Determination of chromosome knob number in Mexican races of maize

Observations of chromosome knobs were made in 45 collections of Mexican maize representing 23 recognized races of Zea mays L. Pollen mother cells were collected and fixed from 5 randomly selected plants within each of the 45 populations.

Observations of the pachytene stage of meiosis were made on 10 cells from each plant. Data were recorded concerning number and size of knobs, characteristics of individual knobs and any anomalous knob behavior. A statistical analysis-was performed with the mean number, variance and standard error being calculated for plants and populations (see table). Knob number variability was quite low within plants and within the range of ± 1 knob among plants within populations. In most instances mean knob number determinations among populations within a race were very similar. However, appreciable variation in mean knob number was observed among the different races examined, ranging from 4.5 knobs in Chapalote to 13.92 knobs in Tehua. Knob size also varied greatly among populations, with size generally showing an inverse relationship to number. In a few races such as Zapalote Chico, an obvious mixture of both large and small knobs was observed.
 
MEXICAN RACES POPULATION MEAN KNOB NUMBER VARIATION STANDARD ERROR
ARROCILLO AMARILLO PUEBLA 91 7.86 .08 .13
BOLITA OAXACA 28 7.34 .88 .42
" " OAXACA 40 6.72 .14 .17
" " OAXACA 44 8.10 .22 .21
CELAYA GUANAJUATO 28 7.42 .79 .40
" " GUANAJUATO 29 8.94 .10 .14
CHALQUENO HILDAGO 7 7.64 .15 .17
" " MEXICO 48 7.72 .17 .19
" " ZACATECAS 4 7.36 .70 .37
CHAPALOTE SINALOA 2 10.76 .01 .05
COMITECO CHIAPAS 206 8.4 .20 .20
CONICO MEXICO 72 4.78 .65 .36
CONICO NORTENO AGUAS CALIENTES 8 7.56 .77 .39
" " AGUAS CALIENTES 14 6.28 .73 .38
" " AGUAS CALIENTES 15 5.8 .17 .19
" " GUANAJUATO 34 9.18 .35 .26
" " GUANAJUATO 49 9.16 .89 .42
" " GUANAJUATO 56 6.82 .79 .40
" " GUANAJUATO 68 6.12 .04 .09
" " QUERETARO 1 8.80 .37 .27
" " QUERETARO 3 9.38 .34 .26
ELOTES OCCIDENTALES NAYARIT 29 7.38 .11 .15
" " NAYARIT 38 7.02 .98 .44
HARINOSO DE OCHO NAYARIT 24 4.5 .16 .18
JALA NAYARIT 6 7.30 .14 .16
NAL-TEL YUCATON 7 6.26 .15 .17
OLOTON CHIAPAS 92 4.92 .23 .21
REVENTADOR NAYARIT 15 5.18 .43 .29
TABLONCILLO JALISCO 42 7.14 .18 .19
" " JALISCO 43 10.18 .13 .16
" " JALISCO 87 6.56 .43 .29
" " JALISCO 103 8.60 .09 .13
TABLONCILLO NAYARIT 12 6.82 .42 .29
TEHUA CHIAPAS 29 6.5 .40 .28
" " CHIAPAS 204 13.92 .76 .39
TEPECINTLE CHIAPAS 76 8.72 .20 .20
TUXPENO OAXACA 7 6.94 .57 .33
" " VERACRUZ 39 7.44 .19 .20
VANDENO GUERRERO 96 7.96 .11 .15
ZAPALOTE CHICO OAXACA 50 12.72 .50 .32
ZAPALOTE GRANDE CHIAPAS 224 7.4 .57 .34

A. L. Rayburn III, J. D. Smith, and H. J. Price

Please Note: Notes submitted to the Maize Genetics Cooperation Newsletter may be cited only with consent of the authors.

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