The "treasure" gene helps the corn seeds dehydrate quickly

the realization of grain harvest is an important direction of the development of corn industry in China, and the moisture content of mature grain of corn is the key factor to determine the mechanized harvest of grain.
" corn seed moisture content belongs to the typical quantitative characteristics of genetic, control of its characteristics of the gene is more complex, cumbersome measurement methods, the current progress in basic research is slow, but also restrict the process of selection and breeding of dehydrated fast corn varieties. Yan Jianbing, a professor in the corn team at Huazhong Agricultural University, told China Science Daily.
Recently, the corn team of Huahua Agricultural University published the latest results in the journal Plant Biotechnology, revealing the genetic structure of the dynamic changes in the moisture content of corn grains, and for the first time cloned a main gene
that affects the dehydration of corn seeds, providing valuable genetic resources for the selection of fast dehydrated corn."In the past, our country's corn harvest depended on labor, farmers to the field to pick corn spikes, when labor costs were very low. But now China's rural labor costs have greatly increased, to improve corn cultivation income must rely on mechanized harvesting. Xu Mingliang, a professor at china Agricultural University who has long been involved in corn research, told China Science Daily.
, the mechanized direct harvest of corn seeds is a very important link in corn production. One of the main factors is the moisture content of corn seeds at harvest.
grain moisture content needs to be less than 25%, and most corn varieties in China harvest grain moisture content between 30% and 35%.
Yingjie, co-author of the paper and an associate professor at Huahua Agricultural University, said that the moisture content of corn grain harvest is mainly determined by the moisture content of the grain when physiologically mature and the rate of dehydration after maturity.
found that the rate of dehydration after the grain matures is dominated by environmental factors, and when the water content exceeds 30%, it is mainly affected by temperature and air humidity.
In fact, by the field for a long time station dehydration can make corn seed moisture content to meet the requirements of the machine harvest, however, most of China's corn cultivation areas have adopted a rotating system, "after receiving corn immediately to plant a crop, such as the Huanghuaihai region to immediately plant winter wheat, timely grab heat, otherwise it will seriously affect the wheat harvest." Yan Jianbing said.
Not only is the rotation area corn too late to wait until the water content drops to be harvested, the mature corn in the northeast corn growing area also needs to be dehydrated quickly, otherwise encounter frost or temperature is too low, moisture can not fall to the level of machine demand.
addition, "additional drying or drying will increase labor and transportation costs." Yan Jianbing believes that since the external environment can not be changed, the breeding scientists have to start from the corn varieties, through genetic improvement to select rapid dehydrated corn varieties, to adapt to the current mechanized harvest demand is an important demand for industrial development.
Xu Mingliang believes that in order to cultivate varieties that meet the conditions of corn cultivation in China, we must rely on the strength of domestic scientists. Although China has introduced some foreign corn varieties, they can also meet the conditions of direct grain harvest, but these varieties are not much area of cultivation, far from meeting the needs of large-scale machine harvest.
, in the past ten years, China's agricultural scientists began to study how to cultivate suitable for China's mechanized corn cultivation varieties.
Yan Jianbing told reporters that the United States corn machine harvest varieties have gone through more than 100 years of breeding process, because the U.S. corn cultivation industry from the beginning to rely on mechanical harvesting. China's related research started late, because China's agricultural demand for mechanization is only in the past ten years.
a difficult problem for scientists to develop varieties that match the direct yield of corn grains in a short period of time.early studies suggest that the water content of corn grains is controlled by genetic factors when they mature physiologically.
Xiao Yingjie introduced, because of the physiological maturity of different corn genotype differences, early study of grain moisture content, mainly through the measurement of biomass differences after drying to indirectly measure water content, the method is cumbersome, time-consuming and labor-consuming, can not directly guide breeding applications, it is difficult to understand the dynamic changes in the physiological maturation process of grain moisture.
, there have been no reports of gene cloning related to the moisture content of corn grains, and basic research has lagged behind.
