Indução de haploides em milho tropical superdoce e determinação de ploidia no estágio de plântulas

O objetivo deste trabalho foi verificar a possibilidade de indução de haploidia em milho superdoce tropical (Zea mays L. var. saccharata) por meio de indutor maternal, bem como identificar métodos alternativos para seleção de haploides. Um híbrido simples de milho comum e 11 populações de milho superdoce tropical foram cruzados com o indutor de haploidia. Os haploides foram pré-selecionados pelo marcador R1-navajo e diferenciados em haploides ou falsos positivos, no estágio V2-V3, com base na cor da primeira bainha foliar e no comprimento das células-guarda dos estômatos foliares. Os resultados obtidos são indicativos da possibilidade de induzir haploides maternos em populações de milho superdoce tropical. Contudo, muitos haploides falso-positivos foram selecionados incorretamente pelo marcador R1-navajo. A coloração da primeira bainha foliar foi eficiente na identificação de haploides em populações de milho superdoce, e o método baseado na morfometria dos estômatos pode ser usado quando não há distinção de cor da primeira bainha foliar.

Termos para indexação:
Zea mays L. var. saccharata; duplo haploide; taxa de indução de haploide; R1-navajo; estômatos

Autoria

Alline Sekiya

Universidade Estadual de Londrina, Departamento de Genética e Biologia Molecular, Rodovia Celso Garcia Cid, Pr 445, Km 380, Campus Universitário, CEP 86057-970 Londrina, PR, Brazil. E-mail: allinesekiya@gmail.com, jessicakpestana@gmail.com, maikon.baptistella@gmail.com, krause.d.matheus@gmail.com, carlosrobertomax@gmail.com, josuemf@uel.brUniversidade Estadual de LondrinaBrazilLondrina, PR, Brazil Universidade Estadual de Londrina, Departamento de Genética e Biologia Molecular, Rodovia Celso Garcia Cid, Pr 445, Km 380, Campus Universitário, CEP 86057-970 Londrina, PR, Brazil. E-mail: allinesekiya@gmail.com, jessicakpestana@gmail.com, maikon.baptistella@gmail.com, krause.d.matheus@gmail.com, carlosrobertomax@gmail.com, josuemf@uel.br

https://orcid.org/0000-0002-5993-8410

Jéssica Kelly Pestana

https://orcid.org/0000-0002-6057-3391

Maikon Guerith Baptistella da Silva

https://orcid.org/0000-0003-1210-1661

Matheus Dalsente Krause

https://orcid.org/0000-0003-2411-9287

Carlos Roberto Maximiano da Silva

https://orcid.org/0000-0002-9134-9704

Josué Maldonado Ferreira ^**Corresponding author: josuemf@uel.br

https://orcid.org/0000-0002-0085-6891

*Corresponding author: josuemf@uel.br

SCIMAGO INSTITUTIONS RANKINGS

Figuras | Tabelas

Figuras (3)
Tabelas (1)

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Figure 1.
Seed classification and mosaic seeds obtained by the process of haploid induction in supersweet corn (Zea mays L. var. saccharata) populations. A, class 1, diploid seed; B, class 2, putative haploid seed; C, class 3, seed without marking; D, parental supersweet corn seed; E, front and rear vision of mosaic seeds; and F, putative haploid seedlings at the V2-V3 stage, showing seedlings with purple first leaf sheath (a), seedlings with green first leaf sheath (b), and albino seedling (c).

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Figure 2.
Metaphasic nuclei obtained from supersweet corn (Zea mays L. var. saccharata) root tips and microscopic images of stomata guard cells of V2-V3-stage seedlings, showing: A1, false positive haploids represented by diploid plants with 2x=20 chromosomes; A2, true haploids represented by plants with x=10 chromosomes; B, F1 diploid plants, originated from class 1 seeds, based on the R1-nj marker; C, parental non-inducer diploid plants; D, putative haploid plants, originated from class 2 seeds by R1-nj and confirmed as diploids by chromosome counting; and E, haploid plants, originated from class 2 seeds by R1-nj and confirmed as haploids by chromosome counting.

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Figure 3.
Averages and mean confidence intervals of stomata guard-cell lengths for 12 populations and four plant categories (DPF1, PDP, HPD, and HPH), with respective comparison of the overall average of each category (lowercase letters above the column) by Tukey’s test, at 5% probability. DPF1, F1 diploids originated from seeds of class 1; PDP, parental non-inducer diploid; HPD, putative haploid confirmed as a diploid by chromosome counting; and HPH, putative haploid confirmed as a haploid by chromosome counting.

