Transcriptome Analysis Of Maize Seedlings Response To Simulated Shade By RNA-seq

As one of the major grain crops in China, maize accounted for 35% of the total grain yield. As a conventional grain, maize also has a wide range of usages in chemical industry, fodder and many other fields. Maize play an important role in the development of the national economy and social stability. Current research indicate that improvement of the maize yield mainly by increasing the planting density, in terms of the world. Dense planting of maize will shade each other, so the light intensity will decline and the light qualitative will change (R/FR reduced). Decrease of R/FR can lead to shade avoidance syndrome, which is characterized by a decrease in chlorophyll content, a reduction in the number of tillers, an increase in both plant height and leaf blades length, and an enlongation of internodes and leaf sheaths.In order to explore the regulation network of shade avoidance in maize, we simulated shade-avoidance by changing R/FR percentage. RNA-seq results are as follows:(1) The phenotype of maize seedlings grown under simulated shade avoidance condition was observed. Seedlings under shade light grow higher than white light, and showed longer both nodal distance and leaf blades length. Besides, the accumulation of pigment and chlorophyll were reduced.(2) In this study, maize seedlings were transferred to low R/FR light condition after two weeks grown under white light. Tissues were harvested under a safe green light. We extracted the total RNA and sent them to Berry Genomics for the transcriptome sequencing. Analyzing the data, we found out about 1087gene expression changed significantly.(3) Under shade light, the expression of photosynthesis related genes was reduced. The expression of cell wall protein related genes and GA pathway related genes was increased. JA synthesis related genes were inhibited by shade light and caused resistant to stress declined.(4) According to previous reports, we selected 35 key genes responded to shade light, in different maize inbred lines.(5) Four shade response genes of maize were cloned and expressed in Arabidopsis.In summary, RNA-seq was used in the research of regulation network of shade avoidance in maize to explain the mechinisms of shade avoidance in molecular level and provide basis for the high yield varieties breeding of maize in the future.