“焦核”是荔枝品质的一个优良性状，然而，焦核品种在商品化荔枝品种中仅占少数，且性状不稳定，生理落果现象严重。目前，荔枝焦核形成的生理生化和分子生物机制还不清楚。我们前期研究发现种柄中细胞壁转化酶（CWIN）活性与荔枝焦核发生密切相关，大核品种的CWIN活性较高，而焦核品种的CWIN活性较低。本项目将在以上生理学研究基础上，从分子生物学水平上对CWIN基因与荔枝焦核发生的相关性进行深入研究，通过病毒诱导的基因沉默（VIGS）验证是否可以通过调控CWIN活性影响荔枝种子大小，并从编码区、启动子和抑制子水平上寻找导致焦核品种CWIN活性较低的分子生物学基础，探讨荔枝焦核发生的分子生物学机制，为选育或培育焦核荔枝品种提供理论依据。

Stenospermocarpy is a good trait in lychee quality, however, there are few commercial varieties with this trait, and physiological fruit drop is serious. At present, the physiological, biochemical and molecular biological mechanism regulating stenospermocarpy formation is still not clear. Our pervious study showed a compelling correlation between seed size and the activity of cell wall invertase (CWIN) in seed pediel, higher CWIN activity in large seed varieties, while lower CWIN activity in small seed varieties. Based on the above research on physiology, we will study the correlation of CWIN gene with stenospermocarpy formation at molecular biology level in this project. We will verify the possibility of the litchi seed size can be influenced by regulating CWIN activity through virus induced gene silencing (VIGS). Finally, we will find the reason for lower CWIN activity in small seed varieties by comparing coding region, promoter activity, and the repressor gene. All these studies will shed light on the molecular mechanisms of stenospermocarpy formation and provide a theoretical basis for the selection and breeding of litchi varieties with small seeds.