Mechanism Of Fertility Conversion In Thermo-sensitive Male Sterile Wheat Line Yanzhan 4110S

Male sterility is prevalent in the plant kingdom and it plays an essential role to exploit heterosis.The photo-thermosensitive male sterility(PTMS)line can applied in the two-line hybrid farming systems,where it can keep male sterility via self-pollination at certain temperature and can be crossed with a pollen donor to produce hybrid wheat seeds in other conditions.In particular,the growth of the PTMS system has accelerated hybrid wheat breeding.The plant materials used in this study included the wheat male sterile line Yanzhan 4110 S,which is a genic male sterile line derive from a cross between Xinong 291 S and wheat cultivar ‘Yanzhan 4110',and successive selfing and backcrossing.The line Yanzhan 4110 S has the same thermosensitive trait as Xinong 291 S.Yanzhan 4110 S is completely sterile under high-temperature conditions but fertile under low-temperature environment and it has potential application in two-line wheat cross breeding.Neither morphological and physiological aspects,nor its molecular mechanism about fertility change remains to research.The TGMS wheat line Yanzhan 4110 S and the control cultivar(Yanzhan 4110)were as materials.Firstly,we characterize the Yanzhan 4110 S by the interval method planting and the tiller regeneration technique.Crucial growth stage and temperature for fertility conversion were confirmed by warm greenhouse study.Phenotypic and cytologic observation were applied to find out the fertility conversion characteristics and mechanism.And RNA-Seq was also applied to study pathways network associated with fertility based on different expression genes.The purpose of this experiment is to get the molecular system of fertility change and provide contribution to the production and utilization of thermo-sensitive male sterile wheat materials.The results of study are as following:1.The interval method planting and the tiller regeneration technique were used under natural conditions,the selfed seed set rate of Yanzhan 4110 S was zero,which indicated that its fertility was changed and it obviously exhibited a fertility transformation trait.Moreover,the fertility changes in Yanzhan 4110 S were significantly correlated with the mean temperature.In the study of warm greenhouse,male sterility occurred when the mean day temperatures exceed 20? and the crucial growth period was the later uninucleate stage.Therefore,Yanzhan 4110 S is a TGMS line induced by high temperature.2.According to phenotypic characteristics,there were differences between the sterile and fertile plants during the trinucleate stage,the anthers were fully plump and the pollen abortion type was stainable abortion.Moreover,cytological study showed delayed tapetum PCD under high-temperature conditions which affected microsporogenesis especially at the later uninucleate stage,with defective pollen exine,finally led to male sterility.3.To provide a new opinion of the fertility change system in Yanzhan 4110 S wheat line at molecular level,we are dedicated to investigate the transcriptional of wheat anthers by RNA-seq and identified the DEGs related to fertility conversion.There were 3420 DEGs in total,including 2331 up-regulated genes and 1089 down-regulated genes.1494 DEGs were annotated into 25 groups by KOG.GO assignment was used to assign 3420 DEGs to 54 functional groups in the three broad categories.We studied the key enzymes involved in phenylpropanoid biosynthesis,long chain fatty biosynthesis and jasmonic biosynthetic network pathways.The down-regulation of key enzymes in these pathways might result in a decreased production of final products,affecting the development of pollen wall and anther dehiscence,finally caused male sterility.The qRT-PCR results of DEGs were consistent with the RNA-seq results.The final production jasmonic acid content was also coincidence with pathways.This article laid a foundation for further study of gene function.In this study,the molecular mechanism of sterility of Yanzhan 4110 S was revealed by field and warm greenhouse study,phenotypical and cytological observation,RNA-Seq analysis and the verification,which constitutes a regulatory network.This study provided theoretical support for male sterility.