Genetic Analysis And Gene Localization Of Petiole Mutants In Nicotiana Tabacum L.

Petiole is an important part of tobacco leaves,the upper end of which is connected with the blade through the vascular bundle,and the lower end is connected with the stem through the vascular bundle.The water,hormones and nutrients needed for the development of the leaves were transported by the petiole.We study petiole traits of Nicotiana tabacum L.to isolate and identify the genes related to the development of tobacco petiole.A long petioles stable mutant?M50?and a short stable petioles mutant?M46?,whose wild type had no petioles,was obtained respectively from Nicotiana tobacum L.varieties Honghuadajinyuan and Zhongyan100 by EMS mutagenesis.Two petioles mutants were hybridized with their own wild type Honghuadajinyuan and Zhongyan100 respectively,as well as Nicotiana tobacum L.variety Gexinsanhao?G3?,resulting in the formation of F₁.The F₁ was self-crossed to obtain F₂population and were then backcrossed to respective wild types to get BC₁F₁ population.All kinds of materials were cultivated at the same time and were carried on Phenotypic investigation and statistical analysis.The M50 and M46 mutant genes were mapped to LG18 and LG16 by SSR markers.The main results are as follows:?1?Phenotypic identification:The mutant leaves,compared with Honghuadajinyuan?control?,of the long petiole mutant M50degenerated from the leaf auricles connecting the leaf base of the stem to the central of leaves.Only the remaining main vein and degraded the leaf auricle form a long petiole trait.No degraded part of the leaf still forms the normal blade.The whole leaf,different with the leaf auricle of wild type,shows the abnormal leaf trait of no leaf auricle.The mutant leaves,compared with Zhongyan100?control?,of the short petiole mutant M46 only degenerated from the leaf auricles connecting the leaf base of the stem,forming a bit of petiole.no degraded part of the leaf still forms the normal blade,the shape of which becomes a peach leaf.The whole leaf,different with the leaf auricle of wild type,shows the abnormal leaf trait of no leaf auricle.?2?The results of genetic analysis:A long petioles mutant?M50?used as male parent was hybridized and backcrossed with their own wild type Honghuadajinyuan and Nicotiana tobacum L.variety Gexinsanhao,respectively,resulting in the genetic population formation of F₁,F₂,BC₁F₁.Genetic analysis showed that F₁ hybridized by a long petioles mutant M50 and Honghuadajinyuan or Gexinsanhao were all characterized by a long petiole mutation phenotype with the same mutant M50.It was preliminarily determined that the long petiole mutant trait of the long petioles mutant M50 was dominant.Observation separation ratio of the long petiole mutant phenotypes and no petiole wild type phenotypes were respectively 3.17:1 and 3.30:1 in F₂ groups of a long petioles mutant M50 and Honghuadajinyuan or Gexinsanhao.Theoretical separation ratio all conformed to 3:1 by the chi square(?² value<?²_0.05=3.841)test validation:0.069<3.841 and0.140<3.841.The results showed that the long petiole mutant trait of the long petioles mutant M50 was controlled by a pair of dominant genes.Observation separation ratio of the long petiole mutant phenotypes and no petiole wild type phenotypes were respectively 0.86:1 and 1.27:1 in BC₁F₁ groups of a long petioles mutant M50 and Honghuadajinyuan or Gexinsanhao.Theoretical separation ratio all conformed to 1:1 by the chi square(?² value<?²_0.05=3.841)test validation:0.400<3.841 and1.190<3.841.The results were verified that the long petiole mutant trait of the long petioles mutant M50was controlled by a pair of dominant single gene.A short petioles mutant?M46?used as male parent was hybridized and backcrossed with their own wild type Zhongyan100 and Nicotiana tobacum L.variety Gexinsanhao,respectively,resulting in the genetic population formation of F₁,F₂,BC₁F₁.Genetic analysis showed that F₁ hybridized by a short petioles mutant M46 and Zhongyan100 or Gexinsanhao were all characterized by a short petiole mutation phenotype with the same mutant M46.It was preliminarily determined that the short petiole mutant trait of the short petioles mutant M46 was dominant.Observation separation ratio of the short petiole mutant phenotypes and no petiole wild type phenotypes were respectively 2.76:1 and 2.54:1 in F₂ groups of a short petioles mutant M46 and Zhongyan100 or Gexinsanhao.Theoretical separation ratio all conformed to 3:1 by the chi square(?² value<?²_0.05=3.841)test validation:0.211<3.841 and0.949<3.841.The results showed that the short petiole mutant trait of the short petioles mutant M46 was controlled by a pair of dominant genes.Observation separation ratio of the short petiole mutant phenotypes and no petiole wild type phenotypes were respectively 0.98:1 and 1.27:1 in BC₁F₁ groups of a short petioles mutant M46 and Zhongyan100 or Gexinsanhao.Theoretical separation ratio all conformed to 1:1 by the chi square(?² value<?²_0.05=3.841)test validation:0.024<3.841 and0.095<3.841.The results were verified that the short petiole mutant trait of the short petioles mutant M46 was controlled by a pair of dominant single gene.?3?The results of gene localization:Gene mapping population is BC₁F₁ backcrossed by a long petioles mutant M50 or a short petioles mutant M46 and Gexinsanhao.Using BSA method,the M50 mutant gene and M46 mutant gene were respectively located by SSR markers of evenly distributed on 24 chromosomes of tobacco.At last,the long petiole M50 mutant gene was located between the marker PT51191 and the marker TM10541 of eighteenth linkage group.The genetic distance between the gene and the two markers was respectively1.98cM and 1.98cM.The short petiole M46 mutant gene was located between the marker PT51801 and the marker PT20196 of sixteenth linkage group.The genetic distance between the gene and the two markers was respectively 6.42c M and 4.26cM.