Is it a genetic mutation that normal stamens of wheat become pistils?

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Genetic Analysis of Male and Female Mutants in Rice

1. Genetic analysis of stamens and pistils mutants in rice (literature review)

Wang Changjian [1](2020) pointed out in the paper "Identification and gene mapping of rice floral organ development gene DPS2" that rice is one of the important food crops in China and a monocotyledonous model plant, and the formation and development of floral organs are closely related to rice yield. Cloning and functional analysis of genes related to floral organ development in rice are not only helpful to further understand the regulation mechanism of floral development in rice, but also of great practical significance for high-yield breeding in the future. In this study, a sterile mutant with pistil development defect was found from the substitution lines of CJ06 and TN 1, named DPS2 (pistil development defect 2). The differences of main agronomic characters and morphological characteristics of flower organs between mutant dps2 and wild type CJ06 were compared under the conventional planting conditions in the field. The anther structure was observed by scanning electron microscope and paraffin section, and the fertility of pollen and embryo sac was observed by dyeing. Fine gene location by map-based cloning method; Transcriptome sequencing and RT-PCR were used to analyze the expression levels of genes related to flower development in wild type and mutant. The results are as follows: the heading period of dps2 mutant is longer, the lemma and lemma of spikelet develop normally, and they can't bloom and bloom normally. At the mature stage, spikelets have residual floral organs and cannot bear fruit normally. Other agronomic characters of mutant dps2, such as plant height, tiller number, ear length, primary branch number and secondary branch number, have not changed significantly. The stamens of dps2 mutant are shriveled in different degrees, the color is transparent and light yellow, the number of stamens is increased, the pistil is shriveled and the number of stigmas is increased. Further observation showed that the anther cavity of dps2 mutant collapsed, the epidermal cells were folded and arranged irregularly, the outer surface was smooth, there were no linear substances such as wax and keratin, there were no visible microspores inside, some anthers could form cavities, pollen grains withered and no starch accumulated, so only a few pollen of the mutant were active. In addition, the development of embryo sac of dps2 mutant was affected, and the central nuclear structure of embryo sac showed signs of cell degeneration. Genetic analysis showed that mutant dps2 was controlled by a recessive single gene. Through map-based cloning, we located the DPS2 gene in the 9 1.2 Kb range on the short arm of chromosome 4, and no gene related to floral organ development was reported in this range. Transcriptome sequencing analysis showed that compared with wild type, 73 1 gene was up-regulated, and 1679 gene was regulated by dps2. These differentially expressed genes are involved in biological metabolism and biological regulation, and 9 genes are involved in auxin synthesis and signal transduction pathway. It was found by real-time fluorescence quantitative PCR that the expression of auxin synthesis-related gene TDD 1 was significantly decreased, while the expression of auxin response genes OsIAA3, OsARF 1 1, OsARF3 and OsARF 15 were significantly increased. The expression of class B genes OsMADS2, OsMADS4, osmads416 and class E genes OsMADS6, OsMADS7 and OsMADS8 in the MADS-box gene family increased significantly in dps2. The above results indicate that the mutation of dps2 may affect the synthesis or metabolism of auxin, and the stamens and pistils of DPS2 mutant develop abnormally, eventually leading to infertility. It is speculated that DPS2 may play an important role in regulating the third round stamen development and the fourth round pistil development in rice.

