Overexpression of a rice heme activator protein gene ( OsHAP2E ) confers resistance to pathogens, salinity and drought, and increases photosynthesis and tiller number

摘要

Heme activator protein (HAP), also known as nuclear factor Y or CCAAT binding factor (HAP/NF?￠????Y / CBF), has important functions in regulating plant growth, development and stress responses. The expression of rice HAP gene ( OsHAP2E ) was induced by probenazole (PBZ), a chemical inducer of disease resistance. To characterize the gene, the chimeric gene ( OsHAP2E::GUS ) engineered to carry the structural gene encoding ???2?￠????glucuronidase (GUS) driven by the promoter from OsHAP2E was introduced into rice. The transgenic lines of OsHAP2Ein::GUS with the intron showed high GUS activity in the wounds and surrounding tissues. When treated by salicylic acid (SA), isonicotinic acid (INA), abscisic acid (ABA) and hydrogen peroxide (H 2 O 2 ), the lines showed GUS activity exclusively in vascular tissues and mesophyll cells. This activity was enhanced after inoculation with Magnaporthe oryzae or Xanthomonas oryzae pv. oryzae . The OsHAP2E expression level was also induced after inoculation of rice with M. oryzae and X. oryzae pv. oryzae and after treatment with SA, INA, ABA and H 2 O 2, respectively. We further produced transgenic rice overexpressing OsHAP2E . These lines conferred resistance to M. oryzae or X. oryzae pv. oryzae and to salinity and drought. Furthermore, they showed a higher photosynthetic rate and an increased number of tillers. Microarray analysis showed up?￠????regulation of defence?￠????related genes. These results suggest that this gene could contribute to conferring biotic and abiotic resistances and increasing photosynthesis and tiller numbers.