Wang Haiyang's team revealed a transcriptional regulation network for maize inflorescences with UB2/UB3/TSH4 as the core

Recently, the Wang Haiyang Research Group of College of Life Sciences, South China Agricultural University, State Key Laboratory of Subtropical Agricultural Biological Resources Conservation and Utilization, Guangdong Laboratory of Lingnan Modern Agricultural Science and Technology, and the Institute of Biotechnology, Chinese Academy of Agricultural Sciences, published a report entitled UB2/UB3/TSH4-anchored transcriptio in The Plant Cell (impact factor 12.
085).
nal networks regulate early maize inflorescence development in response to simulated shade", which analyzed the transcriptional regulatory changes of male and fruit ear development in maize in response to simulated dense planting conditions, and identified a process with UB2/UB3/ TSH4 as the core transcriptional regulatory network regulates the development of maize inflorescences in response to dense plant shade signals
.
(Paper online website https://doi.
org/10.
1093/plcell/koac352
).

 

Maize (Zea mays) is one of the world's most important crops and is widely used in food, feed and bioenergy
.
To meet the growing global demand for corn production, breeders have been continuously selecting corn varieties that can be grown at higher densities to increase yields over corn land area
.
However, under high planting density conditions, neighboring plants will consume photosynthetic active radiation (PAR), resulting in a decrease in the ratio of red light to far-red light (R:FR), causing shade syndrome (SAS) in plants, which is manifested by increased plant height, increased risk of lodging, early flowering, prolonged interval between male and female spike spinning (ASI), and reduced male panicle size and number of grains per panicle decrease, ultimately leading to severe yield
reduction.
Maize is a typical dioecious plant, with male inflorescences (male spikes) growing on top of the plant, while female inflorescences (female spikes) develop into lateral branches of leaf axils, located on
several nodes below the male panicles.
Male and female panicles are the reproductive organs of maize and are not only important determinants of maize yield, but also model systems
for studying plant organogenesis.
However, the molecular regulatory mechanism of SAS in maize is still unclear
.

 

In order to explore the effect of high-density planting on the development of maize inflorescences, the researchers performed far-red light (EOD-FR) and daytime normal light supplementation (WL+FR)) treatments to simulate shade avoidance conditions after the end of the day, and systematically studied
the continuous developmental stages of male (V3-V9) and female panicles (V8-V12) of maize 。 Using stereo microscopy system observation, the researchers revealed that simulated shade treatment effectively accelerated the transition from shoot apical meristem (SAM) to inflorescence meristem (IM), leading to the early development of various types of
meristem in male and female spikes.

 

In order to analyze the molecular basis of the effect of simulated shade treatment on the development of maize male inflorescences, the researchers performed RNA-seq comparative analysis
of stem tips and immature male panicles of maize seedlings grown under normal white light conditions and EOD-FR treatment (V3 to V9).
A total of 1.
92 billion high-quality reads were generated using the Illumina sequencing platform, which were then mapped to the B73 reference genome (RefGen_V4)
using Hisat2.
In 26 datasets, a total of 21,367 gene expressions
were found.
WGCNA (weighted gene co-expression network) analysis revealed that three homologous Squamosa promoter binding protein (SBP)-like (SPL) transcription factors UB2, UB3 and TSH4 are key regulatory centers for the development of male spikes, functionally related to 3233, 3233 and 2473 genes, including many belonging to MADS, TCP, BHH, WRKY, Genes
from the EREB and ARF gene families.
Furthermore, the DNA affinity purification sequencing (DAP-seq) data of UB2 and UB3 were superimposed with RNA-seq data to identify a batch of candidate target genes
directly regulated by UB2 and UB3 。 Furthermore, RT-qPCR, in situ hybridization, yeast single hybridization (Y1H), protoplast diluciferase activity, gel electrophoresis mobility transfer assay (EMSA) proved that UB2/UB3/TSH4 can directly bind to the promoters of BIF2 and ZmTCP30 genes, directly activate their expression and regulate the formation and development
of male and female ears of maize 。 This study not only revealed a transcriptional regulatory network of maize inflorescence development response shade avoidance with UB2, UB3 and TSH4 as the core, but also identified a number of key transcription factors and plant hormone signal response factors that responded to dense cultivation conditions, which provided a theoretical basis and genetic resources
for the cultivation of densely tolerant maize varieties.

 

Associate Professor Kong Dexin of College of Life Sciences, South China Agricultural University is the first author of the paper, Dr.
Li Changyu, Ph.
D.
student of the Institute of Biotechnology, Chinese Academy of Agricultural Sciences, doctoral student Xue Weicong and Associate Professor Wei Hongbin of the School of Life Sciences of our university are the co-first authors of the paper, Professor Wang Haiyang is the corresponding author of the paper, and Associate Professor Liu Qing is the co-corresponding author
of the paper.
Professor Wu Hong provided a platform for cytology observation in this study and participated in part of the work
.
This paper has been supported
by the National Key Research Program of China, the National Natural Science Foundation of China, the Natural Science Foundation of Guangdong Province and other projects.

 

Professor Wang Haiyang's team has long been engaged in the research
of maize shade avoidance response and the regulation mechanism of dense tolerance ideal plant type.
In previous studies, the team has demonstrated that maize phyB (ZmphyB1 and ZmphyB2), phyC (ZmphyC1 and ZmphyC2), and 7 ZmPIF genes are involved in the maize shade avoidance response
。 In addition, the team also systematically analyzed the breeding selection fingerprint of inbred line tolerance genetic improvement in the process of modern maize breeding, as well as the genetic improvement law of paternal and maternal groups in different heterooptimal models, in Nature Genetics, Nature Plants, The Plant Cell, New Phytologists, Plant Biotechnology Journal, Plant Physiology and other journals have published a series of research results, which have received extensive attention
from the industry.