Shasha Li1,2,3, Xiangyu Geng1,2,3, Shuo Chen1,2,3, Keke Liu1,2,3, Saisai Yu1,2,3, Xiping Wang1,2,3, Chaohong Zhang1,2,3, Jianxia Zhang1,2,3, Yingqiang Wen1,2,3, Qiangwei Luo4, Yan Xu5,6,7, Yuejin Wang8,9,10. 1. College of Horticulture, Northwest A & F University, Yangling, 712100, Shaanxi, People's Republic of China. 2. Key Laboratory of Horticultural Plant Biology and Germplasm Innovation in Northwest China, Ministry of Agriculture, College of Horticulture, Northwest A & F University, Yangling, 712100, Shaanxi, People's Republic of China. 3. State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A & F University, Yangling, 712100, Shaanxi, People's Republic of China. 4. Research Institute of Xinjiang Grape, Melon and Fruit, Shanshan, 838200, Xinjiang, People's Republic of China. 5. College of Horticulture, Northwest A & F University, Yangling, 712100, Shaanxi, People's Republic of China. yan.xu@nwsuaf.edu.cn. 6. Key Laboratory of Horticultural Plant Biology and Germplasm Innovation in Northwest China, Ministry of Agriculture, College of Horticulture, Northwest A & F University, Yangling, 712100, Shaanxi, People's Republic of China. yan.xu@nwsuaf.edu.cn. 7. State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A & F University, Yangling, 712100, Shaanxi, People's Republic of China. yan.xu@nwsuaf.edu.cn. 8. College of Horticulture, Northwest A & F University, Yangling, 712100, Shaanxi, People's Republic of China. wangyj@nwsuaf.edu.cn. 9. Key Laboratory of Horticultural Plant Biology and Germplasm Innovation in Northwest China, Ministry of Agriculture, College of Horticulture, Northwest A & F University, Yangling, 712100, Shaanxi, People's Republic of China. wangyj@nwsuaf.edu.cn. 10. State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A & F University, Yangling, 712100, Shaanxi, People's Republic of China. wangyj@nwsuaf.edu.cn.
Abstract
MAIN CONCLUSION: The seed coat gene VviAGL11 coordinates with endosperm development genes FIS2, PHERESE1 and IKU2 and functions as the key regulator in seed development and abortion processes in grapevine. Seed development is essential for the reproduction of flowering plants. Seed abortion is a specific characteristic that produces seedless berries and is often observed in cultivated grapevines. Although seedlessness is an important trait for table and dried grapevine production, the mechanism of seed abortion remains poorly understood. This research aimed to analyze the co-expression of the seed coat development gene VviAGL11 and the endosperm development genes FERTILIZATION INDEPENDENT SEED2 (FIS2), PHERESE1 and HAIKU2 (IKU2) that regulate seedless fruit development in grapevine. The transcript levels of VviAGL11, FIS2, PHERESE1 and IKU2 all decreased during seed abortion in the seedless grape 'Thompson Seedless' plants, compared to those of the seeded grape 'Pinot Noir'. The transcript levels of the salicylic acid (SA)-dependent defense response genes EDS1, NPR1, NDR1 and SID2 were higher in 'Thompson Seedless' than 'Pinot Noir' during seed development. Also, WRKY3, WRKY6 and WRKY52, which participate in the SA pathway, were higher expressed in 'Thompson Seedless' than in 'Pinot Noir', indicating that SA-dependent defense responses may regulate seed abortion. The genes related to synthesis and metabolism of gibberellic acid (GA) and abscisic acid (ABA) also showed differential expression between 'Thompson Seedless' and 'Pinot Noir'. Exogenous applications of plant growth regulators (PGRs) to inflorescences of three stenospermocarpy grapevines before flowering showed that GA3 was critical prominently in seed development. Therefore, the co-expression of seed coat and endosperm development-related genes, SA pathway genes, and genes for the synthesis and metabolism of GA3 together enhance seed abortion in seedless grapes.
MAIN CONCLUSION: The seed coat gene VviAGL11 coordinates with endosperm development genes FIS2, PHERESE1 and IKU2 and functions as the key regulator in seed development and abortion processes in grapevine. Seed development is essential for the reproduction of flowering plants. Seed abortion is a specific characteristic that produces seedless berries and is often observed in cultivated grapevines. Although seedlessness is an important trait for table and dried grapevine production, the mechanism of seed abortion remains poorly understood. This research aimed to analyze the co-expression of the seed coat development gene VviAGL11 and the endosperm development genes FERTILIZATION INDEPENDENT SEED2 (FIS2), PHERESE1 and HAIKU2 (IKU2) that regulate seedless fruit development in grapevine. The transcript levels of VviAGL11, FIS2, PHERESE1 and IKU2 all decreased during seed abortion in the seedless grape 'Thompson Seedless' plants, compared to those of the seeded grape 'Pinot Noir'. The transcript levels of the salicylic acid (SA)-dependent defense response genes EDS1, NPR1, NDR1 and SID2 were higher in 'Thompson Seedless' than 'Pinot Noir' during seed development. Also, WRKY3, WRKY6 and WRKY52, which participate in the SA pathway, were higher expressed in 'Thompson Seedless' than in 'Pinot Noir', indicating that SA-dependent defense responses may regulate seed abortion. The genes related to synthesis and metabolism of gibberellic acid (GA) and abscisic acid (ABA) also showed differential expression between 'Thompson Seedless' and 'Pinot Noir'. Exogenous applications of plant growth regulators (PGRs) to inflorescences of three stenospermocarpy grapevines before flowering showed that GA3 was critical prominently in seed development. Therefore, the co-expression of seed coat and endosperm development-related genes, SA pathway genes, and genes for the synthesis and metabolism of GA3 together enhance seed abortion in seedless grapes.