calycanthus fertilis var. ferax 182/188 (96) 466/477 (97) 213/229 (93) 429/438 (97 228/239 (95) 284/309 (91) 543/593 (91) 88/106 (83) 104/121 (85) 62/70 (88) 55/66 (83) 466/477 (97) 600/609 (98) 601/612 (98) 336/347(96) 1e-88 0.0 4e-86 0.0 7e-103 1e-108 0.0 2e-37 2e-19 2e-10 0.0 0.0 0.0 5e-168
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• the male and female genome might be rather
  homologous
• the non-recombining region in Leucadendron is
  very small
• chloroplast copy number may differentiate male
  and female L. discolor

Leucadendron