Effects Of Boron Deficiency On The Growth And Development Of Apple Rootstock Seedlings And The Expression Of Transporters

Boron is one of the important trace elements in the growth and development of plants.Excessive use of macroelement fertilizers for a long time in production ignores the use of trace element fertilizers.Boron deficiency generally occurs in apple orchard soil.Boron deficiency will affect the absorption of other elements by apples,which in turn affects the output,commodity value and edible value of apples.Rootstocks affect the growth and nutrient absorption of apple trees,and the occurrence of boron deficiency symptoms is also related to rootstocks.Therefore,it is of great significance to study the influence of boron-deficient apple rootstocks.In this experiment,apple tissue culture seedlings of M₂₆and T₃₃₇ were used as test materials.The two rootstocks were treated with boron deficiency to determine the relevant physiological indicators,including fresh weight,dry weight,plant height,boron content,boron cumulative amount,cell wall boron,Sugar alcohols,organic acids,chlorophyll content and photosynthetic parameters were analyzed for boron deficiency in two varieties of rootstocks.This paper also identified 9 apple BOR genes,and analyzed the expression of these two apple rootstocks at different positions and at different times after boron deficiency treatment by real-time fluorescence quantitative analysis,laying the foundation for further research on these BOR genes.The results are as follows:After boron deficiency treatment,the dry weight,fresh weight and plant height of the apple rootstocks of the two varieties were lower than the control,and the plant height of T₃₃₇ was significantly higher than that of M₂₆.After the boron deficiency treatment,photosynthetic pigments were reduced to different degrees compared with the control.The photosynthetic pigment content of the leaves of T₃₃₇ and M₂₆ was lower than the normal boron content,and there were significant differences;the chlorophyll a of these two varieties was reduced by 13.58%,9.29%,chlorophyll b decreased by 33.43%,17.43%,total chlorophyll 17%,11%.The cell wall boron content of these two varieties decreased after the boron deficiency treatment;the cell wall boron content of T₃₃₇ and M₂₆ decreased by 4.3%and 14.2%respectively after the boron deficiency treatment,but the decline of M₂₆was greater than that of T₃₇₇.Regardless of boron deficiency,the net photosynthetic rate,stomatal conductance,and transpiration rate of apple leaves were significantly higher than those of the control.After the boron deficiency treatment,the contents of inositol and sorbitol in the leaves of T₃₃₇ and M₂₆ decreased compared with the control,M₂₆ The decline is even greater.Candidate members of the apple BOR gene family were identified;through bioinformatics analysis,9 BOR genes were identified from the apple genome.The 9MdBORs genes of the apple BOR gene were located on No.6,9,13,14,and 16.On 6chromosomes such as No.17 and No.17,the apple MdBOR protein family is mainly distributed on the plasma membrane by subcellular localization analysis.After the same boron deficiency treatment,through the analysis of the expression levels of the two apple rootstocks at different positions and at different times,the results showed that the expression levels of most genes in the leaves were relatively high,and the expression levels of a few genes in the roots and stems were significantly higher than those in the roots and stems.Leaves,in M₂₆,MdBOR1,MdBOR2,MdBOR4,MdBOR6,MdBOR7,MdBOR8 and other 6 genes have the highest expression levels in leaves,all higher than roots and stems;while MdBOR3 and MdBOR9 expression levels in roots are the highest,high On stems and leaves;the expression trends of these two apple rootstocks are basically the same in each part.