Functional Verification Of SGT1and RAR1and Study On WRKY Transcription Factor In Carica Papaya L.

RAR1and SGT1play a very important role in the signaling transduction pathway of the plant disease resistance when plants subject to abiotic and biotic stresses in their whole life, and WRKY transcription factors have an important effect to improve resistance when the plants suffer various of abiotic and biotic stresses. The experiment which researched the expression pattern of WRKY transcription factors of papaya aimed to reveal its resistance mechanism and provide powerful basis for screening the candidate resistance gene the papaya. Poly-y-glutamic acid (y-PGA) has excellent characters such as completely biodegradable, non-toxic to human and environment which have been used widely in agriculture. At present, its effects on enhancing the growth of crops are found, however, the physiological mechanism in plants’ resistance has not known yet.In this paper, we identified the function of SGT1and RAR1in different transgenic lines of Arabidopsis T1progeny. We apply the papaya seedlings with the y-PGA, then we used real-time PCR to detect the10Carica Papaya WRKY transcription factors expression levels after stresses. The main results were obtained:1. The comparisons of the taproot length and rachis length between the different transgenic lines of Arabidopsis and wild-type were different. Under osmotic stress conditions, the rate of seed germination the pBI121-RAR1transgenic lines (R1、 R2、R3) showed higher than the ecotype Col-0, which improved that the RAR1played a important role during the early stage in the growth and development. But the different transgenic lines had the different rate of seed germination. R3(one of RAR1over-expression transgenic lines) showed a higher germination than R2and R1when they suffered the osmotic stress. S1(one of SGT1over-expression transgenic lines) showed a lower germination than S2and S3. The results also showed that the root length of the six transgenic lines was longer than wild-type’s under osmotic stress conditions. While the pBI121-RAR1transgenic lines had a higher sensitivity in salt stress than pBI121-SGT1transgenic lines. Above shows that RAR1and SGT1play a role in resistance reactions to osmotic stress in the growth and development in Arabidopsis. Under the condition of oxidative stress, the leaves of wild-type suffered the severe browning and dried up after48h, and the six transgenic lines also suffered the browning and dry phenomenon but delayed. Detached Arabidopsis leaves were infiltrated with the hypha of Ep-1PNA367. The incidence rate of the six transgenic lines was lower than the wild-types after20h infiltration. The wild-type leaves had been covered almost full of disease spots after40h infiltration, while the disease spots on the detached leaves of the six transgenic lines were not obvious.These results indicated that SGT1and RAR1play a certain role for the resistance reactions in Arabidopsis. We studied the relationship between the expression of four related resistance genes including EDS1, NDR1, LOX2and RPP5with the SGT1and RAR1over-expression. After the SA, MeJA, ABA treatment and salt stress, we got that the expression of four related resistance genes were higher in the six transgenic lines. The result showed that the expression of the related resistance genes had a relationship with the SGT1and RAR1over-expression. While the expression of related resistance genes was different in the transgenic lines, this suggested that the expression of the related resistance genes may be related to the plant hormone levels and exogenous gene copy number.2. The experimental group which the papaya seedlings applied with PGA nutrient solution had a more health growth and the longer taproot comparing to the control group which the papaya seedlings didn’t apply with PGA nutrient solution. After using the SA, low temperature, drought and pathogeny infecting the seedlings, we found that the experimental group had a better growth condition than the control group after7days infection. The results had proved that PGA could enhance plant resistance.3. We analyzed the transcriptional levels of10WRKY transcription factor to detect the gene expression diversity by using Real-time PCR after using the salicylic acid(SA)、 low temperature、drought and pathogeny infecting the seedlings. The results showed that the expression of the four WRKY transcription factor (TF12.199, TF12.62, TF18.51, TF21.156) were upregulated at very significantly after the stress to the control group; the expression of the three transcription factor (TF5.242, TF72.14, TF807.3) were upregulated at very significantly after the stress to the experimental group. We included that ten WRKY transcription factors are involved in the regulation of the response to abiotic stress and biotic stress. The PGA was also involved in the regulation of the response to abiotic stress and biotic stress because the expression of transcription factors was different. These suggested that the PGA can enhance Plants’resistance by inducing the expression of the related resistance genes.