LLAVALLOL, ARGENTINA
Instituto Fitotéc. Santa Catalina (FCAF, UNLP), Centro Invest. Genét. (UNLP-CONICET-CIC)

B chromosomes in native races of maize from Argentina. I. Populational frequency and altitude
--Chiavarino, AM; Rosato, M; Cámara Hernández, J; Naranjo, CA; Poggio, L

In twenty one native populations, corresponding to 13 races of maize cultivated at different altitudes (80-3620 m), the frequency of B-chromosome (Bs) was studied (Table 1). The sampling was made by the authors, from original indigenous populations, and was carried out in order to study the present correlations. The names and provenances of the races are the following:

ALTIPLANO -- Collection material: Salta Province, Santa Victoria Department, from El Puesto, at about 3000m above sea level, VAV-6167; Jujuy Province, Susques Department, from Susques, at about 3620m above sea level, VAV-6473; from Mal Paso of Susques, at about 3520 m above sea level, VAV-6474.
AMARILLO CHICO -- Collection material: Salta Province, Santa Victoria Department, , from El Condado, at about 2000m above sea level VAV-6451; Jujuy Province, Capital Department, from Termas de Reyes, at about 1690 m above sea level, VAV-6476; Jujuy Province, Tumbaya Department, from Tumbaya, VAV-6484.
AMARILLO GRANDE -- Collection material: Jujuy Province, Tumbaya Department, from La Ciénaga of Purmamarca, at about 2420 m above sea level, VAV-6480.
BLANCO POPULATION -- Grain collection: Jujuy Province, Tumbaya Department, from Purmamarca at about 2180 m above sea level, VAV-6479 and Tilcara Department, from Colonia San José, at about 2670m above sea level, VAV-6485.
CAPIA BLANCO -- Collection material: Salta Province, Santa Victoria Department, from Acoyte, at about 2600m above sea level, VAV-6418.
CAPIA ROSADO -- Collection material: Salta Province, San Victoria Department, from Rodeo Pampa, at about 2900m above sea level, VAV-6162.
CHIRIGUANO -- Collection material: Salta Province, Santa Victoria Department, from El Condado, at about 2000m above sea level, VAV-6218. Observations: Race Chiriguano is only distributed within Santa Victoria Department, province of Salta. It does not have the ample distribution of other races of the highlands in the provinces of Jujuy and Salta.
COLORADO -- Collection material: Formosa Province, Pilcomayo Department, from Frontera and Pilagás Department, from Misión Tacaaglé, both at less than 100m above sea level, VAV-6169 and 6223, respectively,.
HARINOSO -- Collection material: Salta Province, Iruya Department, from Iruya, at about 3400 m above sea level, VAV-6475.
PICHINGA -- Collection material: Formosa Province, Pirané Department, from Villa Dos Trece, at less than 100 m above sea level, VAV-6170.
PISINGALLO -- Collection material: Salta Province, Santa Victoria Department, from Acoyte, about 2600m above sea level and Catamarca Province, Ambato Department, from Piedras Blancas, Los Tordillos, at about 1600m above sea level, VAV-6416 and 6313, respectively.
OCHO RAYAS -- Collection material: Salta Province, Metán Department, from Metán Viejo, at about 750 m above sea level, VAV-6481; Tucuman Province, Trancas Department, Las Arcas, about 1250 m above sea level, VAV-6483.
ORGULLO CUARENTON -- Collection material: Salta Province, Candelaria Department, from La Candelaria, at about 910 m above sea level, VAV-6482.

The Bs were mitotically stable and present in at least one population of each race studied. A numerical polymorphism for Bs was found in 19 populations while it was absent in the remaining two (VAV 6473 and 6474) (Table 1). The number of Bs per plant ranged from 1 to 8, with 1, 2 and 3 being the more frequent. The variation in the percentage of plants with Bs among populations was very wide (0-94%) (1120 plants studied) (Table 1). A highly significant positive correlation between the adjusted mean number of Bs per plant per population and altitude of cultivation was demonstrated (r=0.6024, p=0.0063), when all populations with numerical polymorphism for Bs were considered (Fig. 1). Populations cultivated between 1600-3240m have, in general, the higher frequency of plants with Bs (19.6-94.2%) while those cultivated at altitudes lower than 1600m have the lower frequencies (2-26%) (Table 1). The populations without Bs (VAV 6474 and 6473), which grow at 3520 m and 3620 m, respectively, are placed in a marginal area in the Andean region of Jujuy Province under very extreme environmental conditions for this crop. When these populations were included in the statistical analysis the correlation was not significant (r = 0.3498, p = 0.1201).

The frequencies recorded in the present study would be the highest ones if compared with the previous few populational studies carried out on individuals with B frequencies in native races of maize.

Figure 1. Correlation between mean number of Bs (adjusted) and altitude.

Table 1. B chromosome frequencies and collection data.
 
Race Population (*) Altitude (m) Number of plants with different doses of Bs (0-8Bs) Plants with Bs Number of Bs
0 1 2 3 4 5 6 7 8 total
Blanco VAV 6479 2180 3 13 9 14 6 5 1 1 52 94.2 2.615
Blanco VAV 6485 2670 10 10 11 9 2 1 1 44 77.3 1.795
Amarillo grande VAV 6480 2420 15 12 13 7 2 2 1 52 71.2 1.596
Altiplano VAV 6167 3000 15 4 9 2 4 34 55.9 1.294
Harinoso VAV 6475 3240 20 15 8 4 3 50 60.0 1.100
Capia blanco VAV 6418 2600 24 8 11 1 4 48 50.0 1.020
Amarillo chico VAV 6451 2000 45 44 9 11 1 110 59.1 0.900
Pisingallo VAV 6416 2600 20 13 3 2 2 1 41 51.2 0.854
Pisingallo VAV 6313 1600 100 59 10 13 2 184 45.6 0.685
Capia rosado VAV 6162 2900 19 14 3 1 37 49.6 0.649
Colorado VAV 6169 80 25 7 2 34 26.5 0.323
Chiriguano VAV 6218 2000 22 6 1 29 24.1 0.276
Amarillo chico VAV 6476 1690 41 7 3 51 19.6 0.255
Blanco y ocho rayas VAV 6481 750 48 1 5 1 55 12.7 0.255
Amarillo chico VAV 6484 2010 45 2 2 49 8.2 0.204
Orgullo cuarentón VAV 6482 910 44 4 1 49 10.2 0.122
Blanco y ocho rayas VAV 6483 1250 34 2 36 5.5 0.111
Colorado VAV 6223 80 37 2 39 5.1 0.051
Pichingá VAV 6170 80 42 1 43 2.3 0.023
Altiplano VAV 6474 3520 40 40 0.0 0.000
Altiplano VAV 6473 3620 43 43 0.0 0.000
Total 692 222 102 66 26 9 2 2 1 1120 38.2
(*)-The materials have been deposited in the seedbanks of Vavilov Laboratory (VAV, Fac. Agr., UBA) and of IFSC (UNLP).
 


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