Differential Response of Floret Opening to Exo-Methyl Jasmonate Between Subsp.Indica and Subsp. Japonica in Rice
Differential Response of Floret Opening to Exo-Methyl Jasmonate Between Subsp.Indica and Subsp. Japonica in Rice
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发表时间：
2014
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通讯作者：
Yan Zhi-qian
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作者：
Yan Zhi-qian
【目的】籼粳稻杂交可产生显着的杂种优势或杂种优势，其应用可提高水稻的产量和对生物和非生物胁迫的耐受性。限制杂种优势在水稻上应用的主要因素之一是两个亚种一天开花时间差异较大。籼稻开花早，粳稻开花晚。开花不同步会降低杂交种子的产量，提高杂交种子的生产成本，进一步制约两个亚种间杂种优势的应用。前期研究结果表明，喷洒茉莉酸甲酯（MeJA）可以有效促进水稻白天开花。但水稻品种的开花时间对 MeJA 的敏感性仍不清楚。本研究旨在探讨籼粳稻花开放对MeJA的差异响应，为提高亚种间杂交水稻制种产量、增强籼粳杂种优势直接利用的可能性提供理论依据。沉阳农业大学水稻研究所试验站分别于2012年和2013年种植籼粳和粳稻。分别于昨晚17:00、下午6:00和8:00在水稻穗部和顶叶喷施0.04 mmol·L-1、0.4 mmol·L-1和4 mmol·L-1三种浓度的MeJA。分别是早上。使用不添加MeJA的水作为对照(CK)。考察了不同时期施用MeJAs后籼稻和粳稻的始花时间（FBT）、盛花时间（VFT）、盛花结束时间（FET）、开始开花到盛花时间（BVT）、开始盛花到盛花时间（VET）、盛花到结束时间（BET）。确定开花时间的标准如下：分别用第一朵花开放的时间、最多花开放的时间和所有花关闭的时间分别作为FBT、VFT和FET的测量。试验采用随机区组设计，重复3次。【结果】与无MeJA处理（CK）相比，MeJA浓度能显着促进籼稻开花时间。 MeJA 治疗之间没有显着差异。粳稻一天的开花时间仅对高浓度（4 mmol·L-1）和中浓度（0.4 mmol·L-1）MeJA有响应。高浓度和中浓度MeJA处理之间存在显着差异。与CK相比，MeJA浓度对籼稻和粳稻的BVT和VET没有显着影响。然而，施用MeJA，无论浓度如何，都可以明显延长籼稻的BET。喷药时间不影响籼稻的开花时间。与籼稻相比，在一天中的不同时间喷洒MeJA，如下午5:00、上午6:00、早上8:00，对粳稻的开花时间有显着影响。结果还表明，高浓度MeJA可以同等地促进籼稻和粳稻的开花时间。但低浓度（0.04 mmol·L-1）和中浓度（0.4 mmol·L-1）MeJA对粳稻的加速开花效果优于籼稻。 【结论】施用4 mmol·L-1和0.4 mmol·L-1的MeJA均显着提高了供试籼稻和粳稻品种的花花初始开放时间。 6个籼稻品种一天的开花时间（并非全部）对低剂量MeJA（0.04 mmol·L-1）有反应，表明籼稻比粳稻对MeJA处理更敏感。籼稻品种对 MeJA 的反应比粳稻更快。施用MeJA后，粳稻品种的开花时间延长。下午17:00用高浓度（4 mmol·L-1）MeJA处理是促进粳稻开花的最佳组合。促进籼稻开花的最佳组合因品种而异。最经济有效的组合是早上喷洒0.04 mmol·L-1 MeJA。
【Objective】 hybrids between indica and japonica rice can produce significant hybrid vigor or heterosis, application of which can improve yields and tolerance to the biotic and abiotic stresses of rice. One of the major factors limiting the application of heterosis in rice is the big difference of flowering time in a day between the two subspecies. Indica rice often blooms early, but japonica rice blooms later. The flowering asynchronism will reduce the yields of hybrid seeds, enhance the cost of hybrid seed production, and further constrain the application of heterosis between the two subspecies. Previous results show that spraying methyl jasmonate(MeJA) can effectively promote rice flowering in the day. But the sensitivity of flowering time of rice varieties to MeJA remains obscure. In this study, the differential responses of the floret opening to MeJA between indica and japonica rice were investigated, which will provide a theoretical basis for improving the yields of the inter-subspecies hybrid rice seed production and enhancing the possibility to utilize the heterosis between indica and japonica rice directly.【Method】 To investigate the dynamics of floret opening, six varieties of subsp. indica and japonica were respectively, planted in the experimental station of Rice Research Institute at Shenyang Agricultural University in 2012 and 2013. Three concentrations of MeJA, 0.04 mmol·L-1, 0.4 mmol·L-1, and 4 mmol·L-1, were sprayed on the panicle and top leaves of the rice plants at 17:00 last afternoon, 6:00 and 8:00 in the morning, respectively. Water, no addition of MeJA, was used as control(CK). The flowering-begin-time(FBT), the vigorous-flowering-time(VFT), the flowering-end-time(FET), the time from the beginning of flowering to vigorous flowering(BVT), the time from the beginning of vigorous flowering to flowering end(VET), the time from the beginning of flowering to end(BET) of indica and japonica rice were investigated after application of MeJAs at different times. Criteria for determining the flowering time were as follows: The time of the first flower opening, the time of the most flowers opening, and the time of all the flowers closed were used as the measurement of the FBT, the VFT, and the FET, respectively. The experiment was designed on the randomized block with three replications.【Result】 The concentration of MeJA could significantly promote the flowering time of indica rice compared to the no MeJA treatment(CK). There was no significant difference among the MeJA treatments. Flowering time in a day of japonica rice only responded to the high(4 mmol·L-1) and medium(0.4 mmol·L-1) concentrations of MeJA. There was a significant difference between high concentration and medium concentration of MeJA treatments. The concentration of MeJA had no significant effect on the BVT and VET of both indica rice and japonica rice in contrast to CK. However, the application of MeJA, no matter of the concentration, could obviously extend the BET in indica rice. The spraying time did not affect the flowering time of indica rice. In contrast to indica rice, spraying MeJA at different times of a day, such as 5:00 pm last afternoon, 6:00 am, and 8:00 am in the morning, had significant effects on the flowering time of japonica rice. The results also indicated that high concentration of MeJA could promote the flowering time of indica and japonica rice equally. But lower(0.04 mmol·L-1) and medium(0.4 mmol·L-1) concentrations of MeJA were more effective on accelerating flowering of japonica rice than that of indica rice.【Conclusion】The initial time of floret opening in all indica and japonica rice varieties tested was significantly promoted by applying 4 mmol·L-1 and 0.4 mmol·L-1 of MeJA. The flowering time in a day of six indica varieties, not all, was response to the low dosage of MeJA(0.04 mmol·L-1), suggesting that indica rice was more sensitive to the MeJA treatments compared to japonica rice. The varieties of indica rice responded to MeJA more quickly than japonica rice. Longer time was needed for varieties of japonica rice to flowering as the results of applying MeJA. Treatment with high concentration(4 mmol·L-1) of MeJA at 17:00 last afternoon was the best combination to promote flowering of japonica rice. The optimal combination to promote flowering of indica rice varied from cultivar to cultivar. The most economic and efficient combination was 0.04 mmol·L-1 MeJA sprayed in the morning.