| Heterostyly is a genetic controlled polymorphism,including distyly and tristyly.It has been reported that the heterostyly are present in the families of at least 28 species of the plant,and the reports and research on the heterostyly have been more than a century.The early investigation on the Acantholimon alatavicum showed that the plant had part of the characteristics of distyly,but it is different from the typical distyly and tristyly.What kind of heterostyly type and polymorphism of this plant is a problem worth exploring.Therefore,the following studies were carried outsuch as population structure,ancillary polymorphism of pollen and stigma morphology,pollen transfer proficiencis and heteromorphic incompatibility system,floral morph and fruiting set of several populations in different distribution regions in Acantholimon alatavicum.The results were summarized as follows:1)The flowering time of Acantholimon alatavicum in different distribution areas was different,the BC population entered the flowering period in early may,lasting for more than 20 days;After opening,the single flowers did not close until to the second day.The three populations with differentdistributions are all composed of long styled-morph(L-morph),short styled-morph(S-morph),H-morph with pistils and stamens at the same height and some morph with lightly higher pistils than stamens(PL-morph)and lightly higher stamen than pistils(PS-morph).This species has dimorphis for pollen exine sculpturing and stigmatic papillae morphology.S-morph,PS-morph and H_S-morph flowers produce pollens with finely reticulated sexine(pollen type B)and papillate stigmas;L-morph,PL-morphand H_L-morph flowers produce pollens with a coarse reticulate sexine(pollen type A)and a cob-like stigmatic papillae.2)The proportion of S-morph individuals in BC population,WS population and TC population were 1.78,2.03 and 1.29 times higher than that of L-morph individuals,respectively.All of them showed the characteristics of more S-morph individuals with lower degree of differentiation and fewer PS-morph,H_S–morph individuals compared with L-morph individuals.According to the morphology of stigmas and pollen,the floral morph of three populations were classified and found that the number of flower morph with papillate cells on stigmas surface and cob-like stigmatic surface cells was in accordance with the flower morphs ratio of 1:1.3)It was found that there was no significant difference between the L-morph and the S-morph and H(H_L)morph in the parameters such as the the corolla open diameter,corolla tubelength,corolla tube diameter,and ovule numbers.The degree of reciprocity is higher in high-level(R_H=0.01)organs than in low-level(R_L=0.03)organs between sex organs of L-morph and S-morph individuals.H-morph whose sex organs was lack of reciprocity between L-morph or S-morph individuals.4)In natural population,the total number of pollen grains on the S-morph stigma was significantly lowerthan that of the L-morph.But there were no significant differences in the number of the compatible pollen grains in different floral morphs.The stigma-adhesion pollen experiment was carried out on the L-morph,S-morph individuals of the BC group.And the adhesion of the stigma to the compatible pollen grains of the S-morph was higher than that of incompatible pollen grains(t=3.99,P<0.01).However,there was no difference in the adhesion ability of L-morph stigmas to the two kinds of pollen(t=-0.18,P>0.05).It is suggested that the difference of the number of the pollen grains in the stigmas of different floral morphs may be related to the pollen ornamentation and morphology of the stigma cells.5)The pollinators of Acantholimon alatavicum are mainly divided into two types:long-tongued and short-tongued,showed no visiting preference among morphs within BC population(F=0.345,P>0.05),the frequency of visiting flowers in three morphs were 0.21±0.06 times/single flower/h(S-morph),0.17±0.08 times/single(L-morph)flower/h,0.10±0.05 times/single flower/h(H-morph),respectly.6)The seed setting rates of the three floral morphs after intra-moprh pollinations were 0(L-morph),3.45%,(S-morph)and 14.29%(H-morph),respectively.The fruit set rates are not significiant differerce among three morphs in each population,but the average natural seed setting rate of different populations has a detectable difference,and in TC population was 77.11%,and in WS population was 64.95%.7)The style polymorphism of Acantholimon alatavicum in these populations may be an intermediate transition floral morph evolution of distyly.H-morph and the morph of pistil and stamen is longer or shorter may be caused by gene mutations that control the length of style.Among the floral morphs which lack the reciprocal herkogamy,the ancillary polymorphism of pollen-stigma morphology has the function of promoting the disassortative pollination... |
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