Hormonal changes play important roles in the key period of superior and inferior earshoot differentiation in maize

doi:10.1016/S2095-3119(20)63337-8

摘要/Abstract

摘要：

生产中，强优势单果穗玉米品种通常拥有较高的产量潜力及资源利用效率。为了明确幼穗强、弱势差异分化的关键时期及内源激素在该时期的调控作用，本研究选用穗间强弱势差异显著的玉米品种苏玉41号 (单穗型，幼穗间强弱势差异显著和AN101(双穗型，幼穗间强弱势差异较小)，于2017和2018年在江苏大丰稻麦原种场进行试验。结果表明：弱势幼果穗发育较强势穗分化滞后，其滞后分化不仅与分化起始时间延后有关，还与其在小穗分化期和性器官形成期的持续时间延长有关。该时期强弱势幼穗间激素差异显著。从吐丝前12天开始到吐丝当日，吲哚-3-乙酸(IAA)，玉米素+玉米素核苷(ZR+ZT)和赤霉素(GA₃)的含量在两品种强、弱势幼穗内均先上升后急剧下降且在两品种间差异显著。脱落酸(ABA)则是在强、弱势幼穗内先缓慢上升，然后在苏玉41号中逐渐下降，在AN101中维持较高水平。吐丝前8天是形态上强弱势分化的关键时期，此时上位幼穗(强势穗)处于小花分化到性器官形成的过渡期。此期，在苏玉41中强、弱势幼穗日生长量差值、IAA、(ZR+ZT)和GA₃含量差值均高于AN101。同时，苏玉41号强、弱势间IAA比值及(ZR+ZT)比值均要高于AN101，而GA₃和ABA则无明显差异。强、弱势幼穗间日生长量差值及内源激素差值的相关性分析表明内源激素在调控幼穗强、弱势差异分化中的作用存在差异。本研究结果表明，弱势果穗的滞后发育及其完成小穗分化和性器官形成时间过长有关；IAA和ZR+ZT在此过程中发挥重要调控作用，GA₃似乎在更早时期参与强、弱势幼穗分化，而ABA未能观察到在此过程中发挥重要作用。

Abstract:

The upper earshoots with higher superiority usually have higher yield potential and higher efficiency. To determine the key period for the asynchronous differentiation of superior and inferior earshoots and how hormones are involved in this process, a two-year experiment was designed using two maize hybrids: Suyu 41 (S41, single-ear hybrid) and AN 101 (A101, double-ear hybrid). The results showed that the lag of lower earshoot differentiation was not only caused by the delay of the differentiation starting time but also related to extension of the duration in spikelet differentiation (stage II) and sexual organ formation stage (stage IV). From 12 days before silking (DBS), the contents of indole-3-acetic acid (IAA), zeatin riboside (ZR)+zeatin (ZT), and gibberellic acid (GA₃) in both upper and lower earshoots of the two hybrids increased dramatically and then decreased quickly. ABA slightly increased in the two hybrids and then decreased slowly in S41, while it was maintained at a high level in A101. At 8 DBS, i.e., the transition period from floret differentiation to sexual organ formation stage, not only the growth of upper-to-lower earshoot difference (ULED), but also the values for ULED of IAA, ZR+ZT and GA₃were all significantly higher in S41 than in A101. Furthermore, the upper-to-lower hormone ratios IAA_U/IAA_Land (ZR+ZT)_U/(ZR+ZT)_L were also much higher in the single-ear hybrid than in the double-ear hybrid, while the GA_3U/GA_3Land ABA_U/ABA_L had no significant differences. In addition, the time course of ULED_hormone/ULED_earshoot _{growth rate} also suggested that the hormones work in different ways in earshoot superiority/inferiority formation. The delayed differentiation of lower ear shoots was conclusively related to the later initiation of differentiation and the longer durations of specific differentiation stages. Compared with the regulating roles of IAA and ZR+ZT in the key period (8 DBS) of superiority/inferiority differentiation, GA₃seems to be affected earlier, while ABA contributes little to this process.

Key words: maize (Zea mays L.) , earshoot , plant hormone , superior/inferior differentiation

. [J]. Journal of Integrative Agriculture, 2021, 20(12): 3143-3155.

DU Kang, ZHAO Wen-qing, ZHOU Zhi-guo, SHAO Jing-jing, HU Wei, KONG Ling-jie, WANG You-hua. Hormonal changes play important roles in the key period of superior and inferior earshoot differentiation in maize[J]. Journal of Integrative Agriculture, 2021, 20(12): 3143-3155.

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