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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