Severe Shading Reduces Early Fruit Growth in Apple by Decreasing Cell Production and Expansion
Severe Shading Reduces Early Fruit Growth in Apple by Decreasing Cell Production and Expansion
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DOI：
10.21273/jashs.137.5.275
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发表时间：
2012-09-01
影响因子：
1.9
通讯作者：
Malladi, Anish
中科院分区：
文献类型：
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作者：
Dash, Madhumita;Johnson, Lisa K.;Malladi, Anish
苹果（Malus x Domestica）早期果实发育过程中的遮荫会降低果实生长并引发果实脱落。因遮荫而导致果实生长下降的机制尚不清楚。在这项研究中，研究了早期果实发育过程中的遮荫对细胞产生和扩张的影响。此外，还研究了遮荫对与碳水化合物代谢、果实生长以及细胞产生和扩增相关的基因表达的影响，以更好地理解分子机制并鉴定介导果实生长减少的基因。盛花后 15 至 18 天对孤立的树枝或整棵树进行遮荫会导致处理后 3 天果实生长急剧下降。处理后 3 天内，果实生长的减少始终是由细胞产量的下降介导的。在两个不同的年份，遮荫后 3 至 7 天，果实生长减少也与细胞尺寸减小有关。这些数据表明，遮荫导致的果实生长减少是由细胞产生和扩增的减少介导的。两个山梨醇脱氢酶 (SDH) 基因 MdSDH1 和 MdSDH2 在遮荫果实中的表达量最高达 10 倍，表明 SDH 活性增加以满足发育中果实的直接呼吸需求。生长素反应因子 (ARF) MdARF 106 在阴影果实中的表达量高出大约 3 倍，这表明它参与了介导果实生长减少的调节机制。两种与细胞生成呈正相关的 A2 型细胞周期蛋白 MdCYCA2;2 和 MdCYCA2;3 在阴影果实中的表达量降低了 4.6 倍。相反，与细胞生产负相关的细胞周期基因 MdKRP4 和 MdKRP5 在阴影果实中的表达量分别高出 3.9 倍和 5.3 倍。此外，与细胞扩张相关的两个基因 MdCOB1 (cobra1) 和 MdEXPA10;1 (expansin) 在阴影果实中表达较低。总之，这些数据表明，遮荫会导致碳水化合物代谢相关基因、与果实生长相关的关键转录因子以及与细胞产生和扩增相关的基因的表达发生协调变化。这些变化随后可能会降低介导果实生长的主要过程的进展。
Shading during early fruit development reduces fruit growth and initiates fruit abscission in apple (Malus x domestica). The mechanisms mediating the decline in fruit growth in response to shading are not well understood. In this study, the effects of shading during early fruit development on cell production and expansion were investigated. Additionally, the effects of shading on the expression of genes associated with carbohydrate metabolism, fruit growth, and cell production and expansion were investigated to develop a better understanding of the molecular mechanisms and to identify genes that mediate the reduction in fruit growth. Shading of isolated branches or entire trees m.,15 to 18 days after full bloom resulted in a sharp decline in fruit growth by 3 days after treatment. Reduction in fruit growth was consistently mediated by a decline in cell production within 3 days after treatment. Reduced fruit growth was also associated with lower cell size by 3 to 7 days after shading in two different years. These data indicate that the reduction in fruit growth as a result of shading is mediated by a reduction in cell production and expansion. The expression of two sorbitol dehydrogenase (SDH) genes, MdSDH1 and MdSDH2, was higher in the shaded fruit by up to 10-fold, suggesting an increase in SDH activity to meet the immediate respiratory demands of the developing fruit. The auxin response factor (ARF), MdARF 106, displayed approximate to 3-fold higher expression in the shaded fruit, suggesting its involvement in regulating mechanisms that mediate the reduction in fruit growth. Two A2-type cyclins, MdCYCA2;2 and MdCYCA2;3, which are positively associated with cell production, displayed lower expression in the shaded fruit by up to 4.6-fold. Conversely, MdKRP4 and MdKRP5, cell cycle genes negatively associated with cell production, displayed 3.9- and 5.3-fold higher expression in the shaded fruit, respectively. Additionally, two genes associated with cell expansion, MdCOB1 (cobra1) and MdEXPA10;1 (expansin), displayed lower expression in the shaded fruit. Together, these data indicate that shading results in coordinated changes in the expression of carbohydrate metabolism-related genes, key transcription factors related to fruit growth, and genes associated with cell production and expansion. These changes may subsequently decrease the progression of the primary processes that mediate fruit growth.