Yang Qian [2](2020) pointed out in the function of TaWin 1 gene in the process of wheat flower development that stamens are important flower organs in plants, and their growth and development directly affect plant breeding and crop yield. Male sterility is a phenomenon that can not produce fertile offspring due to abnormal stamen development, which is widespread in the plant kingdom. In the research of crop hybrid breeding, male sterile lines play a very important role in cultivating high-quality and high-yield varieties. Wheat is one of the three major food crops in the world. Therefore, it is of great significance to study the development of male and female stamens in wheat for improving wheat quality and increasing wheat yield. Wheat stamen-pistil homologous transformation mutant (HTS- 1) is a new mutant discovered by Professor Peng in the process of cultivating wheat near-isogenic lines. In the floret of HTS- 1, all or part of the stamens are transformed into pistils, so the number of pistils is generally 4-6. Therefore, the mutant is completely or partially sterile, and the average seed setting rate in natural state is only 15.3%. Genetic analysis showed that the mutant was controlled by at least two recessive genes (Pis 1 and hts) and had nothing to do with cytoplasmic inheritance. Among them, Pis 1 gene has been located on the 2D chromosome, which controls three pistil characters of three pistil wheat. Hts is based on a 7.2Mb interval located on the 4A chromosome. Combined with previous transcriptome analysis, a gene with abnormally high expression in abortive pistil (PS) was found in this interval, namely TaWin 1 gene. Therefore, it is speculated that the over-expression of TaWin 1 gene will lead to the homologous transformation of wheat stamens to pistils. In order to further explore the function of TaWin 1, three near-isogenic lines CSTP, CM28TP and wheat stamen were used as experimental materials, and the functions of TaWin 1 gene were analyzed by gene cloning, exogenous ethephon and 1- methylcyclopropene treatment, real-time PCR detection and transgenic Arabidopsis thaliana. The main results are as follows: the sequence similarity between CM28TP and HTS- 1 zhong 1 and TaWin 1 is 99.77%, the only difference is that two thymine (t) are inserted into the ORF downstream fragment of TaWin 1 gene in HTS- 1. Therefore, the fragment size of TaWin 1 gene in CM28TP and HTS- 1 is 883bp and 885bp respectively, and its open reading frame (ORF) length is 408bp. In the whole coding region, the amino acid sequence of TaWin 1 is 96.38% similar to Aegilops tauschii Win 1, and 64.23% similar to Leymus breviflora Win 1 and Aegilops bicolor win 1. The similarity with maize Z.mays Win 1 was 58.82%, and with Arabidopsis subspecies A.lyrata was 38.57%. Lyrata Win 1 is 62.77% similar to rice Win 1. Phylogenetic tree analysis showed that TaWin 1 protein belonged to Aegilops tauschii Win 1, anther wild rice Win 1, rice Win 1, sorghum Win 1 and corn win 1. And TaWin 1 has the closest genetic relationship with Aegilops tauschii Win 1, which further proves that TaWin 1 and Win 1 belong to the same gene family. Real-time PCR analysis showed that the expression of TaWin 1 gene in pistils and stamens of HTS- 1 was the highest, which was about 94 times that of normal pistils and 86 times that of normal stamens. 2. When ethrel and 1- methylcyclopropene (1-MCP) treated CSTP and HTS- 1 respectively, the pistil and pistil of HTS- 1 changed obviously, and the pistil of untreated HTS- 1 was 59.6. Compared with HTS- 1 without any treatment, the gynoecium of HTS-1 treated with1decreased by 24.34%, and the gynoecium rate of CSTP treated with ethephon increased by 40.23%. The expression of key genes in ethylene pathway was analyzed by real-time PCR. The results showed that the expression levels of ACO2, CTR 1 and EIN2 _ 2 in HTS- 1 young panicle were higher than those in CSTP. The expression level of HTS- 1 decreased after 1-MCP treatment, and the expression level of CSTP increased after ethephon treatment. The expression levels of ETR 1 and SAM genes in HTS- 1 young spike were significantly higher than those in CSTP, and the expression levels of HTS- 1 decreased after 1-MCP treatment. The expression levels of ETR and SAM genes in CSTP treated with ethephon and untreated CSTP were low, and the difference was not obvious. The expression level of ACS in HTS- 1 was higher than that in CSTP (about 6 times), and the expression level of HTS- 1 was significantly increased after treatment with 1-MCP. The expression of ACS in young panicles of CSTP treated with ethephon was higher than that of untreated CSTP. Among the six genes detected, the expression difference of EIN2 gene is the most obvious. In HTS- 1 treated with 1 MCP, the expression of EIN2 gene is about 5 times lower than that of untreated HTS- 1, but it is about 6 times higher than that of CSTP treated with ethylene. The expression of TaWin 1 gene in HTS- 1 young panicle was higher than that in CSTP. After HTS- 1 was treated with 1-MCP, the expression of TaWin 1 gene was up-regulated by about 9.5 times. However, there was no significant change in the expression of TaWin 1 gene in the young spike of CSTP treated with ethephon. 3. The function of TaWin 1 gene was further analyzed by transgenic Arabidopsis technology. The results showed that the overexpression of TaWin 1 gene in Arabidopsis thaliana led to a series of phenotypic changes, such as the obvious shortening of filament and pedicel length, filament degradation, filament degradation and so on. Real-time PCR was used to analyze the expression of three key enzymes in Arabidopsis thaliana ethylene synthesis in transgenic Arabidopsis thaliana and wild Arabidopsis thaliana. The results showed that except At ACS gene, the expression of other two key enzyme genes, ACS and AtSAM, was up-regulated in transgenic Arabidopsis thaliana. This indicated that TaWin 1 promoted ethylene synthesis in Arabidopsis thaliana to some extent.