全 文 ：武汉植物学研究1999 , 17 ( 1) : 1～4
Journal of Wuhan Botanical Research
INHERITANCE AND DIVERSITY OF PGI
IN CHESTNUT (CASTANEA)


Huang Hongw en
1　Fenny Dane2　Jiang Zhengw ang 1
( 1 Wuhan Inst itut e of Botany , The Chinese A cad emy of S ciences　Wuhan, China　430074)
( 2 Dep artment of H orti culture, A uburn Univ ersity　Auburn AL 36849 U . S . A. )
Abstract　I nher itance of PG I isozymes in chestnut species wa s analy zed using iso elect ric fo-
cusing on thin-layer po lyacry lamide slab gels and sing le-tree-progeny method. T hree alleles at
one Pg i lo cus ( Pgi-1) w ere found to be codominantly inher ited. T w o additional alleles w ere
det ect ed in samples o f natural populat ions. Consider able v ariations in allele frequency and
hetero zygosity w er e found in popula tions of the Amer ican (Castanea dentata) and Chinese
( C . mollissima) chestnut species. Heter ozygosit y at the Pgi locus w as generally higher in
Chinese t han in American chestnut. Significant ly higher heter ozygosity o f t he Pg i w as detect-
ed in the southernmost lo cat ion of t he natural r ange of the American chestnut. The highest
and low est het ero zy go sity w as observ ed in Chinese chestnut populations fr om the Chang jiang
River and southeast r egion of China, respectively .
Key words　Cas tanea, PG I, I so zyme, Het ero zy go sity , Diver sity
Considerable effor ts are underw ay to develop a linkage map of chestnut g enome integ ra ting 5 mor-
pho lo gica l, 3 isozyme, 14 RFLP and 177 RAPD marker s〔1, 2〕. Because o f the codominant nature and low
sampling cost of allozym es, these marker s have been used ex tensively in st udies of the genetic div ersit y
and gene str uct ur e in natur al populat ions〔3〕. P olym orphic iso zyme lo ci in Amer ican (Castanea d entata
Bo rkh. ) and Chinese chestnut (C . mollissima Bl. ) species w ere evaluated using contr olled cr osses and
the sing le-tree-progeny method o f Gillet〔4〕. T he single-tr ee-progeny method proved successful fo r
isozyme genetic studies〔5〕. A s par t of our continuous effor ts to evaluate the genetic diver sity and popula-
tion str uct ur es o f chestnut species, the inher it ance and var iabilit y of pho sphogluco isomerase ( PG I )
isozyme in Amer ican and Chinese chestnut w as studied. PG I is know n to be a dim eric pr ot ein and tw o
loci are usually found in plants, one specific to the plastid and the o ther to cyt oplasm〔6, 7〕. Fineschi et
al. 〔8〕r epo r ted the pr esence of one PGI zone with 3 alleles in the European chestnut (C . sativ a Mill. ) .
1　Materials and Methods
Sing le-tree-progeny families der iv ed from five Chinese cult ivar s w er e used fo r genetic analysis
( T able 1) . Open-pollinated seeds w ere r andom ly har vested from each par ent t ree. Enzymes w ere ex-


收稿日: 1997-12-08,修回日: 1998-02-09。第一作者:男, 41岁,研究员,从事植物遗传育种研究。
国家自然科学基金及中国科学院生物科学技术研究特别支持费(财政部专项)资助项目。
tr act ed fr om co tyledon tissue and w ere assayed for PGI using an isoelectric focusing polyacr ylamide gel
system w it h pH 4～9〔9〕and the staining pr oto co l of Wendel and Weeden〔10〕with modificat ion o f 1% a-
gar ose over lay.
2 t est s wer e used to determine the goodness-of -fit of the segr egation rat ios to the ex-
pected relationships o f pr o geny genotypes ( Table 1) .
