Studies On The Functional Expression Of Wheat Variety Xinong 1376 With Leaf Senescence-Inhibition Gene P_SAG12-IPT

Dry matter content of crop kernels is maily product of assimilation of leaf photosynthesis, especially photosynthesis of flag leaves after anthesis. According to studies, in the late period of crop growth if functional period of leaves prolongs one day, crop yield can increase 2%, which shows study on regulation of leaf senescence to prolong photosynthetic functional period of flag leaves and improve photosynthetic performance is of great importance to crop production and kernel yield increase. Crop transgenic technologies are becoming maturer and maturer day by day which can effectively break reproductive isolation and diversify crop genetic basis, thus becoming important supplementary means of crop breeding. However, whether introducing outside genes into crops can express characters of directive improvement of crops is the ultimate key to measuring transgenic success and also the final goal of crop genetic engineering. Therefore, studying the expression of outside genes after being introduced into crops is quite necessary. This paper studied the functional expression of leaf senescence-inhibition gene PSAG12-IPT in the genetic background of ordinary wheat by focusing on transgenic lines of XiNong 1376 claiming many earlier progeny and with transferrred leaf senescence-inhibition gene PSAG12-IPT from aspects like net photosynthetic rate of flag leaves, chlorophyll content, kernel filling characters and so on. The results indicated the following:1. As to photosynthetic rate, there was no obvious difference between transgenic wheat plant lines and their control, non-transgenic XiNong1376 in the early and middle grain filling period. However, in the late period, the photosynthetic rate of five T6 progeny of transgenic plant lines was all higher than their control, among which three transgenic lines 141, 95 and 153 were significantly higher than the control. This showed that wheat variety XiNong1376 with transferred leaf senescence-inhibition gene can improve net photosynthetic rate in the late period of growth.2. Leaf senescence-inhibition gene PSAG12-IPT began to express itself specially when plants started to mature 33 days after anthesis. Chlorophyll content of the five transgenic wheat lines except 140 was all higher than the control, non-transgenic XiNong1376, especially the line 141. High chlorophyll content of transgenic wheat provided material basis for its high photosynthetic rate.3. Richard equation can simulate well the dynamic change of grain filling and several TKW increase of study materials all followed the dynamic change of development"slow-fast-slow". Kernel weight of the majority of transgenic wheat lines was higher than the control, non-transgenic XiNong1376, grain filling period was prolonged and grain filling rate in the late period was higher than the control. This indicated that wheat variety XiNong1376 with transferred leaf senescence-inhibition gene prolonged the growing period, increased kernel weight and provided basis for higher yield.4. Net photosynthetic rate of three transgenic plant lines 95, 141 and 153 in the late period of growth was very significantly higher than the control; chlorophyll content of four transgenic plant lines 95, 106, 141 and 153 was noticeably higher than the control; dynamic changes of Richard equation simulated grain filling indicated that three transgenic plant lines 95, 106 and 153 were obviously superior to the control. Transgenic plant lines 95 and 153 were higher than the control in all the three indexes, which showed that leaf senescence-inhibition gene PSAG12-IPT can express relatively well in wheat genetic background and plant lines 95 and 153 were two wheat lines that expressed best of PSAG12-IPT.