Genetic variations in morphology, chromosome number, and physiology of backcross progeny of the triploid hybrid clone 'Beilinxiongzhu 1#'.

BACKGROUND

Aneuploidy in plants commonly presents as large variations in morphology, physiology, biochemistry, and genetic effects owing to its karyotypic imbalance.

RESULTS

In this study, the trait variations of 393 offspring obtained by pollinating Populus alla × Populus glandulosa 'YXY 7' (2n = 2x = 38) with Populus 'Beilinxiongzhu 1#' (2n = 3x = 57) were explored. The results showed several morphological variations in the cotyledons, including two (69.68%), three (24.07%), and four cotyledons (6.25%). Additionally, the progeny exhibited extensive segregation of ploidy levels, ranging from 38 to 74. Furthermore, seedlings with different chromosome numbers varied in growth traits and physiological activities during growth and development. The backcross progeny with 51-60 chromosomes had a significantly larger basal diameter and seedling height than those with other chromosome numbers. The phenotypic correlations between the traits indicated that the dose effect of the chromosomes significantly affected the basal diameter, petiole length, and leaf length, particularly with stomatal length and stomatal density. Weak and negative estimated correlations were observed between the physiological traits associated with photosynthesis and most of the studied traits.

CONCLUSIONS

This study provides new genetic material with different chromosome compositions, which will contribute to analyzing chromosomal function and integrate the variations in chromosomal dosage into Populus breeding programs.