The corn moisture regulatory gene is a quantitative sex gene, that is to say, the number of genes that control the sex is large, each gene has little effect, so it is a very complex study to find the main gene or all the genes that regulate the sex.
"We solved this problem with very good corn materials and high-density marking." Yan Jianbing said.
Previously, Yan Jianbing's team, based on the corn-related groups it led and widely used by domestic and foreign counterparts, integrated the genome, transcription group, esogroup, metabolic group, oscic genome, genetic variation and genetic positioning results, and constructed ZEAMAP, an integrated database of corn genus.
the first author of the paper, Li Wenqiang of Huazhong Agricultural University, introduced that using the above-mentioned corn-related groups of 507 self-intersecting departments, Yan Jianbing team in five typical environments in the country arranged field experiments. Continuous dynamic monitoring of cornseed water content with handheld moisture meter, through artificial control of pollination time, to ensure the uniformity of the measurement time, every 6 days, 5 consecutive measurements, a total of more than 750,000 water content data points collected. Through the comparative analysis of the data, a relatively simple and operanose field moisture detection technology is established.
Yan Jianbing likened the process to digging "treasures". The grain moisture control gene hidden in the corn genome is like a grain of gemstone.
, the research team needs to make sure that there is definitely a place to "dig" to the gem. "The 507 self-relationships we built in the corn-related population covered more than 80 percent of the genetic diversity of cultivated corn, which contained the vast majority of corn-like genes, including water-control genes."
, the research team will find a good way to "dig" out the gems. "It's like there must be gems in the straight line from Beijing to Wuhan, which used to be dug every 10 kilometers, and now we dig every 1 kilometer, and the probability of digging gems is much higher." In the study, the "excavation" distance was determined by the 1.25 million high-quality single nucleotide polymorphism (SNP) markers previously obtained, meaning that they had as many as 1.25 million "excavation points" in the corn genome.
combined with the esolysic data of cornseed moisture content obtained from the above field experiments, at the genome-wide level, they identified a total of 71 quantity points (QTL) that affected the water content of the grain. "71 gems were dug." Yan Jianbing said.further, they found significant interactions between these quantitative feature points, as well as between quantitative presences and the environment.
Yan Jianbing explained that a single quantitative status points often have to be combined with other locations to play a role in regulating downstream genes or molecular mechanisms, thereby affecting the moisture content of corn seed, while some quantitative status points respond to environmental temperature and humidity, are activated in different environments, thus initiating subsequent molecular mechanisms, but also regulating the moisture content of corn seeds at different times.
" also suggests that breeders need to take full account of gene and gene interoperability, as well as gene-environment interoperability, as well as esoterype assays and time nodes. Yan Jianbing said.
, using genome-wide association analysis, they detected a primary quantitative characterity bit on chromosomes 7 and 9 of the corn. Combined with further analysis, the team nominated two candidate genes and verified the function of one of the candidate genes.
the gene encodes a gar2-related nuclein protein and is therefore named
.
Li Wenqiang, the experiment found that the gene's functional loss mutation can improve grain moisture content and slow down the rate of dehydration, indicating that GAR2 is a negative regulatory factor for corn seed moisture content.
"This is the first time that a clone has been made to a point of quantity that regulates the moisture of cornseed grains." Xu Mingliang said that Yan Jianbing's team will conduct further research on the molecular regulatory mechanism of the gene. If the natural variation of the plant can be found at this point, further verification will be helpful to gain an in-depth understanding of the regulatory mechanism of the relevant genes.
this work will provide a viable technical path and valuable genetic resources for the next step in the cultivation of rapidly dehydrated maize varieties to meet the critical needs of the state and industry.
" Of course, this is the first corn seed moisture control gene found so far, the follow-up needs to find in nature dehydration fast, low water content of the excellent alleloic variation, to clarify its molecular regulation mechanism, it can be better used in actual production. Xu Mingliang said.
relevant paper information: