Intraspecific variation of genome size in maize: cytological and phenotypic correlates.

REALINI, MARÍA FLORENCIA; POGGIO LIDIA; CÁMARA HERNÁNDEZ, JULIÁN; GONZÁLEZ, GRACIELA

AoBPlants

Oxford University Press

Lugar: Oxford; Año: 2016

The goal of the present research was to investigate intra-specific variation of DNA content in maize populations from NEA and further explore the relationship between genome size and the phenotypic traits seed weight and length of vegetative cycle. Moreover, cytological parameters such as the percentage of heterochromatin as well as the number, position and sequence composition of knobs were analyzed and their relationships with 2C DNA values were explored. The populations analyzed presented significant differences in 2C DNA amount, from 4.62pg to 6.29pg, representing 36.15% of inter-populational variation. Moreover intra-populational genome size variation was found, varying from 1.08-fold to 1.63-fold. Variation in the percentage of knob heterochromatin as well as in the number, chromosome position and sequence composition of the knobs was detected among and within the populations. Although a positive relationship between genome size and percentage of heterochromatin was observed, a significant correlation was not found. This confirms that other non-coding repetitive DNA sequences are contributing to the genome size variation. While a positive relationship between DNA amount and seed weight have been reported in a large number of species, this relationship was not found in the populations here studied. The length of vegetative cycle showed a positive correlation with the percentage of heterochromatin. This result allowed attributing an adaptive effect to heterochromatin, since vegetative cycle length would be optimized via selection for an appropriate percentage of heterochromatin.