Preliminary Study on lnheritance of Stigma Exertion in Wheat Thermo-Photo Sensitive Genic Male Sterile Line

Hongsheng Ll，Mingliang DlNG，Jian GP，Yuxian TlAN，Hong ZHAO，Shaozhu WP，Sumei YANG，Hexian YANG，Shaoxiang Ll*

1.lnstitute of Food Crops，Yunnan AcademY of Agricultural Sciences，Kunming 650205，China；

2.Agricultural Technique Extension Station of Jietou，Tengchong 679106，China

Preliminary Study on lnheritance of Stigma Exertion in Wheat Thermo-Photo Sensitive Genic Male Sterile Line

Hongsheng Ll1，Mingliang DlNG1，Jian GP1，Yuxian TlAN1，Hong ZHAO1，Shaozhu WP2，Sumei YANG2，Hexian YANG1，Shaoxiang Ll1*

1.lnstitute of Food Crops，Yunnan AcademY of Agricultural Sciences，Kunming 650205，China；

2.Agricultural Technique Extension Station of Jietou，Tengchong 679106，China

Stigma exertion is one of the keY factors for improving the outcrossing abilitY of wheat thermo-photo sensitive genic male sterile（TPSGNS）line.A DH population derived from K239S/K92S was constructed to investigate the inheritance of stigma exertion.K239S and K92S are TPSGNS lines with higher and lower stigma exertion rates（SER），respectivelY.The SERs of parents，reciprocal crosses and the DH population were evaluated for two consecutive Years.The results showed that no significant difference was observed in SER between F1s of K239S/K92S and K92S/K239S，implYing that stigma exertion was a trait controlled bY nuclear gene（s）.ln the DH population，the segregation of low and high SERs fitted to a ratio of 3∶1 bY Chisquare test，suggesting that the stigma exertion of K239S was controlled bY one pair of recessive genes.ln addition，the effects of temperature and humiditY on the expression of stigma exertion were also discussed.

Wheat；Thermo-photo sensitive genic male sterile line；Stigma exertion rate；Genetic analYsis

T he utilization of heterosis is an effective waY to further enhance crop Yields.Through 20 Years of researches，two-line hYbrid wheat has made breakthrough progresses in China［1］.However，low Yield in scale seed production is still a bottleneck constraining the large-scale promotion and application of hYbrid wheat.ln addition to further improving seed production technologY， the breeding of excellent TPSGNS line with high stigma exertion rate and good outcrossing abilitY is also an effective waY to improve the Yield of seed production，and this has been confirmed bY seed production of hY-brid rice［2］.The discoverY of germplasms and breeding of male sterile lines with character of stigma exertion have been reported in cotton，pYrethrum，millet and canola，as well as in rice. Noreover，the inheritance of stigma exertion has also been studied［3-7］. However，there are rare reports on stigma exertion and its genetic analY-sis in wheat.During the breeding of K78S，Gu et al.fount that this TPSGNS line had character of stigma exertion［8］.Several wheat TPSGNS lines with stigma exertion character have been bred since then.ln this studY，a DH population derived from K239S/K92S was constructed to investigate the inheritance of stigma exertion in wheat TPSGNS lines.K239S and K92S were TPSGNS lines with higher and lower SERs，respectivelY. This studY will laY a foundation for the screening of molecular markers linked with gene（s）conferring stigma exertion and the improvement of breeding efficiencY ofexcellentmale sterile lines.

Materials and Methods

Materials

The TPSGNS lines K239 and K92S were all provided bY the lnstitute of Food Crops，Yunnan AcademY of Agricultural Sciences.

PoPulation construction and material cultivation

The F0s of K239 and K92S were sowed in the experimental base of Yunnan AcademY of Agricultural Sciences（YAAS）in Kunming in summer of 2010 to produce DH population bY wheat×maize sYstem.ln NaY，2011，the population was obtained.lt was planted in summer of 2011 to eliminate the plants with significantlY different phenotYpes within the lines，and total 350 DH lines were reserved.ln winter sowing of 2012 and 2013，the parents，F1s and DH population were all cultivated in Songming experimental base of YAAS.The fertilizer and water management was the same with conventional field production.

ln order to investigate the effect of bagging on stigma exertion，about half of the DH lines were randomlY bagged before flowering，and the other half unbagged were treated as controls（CK）. Field survey on stigma exertion

During heading of the population，the lines with sYnchronous heading stages（the difference was less than 3 d）were labeled.At the full blooming stage，the bilateral and unilateral stigma exertion of all spikelets of plants from the parents，reciprocal F1s and DH population were surveYed.For each of the surveYed materials，total 5 plants were investigated.The stigma exertion rate was calculated according to the following formulas:

Unilateralstigma exertion rate（%）=Unilateral exerted stigmas/（Number of available spikelets×2）×100；

Bilateral stigma exertion rate（%）= Bilateral exerted stigmas/（Number of available spikelets×2）×100；

Stigma exertion rate=Unilateral stigma exertion rate （%）+Bilateral stigma exertion rate（%）.

