睡莲叶脐着生胎芽与叶片不同部位碳水化合物代谢的关系

为了解睡莲叶脐胎芽的发育机理,以广热带亚属胎生睡莲‘玛格丽特’和‘鲁比’为材料,非胎生睡莲‘粉星’为对照,采用石蜡切片技术观察叶脐胎芽发育4个时期的形态变化,并比较胎生与非胎生睡莲叶片不同部位碳水化合物代谢的差异性。结果表明: 叶片展开后,胎生睡莲叶脐表皮以下细胞不断分裂和生长,形成排列紧密的细胞群,并逐渐向上凸起呈球形,非胎生睡莲叶脐则无任何变化。随着叶片的不断发育,除蔗糖和酶活性以外,各生理指标在胎生睡莲叶片中的含量均表现为先升后降,显著高于非胎生睡莲;从不同部位来看,碳水化合物含量总体表现为叶片>叶脐>叶柄(淀粉含量除外,其叶脐高于叶片和叶柄);不同品种蔗糖代谢酶活性表现为蔗糖合成酶(SS)和酸性转化酶(AI)活性高于蔗糖磷酸合成酶(SPS)和中性转化酶(NI)活性,胎生睡莲不同组织中的SPS和NI活性均显著高于非胎生睡莲,但SS和AI活性在胎生睡莲中并未表现出明显的品种优势;AI活性在品种间差异大,NI活性在品种间差异较小,且在不同组织中均处于较低水平。相关性分析表明,‘鲁比’叶片的蔗糖含量与SPS和AI呈极显著正相关,与NI呈显著正相关,且蔗糖含量的积累主要增加了睡莲叶片的SS和NI活性,有利于促进胎芽的形成。

Relationship between epiphyllous bud of tropical waterlily (Brachyceras)umbilics and carbohydrate meta-bolism in different parts of leaves

To understand the development mechanism of the epiphyllous bud of waterlily, we examined the morphological anatomy of the leaf-navel epiphyllous bud by paraffin section technique at four stages, and compared the differences of carbohydrate metabolism between viviparous and non-viviparous waterlily leaves. Three tropical waterlily cultivars of Brachyceras were used, including two viviparous cultivars Nymphaea ‘Margaret Mary’, Nymphaea ‘Ruby’, and a non-viviparous cultivar Nymphaea ‘Pink Star’. The results showed that parenchyma cells below the epidermis of leaf-navel divided and grew continuously after the leaf unfolded, forming a closely arranged cell cluster in viviparous waterlily and raised upward to a spherical shape. In contrast, no change was observed in leaf-navel of non-viviparous waterlily with the expansion of leaves. With the development of leaves, the contents of all physiological variables except sucrose and enzyme activities in the leaves of viviparous waterlily showed a first increase and then a decrease, which was significantly higher than those of non-viviparous waterlily. The carbohydrate contents in different parts showed the order of leaf > leaf-navel > petiole (except for starch content, which was highest in the leaf-navel). The activities of sucrose synthase (SS) and acid invertase (AI) were higher than those of sucrose phosphate synthase (SPS) and neutral invertase (NI). The activities of SPS and NI in different tissues of viviparous waterlily were significantly higher than those in non-viviparous one, but SS and AI did not show pronounced cultivar advantage in viviparous cultivars. AI activity varied greatly among cultivars, whereas NI activity varied less and was at a low level in different tissues. The sucrose of Nymphaea ‘Ruby’ leaves was positively correlated with the SPS and AI, and significantly associated with NI. The accumulation of sucrose content increased the activities of SS and NI of waterlily leaves, which was conducive to promoting the formation of epiphyllous buds.