Pollen Morphological Variation And Its Systematic Taxonomic Significance Of Sect.Ranunculoides In Primula L.

The sect.Ranunculoides(Primulaceae)is an important flower germplasm resource.In this paper,the pollen morphology of the sect.Ranunculoides was studied,and the phylogenetic tree constructed by ITS sequence was used to investigate the regularity of pollen morphological variation and its systematic taxonomic significance.The main results are as follows:1.Pollen morphological variation in the sect.RanunculoidesAccording to the type of pollen aperture,the pollen morphology of the sect.Ranunculoides can be divided into three types: stephanocolpate type,pantoporate type and colpi-and-pores type.Primula merrilliana distinctly distinguished from other species in the same group by the petal apex circle,and it also forms an independent branch on the phylogenetic tree.However,it has two types of pollen,which are stephanocolpate type and pantoporate type.The 11 populations located in the Qiupu River Basin are stephanocolpate type pollen,and the other populations are pantoporate type pollen,and the pollen morphology is stable within the population.The group of stephanocolpate type and pantoporate type also has obvious genetic differentiation.Therefore,the pollen morphology shows that Primula merrilliana is a complex containing two(or more)species.In addition,the pollen size and pollen aperture size of DSC population are different from other populations of pantoporate type,which may also indicate that it has differentiated into independent species.The suspicious species A located in the northern part of Qiandao Lake is similar in leaf morphology and corolla morphology to Primula cicutariifolia.The two are genetically clustered together,but there is a clear difference between the former who is the homostyled flower(inflorescence 2-3 layers)and the latter who is the distyled flower(inflorescence layer).Their are similar in pollen morphology.They all have stephanocolpate type,pantoporate type and colpi-and-pores type,and there are large variations in the population.Therefore,in terms of pollen morphology,it is temporarily impossible to distinguish whether the two species are independent species or the variation of the two flower patterns of the same species.Primula jiugongshanensis,suspicious species B,suspicious species C and Primula ranunculoides are gathered together as one on the phylogenetic tree,and the distribution area also overlaps,but Primula ranunculoides is stephanocolpate type pollen,while Primula jiugongshanensis are pantoporate type pollen,and both are stable within the species(also in population).And they are genetically distinctly differentiated,so the pollen morphology supports Primula jiugongshanensis as an independent species.The suspicious species B is similar in morphology and pollen morphology to the suspicious species C and Primula jiugongshanensis.However,the former is the homostyled flower and the latters are distyled flower,and it is not possible to further classify it from the pollen morphology.In summary,the pollen aperture type(stephanocolpate and pantoporate)of the sect.Ranunculoides has undergone multiple origins and parallel evolution,and has a high classification value of species.2.Differences in pollen size between homostyled and distyled flowersSome of the populations(such as QD and TL)of Primula merrilliana(complex)have stigmas and anthers in the middle or mouth of the corolla tube,which is suspected to be the same type of long-homostyly or short-homostyly.Pollen size studies showed that the pollen size of the suspected long-homostyly was similar to that of the short-styly(S),which was significantly larger than that of the suspected short-homostyly,while the latter was similar to the pollen size of the long-styly(L).Therefore,there are four typical floral morph types in the pollen size supporting Primula merrilliana(complex),namely long-styly,short-styly,long-homostyly and short-homostyly.