Genetic Identification Of Tobacco Leaf Vein Mutants And Analysis Of Physiological Characteristics Under Drought Stress

Tobacco(Nicotiana tabacum L.)is an important foliar economic crop,and its leaf growth directly affects its economic value.Leaf veins can provide moisture and nutrients to the leaves and play a mechanical support role.It is helpful to understand the physiological characteristics and inheritance laws of traits of leaf vein mutants,which is helpful to understand the related mechanisms of leaf veins in plants.The leaf vein mutant plants and wild-type plants were selected to cross and then selfed,and the trait separation status of the selfed progeny population was analyzed.After drought treatment,the relevant physiological indexes of mutant and wild-type progeny plants were determined and compared to study their drought resistance potential.On the basis of understanding the vein formation mechanism of other plants,the expression of AUX and PIN related genes in tobacco tissues was analyzed.The research results are as follows:1.Genetic analysis and phenotypic observation of common tobacco leaf vein mutantsThrough genetic analysis,it was found that the leaf vein mutation trait is a dominant trait caused by a single gene mutation.The main veins of the leaf vein mutants are fused fine veins,the second and third level veins are more and disordered,and the leaf vein density and stomatal density are greater than those of wild-type plants.2.Phenotype observation and physiological characteristics detection of mutant plants under different water conditionsTo explore the physiological characteristics of mutant plants under drought,mutant and wild-type tobacco seedlings at the six-leaf stage were selected for drought stress treatment.The results showed that the leaves of the mutant plants had stronger drought tolerance and recovery ability,and the indicators of photosynthetic characteristics under drought stress were better than those of the wild-type plants;the mutant plants had higher proline content than the wild-type plants,and were more resistant to oxidation Sex and damage resistance are stronger,indicating that the mutant plants are more resistant to drought.3.Determination of IAA and CTK contents in different parts of leaves of mutant and wild plants under different water conditionsCompare the changes of IAA and CTK contents in different parts of leaves of mutant and wild plants.The results showed that under normal watering,the IAA content in different partsof the leaves of the mutant plants was significantly lower than that of the wild type,the IAA content of the leaf tip was significantly lower than that of the leaf base,and its CTK content was significantly higher than that of the wild type plants;The IAA and CTK contents of wild-type plants and wild-type plants both increased first and then decreased,but the wild-type plants decreased to a greater extent.4.Analysis of the expression levels of genes related to auxin transport in the roots,stems and leaves of mutant and wild plants under different water conditionsThe mutant and wild-type plants at the 6-leaf stage were subjected to drought treatment,and normal watering was used as a control to determine the predicted gene expression changes.The results showed that under normal watering conditions,the predicted genes of mutant plants and wild-type plants had different expression levels.The genes related to the IAA output vector NtPIN1 a and NtPIN1 b in the PIN gene family related to the vein development in roots,stems and leaves,Nt PIN6 and leaf vein morphogenesis-related genes NtATHB-8 expression levels are higher in mutant plants than wild-type plants,which may be related to the generation of fused leaf veins in mutant plants.Drought stress response gene NtNAC1 expression is higher than that of wild-type plants,which corresponds to the results of mutant plants having better drought resistance in the determination of physiological characteristics.Under drought treatment,the expression levels of the six predicted genes between the mutant plants and the wild-type plants were different,all of which showed that the expression levels of the mutant plants were higher than those of the wild-type plants;at the same time,compared with normal watering,IAA The NtAUX1 gene expression of the input vector was different in the roots,stems,and leaves of mutant and wild plants,and the expression of NtATHB-8,a gene related to leaf vein construction,was different in the roots.