Production of viable male unreduced gametes in Brassica interspecific hybrids is genotype specific and stimulated by cold temperatures

Table 4 Unreduced and abnormal male gamete production in interspecific hybrids of three amphidiploid Brassica species estimated by sporad counts.

Parental species in hybrid	Hybrid combination	No. plants	Total sporads	Abnormal sporads^†	Abnormal male gametes (%)	Dyads	Giant sporads	2n male gametes (%)
B. j × B. c	J1C1	13	4579	79	1.97%	2	2	0.07%
B. j × B. c	J1C2	6	1812	10	0.74%	2	0	0.06%
B. j × B. n	J1N1	12	4346	292	6.17%	113	3	1.38%
B. j × B. n	J1N2	5	1710	202	9.33%	97	0	2.92%
B. j × B. n	J1N3	4	2255	209	5.94%	143	0	3.29%
B. j × B. n	J1N4	3	956	56	3.74%	36	0	1.93%
B. j × B. n	J1N5	7	2197	97	2.72%	73	0	1.69%
B. n × B. c	N1C1	6	2417	85	2.45%	52	10	1.51%
B. n × B. c	N1C2	6	1911	111	5.46%	40	0	1.05%
B. n × B. c	N2C2	6	2108	68	2.23%	46	0	1.10%
B. n × B. c	N3C1	1	301	1	0.17%	1	0	0.17%
B. n × B. c	N4C1	2	609	9	0.95%	6	0	0.50%
B. n × B. c	N4C2	6	2261	155	5.43%	68	0	1.53%
	Total	77	27462	1374	Av: 3.64%***	679	15	Av: 1.32%**

** Significant differences between genotypes (p < 0.01, one-way ANOVA)
***Significant differences between genotypes (p < 0.001, one-way ANOVA)
^† Both dyads and giant sporads were assumed to produce unreduced (2n) male gametes, and monads, dyads, triads, pentads, hexads and heptads and giant sporads were assumed to produce abnormal male gametes.
Hybrids were produced between five doubled-haploid derived genotypes of B. napus (B. n: N1, N2, N3, N4 and N5), two doubled-haploid derived genotypes of B. carinata (B. c: C1 and C2) and one near-homozygous inbred genotype of B. juncea (B. j: J1). Interspecific hybrid combinations are given as a combination of parent codes. Hybrid combinations with different maternal parent but the same parent genotypes were pooled after the model unreduced gametes ~ genotype + maternal parent revealed no significant effect of maternal parent on unreduced gamete production.

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