玉米近缘种大刍草(Zea luxurians)光周期敏感性与育种利用

Flower Induction and Utilization of Zea luxurians in Maize Breeding

【目的】探索大刍草短日照敏感苗龄和最佳日照时数,使其与栽培玉米花期相遇,通过杂交导入有利性状进行玉米品种改良与种质资源创新。【方法】设置苗龄和日照时数两个处理,以自然光照为对照,研究不同短日照处理后不同苗龄大刍草的生长发育情况;自制酶液,测定各处理的过氧化物酶(POD)活性,并对其同工酶进行电泳分析;利用诱导开花的大刍草与玉米自交系授粉杂交、回交并自交选育新自交系。【结果】19—26 d是大刍草能否接受诱导的临界苗龄,苗龄(5—47 d)越大诱导效果越好;9 h是诱导生殖生长的最佳日照时数;各日照时数处理的POD活性随苗龄的增大呈现一定的规律性变化,但不能直接反映大刍草生长发育状况;a、b、c、d四条POD酶带是大刍草处于营养生长阶段的标记,e、f、g三条POD酶带的出现表明进入生殖生长阶段,POD酶的相对含量主导着大刍草的生长发育方向;采用40—47 d苗龄每日9 h短日照处理的大刍草与玉米掖478、综31花期相遇,通过远缘杂交育成NX3153等玉米自交系。【结论】在中国北方可以通过短日照处理诱导大刍草幼苗提前开花,与普通玉米花期相遇,通过远缘杂交实现基因导入,创新玉米种质。

[ Objective] Zea luxurians is a short-day plant, which can＇t reproduce in temperate regions. The objective of this study is to induce Zea luxurians flower by changing photoperiod, therefore to eliminate flowering time difference to cross it with elite maize cultivars and to create novel maize germplasm resources. [ Method ] Using normal light condition as a control, the effects of different short-day treatments on the development ofZea luxurians were checked, the activity ofperoxidases （POD） was measured and POD isoenzyme patterns were characterized. Then, flowering Zea luxurians was successfully crossed with common maize inbred lines. [Result]The results showed that the critical productive induction stage in Zea luxurians was between 19 d and 26 d at seedling age. The induction rate was higher when the Zea luxurians seedlings were older （from 5 d to 47 d）. The optimal day-length for reproductive induction was 9 hours. POD activity had certain correlation with the seedling age, but had no implication on the growth conditions. Four types of POD isoenzymes, i.e. a, b, c and d, were good characteristics for vegetative growth, and the POD isoenzymes of e, f, g featured reproductive growth. Furthermore, the composition of these POD isoenzymes determines whether Zea luxurians, entered into reproductive growth. [Conclusion] In northern China, the flowering time of Zea luxurians can be synchronized with elite maize cultivars through short-day treatment, thus facilitates the distant hybridization and makes it possible to transfer novel genes into elite inbred lines to create new maize germplasms.