Allelic Variation Analysis Of CrtRB1and LcyE Genes Controlling Vitamin A Content In Maize Inbred Lines In China

Vitamin A (VA), also known as retinol, is one of the13essential vitamins for human and animal health. VA helps to maintain visual function, and promotes bone growth. VA uptakes are mainly through daily diet; therefore, improper food absorption will cause VA deficiency and affect human health. As one of three major crops, maize is the staple food in many places in the world. Thus, improving maizeVA content is important for ensuring people health in those regions. In2010, by studying the biosynthetic pathway of carotenoids and its related genes in maize, Yan et al. found that (3-hydroxylase gene (crtRB1) can increase the (3-carotene content by18times. Furthermore, Yan et al. also revealed that β-carotene content can be increased by the function of ε-lycopene cyclase gene (lcyE), which increases the ratio of β-carotene/α-carotene. Based on the theory, researches on breeding of high VA content maize had great developments by using functional markers of these two genes. To study the mechanism of high VA content in maize, this study used the functional markers of different loci (crtRB13’TE, crtRBl5’TE, crtRB1InDel4and lcyE5’TE) of the two genes crtRB1and lcyE to detected179maize inbred lines. The results are as follows:1.In the179maize inbred lines, there were4.5%of the tested samples contained the optimal allelic variation of locus crtRB13’TE,0.6%contained the optimal allelic variation of locus crtRBl5’TE,1.7%contained the optimal allelic variation of locus crtRB1InDel4,and1.1%contained the optimal allelic variation of locus lcyE5’TE. Furthermore, sample1-7-10-2contained the optimal allelic variation of all loci of crtRB1gene; Anhui08-67contained the optimal allelic variation of both loci crtRB13’TE and crtRB1InDel4. The results mean that these two materials can be used for breeding high VA content maize.2. In the six major maize production areas in China, no optimal allelic variation of the four loci had been detected in northwestern irrigated maize production area and the Tibetan Plateau maize production area. Moreover, the maize inbred lines only had less allelic variation at each locus in these two areas. It shows that these two areas should pay attention to the improvement of the region’s maize germplasm and the use of exotic germplasm. Other maize production areas all had various variations.3. In the six heterotic populations, the optimal allelic variations were detected at locus lcyE5’TE in PA population, locus crtRBl3’TE in Tangsipingtou population, loci crtRBl3’TE and crtRB1InDel4in Lvdahonggu population. Therefore, the use of these3heterotic groups would be more likely to create a high VA maize. No optimal allelic variation had been detected in other populations.4. A new allelic variation has been identified by sequencing locus crtRB1InDel4from Liaoning138. Further studies on the function of the new allelic variation and its effects on VA content and other characters of maize should be continued.Using of functional markers greatly improved the efficiency and accuracy of marker-assisted breeding technology. The developments and applications of functional markers are important for maize breeding. The results of this study will be valuable for the high VA content maize breeding and other breeding purposes.