Quantifying cutin and wax deposition in developing apple fruit

外观决定了大多数肉质水果的新鲜市场价值。即使是表面上的损坏也会严重降低市场价值。经济上重要的例子包括苹果的赤霉病和皮斑病。这两种疾病之前都有表皮膜（CM）的微观失效，导致屏障功能受损。保持完整的CM需要更好地了解角质层的形成在发展水果。最近的研究表明，角质和蜡的连续沉积在最小化发育中的苹果CM中的应力和应变从而最小化CM失败的风险方面起着重要作用。我们的研究的目的是（1）建立一个系统，用于定量角质和蜡沉积在发展中的苹果果实使用标记的前体，（2）比较使用13 C-标记的前体（稳定同位素）建立的沉积速率与重量测定和（3）量化角质层内的沉积的任何空间径向异质性。在第一年和第二年，我们将利用14C（在实验室）和13C标记（在现场）C16和C18脂肪酸前体来量化角质和蜡沉积的速率。在实验室实验中，确定与角质和蜡部分相关的放射性的量，并确定导致最大掺入的处理条件。在现场，13C掺入将通过质谱法定量，并与重量法测定的沉积速率进行比较。第三年将集中在潜在的空间异质性的角质和蜡沉积在发展中的水果供应13 C脂肪酸。该方法的建立将有助于研究角质和蜡质沉积在基因型和环境因素影响下苹果赤霉病易感性中的作用。

Appearance determines the fresh market value in most fleshy fruit. Even cosmetic damage severely reduces the market value. Economically important examples include russeting and skin spot of apple. Both disorders are preceded by microscopic failure of the cuticular membrane (CM) resulting in impaired barrier function. Maintaining an intact CM requires a better understanding of cuticle formation in developing fruit. Recent studies suggest that continuous deposition of cutin and wax plays an important role in minimizing stress and strain in the CM of developing apple thereby minimizing the risk of CM failure. The objectives of our study are to (1) establish a system for quantifying rates of cutin and wax deposition in developing apple fruit using labeled precursors, (2) compare rates of deposition established using 13C-labeled precursors (stable isotopes) with those determined gravimetrically and (3) quantify any spatial radial heterogeneity in the deposition within the cuticle. In the first and second year, we will utilize 14C (in the lab) and 13C -labeled (in the field) C16 and C18 fatty acid precursors to quantify rates of cutin and wax deposition. In laboratory experiments the amount of radioactivity associated with the cutin and wax fraction is determined and treatment conditions leading to maximum incorporation are identified. In the field 13C incorporation will be quantified by mass spectrometry and compared with deposition rates determined gravimetrically. The third year will focus on potential spatial heterogeneity of cutin and wax deposition in developing fruit supplied with 13C fatty acid. The methods developed will be useful in studying the role of cutin and wax deposition in russet susceptibility of apple as affected by genotype and environmental factors.