Epidermal Wax Analysis Of Apple Peel In Wet And Dry Areas

Plant epidermal wax usually consists of the outer wax covering the outermost layer of the stratum corneum and the inner wax embedded in the stratum corneum.The outer waxy crystal structure often accumulates in the outermost layer of the stratum corneum in a three-dimensional structure,which can be clearly observed by scanning electron microscope,but the inner wax has no specific shape.The epidermal wax of apple fruit usually has a flaky structure,and there are obvious differences among different apple varieties.Apple peel wax is mainly composed of very long chain fatty acids and their derivatives.The very long chain aliphatic waxes in apple peel mainly include alkanes,primary alcohols,secondary alcohols,aldehydes,ketones and esters.However,the specific components vary greatly in different varieties.Orchard environment can affect the growth and development,yield and quality of apples.Temperature,light,water and soil directly affect the growth and development of fruit trees.However,little is known about the effect of environmental factors on apple wax biosynthesis.In this experiment,the marshal apple ‘EAiErHao' was used as the experimental material to study the composition,content and shape of apple epidermal wax in dry and wet areas.The correlation between environmental factors and the apple wax content at 90 days after flowering(DAF)was analyzed.The main results are as follows:(1)At 90 DAF and 150 DAF,apple epidermal wax accumulation in humid area was less than that in arid area,and the difference was significant at 90 DAF.(2)Apple wax components analysis by GC-MS showed that in the 90 DAF,the proportion of VLCFA compounds in humid areas was higher than that in arid areas,while the proportion of triterpenes was less.In the VLCFA compounds,the content of fatty aldehyde in humid area is higher,and the content of fatty acid is less than that in arid area.(3)Using SEM to observe the wax crystal structure of apple pericarp,it was found that the waxy papillae structure of apple pericarp in wet area was more than that in arid area,and the wax in dry and wet area was stacked in flakes.(4)The correlation analysis between the total wax content of apple pericarp at 90 DAF and environmental factors showed that there was a very significant negative correlationbetween the synthesis of apple epidermal wax and the average relative humidity of the orchard.The higher average relative humidity of orchard,the less wax synthesis.