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Table 1.
Percentage of seeds classified by the R1-navajo (R1-nj) marker in crossings for haploidy induction between 11 supersweet corn (Zea mays L. var. saccharata) populations and a control, rates of true haploids and false positives, correlation between seeds without R1-nj marking and identified haploids, and factorial analysis of variance for the 12 plant populations and four categories evaluated for stomata guard-cell lengths (μm) and coefficient of variation (CV).

Figure 1. Seed classification and mosaic seeds obtained by the process of haploid induction in supersweet corn (Zea mays L. var. saccharata) populations. A, class 1, diploid seed; B, class 2, putative haploid seed; C, class 3, seed without marking; D, parental supersweet corn seed; E, front and rear vision of mosaic seeds; and F, putative haploid seedlings at the V2-V3 stage, showing seedlings with purple first leaf sheath (a), seedlings with green first leaf sheath (b), and albino seedling (c).

Figure 2. Metaphasic nuclei obtained from supersweet corn (Zea mays L. var. saccharata) root tips and microscopic images of stomata guard cells of V2-V3-stage seedlings, showing: A1, false positive haploids represented by diploid plants with 2x=20 chromosomes; A2, true haploids represented by plants with x=10 chromosomes; B, F1 diploid plants, originated from class 1 seeds, based on the R1-nj marker; C, parental non-inducer diploid plants; D, putative haploid plants, originated from class 2 seeds by R1-nj and confirmed as diploids by chromosome counting; and E, haploid plants, originated from class 2 seeds by R1-nj and confirmed as haploids by chromosome counting.

Figure 3. Averages and mean confidence intervals of stomata guard-cell lengths for 12 populations and four plant categories (DPF1, PDP, HPD, and HPH), with respective comparison of the overall average of each category (lowercase letters above the column) by Tukey’s test, at 5% probability. DPF1, F1 diploids originated from seeds of class 1; PDP, parental non-inducer diploid; HPD, putative haploid confirmed as a diploid by chromosome counting; and HPH, putative haploid confirmed as a haploid by chromosome counting.

Table 1. Percentage of seeds classified by the R1-navajo (R1-nj) marker in crossings for haploidy induction between 11 supersweet corn (Zea mays L. var. saccharata) populations and a control, rates of true haploids and false positives, correlation between seeds without R1-nj marking and identified haploids, and factorial analysis of variance for the 12 plant populations and four categories evaluated for stomata guard-cell lengths (μm) and coefficient of variation (CV).

	Population	Seed total	Seed class by R1-nj (%)⁽¹⁾			Class 2 seeds (%)⁽²⁾
	Population	Seed total	Class 1	Class 2	Class 3	True haploid rate		False positive
	PD1003	7,820	53.8	10.9	35.0	3		97
	PD1010	5,808	41.8	9.1	48.9	2		98
	PD2001	11,579	37.5	5.2	57.3	3		97
	PD2002	7,610	46.3	6.6	47.1	14		86
	PD2003	9,076	41.3	8.7	50.0	9		91
	SD3001	7,518	26.6	1.4	72.0	2		98
	SD3002	4,374	89.0	10.5	0.5	9		91
	SD3004	8,945	86.7	7.2	6.1	16		84
	SD3005	12,970	83.7	11.5	4.8	6		94
	SD3006	16,064	93.0	6.3	0.6	10		90
	SD3007	12,393	58.0	4.2	37.8	5		95
	30F53	14,192	60.8	13.1	26.1	5		95
	Correlation							r
	Class 3 seeds (without marking) x class 2 seeds (putative haploids)							-0.52
	Class 3 seeds (without marking) x true haploid rates							-0.45
Analysis of variance
Source of variation			Populations (P)		Categories (C)	P x C	Error	Average	CV (%)
Degrees of freedom			11		3	32	179	40.5	14.6
Mean square			72.749*		1,930.3**	34.711^ns	34.790

⁽¹⁾
R1-nj seed classes: class 1, diploid; class 2, putative haploid; and class 3, without marking. ⁽²⁾Percentages obtained from 100 class 2 seedlings for each cross. True haploid rates were obtained from haploids identified through first-leaf sheath color, with ploidy level confirmation by chromosome counting. False positives were considered class 2 seeds not identified as haploids by these methods. * and **Significant by the F-test, at 5 and 1% probability, respectively. ^nsNonsignificant.

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Indução de haploides em milho tropical superdoce e determinação de ploidia no estágio de plântulas

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[1] *Corresponding author: josuemf@uel.br