Chromosome number, meiotic behavior and pollen fertility of six species of Chrysolaena (Vernonieae, Asteraceae)

Figures & data

Table 1. Examined specimens and somatic chromosome numbers (2n) observed in six species of Chrysolaena.

Species	2n	Location and voucher specimens
C. cognata (Less) Dematt.	2n = 6x = 60	Argentina. Chaco. Dept. 1° de Mayo. Colonia Benitez. High fields near the village entrance. M. Dematteis 3029 (CTES).
C. flexuosa (Sims) H. Rob.	2n = 2x = 20	Argentina. Misiones. Dept. Capital. Low fields near the Zaimán stream. M. Dematteis, R. Salas and A. Vega 3035 (CTES).
C. lithospermifolia (Hieron.) H. Rob.	2n = 4x = 40^+	Argentina. Corrientes. Dept. San Roque. Joint routes 123 and 12, sandy soil, high. M. Dematteis and M. Seo 2469 (CTES).
C. obovata (Less) Dematt.	2n = 4x = 40^∗	Bolivia. Dept. Santa Cruz. Prov. Ñuflo de Chávez. 3 km NW of San Javier, way to the tannery. M. Dematteis, J. P. Coulleri, E. Meza Torres and A. Vega 3475 (CTES).
C. platensis (Spreng.) H. Rob.	2n = 2x = 20	Argentina. Misiones. Dept. General Manuel Belgrano. 2.2 km S of Dos Hermanas. Low fields. M. Dematteis, R. Salas and A. Vega 3083 (CTES).
C. propinqua (Hieron.) H. Rob. var. propinqua	2n = 2x = 20	Argentina. Misiones. Dept. Capital. Low fields near the Zaimán stream. M. Dematteis, R. Salas and A. Vega 3038 (CTES).
^∗First chromosome count for the taxon^+New cytotype for the taxon.

Figure 1 Meiotic behavior in Chrysolaena. (A–D) C. flexuosa: (A) diakinesis, 10II; (B) diakinesis, 9II + 2I (arrows); (C) off-plate chromosomes in metaphase I (arrows); (D) chromosome bridge with fragment in anaphase I. (E–G) C. platensis: (E) diakinesis, 9II + 2I (arrows); (F) diakinesis, 10II; (G) anaphase I with one bridge and fragment. (H–I) C. propinqua: (H) diakinesis, 10II; (I) bridge and fragment in anaphase I. (J–M) C. obovata: (J) diakinesis, 20II; (K) diakinesis, 18II + 1VI (arrows); (L) bridges and lagging chromosomes in anaphase I; (M) off-plate chromosome in metaphase II. (N–P) C. cognata: (N) diakinesis, 26II + 1VI + 2I (arrows); (O) bridges in anaphase I; (P) lagging chromosome in anaphase I. (Q–R) C. lithospermifolia: (Q) diakinesis, 5IV + 1III + 2II + 13I (arrows indicate tetravalent); (R) bridges and lagging chromosomes in anaphase II. Scale = 5 μm.

Table 2. Number of pollen mother cells analyzed (N°) and percentage of meiotic irregularities found in six species of Chrysolaena.

Phase	C. platensis		C. flexuosa		C. propinqua		C. obovata		C. cognata		C. lithospermifolia
	No.	%	No.	%	No.	%	No.	%	No.	%	No.	%
Metaphase I
Regular	107	82.31	177	94.65	150	92.02	84	71.79	78	91.76	219	89.75
Precocious migration	1	0.77	1	0.53	2	1.23	2	1.71	3	3.53	2	0.82
Off-plate chromosomes	22	16.92	9	4.82	11	6.75	31	26.5	4	4.71	23	9.43
Total	130	100	187	100	163	100	117	100	85	100	244	100
Anaphase/telophase II
Regular	69	93.25	79	77.45	98	76.56	75	72.12	67	87.01	164	96.48
Lagging	2	2.7	4	3.92	9	7.03	6	5.77	4	5.19	3	1.76
Bridges with fragment	1	1.35	4	3.92	2	1.56	4	3.84	2	2.6
Bridges without fragment	2	2.7	15	14.71	19	14.85	19	18.27	4	5.2	3	1.76
Total	74	100	102	100	128	100	104	100	77	100	170	100
Metaphase II
Regular							35	75.55			42	91.3
Precocious migration
Off-plate chromosomes							9	20.45			4	8.8
Total							44	100			46	100
Anaphase/telophase I
Regular			15	83.34					13	86.67	85	74.56
Lagging											24	21.05
Bridges with fragment											2	1.76
Bridges without fragment			3	16.66					2	13.33	3	2.63
Total			18	100					15	100	114	100

Table 3. Meiotic configurations and pollen fertility (%) in six analyzed species of Chrysolaena.

Species	Configuration	No. cells	%	Pollen grains	Pollen fertility
C. cognata	30 II	4	66.66	382	89.27
	26 II + 1 VI + 2 I	1	16.67
	25 II + 2 IV + 2 I	1	16.67
C. flexuosa	10 II	17	94.44		92.10
	9 II + 2 I	1	5.56	342
C. lithospermifolia	20II	2	66.66	589	90.66
	5IV + 1III + 2II + 13I	1	33.34
C. obovata	20 II	10	43.48	475	97.46
	18 II + 1 IV	6	30.44
	16 II + 2 IV	7	26.08
C. platensis	10 II	14	87.5	357	98.04
	9 II + 2 I	2	12.5
C. propinqua	10 II	13	100	526	95.06