Yilin Cai

Identification and characterization of paternal-preferentially expressed gene NF - YC8 in maize endosperm

Gene imprinting describes an epigenetic phenomenon, whereby genetically identical alleles are differentially expressed dependent on parent-of-origin. Some imprinted genes belonged to NUCLEAR FACTOR Y (NF-Y) transcription factors, which were involved in many important metabolic processes in plant. The characterizations of imprinted genes are of great importance for their function exploration. In this paper, 15 non-redundant NF-YC genes were identified in the maize genome and the paternally expressed gene NF-YC8 was further analyzed. NF-YC8 primarily expressed in maize immature ear and tassel and phylogenetic analysis showed that NF-YC8 was highly homologous with Arabidopsis thalianaNF-YC2 genes which function in regulation of the flowering processes, ER stress response. Furthermore, NF-YC8 was a differential, gene-specific imprinted gene at 14 DAP and persistently imprinted throughout later endosperm development in the B73/Mo17 genetic background. Bisulfite sequencing for NF-YC8 in maize endosperm showed that the paternal alleles were higher methylated (CG, CHG and CHH contexts) than maternal alleles in the 5′ upstream region, and the coding region was highly methylated in CG context. Additionally, TE (CG, CHG and CHH contexts) and repetitive region (CG and CHG contexts) were all highly methylated. These results are the first description of evolution and molecular characterization of maize NF-YC8 and will provide new references for maize NF-YC genetic analysis.

Identification of QTL for acid phosphatase activity in root and rhizosphere soil of maize under low phosphorus stress

To provide theoretical and applied references for acid phosphatase (APase) activity of maize, this study was to identify quantitative trait locus (QTL) for APase activity in root and rhizosphere soil of maize under low phosphorus (p) stress. The correlation and the QTL of APase activity in root (APR) and APase activity in rhizosphere soil (APS) were studied for the F2:3 population derived from the cross 082×Ye107 under low P stress in two sites. Analysis for each environment and joint analysis across two environments were used to identify QTL for the F2:3 population. A significant difference in APR and APS was found between 082 (P efficient genotype) and Ye107 (P deficient genotype). A large genetic variation and transgressive segregation of the F2:3 population were observed in Beibei and Hechuan. One stable QTL for APR was detected in different environments, which was located in the interval bnlg1350 to bnlg1449 on chromosome 3. Two stable QTLs for APS were detected, which were located in the interval umc2083 to umc1972 on chromosome 1 and in the interval umc2111 to dupssr10 on chromosome 5. The stable QTLs can be used in MAS breeding and theoretical study of maize.

Overexpression of a maize plasma membrane intrinsic protein ZmPIP1;1 confers drought and salt tolerance in Arabidopsis

Drought and salt stress are major abiotic stress that inhibit plants growth and development, here we report a plasma membrane intrinsic protein ZmPIP1;1 from maize and identified its function in drought and salt tolerance in Arabidopsis. ZmPIP1;1 was localized to the plasma membrane and endoplasmic reticulum in maize protoplasts. Treatment with PEG or NaCl resulted in induced expression of ZmPIP1;1 in root and leaves. Constitutive overexpression of ZmPIP1;1 in transgenic Arabidopsis plants resulted in enhanced drought and salt stress tolerance compared to wild type. A number of stress responsive genes involved in cellular osmoprotection in ZmPIP1;1 overexpression plants were up-regulated under drought or salt condition. ZmPIP1;1 overexpression plants showed higher activities of reactive oxygen species (ROS) scavenging enzymes such as catalase and superoxide dismutase, lower contents of stress-induced ROS such as superoxide, hydrogen peroxide and malondialdehyde, and higher levels of proline under drought and salt stress than did wild type. ZmPIP1;1 may play a role in drought and salt stress tolerance by inducing of stress responsive genes and increasing of ROS scavenging enzymes activities, and could provide a valuable gene for further plant breeding.