Wei Yang1,2, Yanhu Ju1,3, Liping Zuo1,4, Luyue Shang1,4, Xinru Li3, Xiaoming Li1,3, Shangzong Feng5, Xinhua Ding6,7, Zhaohui Chu8,9. 1. State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai' an, 271018, Shandong, PR China. 2. Shandong Pengbo Biotechnology Co LTD, Tai' an, 271025, Shandong, PR China. 3. College of Agronomy, Shandong Agricultural University, Tai' an, 271018, Shandong, PR China. 4. Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Tai' an, 271018, Shandong, PR China. 5. Agro-technical Popularization Centre of Linyi City, Linyi, 276000, Shandong, PR China. 6. State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai' an, 271018, Shandong, PR China. xhding@sdau.edu.cn. 7. Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Tai' an, 271018, Shandong, PR China. xhding@sdau.edu.cn. 8. State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai' an, 271018, Shandong, PR China. zchu@sdau.edu.cn. 9. College of Agronomy, Shandong Agricultural University, Tai' an, 271018, Shandong, PR China. zchu@sdau.edu.cn.
Abstract
BACKGROUND: Bacterial leaf streak (BLS) and bacterial blight (BB) are two major prevalent and devastating rice bacterial diseases caused by the Gram-negative bacteria of Xanthomonas oryzae pv. oryzicola (Xoc) and Xanthomonas oryzae pv. oryzae (Xoo), respectively. Previously, we identified a defence-related (DR) gene encoding a small heat shock protein, OsHsp18.0-CI, that positively regulates BLS and BB resistance in rice. RESULTS: To reveal the regulatory mechanism of the OsHsp18.0-CI response to Xoc and Xoo, we characterized the class B heat shock factor (Hsf), OsHsfB4d, through transcriptional analysis and a transgenic study. OsHsfB4d is upregulated post inoculation by either the Xoc strain RS105 or Xoo strain PXO99a in Zhonghua 11 (wild type, ZH11) as well as in OsHsp18.0-CI overexpressing rice plants. Transient expression of OsHsfB4d can activate the expression of green fluorescent protein (GFP) and luciferase (Luc) via the OsHsp18.0-CI promoter. Rice plants overexpressing OsHsfB4d exhibited enhanced resistance to RS105 and PXO99a as well as increased expression of OsHsp18.0-CI and pathogenesis-related genes. Furthermore, we found that OsHsfB4d directly binds to a DNA fragment carrying the only perfect heat shock element (HSE) in the promoter of OsHsp18.0-CI. CONCLUSION: Overall, we reveal that OsHsfB4d, a class B Hsf, acts as a positive regulator of OsHsp18.0-CI to mediate BLS and BB resistance in rice.
BACKGROUND: Bacterial leaf streak (BLS) and bacterial blight (BB) are two major prevalent and devastating ricebacterial diseases caused by the Gram-negative bacteria of Xanthomonas oryzae pv. oryzicola (Xoc) and Xanthomonas oryzae pv. oryzae (Xoo), respectively. Previously, we identified a defence-related (DR) gene encoding a small heat shock protein, OsHsp18.0-CI, that positively regulates BLS and BB resistance in rice. RESULTS: To reveal the regulatory mechanism of the OsHsp18.0-CI response to Xoc and Xoo, we characterized the class B heat shock factor (Hsf), OsHsfB4d, through transcriptional analysis and a transgenic study. OsHsfB4d is upregulated post inoculation by either the Xoc strain RS105 or Xoo strain PXO99a in Zhonghua 11 (wild type, ZH11) as well as in OsHsp18.0-CI overexpressing rice plants. Transient expression of OsHsfB4d can activate the expression of green fluorescent protein (GFP) and luciferase (Luc) via the OsHsp18.0-CI promoter. Rice plants overexpressing OsHsfB4d exhibited enhanced resistance to RS105 and PXO99a as well as increased expression of OsHsp18.0-CI and pathogenesis-related genes. Furthermore, we found that OsHsfB4d directly binds to a DNA fragment carrying the only perfect heat shock element (HSE) in the promoter of OsHsp18.0-CI. CONCLUSION: Overall, we reveal that OsHsfB4d, a class B Hsf, acts as a positive regulator of OsHsp18.0-CI to mediate BLS and BB resistance in rice.