Marker-assisted selection of maintainer lines within an onion tropical population

Abstract

The traditional onion (Allium cepa) hybrid production requires the development of maintainer and male sterile lines and also a pollinator line with good specific combination ability. We report the identification of maintainer and male-sterile onion lines within the Brazilian 'Baia Periforme' derived population, 'Alfa São Francisco', associating random field pairing of male-fertile plants with selected male-sterile plants and PCR-based marker system monitoring S, T and N-cytoplasms. Male-sterile plants produced flowers with light green anthers which were easily detected in the field. A frequency of 2.0% of male-sterile plants was estimated in the 'Alfa São Francisco' sampled population. Male-sterile plants produced the 5´cob-marker 180-bp and the orfA501-marker 473-bp fragments, suggesting the T-cytoplasm type, while the maintainer line produced only the 5´cob-marker 180-bp. These identified lines will be important to develop tropical onion hybrids welladapted to Brazilian low latitudes and to future comparative studies with other onion cytoplasmic genic male sterility systems. Key words: Allium cepa, CMS, 'Alfa São Francisco', tropical hybrid Seleção assistida por marcadores de linha mantenedora dentro de uma população de cebola tropical RESUMO: A produção tradicional de híbrido de cebola (Allium cepa) requer o desenvolvimento de linhas mantenedoras e linhas macho estéreis, bem como uma linha polinizadora de boa capacidade específica de combinação. Reporta-se a identificação de linhas de cebola mantenedora e macho-estéreis numa população 'Alfa São Francisco' derivada da brasileira 'Baia Periforme', associando pareamento ao acaso no campo de plantas férteis com plantas macho-estéreis e sistema de PCR para monitoramento dos citoplasmas S, T e N. Plantas macho-estéreis produziram flores com anteras verde-claras, que foram facilmente identificadas no campo. A freqüência de 2,0% de plantas macho-estéreis foi estimada dentro de uma amostra da população 'Alfa São Francisco'. Plantas macho-estéreis produziram o marcador 5´cob de 180-pb e o marcador orfA501 de 473-pb, sugerindo que o citoplasma é do tipo T, enquanto a linha mantenedora da macho-esterilidade produziu apenas o marcador 5´cob de 180-pb. Essas linhas identificadas serão importantes para o desenvolvimento de híbridos de cebola tropical, bem adaptados às áreas de baixa latitude do Brasil e para estudos comparativos no futuro com outros sistemas da macho-esterilidade citoplasmática gênica de cebola.

Limitations of PCR‐based molecular markers to identify male‐sterile and maintainer plants from Indian onion (Allium cepa L.) populations

“…Although Kim (2014) developed markers identifying T cytoplasm, he could not exclude the possibility that the cytoplasm classified as CMS-T by Schweisguth (1973) might be different from the cytoplasm used by him. Pathak (1997) reported that flowers with light green anthers were male sterile and these findings agreed with Santos et al (2010). However, our findings are in contrast, and we found male sterility in flowers having light green, dark green or yellow anthers.…”

“…Pathak () reported that flowers with light green anthers were male sterile and these findings agreed with Santos et al. (). However, our findings are in contrast, and we found male sterility in flowers having light green, dark green or yellow anthers.…”

Partial success of marker-assisted selection of ‘A’ and ‘B’ onion lines in Brazilian germplasm

“…Marker-assisted selection in onions has been used to differentiate 'N', 'S', and 'T' cytoplasm (Khar and Saini, 2016;Patil et al, 2016;Ragassi et al, 2012Ragassi et al, , 2010Santos et al, 2010), contributing to reduce the number of test crosses required to identify 'A' and 'B' lines. Markers for the Ms locus, developed by Huo et al (2015) and Kim et al (2015), enabled the full assisted identification of 'A' and 'B' lines, and have been applied in Indian germplasm (Khar and Saini, 2016) and in Brazilian germplasm (Ferreira et al, 2017) for the simultaneous identification of the cytoplasm type and recessive condition of the Ms allele.…”

“…The obtainment of onion hybrids by the conventional method is costly and takes almost 20 years in temperate regions, including the identification of 'A' lines (male-sterile lines) and 'B' lines (maintainer lines) in the open-pollinated populations (Pike, 1986). Previous attempts to identify 'A' and 'B' lines in the Brazilian germplasm by conventional methods were not successful in the development of onion hybrids (Santos et al, 2010).…”

Male Sterility and its Commercial Exploitation in Hybrid Seed Production of Vegetable Crops: A Review

“…Partial chlorosis in addition to glossy foliage was suggested as the marker gene criteria for identification in both the A and B lines (Johnson (1966). Use of brown seed and seed coat colour was suggested for identification of male sterile lines and black seed colour for identification of male fertile plants for hybrid seed production (Davis (1966) whereas light green anthers was used for detection of male sterile lines in variety Alfa São Francisco' (Santos et al, 2010).…”