Induction and study of tetraploid opaque-2 maize

In this paper we present the results on induction and study of tetraploid maize forms containing opaque-2 gene which determines a high content of lysine in grain protein, in order to exploit the biochemical effect of this mutation at the tetraploid level. By applying colchicine of 0,15% concentration on plants of hybrid Chişiniovschi 307 PL at 3-4 leaf stage, tetraploid forms were obtained, characterized by vigorous stems, but shorter size and internodes, leaves with darker green hues, poorly branched panicle, but with thicker branches, especially the central one. Study of leaf epidermis revealed larger stomata but fewer per unit area. Diploid pollen of tetraploid forms was larger compared to the haploid, but the degree of fertility was lower in tetraploid forms. Analysis of the phenotypic expression of opaque-2 mutation of maize tetraploid forms showed that this gene inherits at random chromosomal segregation in a phenotypic ratio of 35:1, which is confirmed by χ2 test application. With ploidy level increased the amount of grain protein and fat content was reduced. Lysine content in grain protein containing opaque-2 gene increased in proportion to the dose level in triploid and, partly, in the hexaploid endosperm

QTL Mapping for Haploid Inducibility Using Genotyping by Sequencing in Maize

Doubled haploid (DH) technology in maize takes advantage of in vivo haploid induction (HI) triggered by pollination of donors of interest with inducer genotypes. However, the ability of different donors to be induced—inducibility (IND), varies among germplasm and the underlying molecular mechanisms are still unclear. In this study, the phenotypic variation for IND in a mapping population of temperate inbred lines was evaluated to identify regions in the maize genome associated with IND. A total of 247 F2:3 families derived from a biparental cross of two elite inbred lines, A427 and CR1Ht, were grown in three different locations and Inclusive Composite Interval Mapping (ICIM) was used to identify quantitative trait loci (QTL) for IND. In total, four QTL were detected, explaining 37.4% of the phenotypic variance. No stable QTL was found across locations. The joint analysis revealed QTL × location interactions, suggesting minor QTL control IND, which are affected by the environment