Articles
Leaf heteroblasty during vegetative development of apple (Malus × domestica Borkh.)
Article number
1439_44
Pages
341 – 348
Language
English
Abstract
Several plant species undergo an abrupt change in morphology and functioning during their life cycle, with distinct alterations in stem structure, trichome patterning, leaf size, shape and arrangement.
This phenomenon, known as heteroblasty, is thought to result from evolutionary adaptation to differences in competition and resource availability throughout the plant’s life cycle and is therefore linked to its developmental status.
In many plant species, heteroblastic changes coincide with the vegetative phase change (VPC), and as such serve as an indicator of juvenility, i.e. the vegetative state at which plants are not able to flower, even under inductive conditions.
In apple, the juvenile period can last up to 15 years depending on the genotype and the latitude, forming a major bottleneck in selective breeding due to delayed phenotypic evaluation and the inability to perform rapid consecutive hybridizations in DNA-based programs.
Our research focuses on developing strategies to shorten the overall seed-to-seed generation time in apple and thus enable faster cycles of genetic improvement, increasing the efficiency and genetic gain in conventional breeding programs.
In this study, we employed image analysis software to accurately monitor and quantitatively measure changes in overall leaf morphology throughout the growth of apple seedlings in greenhouse conditions and link this with the vegetative phase status.
Our data reveal significant developmental variation in many leaf morphometric parameters, including leaf calliper, centroid size, perimeter, length and width, that all correlate positively with plant height (and, thus, internode number) a commonly used parameter for determination of juvenility.
By combining morphometric data with quantitative molecular assessment of the tree’s juvenility state we will be able to construct a model for predicting the vegetative status of the seedling based upon simple leaf imaging.
This approach could then be integrated in genetics studies on juvenility and timing of VPC to identify underlying QTLs and to develop markers that can be readily implemented in apple breeding.
This phenomenon, known as heteroblasty, is thought to result from evolutionary adaptation to differences in competition and resource availability throughout the plant’s life cycle and is therefore linked to its developmental status.
In many plant species, heteroblastic changes coincide with the vegetative phase change (VPC), and as such serve as an indicator of juvenility, i.e. the vegetative state at which plants are not able to flower, even under inductive conditions.
In apple, the juvenile period can last up to 15 years depending on the genotype and the latitude, forming a major bottleneck in selective breeding due to delayed phenotypic evaluation and the inability to perform rapid consecutive hybridizations in DNA-based programs.
Our research focuses on developing strategies to shorten the overall seed-to-seed generation time in apple and thus enable faster cycles of genetic improvement, increasing the efficiency and genetic gain in conventional breeding programs.
In this study, we employed image analysis software to accurately monitor and quantitatively measure changes in overall leaf morphology throughout the growth of apple seedlings in greenhouse conditions and link this with the vegetative phase status.
Our data reveal significant developmental variation in many leaf morphometric parameters, including leaf calliper, centroid size, perimeter, length and width, that all correlate positively with plant height (and, thus, internode number) a commonly used parameter for determination of juvenility.
By combining morphometric data with quantitative molecular assessment of the tree’s juvenility state we will be able to construct a model for predicting the vegetative status of the seedling based upon simple leaf imaging.
This approach could then be integrated in genetics studies on juvenility and timing of VPC to identify underlying QTLs and to develop markers that can be readily implemented in apple breeding.
Authors
G. Vighi, M. Rymenants, N. De Storme
Keywords
leaf morphology, juvenility, apple breeding, vegetative phase change, apple flowering
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