油茶自交不亲和性的解剖特征

油茶自交不亲和性的解剖特征

高超;袁德义;杨亚;王碧芳;刘冬明;邹锋;谭晓风

【摘要】【目的】比较研究油茶自交与异交授粉后花粉管在雌蕊中生长行为的差异，探明油茶自交不亲和性的类型及特征，进一步认识油茶生殖特性的同时丰富、完善其生殖生物学研究资料，为促进油茶增产提供理论依据和研究基础。【方法】根据花粉管荧光显微观察的试验原理并有针对性地结合油茶雌蕊的特点，综合运用荧光显微镜结合经过改良的荧光压片法、荧光切片法和常规石蜡切片法观察油茶雌蕊结构特征和花粉管在雌蕊中的生长情况，运用扫描电镜重点观察油茶自交花粉管发生的不亲和反应特征，对油茶自交不亲和性进行解剖学方面的研究。【结果】油茶为开放型花柱，两边贴合的中空花柱道是花粉管生长通道，由一层特化的内表皮细胞构成，多根花柱在基部合生进而形成子房中的空心中轴胎座。自交与异交授粉后，花粉管在柱头、花柱中部的生长情况无明显差异。到达花柱基部时，自交花粉管生长减缓，大部分生长停滞，只有少数能够长入子房，但最终也在子房中停滞而未能达到胚珠。生长停滞的花粉管末端荧光异常明亮，并伴随出现膨大、分叉、卷曲、折叠、波浪状等形状，呈现出不亲和反应。扫描电镜观察这些异常现象是由于花粉管壁局部加厚。自交花粉管的不亲和反应伴随花柱道内表皮细胞从花柱基部到子房的逐渐紧贴而出现。异交花粉管可顺利进入子房，经珠柄到达珠孔处转弯90°进入胚囊。【结论】通过解剖学结果可明确油茶为自交不亲和性植物，自交不亲和反应发生在花柱基部接近子房处，为合子前期不亲和类型。油茶自交花粉管生长受到抑制的生理、分子机制是今后研究的方向。针对生产中不同油茶品种间座果率不同的现象，探讨各品种间自交不亲和强度存在差异的机制也是研究的重点。油茶自交不亲和性反应发生在中空且花柱道相互贴合较为紧密的花柱基部接近子房处，而却未发生在花柱道间隙相对宽松的花柱中，这一现象是否普遍存在于中空型花柱的

自交不亲和性植物中及这一特征是否为山茶属中其他自交不亲和性植物所共有还有待广泛探讨。%Objective]To investigate difference in the growth behavior of pollen tube in the pistil of Camellia oleifera after self-and out-cross pollination and to identify the types and characteristics of self-incompatibility of the plant. Further to enrich and complement the current understanding of C. oleifera in reproductive biology and also to provide a theoretical basis for increasing oil production.[Method]The structural characteristics of C. oleifera and the growth process of pollen tube in the pistil were observed using fluorescence microscopy combined with the modified fluorescent pallet method, fluorescence sectioning,and the routine paraffin method,according to the experimental principles of observation of the pollen tube under a fluorescence microscope as well as the characteristics of the pistil of C. oleifera. The incompatibility responses of the self-crossed pollen tube were observed using scanning electron microscopy to characterize the anatomic properties of the self-incompatibility of C. oleifera. [Result]The growth of the pollen tubes was observed via the stylar canal,comprised of a layer of specialized canal cells. The styles were open type and connected at the stylar base and formed a hollow placenta. After pollination,no significant difference was observed in the pollen tubes of the self-crossed and out-crossed stigma and medial styles. Pollen tubes of both styles reached the stylar base; however,a majority of the self-crossed pollen tubes grew slowly and resulted in an incompatible callose reaction as they failed to enter the locule. The magnified part of the self-pollinated pollen tubes revealed

intumescence,bifurcation,coiling,folding,and wave lines that resulted from partially increased thickness of the pollen tube walls. The incompatible callose reaction was accompanied by gradual closing of the stylar canal,whereas the out-crossed pollen tubes successfully entered the locule with subsequent entry into the embryo sac at a 90° angle at the ovule micropyle position. [Conclusion]Based on the anatomical characteristics,we ascertained that C. oleifera was a self-incompatible plant and belonged to the prezygotic self-incompatibility type, which occurred between the stylar base and upper ovary. Future studies will be directed to understanding of the physiological and molecular mechanisms that restrict the growth of the self-crossed pollen tubes of C. oleifera. In view of the differences in fruit-setting rates among different varieties,focus will also be placed on the mechanisms behind the difference in the intensity of self-incompatibility of different varieties. Furthermore, self-incompatibility of C. oleifera occurs at the hollow stylar base where the stylar canals close intensely,which is close to the ovary,rather than in the style with a relatively loose interspace of the stylar canal. Whether this phenomenon is universal among the self-incompatible plants with hollow styles or the self-incompatible plants of the genus Camellia remains to be explored.

【期刊名称】《林业科学》

【年(卷),期】2015(000)002

【总页数】9页(P60-68)