Pineapple, an important tropical fruit, belongs to the family Bromeliaceae (Ananas Merr.), and its flower and fruit development theory and transcriptional regulation technology are one of the hot spots in the pineapple industry. Ethylene is one of the important hormones that regulate the flowering and fruit development of pineapple. In the study of watercore disorder in Bali pineapple varieties, it was found that two MYB transcription factors, AcMYB68 and Ac-MYB109, played an important role in fruit development. With the completion of pineapple genome sequencing, 94 pineapple R2R3-MYB transcription factors have been identified in the pineapple genome, which are divided into 26 subfamilies, and are differentially expressed by salt and other stresses and ABA hormones. In this study we proposed a scientific hypothesis that ethylene mediated MYB transcription factors to regulate the development of pineapple fruits. In order to elucidate the molecular regulatory mechanism, a MYB transcription factor AcMYB103 was cloned from the fruit of pineapple Tainong 17, with a total length of 1204 bp, a coding region of 1038 bp, and encoding 345 amino acids. The protein contains two typical SANT domains, localized to the nucleus, without transmembrane domain and signal peptide, and was a member of the plant R2R3 MYB transcription factor family. Cluster analysis of pineapple and Arabidopsis MYB family members showed that AcMYB103 had the highest similarity with Arabidopsis AtMYB80, At-MYB103 and AtMYB35, and belonged to the S19 subfamily. Furthermore, four ethephon concentrations (volume fraction) of 0%, 0.5%, 1.0% and 1.5% were used to treat the fruits at the small fruit stage, expansion stage and ripe stage of the three cultivars Tainong 17, Xiaomushousi and Damushousi, and the expression level of AcMYB103 was analyzed. The results showed that with the increase of ethephon concentration at the small fruit stage, the expression of AcMYB103 in Tainong 17 showed a down-regulated pattern, and upregulated in the Xiaomushousi and Damushousi mode. In the expansion stage, the downward adjustment pattern was shown in the Tainong 17 and Xiaomushousi varieties, and the upward pattern was shown in the fruit of Damushousi. AcMYB103 was not expressed in fruits at the ripening stage, indicating that the expression of AcMYB103 gene was specific in ethephon-treated varieties and fruit development periods, and played a differentiated regulatory role in the early stage of fruit development. This study would lay a foundation for in-depth study of the mechanism of AcMYB103 gene in the regulation of growth and development of pineapple fruit.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |