|Authors: ||A. Li-Mallet, A. Rabot, L. Geny|
|Keywords: ||Vitis vinifera, inflorescence primordia, gene expression, hormones, regulation|
The reproductive cycle of the grapevine (Vitis vinifera) extends over two consecutive years.
Grapevine bud fruitfulness is determined by the number and the size of inflorescence primordia (IP) formed in latent buds during the first year.
Many studies show that up to 60% of the seasonal variation in yield could be explained by bud fruitfulness.
The regulation mechanism of the initiation and differentiation of IP remains little known, but this process seems to be modulated by several molecular regulation factors involved in flowering and embryo development.
Some genes involved in flowering process and regulated by auxins (IAA) and abscisic acid (ABA) have also been recently identified in grapevine latent buds.
Gene expression analysis of VvL1L, VvMFT1 and VvTFL1A in different types of fruitful buds (N0, N1 and N2) were realized during their development stages (88 to 159 days after budbreak) of the first year in 'Merlot' cultivar. VvL1L and VvTFL1A were up-regulated in early stages of bud development during the period of the initiation and differentiation of IP. The relative expression of VvMFT1 showed significant differences between the three types of buds (N0, N1 and N2) in relation with their development.
IAA and ABA contents in latent buds at different stages during the first year were analyzed and correspond to gene expressions: VvTFL1A seems to be activated by IAA, while VvL1L and VvMFT1 might be regulated by IAA/ABA balance.
These results may support the assumption of the involvement of VvL1L, VvMFT1 and VvTFL1A in the regulation of bud fruitfulness and their response to IAA/ABA balance.
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