Author: Qin high Harting

Published by: Institute of Biotechnology, Chinese Academy of Agricultural Sciences

Chinese Core Journal: China Agricultural Science and Technology Review

Research Background:

Transcription regulation can change the level of gene expression, thereby regulating the growth and development of organisms and responding to adversity stress. At present, 2300 transcriptional regulatory factors have been identified in rice. According to their protein structure, they are divided into different families, such as MYC family, MYB family, WRKY family, AP2/EREBP family and TALE family. Among them, the TALE family contains two sub-families: KNOX and BELL. The function of BELL family in rice root development and stress response remains to be studied.

Research ideas

In this study, four BELL4 homologous genes were identified in rice by sequence alignment with Arabidopsis thaliana, and the promoter elements of their homologous genes were analyzed. Furthermore, the expression patterns of BELL4 homologous genes in rice seedling roots under different hormones and abiotic stresses were analyzed. At the same time, OsBELL4 was used to analyze its function in rice root development and its regulatory relationship with WOX family.

background knowledge

1: Plant root system is the contact part of plant and soil. It is also an ideal model for studying plant adaptation to the environment and coping with adversity stress. It plays an important role in the entire growth and development process of plants.

2: The members of the BELL family play important functions in the development of meristems and floral organs, the initiation and maintenance of bud tip meristems, leaf development, flowering, egg cell differentiation and integument development.

Main results:

1: The promoter of BELL4 in rice contains elements that respond to abscisic acid, ethylene, gibberellin and auxin

Analysis of the 2kb promoter region on the start codon ATG of the rice BELL4 homologous gene revealed that the promoters of the four genes contained elements that respond to abscisic acid, ethylene, gibberellin and auxin, indicating that the BELL protein is in rice Function is regulated by plant hormones or external environment

Legend: BELL4 gene promoter sequence analysis

2: Effects of different hormones on BELL4 homologous genes in rice roots

Legend: Expression analysis of rice BELL4 homologous genes under different hormone treatments

Under the treatment of 100 μmol/L IAA and ACC, the expression of OsBELL4B, OsBELH4A, OsBELH4A and OsBELH4B was rapidly down-regulated in rice roots. Under the treatment of 10 μmol/L GA3, the expression of OsBELL4B and OsBELH4A was down-regulated sharply, and the expression of OsBELH4 was significantly increased. . The effect of ABA on the expression of OsBELH4A and OsBELH4B was not obvious, and the inhibition was partially relieved after 12 h. It shows that the BELL4 homologous genes in rice roots can respond quickly to plant hormones such as ethylene, auxin, gibberellin and abscisic acid.

3: Effects of abiotic stress on BELL4 homologous genes in rice roots

Figure Note: Analysis of the expression pattern of rice BELL4 homologous genes under drought, low temperature and salt treatment conditions

The roots of Nipponbare seedlings were treated with drought, low temperature and salt. The drought treatment inhibited the expression of OsBELL4A and OsBELH4A, but induced the expression of OsBELH4B, and had no significant effect on the expression of OsBELL4B. Under low temperature stress, the gene expression of OsBELL4A and OsBELL4B has a trend of up-regulation, and the later expression level will be suppressed, while OsBELH4A and OsBELH4B have been showing a trend of down-regulation. Under salt stress, OsBELH4A and OsBELH4B showed an up-regulation trend at 0.5 h and 6 h, respectively, and the expression of OsBELL4A and OsBELL4B genes showed a down-regulation trend. This different expression pattern indicates that BELLE homologous genes in rice roots are involved in the growth and development process and stress resistance mediated by these hormone signals.

4: Phenotype analysis of OsBELL4A RNAI interference transgenic plants and analysis of WOX family gene expression

Legend: OsBELL4A RNAi interferes with the root phenotype of transgenic plants at seedling stage

The RNAi of OsBELL4A interfered with the root growth of transgenic plants and was significantly different from that of wild-type (NIP), indicating that OsBELL4A is involved in regulating the development of rice seedling roots. Inhibiting the expression of OsBELL4A can promote the development of crown roots and delay the elongation of primary roots.

Legend: OsWOX gene family expression levels in OsBELL4A RNAI transgenic plants

The two interfering lines of OsBELL4A, RI-49 and RI-58, both showed an increase in the number of crown roots and a decrease in the length of the main root, and the expression of OsWOX9 in these two lines was significantly increased compared to the wild type. This indicates that OsBELL4A's regulation of OsWOX9 gene expression may be the reason why OsBELL4A RNAI interferes with the increase in the number of crown roots of transgenic plants.

in conclusion:

BELL family genes are involved in a variety of plant hormone signal transduction and adversity response responses in rice roots, and OsBELL4A plays a regulatory role in rice root development. This role is closely related to the expression of OsWOX family genes. This research enriches the functions of the BELL family genes and lays a foundation for exploring the functions of the BELL family in rice root development and stress response.