Successful deployment of marker assisted selection (MAS) for inbred and hybrid development in long-day onion (Allium cepaL.)

Abstract

In the present investigation, male sterile and maintainer lines were identified using molecular markers in three long day onion populations. Molecular markers, 5'cob and orfA501 were able to distinguish effectively normal (N) and sterile (S) cytoplasm in all the three populations. The observed frequency of S cytoplasm in VL Piaz 67 (100%), VL Piaz3 (86.4%) and KR1 (90%) was higher than N cytoplasm. Out of the two PCR markers viz., OPT and PsaO used to determine the nuclear fertility restorer locus (Ms locus), OPT was found better than PsaO. Increased frequency of dominant homozygous alleles (87.4%) followed by heterozygous alleles (8.6%) and homozygous recessive alleles (4.0%) was observed. Fertility/sterility of plants were validated by acetocarmine staining of the pollens and correlated with observations made using molecular markers. Out of the three populations studied, only 12 plants (2.15%) happened to be completely male sterile in VL Piaz-3 and KR1 population, whereas there was no male sterile plant observed among the population in VL Piaz 67. Selfing and test crossing of plants having normal (N) cytoplasm led to the development and identification of maintainer lines in VL Piaz3 and KR1 population. This is the first example of deploying DNA markers for identification and purification of male sterility and hybrid development in long day onion in Indian population.

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

“…) as this marker was found to be in linkage disequilibrium in our previous studies with long‐day onion (Saini et al. ). However, we observed discrepancies between molecular genotyping, field inspection and microscopic visualization in the present studies.…”

“…Saini et al. () also did not find any correlation between the anther colour and male sterility. Microscopic analysis of pollen from male‐fertile plants showed normal pollen grains completely stained with elliptical shape, whereas pollen grains of male‐sterile flowers were misshapen, clumped together and did not stain red with acetocarmine.…”

“…Two hybrids, Arka Kirthiman and Arka Lalima, have been released by IIHR, Bengaluru, but somehow they did not gain attention of the farmers and were not released at the national level to the farmers. Preliminary reports on use of PCR markers for cytoplasm determination (Chaurasia et al 2010, Saini et al 2015, Sheemar and Dhatt 2015 have been documented.…”

The use of genetic, manual and chemical methods to control pollination in vegetable hybrid seed production: a review

“…), but their validation is needed before applying them in MAS of maintainer lines (Saini et al. , Khar and Saini ).…”

Vegetable Improvement in India; Recent Past, Present and Future: A Review

“…A fertility restorer and male sterile gene has been tagged through RAPD protocol in chilli (Kumar et al, 2002). For the first time in Indian long day onion population, DNA marker for male sterility and hybrid development has developed and identified with the help of which we can exploit the identified marker in future for hybrid development as well as transfer of male sterility to other onion lines or genotypes through marker assisted selections (Saini et al, 2015). Marker assisted selection has been employed in tomato for the introgression of Ty2 and Ty3 genes to develop tomato leaf curl resistant hybrid (Prasanna et al, 2015).…”