Abstract
Abstract The objective of this work was to analyze the androgenic response of Brazilian wheat genotypes to different pretreatments of the spikes, prior to the culture of isolated microspores, and to the effect of a gelling agent in the induction culture medium. Five genotypes were evaluated for embryo formation, green plant regeneration, and spontaneous chromosome duplication. Wheat spikes were subjected to two pretreatments: cold, at 4ºC for 21 days; and 2-hydroxynicotinic acid, at 32ºC for two days. Culture media were evaluated with or without Ficoll as a gelling agent. Cold produced more embryos and green plants than the chemical pretreatment in four out of five genotypes. Only two genotypes treated with 2-hydroxynicotinic acid were able to produce plants, and one of them produced a single albino plant. Medium containing Ficoll produced more embryos than liquid medium and promoted a higher number of plants. Spontaneous chromosome duplication varies between genotypes and pretreatments, and shows high variability.
Highlights
The significance of haploid (H) plants for plant breeding and genetic research was first recognized in 1921, when Bergner observed this natural phenomenon in Datura stramonium (Blakeslee et al, 1922)
The objective of this work was to analyze the androgenic response of Brazilian wheat genotypes to different pretreatments of the spikes, prior to the culture of isolated microspores, and to the effect of a gelling agent in the induction culture medium
Six genotypes were used to test androgenesis: five Brazilian wheat genotypes with unknown androgenic responses – 'MGS 1 Aliança', 'MGS Brilhante', 'BR 18 Terena', PF020037, and PF020062, and the responsive genotype 'Pavon 76' which was used as a control
Summary
The significance of haploid (H) plants for plant breeding and genetic research was first recognized in 1921, when Bergner observed this natural phenomenon in Datura stramonium (Blakeslee et al, 1922). Four decades later, Guha & Maheshwari (1964) observed that these plants could arise from immature pollen in vitro as an immediate product of meiosis, representing all the diversity of the parental post-meiotic haploid chromosome set. In the absence of homologous pairing, meiosis produces gametes with fewer than the necessary complement of chromosomes. The duplication of chromosomes – spontaneous or induced – overcomes this impasse to yield doubled haploid (DH) and fertile plants. In other words, it can produce completely homozygous plants, genetically normal, phenotypically
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