| Higher plants can’t find their spouse automatically because of their immobility. Inorder to achieve a high reproductive seccucess in different circumstance, it evolved avariety of breeding system, such as heterostyly. Fagopyrum dibotrys, a2ndClassendangered species for conservation in China, and Polygonum chinense, a herbal medicine,are companion species of Polygonaceae. To date, most of the studies on these two speciesfocused on their chemical components, pharmacology and clinical trials, etc. Here, weanalysized the breeding system, flowering phenology, reproductive allocation and strategyof Fagopyrum dibotrys and Polygonum chinense, to reveal their reproductive ecologycharacteristics, the evolutionary trends and mechanism of their distyly. The main goals ofthis study are to provide new perspective and enlightment for the protection, development,utilization of rare genetic resources and Chinese medicine resources. The key results are asfollows:1. Breeding systemThe reproductive traits of Fagopyrum dibotrys and Polygonum chinense, such asfloral characteristics, pollen/ovule ratio, pollen viability, stigma receptivity, out-crossingindex, emasculation, and flower-visiting insects, were investigated to reveal theirreproductive ecology. The results showed that individuals of Fagopyrum dibotrys andPolygonum chinense within a population exhibited two floral morphs as long-styled andshort-styled morphs. Polygonum chinense exists monotype population in the wild, whichbelongs to typical distyly plant and exhibits reciprocal herkogamy floral characteristics.Bagged experiments suggest that F. dibotrys is self-incompatible, but compatible forintramorph and intermorph. The P/O rations of Fagopyrum dibotrys and Polygonumchinense was respectively810±40.48and526.5±42.24,757±36.61and824.5±39.98,which suggests that the breeding system of both plants was facultative outcrossing, butlong-styled flower of F. dibotrys incline to outcrossing, corresponding to the fact that thefruiting rate of long-style is less than short-style, while Polygonum chinense is on thecontrary. Whether this phenomenon means that Polygonum chinense will develop towardhomostyly, or reproducing system crash and choose cloning for reproduction needsfurther research and discuss. The pollen viability of short-styled is higher than that oflong-styled in both species, but F. dibotrys’s pollen quantity of short-styled single floweris lower than long-styled, contrary to Polygonum chinense. The main floral visitors ofFagopyrum dibotrys and Polygonum chinense are insects of Hymenoptera, Diptera,Lepidoptera, Hemiptera and Odonata.19families37species visit F. dibotrys,14speciesfor long-styled flower,35species for short-styled flower,12common species for the twomorphs, which showed short-styled flower has stronger attraction to visiting insects thanlong-styled flower;14families24species visit Polygonum chinense,17species for long-styled flower,18species for short-styled flower,11common species for the twomorphs, which showed there is no difference in the attraction to insects of the two morphsof Polygonum chinense. The fruiting rate of F. dibotrys’ long-styled and short-styled was9.22±0.60%and9.77±0.48%，existing no significant difference (F=0.506，P=0.477); andthat of Polygonum chinense was20.42±2.342%and12.14±1.51%，showing significantdifference (F=9.185，P=0.004).2. Flowering phenologyFagopyrum dibotrys and Polygonum chinense flowered from August to November,mainly in September, centralized flowering contributes to insects pollination and improvesreproductive success. Flowering process figure shows that the lifespan of F. dibotrys’slong-styled and short-styled flower is85days, and that of Polygonum chinense isrespectively79days and73days, the difference is significant, we also find that there ismonotype population in the wild Polygonum chinense through wild research, and theshort-styled flowered earlier than the long-styled; F. dibotrys’s long-styled capitulumflowered15to26days,the mean value is20.36±0.53days, short-styled capitulum flowered14to27days, the mean value is21.42±0.53days, the difference is not significant（F=1.974，P=0.164）;Polygonum chinense’s long-styled capitulum flowered18to33days,the mean value is23.41±1.02days, short-styled capitulum flowered13to29days, themean value is20.63±0.79days, the lifespan of long-styled capitulum is longer than theshort-styled capitulum（F=4.745，P=0.034）. The flower number of F. dibotrys’s long-styledsingle capitulum is26to131, the mean value is76.53±4.00,the short-styled capitulum is36to147, the mean value is83.33±4.16, the difference is not significant（F=1.388，P=0.243）, The flower number of Polygonum chinense’s long-styled single capitulum is38to145, the mean value is85.00±4.96, the short-styled capitulum is27to109, the meanvalue is63.27±4.41, the long-styled single capitulum’s flower number is larger than theshort-styled (F=10.793，P=0.002). Fagopyrum dibotrys and Polygonum chinense flower1to2days for a single flower, the inner stamens disperse pollen first, the outer stamensdisperse pollen later, there is no significant difference in distyly plant in this aspect,showed their self-regulation mechanism. There is only one peak in F. dibotrys’s long-styledand short-styled capitulum flower number, long-styled and short-styled capitulum bothreached maximum11days after flowering,was7.30%and7.20%respectively; butPolygonum chinense owned as many as3to4peaks, the long-style reached maximum of6.01%5days after flowering, the short-style reached maximum of6.80%8days afterflowering. In conclusion, the long-styled and short-styled plant of distyly plant maintainedhigh synchronization of flowering, contributing to increase the reproductive adaptability.3. Reproductive allocation and strategyPistil and stamens length of F. dibotrys showed significant difference in the samefloral morphs, exhibited very significant negative correlation（r=-0.852，P=0.000）, but the total length showed no significant difference, which showed that there is a trade-offrelationship, owing to the significant difference in Polygonum chinense’s total length ofpistil and stamens, there is no trade-off relationship; Fagopyrum dibotrys and Polygonumchinense’s vegetative organs and reproductive organs biomass existed no significantdifference between the long-styled and short-styled, while their floral biomass and plantbiomass showed very significant difference（y=0.0328x+1.2885, R2=0.6097，P=0.000；y=0.0119x+0.0428, R2=0.6191，P=0.000）, F. cymosum’s floral biomass allocation ratio ofthe long-styled（6.34±0.75%）is significantly larger than the short-styled（3.96±0.39%）（F=7.781，P=0.008）; Polygonum chinense’s floral biomass allocation ratio of thelong-styled（1.27±0.11%）is significantly less than the short-styled（1.76±0.15%）（F=7.258，P=0.008）, the total biomass of these two plants showed no significantdifference between the two floral morphs, which showed that there is a trade-offrelationship in these two plant’s vegetative growth and sexual reproduction. |
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