| Chilling damage is a natural disaster that is widespread in the world and has become one of the main factors limiting human agricultural production activities.Rice is one of the most important food crops in China and is affected by temperature factors.In the double-season rice-growing area of ??Hunan,the temperature instability in the early rice seedling stage makes it more vulnerable to cold damage.Brassinolide is a kind of phytohormone which is widely existed in plants and has strong physiological activity.It is a kind of high-efficiency and broad-spectrum plant growth regulator,which can improve the stress resistance of crops,regulate the root morphology of crops and improve crops.The hormone of the leaf dip.At present,the physiological functions of Brassinolide?BR?are mainly studied by soaking seeds,spraying on the leaves,adding in the medium,etc.,and have been applied in the production of some crops.BR soaking can promote the germination of seeds under stress,and spraying 2,4-epibrassinolide?EBR?can alleviate the salt and alkali,drought,and promote the photosynthesis of plants,enhance the activity of antioxidant enzymes,improve water use efficiency and inhibit membrane lipid peroxidation.Damage to plants caused by low temperature,high temperature,pests and other adverse environmental conditions.In this study,the early rice variety‘Xiangzaoxian 45'was used as the test material.A total of 7 treatments were set up,study rice seed germination and seedling growth under low temperature stress The low temperature tolerance and resolution of its molecular regulatory pathways through transcriptome analysis.The research results are as follows:In this study,the early rice variety Xiangzao 45 was used as the test material.A total of 7 treatments were set up?CK1,normal temperature + distilled water;CK2,low temperature + distilled water;T1,low temperature + 0.001umol·L-1EBR;T2,low temperature +0.01 umol·L-1EBR;T3,low temperature + 0.1umol·L-1 EBR;T4,low temperature + 1umol·L-1EBR;T5,low temperature + 10.0 umol·L-1EBR?,enhances rice seed under low temperature stress by brassinolide The optimum concentration of germination and seedling growth was screened.Then the rice seedlings were treated with the selected optimal concentration,and the relevant indicators were sampled and compared.The research results are as follows:1.Low temperature stress inhibited rice seed germination and seedling growth,while spraying EBR could greatly alleviate the inhibition of low temperature stress on its growth.Seed germination was best treated with 0.001?mol·L-1EBR,while seedling growth was best with 1.0?mol·L-1EBR.2.Low temperature stress inhibited the growth of rice seedling roots,and spraying EBR at a suitable concentration could greatly alleviate the inhibition of low temperature stress.Among them,1.0?mol·L-1EBR treatment was better,root length,projected area and pixels.The area,surface area,volume,number of connections and number of root tips were significantly higher than the control,which were 34.29%,13.67%,29.05%,25.07%,14.42%,32.03%,and 42.51% higher than the low temperature control?CK2?,respectively.3.Low temperature stress can cause the dehydration of vesicular cells,resulting in curling of rice leaves,while spraying EBR can reduce the dehydration of vesicular cells and reduce the degree of curling of leaves.4.Low temperature stress increased the activity of antioxidant enzymes and malondialdehyde?MDA?in rice seedlings and roots,inhibiting the accumulation of soluble protein.Spraying EBR could increase the activity of antioxidant enzymes,soluble protein and MDA content.When rice seeds were treated with 0.1?mol·L-1EBR,the activities of antioxidant enzymes in rice buds were the highest under low temperature stress.For rice seedlings,1.0?mol·L-1EBRtreated rice seedlings had the highest antioxidant enzyme activity in the body.5.Photoinhibition caused by low temperature stress caused the photosynthetic efficiency of rice seedlings to decrease,while spraying EBR could increase the photosynthesis of rice seedlings.With the prolongation of low temperature treatment time,the maximum fluorescence?Fm?under the dark adaptation of rice seedlings,the maximum fluorescence?Fm'?under light adaptation,the maximum photochemical efficiency of PSII?Fv/Fm?,the potential photochemical efficiency of PSII?Fv/Fo?,The photochemical quenching coefficient?qP?and electron transport efficiency?ETR?showed a downward trend,which decreased by 56.22%,66.35%,13.27%,40.63%,17.57%,46.85%,and initial fluorescence?Fo?and non-photochemical enthalpy,respectively.The extinction coefficient?NPQ?showed an upward trend,which increased by 16.27% and 44.74%,respectively,at 24 h.6.The results of transcriptome analysis showed that there were 585 differential genes in the low temperature condition?4 °C?spraying EBR compared with the low temperature control,of which 217 were up-regulated and 368 were down-regulated.By changing the composition of cell membrane and plasma membrane of rice seedlings,the structure and function of cell mitochondria under low temperature stress were protected,and the transport efficiency of plants was improved,which promoted the growth of rice seedlings.Compared with the EBR treatment at low temperature?4 °C?,the EBR treatment at normal temperature?25 °C?had 9,834 differential genes,6069 were up-regulated,and 3765 were down-regulated.The rice seedlings were found by differential expression analysis.The intrinsic composition of cell membrane and plasma membrane also changed,the efficiency of material transportation and photosynthesis accelerated,which alleviated the inhibition of growth by low temperature stress and promoted the growth of rice seedlings. |
PDF Full Text Request