Table 1　Genetic analysis at the PGI locus using single-tree-progeny in Chinese chestnut cultivars
Maternal t ree
Name　 Genotype
Progen y genotype
T otal ac cc ce ae ee cd
Ex pected progeny
relat ionship*

2
Cr op per ce 50 15 28 7 N ce= N cc+ N e e 0. 50NS
Homestead ce 85 23 13 26 20 2 1 N ac= N ae 0. 09NS
Ex pected progeny
genotype
A-2-2 cc 50 38 12 cc, ce, ac
Black Beau ty cc 50 30 20 cc, ce, ac
Leader cc 50 36 14 cc, ce, ac
　　* N = T otal number of pr og eny gen otype; NS . Nons ignif icant .
American and Chinese chestnut populat ions w ere assayed fo r PG I po lymorphism . Winter dormant
or sum mer mat ur e buds from 20～50 different tr ees, r andomly collected in the natur al range of the
American chest nut, w er e used fo r enzyme ex tr action and assayed for PG I as descr ibed. The Nor thern
population consisted o f 11 tr ees co llected in Connecticut and 14 trees in New York. The Cent ral and
Southern populations w ere co llected in West V irg inia and A labama , r espectively ( T able 2) . Thr ee popu-
lat ions o f the Chinese chestnut wer e obt ained fr om the China Na tional Chestnut Germplasm P lantat ion
and Hubei Academy of Ag ricultural Science. These populations consisted of seedlings derived fr om open
pollinat ed tr ees of each reg ional cult iva r planting s. T he US na tur alized popula tion o f the Chinese chest-
nut consisted o f the t hird generat ion seedlings der iv ed fr om seeds intr oduced in 1933 by USDA fr om
China to Alabama. Dormant buds w ere used for enzyme ex tr action. A llele fr equencies and obser ved he-
ter ozygosit y ( hob) and unbiased expected hetero zygosity ( hex) values
〔11〕w ere estimated fo r each popula-
tion.
Table 2　Allelic f requencies and heterozygosity at Pgi in populations of the
American and Chinese chestnut
Populat ion
Populat ion
s ize
Pg i-a Pg i-b P gi-c P g i-d P gi-e hob hex
C hinese ch es tn ut
　Northern populat ion 25 0. 060 0. 000 0. 640 0. 000 0. 300 0. 560 0. 507
　C han gjian g river pop ulation 24 0. 083 0. 042 0. 625 0. 042 0. 229 0. 625 0. 558
　S outheast populat ion 20 0. 050 0. 000 0. 800 0. 000 0. 150 0. 400 0. 344
　U S natur aliz ed populat ion 20 0. 075 0. 000 0. 700 0. 000 0. 225 0. 600 0. 465
Am erican ch es tn ut
　Northern populat ion 25 0. 000 0. 000 0. 900 0. 000 0. 100 0. 200 0. 184
　C ent ral populat ion 22 0. 000 0. 018 0. 911 0. 018 0. 054 0. 179 0. 170
　S outhern populat ion 20 0. 000 0. 000 0. 550 0. 000 0. 450 0. 500 0. 508
2　Results and Discussion
Result s indicated that chestnut tissues show ed one po lymorphic PG I zone ( F ig . 1) . Single- or t riple-
2 武汉 植物 学研 究　　　　　　　　　　　　　　　　　第 17卷　
Fig. 1　Interpretative drawing of zymogram and al lel ic
defini tion of PGI isozymes extracted from chestnut seeds
banded pat terns were found in both species
confirming the dimer ic nat ur e of this isozyme,
ag reeing w ith the r esults of F ineschi〔8〕in Euro-
pean chestnut (C . sativa) . Of fiv e Chinese cult i-
va rs used as par ent s fo r sing le-tree-progeny
analysis, Cr opper and Homestead are t riple-
banded hetero zy gotes.
