Identification of transcription factors interacting with a 1274 bp promoter of MaPIP1;1 which confers high-level gene expression and drought stress Inducibility in transgenic Arabidopsis thaliana.
BACKGROUND
Drought stress can severely affect plant growth and crop yield. The cloning and identification of drought-inducible promoters would be of value for genetically-based strategies to improve resistance of crops to drought.


RESULTS
Previous studies showed that the MaPIP1;1 gene encoding an aquaporin is involved in the plant drought stress response. In this study, the promoter pMaPIP1;1, which lies 1362 bp upstream of the MaPIP1;1 transcriptional initiation site, was isolated from the banana genome..And the transcription start site(A) is 47 bp before the ATG. To functionally validate the promoter, various lengths of pMaPIP1;1 were deleted and fused to GUS to generate pMaPIP1;1::GUS fusion constructs that were then transformed into Arabidopsis to generate four transformants termed M-P1, M-P2, M-P3 and M-P4.Mannitol treatment was used to simulate drought conditions. All four transformants reacted well to mannitol treatment. M-P2 (- 1274 bp to - 1) showed the highest transcriptional activity among all transgenic Arabidopsis tissues, indicating that M-P2 was the core region of pMaPIP1;1. This region of the promoter also confers high levels of gene expression in response to mannitol treatment. Using M-P2 as a yeast one-hybrid bait, 23 different transcription factors or genes that interacted with MaPIP1;1 were screened. In an dual luciferase assay for complementarity verification, the transcription factor MADS3 positively regulated MaPIP1;1 transcription when combined with the banana promoter. qRT-PCR showed that MADS3 expression was similar in banana leaves and roots under drought stress. In banana plants grown in 45% soil moisture to mimic drought stress, MaPIP1;1 expression was maximized, which further demonstrated that the MADS3 transcription factor can synergize with MaPIP1;1.


CONCLUSIONS
Together our results revealed that MaPIP1;1 mediates molecular mechanisms associated with drought responses in banana, and will expand our understanding of how AQP gene expression is regulated. The findings lay a foundation for genetic improvement of banana drought resistance.
['Xu|Yi|Y|', 'Jin|Zhiqiang|Z|', 'Xu|Biyu|B|', 'Li|Jingyang|J|', 'Li|Yujia|Y|', 'Wang|Xiaoyi|X|', 'Wang|Anbang|A|', 'Hu|Wei|W|', 'Huang|Dongmei|D|', 'Wei|Qing|Q|', 'Xu|Zhuye|Z|', 'Song|Shun|S|']
D051398:Aquaporin 1 D017360:Arabidopsis D029681:Arabidopsis Proteins D055864:Droughts D015870:Gene Expression D028521:Musa D030821:Plants, Genetically Modified D011401:Promoter Regions, Genetic D013312:Stress, Physiological D014157:Transcription Factors
Transcription factor Promoter Aquaporin Banana 5′ deletion Droutht stress