Δ12-脂肪酸去饱和酶基因(fad2)突变对油菜叶片表面结构和透性的影响

Effects of Δ12-Fatty Acid Desaturase Gene( fad2 ) Mutation on Epidermal Construct and Permeability of Brassica napus Leaf

首次报告了利用简单的叶片氧化实验可区别油菜正常株系及具有高油酸 (低亚油酸 )性状的fad2基因 (Δ12 fattyaciddesaturasegene)突变体。突变体叶片内的有色或具还原性的物质能被次氯酸钠及硝酸银溶液在 5～ 10min漂白或氧化 ,正常株系及突变体的fad2基因功能补偿转化体的叶片被漂白的时间需要 2 4～ 4 8h。通过扫描电镜观察揭示了突变体与正常株系之间叶片表面蜡颗粒沉积均匀性上的差异。实验结果表明 :fad2基因的突变改变了叶片表面蜡的沉积结构并增大了叶片表层的溶液渗透性 ,其原因可能与木质(cutan)的合成受抑制相关。

The mutation of fad2 genes has not only impacts on components of fatty acids in Brassica napus seeds, but also strong impacts on other characters of plants, such as cold tolerance and plant growth. In this work, it is found that the leaf of fad2 gene double mutant can be bleached by sodium hypochlorite solution much faster than that of normal line (Fig.1). A further analysis and test showed that: (a) the easily oxidized character of colored components in the leaf of mutants is linked to fad2 gene mutation (Table 1 and Fig.2), (b) furthermore, the easily oxidized character of colored components in the leaf of mutants is linked to washing out of epicuticular wax on the leaf (Fig.3), (c) the epicuticular wax and cuticle of mutant is made permeable (Fig.4), (d) the difference in permeability of leaf cuticle to water between mutant and normal lines is linked to pellet uniform in ultrastructure of epicuticular wax deposits (Fig.5) . It is possible that the change of epicuticular wax deposit structure is caused by the synthesis of cutan-a non degradable polymers in cuticle. Because cuticle is the outer most protective substance of plants, its damage caused by fad2 gene mutation may be one of the factors leading to undesirable agronomic traitsLeaf oxidation test by solution of sodium hypochlorite and silver nitrate can be used as a rapid and simple method for high oleic acid line identification.