Phenotypic recurrent selection to improve protein quality in non-opaque maize populations

Phenotypic recurrent selection to improve protein quality in non-opaque maize populations

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Maize (Zea mays L.) protein is considered to be of low quality due to low levels of the g5210t-p90 essential lysine and tryptophan amino acids.An alternative to solve this problem is to use the opaque-2 gene, which improves the level of these amino acids, but has negative pleiotropic effects on agronomic characters.

A phenotypic recurrent selection scheme was carried out in two non-opaque maize populations to verify the possibility of improving their protein quality without using this gene.Four cycles were completed and a 20% selection intensity for tryptophan content in the kernels was used in two populations, IG-1 and IG-2.The original and the four-cycle populations were evaluated in three locations for agronomic traits.

For protein and tryptophan content, a separated trial was carried out because plants of the plots were hand-pollinated.No increase in tryptophan content was observed in the IG-2 population, whereas IG-1 presented a small increase (0.70% per cycle).

The ratio tryptophan/protein increased 1.26% per cycle in IG-1 and the protein content did not increase usmc msgt chevron in both populations.The ESALQ-VD2-opaque check was superior in relation to both populations for protein quality, as expected, even after completion of four selection cycles.

The kernel yield (2.5% per cycle) prolificacy, plant and ear heights, decreased with selection cycles, as a correlated response to selection.Phenotypic recurrent selection in non-opaque maize was not able to increase, at reasonable rates, the protein quality of maize kernels.