Analysis On Main Agronomic Traits And Genome Variation In High-fertility Tetraploid Rice

autotetraploid rice is a kind of germplasm devleloped by duplicating chromosome of diploid rice. Indica-japonica autotetraploid hybrid rice F1 has shown distinct biological superiority and yield improvement potential. As Indica-japonica tetraploid hybrid rice F1 show low fertility, they are difficult to be directly utilized in rice production. Through years of effort, our lab had breed high-fertility tetraploid rice, which not only have high fertility, but also can conquer the obstacle of F1 low fertility. For accelerating the ulitization of this germplasm, this research had done following research; firstly, surveying the main agronomic traits and heterosis of 3 high-fertility tetraploid rice; secondly, performing the observation of pollen mother cell meiosis behavior of Hua Duo2, which is a high-fertility tetraploid rice authorized as national new variety; thirdly, studying the genome variation of Hua Duo2 through resequencing, The major results were as folows:(1)High-fertility tetraploid rice show excellent agronomic traits. Compared with tetraploid parents, 3 high-fertility tetraploid rice improve greatly in plant height, filled grain number per plant, seed-seting rate, filled grain weight per plant and 1000-grain weight. Compared with tetraploid parents, high-fertility tetraploid rice Hua Duo2 showed significant improvement in filled grain number per plant, seed-seting rate, grain weight per plant and 1000-grain weight, 192.74%, 193.37%, 236.90% and 19.82% higher than T44, 23.22%, 75.09%, 85.41%, 115.51% and 24.47% higher than T45. When hybridizing high-fertility tetraploid rice with different type of low-fertility autotetraploid rice, F1 not only showed sed-setting rate over 73%, but also shows distinct heterosis, among which F1 of hybridizing with Hua Duo2 showed 135.52%, 67.47%, 57.57% and 134.76% heterosis over mid-parent in filled grain number, total grain number, sed-setting rate and grain weight per plant, which suggest that Hua Duo2 shows utilization potential in polyploid rice breeding.(2)Hua Duo2 showed normal pollen fertility, chromosome abnormalities of pollen mother cell at meiosis stage. The pollen fertility of Hua Duo2 get up to 88%, 62.18% higher than T44 and 46.89% higher than T45. The meiosis process of HUADUO2 was same as that of diploid rice, which had gone through 9 stages. Compared with two parents, Hua Duo2 shows lower frequency of chromosome stragging at metaphase I, 72.77% lower than T44 and 69.34% lower than T45. lower frequency of chromosome lagging at anaphase I, 72.45% lower than T44 and 68.03% lower than T45. All these results suggest that lower chromosome behavior abnormalization frequency may be the reason for high pollen fertility.(3)Through whole genome sequencing variation analysis, there are 23.36 Gb, 21.55 Gb, and 21.49 Gb base obtained in Hua Duo2 and its parents T44 and T45. up to 53 X, 48 X, 49 X in coverage depth. Through compared with its parent T44, there are 965679 SNP, 141155 In Del and 1948 个 SV in Hua Duo2, which showed that HUADUO2 is nearer to T45 in genetic relation than T44. These SNP and In Del is mainly located in intergenic region and gene downstream(intron), up to 88.14% and 86.99%.There are commonly 118961 SNP, 18922 In Del and 972 SV in high-fertility tetraploid rice Hua Duo2, among them 1647 gene has functional effect variation. GO Ontology enrichment analysis showed that 12 gene enriched in pollen-pistil interaction biological process, all these gene may be important to tetraploid rice fertility and can be further studied.In summary, Hua Duo2 showed better seed-setting rate and other yield traits, lower abnormal frequency. High pollen fertility, and strong heterosis. Whole genome resequencing revealed rich genetic variation in HUADUO2, and among them fertility related gene may exist.