Toshi M Foster1, Alla N Seleznyova, Andrew M Barnett. 1. The Horticulture and Food Research Institute of New Zealand Ltd, Palmerston North Research Centre, Tennent Drive, Private Bag 11030, Palmerston North, 4474, New Zealand. tfoster@hortresearch.co.nz
Abstract
BACKGROUND AND AIMS: In kiwifruit (Actinidia), the number of nodes per shoot is highly variable and is influenced by genotype and environmental conditions. To understand this developmental plasticity, three key processes were studied: organogenesis by the shoot apical meristem during shoot growth; expansion of phytomers; and shoot tip abortion. METHODS: Studies were made of organogenesis and shoot tip abortion using light and scanning electron microscopy. The effect of temperature on shoot growth cessation was investigated using temperature indices over the budbreak period, and patterns of shoot tip abortion were quantified using stochastic modelling. KEY RESULTS: All growing buds began organogenesis before budbreak. During shoot development, the number of phytomers initiated by the shoot apical meristem is correlated with the number of expanding phytomers and the mean internode length. Shoot tip abortion is preceded by growth cessation and is not brought about by the death of the shoot apical meristem, but occurs by tissue necrosis in the sub-apical zone. For most genotypes studied, the probability of shoot tip abortion is higher during expansion of the preformed part of the shoot. Lower temperatures during early growth result in a higher probability of shoot tip abortion. CONCLUSIONS: Organogenesis and shoot tip abortion are controlled independently. All buds have the potential to become long shoots. Conditions that increase early growth rate postpone shoot tip abortion.
BACKGROUND AND AIMS: In kiwifruit (Actinidia), the number of nodes per shoot is highly variable and is influenced by genotype and environmental conditions. To understand this developmental plasticity, three key processes were studied: organogenesis by the shoot apical meristem during shoot growth; expansion of phytomers; and shoot tip abortion. METHODS: Studies were made of organogenesis and shoot tip abortion using light and scanning electron microscopy. The effect of temperature on shoot growth cessation was investigated using temperature indices over the budbreak period, and patterns of shoot tip abortion were quantified using stochastic modelling. KEY RESULTS: All growing buds began organogenesis before budbreak. During shoot development, the number of phytomers initiated by the shoot apical meristem is correlated with the number of expanding phytomers and the mean internode length. Shoot tip abortion is preceded by growth cessation and is not brought about by the death of the shoot apical meristem, but occurs by tissue necrosis in the sub-apical zone. For most genotypes studied, the probability of shoot tip abortion is higher during expansion of the preformed part of the shoot. Lower temperatures during early growth result in a higher probability of shoot tip abortion. CONCLUSIONS: Organogenesis and shoot tip abortion are controlled independently. All buds have the potential to become long shoots. Conditions that increase early growth rate postpone shoot tip abortion.
Authors: Michael J Clearwater; Alla N Seleznyova; T Grant Thorp; Peter Blattmann; Andrew M Barnett; Russell G Lowe; Paul T Austin Journal: Tree Physiol Date: 2006-04 Impact factor: 4.196
Authors: Erika Varkonyi-Gasic; Sarah M Moss; Charlotte Voogd; Rongmei Wu; Robyn H Lough; Yen-Yi Wang; Roger P Hellens Journal: BMC Plant Biol Date: 2011-04-27 Impact factor: 4.215
Authors: Rongmei Wu; Tianchi Wang; Ben A W Warren; Andrew C Allan; Richard C Macknight; Erika Varkonyi-Gasic Journal: J Exp Bot Date: 2017-02-01 Impact factor: 6.992