抗枯萎病宝岛蕉早花突变体的筛选与鉴定

Selection and identification of early flowering Baodao banana mutants resistant to wilt disease

【目的】筛选鉴定抗枯萎病香蕉品种宝岛蕉的早花突变体,为进一步利用突变体株系选育适应性更广的香蕉新品种提供参考依据。【方法】利用多代组织培养繁育结合田间种植对比试验,依据生育期短、抗病性强、株高矮、株产高和遗传稳定筛选目标,从宝岛蕉早花突变后代中筛选优良株系,以宝岛蕉为对照,按照香蕉种质资源描述规范对优良突变株系的形态特征和生物学特性等进行观察鉴定,测定分析植株球茎生长点部位碳、氮营养累积以及成花相关激素吲哚乙酸(IAA)、玉米素(ZR)、赤霉素(GA)和脱落酸(ABA)含量差异,通过ISSR分子标记检测突变体及其野生型之间的遗传变异和亲缘关系。以宝岛蕉和主栽品种(桂蕉6号及巴西蕉)为对照,利用伤根浸菌法进行苗期抗病性鉴定,并在广西和海南开展区域种植试验及田间抗病性鉴定。【结果】筛选获得优良突变株系0523(简称0523),其新植蕉平均株高280.0 cm,假茎基围80.5 cm、中围60.0 cm,较宝岛蕉分别减小14.0%、5.8%和11.8%,新抽总叶片数26~29片;果实营养品质和单株产量与宝岛蕉无显著差异(P>0.05,下同)。0523球茎生长点碳氮比较宝岛蕉显著提高19.0%(P<0.05,下同),GA和IAA含量显著降低24.8%和22.6%,ABA和ZR含量与宝岛蕉相比略有增加,差异不显著。抗病性苗期鉴定结果显示0523为中抗且偏强,抗性水平与宝岛蕉相比略有提高,桂蕉6号为高感。突变株系0523与宝岛蕉的多态性比率为8.8%,遗传相似系数为0.95,二者存在差异。0523在广西和海南各试验点第1、2造蕉平均发病率分别为4.5%和3.5%,较主栽品种降低87.8%和94.1%,各试验点发病率均显著低于主栽品种。0523第1、2造蕉的生育期较宝岛蕉显著缩短,与主栽品种无显著差异。【结论】突变株系0523具有抗枯萎病、早熟、矮化、适应性广等优良性状,可用来培育大面积推广的香蕉新品种,或作为亲本育种材料应用于香蕉育种研究。

【Objective】The purpose of the study was to screen and identify Baodao banana early flowering mutant with resistance to wilt disease,to provide a reference basis for further breeding of new banana varieties with wider adaptability using mutant strains.【Method】By using multi-generation tissue culture breeding combined with field planting com‐parative experiments,based on the screening objectives of short growth period,strong disease resistance,short plant height,high plant yield and genetic stability,excellent strains were selected from the early flowering mutant off-spring of Baodao banana.Baodao banana was used as a control,and the morphological and biological characteristics of the excel‐lent mutant strains were observed and identified according to the specification for description of banana germplasm re‐sources.The carbon and nitrogen nutrient accumulation at the growth point of plant corms,as well as the differences in the content of flowering related hormones indole-3-acetic acid(IAA),zein(ZR),gibberellin(GA)and abscisic acid(ABA)were measured and analyzed.Genetic differences and genetic relationship between mutants and their wild types were detected using ISSR molecular markers.Using Baodao banana and the main cultivated varieties(Guijiao No.6 and Brazilian banana)as controls,the disease resistance during the seedling stage was identified using the root injury soaking method.Regional planting experiments and field disease resistance identification were conducted in Guangxi and Hainan.【Result】An excellent mutant strain 0523 was selected(referred as 0523),with an average plant height in newly planted banana of 280.0 cm,a false stem base circumference of 80.5 cm,and a middle circumference of 60.0 cm,which were 14.0%,5.8%,and 11.8%smaller than those of Baodao banana respectively.The total number of newly harvested leaves was 26-29.There was no significant difference in fruit nutritional quality and individual plant yield compared to Baodao banana(P>0.05,the same below).The carbon nitrogen ratio at the growth point of 0523 corm was significantly higher than that of Baodao banana by 19.0%(P<0.05,the same below),while the GA and IAA contents were significantly lower by 24.8%and 22.6%respectively.The ABA and ZR contents were slightly increased compared to Baodao banana,but there was no significant difference.The identification result of disease resistance in the seedling stage showed that 0523 was moderately resistant and slightly stronger.The resistance level was slightly higher than that of Baodao banana,and Guijiao No.6 was highly susceptible.The polymorphism rate between mutant strain 0523 and Baodao banana was 8.8%,with a genetic similarity coefficient of 0.95,indicating a difference between the two.The average incidence rate of wilt disease of the newly planted banana and ratoon plant banana of 0523 in Guangxi and Hainan was 4.5%,and the aver‐age incidence rate of the ratoon bananas was 3.5%,which were 87.8%and 94.1%lower than that of the main cultivated varieties,the incidence in each experimental sites were significantly lower than the main cultivated varieties.The growth period of the newly planted banana and ratoon plant banana of 0523 was significantly shortened compared to Baodao ba‐nana,but had no significant difference compared to the main cultivated varieties.【Conclusion】The mutant strain 0523 has excellent traits such as resistance to wilt disease,early maturity,short plant height,and wide adaptability,which can be used to cultivate new banana varieties for large-scale promotion or further be utilized as a parent breeding material in ba‐nana breeding research.