不同种源秋茄胚轴和幼苗生长性状的地理变异

胚轴是显胎生红树植物秋茄的特殊繁殖体。分析不同种源胚轴和幼苗的表型性状变异规律,以及胚轴营养元素差异,对秋茄种质资源保护利用和遗传育种具有重要意义。本研究收集了5个省11个种源秋茄的胚轴,测定了形态参数和营养元素含量,在浙江省温州市景山试验基地开展种源生长试验,测定幼苗生长指标,并利用方差分析、相关性分析和聚类分析等方法探讨了地理变异特性。结果表明:不同秋茄种源间胚轴表型性状和营养元素含量均存在极显著差异,除碳含量和基径外,各性状种源间变异系数大于种源内,且重复力均在85%以上;胚轴长度、生长高、生物量与纬度、经度呈显著负相关,而与年平均气温呈显著正相关,但胚轴氮、磷含量与纬度、经度呈显著正相关,与年平均气温呈显著负相关;年平均气温与顶径、基径呈显著正相关,年平均降雨量仅与长度显著正相关;通过聚类分析可将11个秋茄种源分为3类:海南海口(HK)和广东湛江(ZJ)为1类,浙江乐清(YQ)、浙江苍南(CN)和福建福鼎(FD)聚为1类,广西北海(BH)、广西防城港(FCG)、广东深圳(SZ)、福建云霄(YX)、福建龙海(LH)和福建泉州(QZ) 6个种源聚为1类。因此,不同种源秋茄胚轴表型性状存在丰富的变异,各性状受较高水平的遗传力控制,并且11个种源划分成3个类群,具有明显的地理区域性,但胚轴大小、幼苗生长与胚轴氮、磷含量呈显著负相关,其机制值得进一步探索。

Geographic variations of hypocotyl and seedling growth traits for Kandelia obovata with different provenances

Hypocotyl is a unique propagator of viviparous mangrove species such as Kandelia obovata.Understanding the geographical variations in the phenotypic traits of hypocotyls and seedlings of K.obovata with different provenances,as well as the differences in nutrition requirements is critical for both conservation and genetic breeding of this valuable mangrove species.In this study,we collected mature hypocotyls of K.obovata of 11 provenances from five provinces in China.Based on their hypocotyl traits,we planted seedlings from 11 provenances at the Jingshan experimental testing site in Zhejiang Province,and monitored their growth traits.Geographic variations of hypocotyls and seedlings were quantitatively analyzed through ANOVA,correlation analysis,and cluster analysis.We found that the phenotypic traits and nutrient contents of hypocotyls among the provenances were significantly different.In addition to carbon content and basal diameter,the coefficient of variations for various traits among the provenances was higher than those within the provenances,with the repeatability of the trait being higher than 85%.Hypocotyl length,height growth and biomass showed significant negative correlations with latitude and longitude,while they were positively correlated with mean annual temperature.Nitrogen and phosphorus contents showed opposite trends.There were positive correlations between:top diameter of hypocotyl and annual mean temperature,basal diameter of hypocotyl and annual mean temperature,and hypocotyl length and mean annual rainfall.Hierarchical cluster analysis further revealed that the 11 provenances could be classified into three groups:(1)HK and ZJ;(2)FD,YQ and CN;(3)BH,FCG,SZ,YX,LH and QZ.Clearly,there were large variations in phenotypic traits in K.obovata provenances,with each trait being subjected to strong genetic control.The 11 provenances of K.obovata were also clustered into three groups with distinct geographic features.The hypocotyl size and seedling growth were negatively correlated with the nitrogen and phosphorus contents of hypocotyl.