2 test w as used to deter-
mine t he goodness-o f-fit o f segr egat ion ratio t o
expect ed relationships o f pr ogeny genotypes
( quantitativ e test fo r single-tr ee-progeny ) . The
o ther Chinese chestnut cult iva rs, A-2-2, Bla ck
Beauty and Leader , are sing le-banded homozygo te w hich can be used fo r qualitative sing le-tree-progeny
test only . Results show n in Table 1 are consistent w ith t he hypothesis t hat one codominant locus w ith
thr ee alleles contr olling the variants o f PGI phenotypes. The most anodal allo zyme was designated as al-
lele a and the o ther alleles as c and e ( Fig. 1) . T he ae geno type exhibit ed a five-banded phenot ype pat-
tern. This could r eflect the pr esence o f a second lo cus ( Pgi-2) overlapping w ith the P gi-1c. The bands
betw een a & c and c & e could r eflect the fo llowing interg enic dimer s Pg i-1a∶Pg i-2a and P gi-1 e∶
Pg i-2a. Heter odimer ic fiv e banded PGI patterns have been ex tensiv ely studied in Clarkia species〔12〕and
w ere examined using stem and po llen tissues. Addit ional studies a re needed to clarify the heter odimer ic
banding pa tterns obser ved in t he Chinese chestnuts. Tw o o ther alleles w er e found in population samples
of the Amer ican and Chinese chestnuts and tentatively assigned as b and d. F ineschi et al. 〔8〕r epo rt ed
that only one PGI zone could be r evealed and thr ee alleles wer e found in European chestnut. Consider-
able variation in allele fr equencies and heter ozygosit y lev els wer e detected in bo th t he American and Chi-
nese chestnut populations ( T able 2) . A llele a w as no t detected in any populations of the Amer ican chest-
nut , w hile allele fr equencies of 5%～8. 3% were found in Chinese chest nut populations. A llele c w as the
most common allele in bo th species. Het ero zy go sity of Pg i-1 w as gener ally higher in the Chinese as
compared t o the Amer ican chestnut ( T able 2) . T his is concordant w ith pr ev ious isozyme studies that
show ed Chinese chestnut, par ticularly popula tions in Chang jiang River reg ion, is the most genetica lly di-
ver se species in genus Castanea〔13〕. A surpr isingly high het ero zy go sity w as no ted in t he population col-
lected in Macon county , AL , the most sout hern lo cation in the natural r ange o f the American chestnut .
The r eason for this is unclear and needs additional study . Difference of P gi-1 heter ozygosity levels was
also det ect ed among populations of the Chinese chestnut. A remarkably low er heter ozygosity w as found
for the southeast ern China population. T his might have been the r esult o f clonal pr opagation of only a
few commercial cultiv ars in t hat ar ea of China〔14〕. Chinese chestnut tr ees have been intr oduced into the
United St ates since last centur y as a sour ce of resist ance t o chestnut blight ( Cryphonectr ia parasi-
tica) 〔15〕. M ost intr oduction show ed a high lev el of resistance t o the fungus and ar e g r ow n acro ss the US.
A lt hough the br eadth of the genetic base o f the intr oduction continues to be debated〔15〕, o ur results indi-
ca te t hat the naturalized populat ions o f Chinese chestnut have a similar level o f heter ozy go sity at the
Pg i-1 lo cus as o ther Chinese chest nut populations ( Table 2) . M ore markers are needed t o accur ately
evaluate the over all genetic div ersity o f the American and Chinese species.
3　第 1期　　　　　　　　　　　　黄宏文等:栗的 PGI遗传和多样性(英)
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栗的 PGI遗传和多样性
黄宏文1　Fenny Dane2　姜正旺1
( 1 中国科学院武汉植物研究所　武汉　430074)
( 2 Dep artment of H orti culture, A uburn Univ ersity　Auburn AL 36849 U . S . A. )
摘　要
　　采用超薄聚丙烯酰胺平板凝胶等电聚焦电泳和单株后代法,分析了栗属种的 PGI 同工酶的遗传。研
究发现 Pg i位点(P gi-1)主要有 3 个等位基因并呈共显性遗传。在栗属的自然居群中还检测到了出现频
率较少的另外 2 个等位基因。美洲栗 (Castanea d entata)和中国板栗(C . mollissima)居群的P gi基因频率
和遗传杂合度存在较大的差异。中国板栗的 Pg i位点的遗传杂合度通常高于美洲栗。在美洲栗自然分布
区中,南端地区的居群存在显著高的 Pgi 遗传杂合度。在中国板栗居群中,长江流域居群 P gi杂合度最
高, 东南部居群最低。
关键词　栗属, 磷酸葡萄糖异构酶, 同工酶, 遗传杂合度, 多样性
4 武汉 植物 学研 究　　　　　　　　　　　　　　　　　第 17卷