关键词: 茶树, 休眠, 越冬芽, AIL基因, 表达分析

Abstract: In tea plant，on the basis of previous transcriptome study on the axillary buds at different dormancy states，a differentially expressed gene related to dormancy regulation was identified，cloned and sequenced. This gene was highly homologous to AINTEGUMEN-LIKE（AIL），and named as CsAIL. Bioinformatic analysis showed that the CsAIL gene contains an open reading frame（ORF）in 1 872 bp，encoding 623 amino acid residues. CsAIL is predicted as a secretory protein with a putative molecular mass of 69.2 kD and theoretical isoelectric point of 6.6. CsAIL contained two conserved AP2 domains and should be grouped into AP2 subfamily，a superfamily closely involved in plant growth and development. Subcellular localization showed that CsAIL protein possibly locates the other organelles except chloroplasts and mitochondria. Homology analysis indicated that 11 and 12 AIL homologous genes were identified at the level of‘Yunkang 10’and‘Shuchazao’tea plant genome，respectively. Analysis of phylogenetic tree and sequence conservatism showed that CsAIL had the closest evolutionary relationship with‘Yunkang 10’CSA001743.1 and‘Shuchazao’TEA027750.1，and had different branches with known Arabidopsis AIL protein，but had typical conserved domain and known important amino acid sites. Promoter sequence cloning and analysis showed that CsAIL gene may be co-regulated by physiological rhythm，light and multiple hormone signals. Comprehensive expression analyses indicated that CsAIL had high expression levels in tea apical buds，axillary buds and stems，but relative low in leaves and extremely in flowers. At the stage of paradormancy，the expression of CsAIL was gradually down-regulated. A pretty low transcript level was maintained during endodormancy period. On the contrary，rapid expression increase was detected during ecodormancy and bud flush. Furthermore，the expression patterns of CsCYCD3.2 and CsCYCD6.1，putative downstream targets of CsAIL，were highly consistent with CsAIL and a high coefficient of association was observed between them. These results suggest that CsAIL may be a pivotal gene in bud dormancy regulation by modulating CsCYCDs among the dormancy-growth cycles in tea plant.

Key words: tea plant, dormancy, overwintering bud, AIL gene, expression analysis