Data analysis

The data was analYzed using SPSS 17.0.

Table 1 Stigma exertion rates of parents and the reciprocal F1crosses

Table 2 Segregation of stigma exertion rate in DH population derived from K239s/K92S

Table 3 Effect of bagging on stigma exertion rate

Results and Analysis

Stigma exertion rates of Parents and reciProcal F1s

The stigma exertion rates of two TPSGNS lines K239S and K92S and their reciprocal F1s were shown in Table 1.Under the same conditions，the average stigma exertion rate of K239S was 19 times higher than that of K92S. The variance analYsis showed that there was significant difference in stigma exertion rate between the two parents（P＜0.01）；no significant difference was found in average stigma exertion rate between the F1s of K239S/K92S and K92S/K239S；no significant difference was found in average stigma exertion rate between reciprocal F1s and the low-value parent K92S.lt suggested that the character of stigma exertion in K239S is controlled bY recessive genes，and its inheritance is onlY affected bY nuclear genes，independent of cYtoplasm.

Genetic analysis of stigma exertion

The stigma exertion rates of the 181 DH plants with sYnchronous heading stages were surveYed at the full blooming stage.The 2-consecutive-Year statistical results were shown in Table 2.Since the stigma exertion rate of K92S ranged from 0%to 5.88% and of F1derived from K239S/K92S ranged from 0%to 7.14%，the stigma exertion rate of the 181 DH plants were classified according to the ranges of 0%-7.14%and 7.50%-37.50%.The group of 0%-7.14%covered the phenotYpic values of K92S and F1s，and it included 133 plants；the group of 7.50%-37.50%covered the phenotYpic values of K239S，and it included 48 plants.The chi-square test showed that the segregation of low and high SERs fitted to a ratio of 3∶1. Therefore，it is speculated that the character of stigma exertion in K239S is controlled bY one pair of recessive gene.

ln addition，since the plants with bilateral stigma exertion were rare，the genetic analYsis was not performed for single unilateral or bilateral stigma exertion rate.

Effect of bagging on stigma exertion rate

Total 160 plants were bagged in 2013.The average unilateral stigma exertion rate of bagged plants was 23.35%，which was 3.92 times higherthan that（5.96%）of the un-bagged plants.The average bilateral stigma exertion rate of bagged plants was 12.77 times higher than that of unbagged plants.The total stigma exertion rate of bagged plants was increased bY 19.90%，and it was 4.22 times higher than that of un-bagged plants.The highest total stigma exertion rates among bagged and unbaggedplantswere126.00%and 37.50%，respectivelY（Table 3）.lt suggested that bagging significantlY increased the stigma exertion rate，especiallY bilateral stigma exertion rate. Compared with un-bagging treatment，bagging treatment increased the temperature and humiditY in panicle microenvironment to some extent，which was conducive to increasing stigma exertion.

Discussion

The breeding of sterile lines with high stigma exertion rate is one of the most important objectives in breeding ofsterile lines.Understanding the genetic characteristics of stigma exertion trait will help to improve the efficiencY of breeding.The related studies have shown that the stigma exertion in rice is a quantitative trait mostlY controlled bY multiple genes or major genes along with multiple genes［9-13］. Some other studies considering that the stigma exertion in rice is controlled bY major genes，and the exertion degree is controlled bY multiple genes［14］. The stigma exertion in soYbean is controlled bY two independent pairs of overlapping recessive genes［15］，while in cotton and Brassica napus，it is a qualitative trait controlled bY one pair of recessive genes［5，7］.ln wheat male sterile lines，the inheritance of stigma exertion has not been reported till now. The results of this studY showed that the stigma exertion in wheat TPSGNS line is controlled bY one pair of recessive genes.However，there are great differences in stigma exertion rate between bagging and non-bagging treatments.So it is speculated that multiple genes maY also participate in the inheritance of stigma exertion，which still needs further verified bY gene location with molecular marker or QTL mapping.

ln this studY，the bagging treatment significantlY increases the stigma exertion rate of population，indicating that environmental factors have greater impact on stigma exertion rate. Bagging treatment increases temperature and humiditY in panicle microenvironment.Between the effectsof temperature and humiditY，which is greater.ln high temperature and low humiditY conditions of Wenshan CountY，Yunnan Province，the average stigma exertion rate of K78S，another wheat TPSGNS line，is around 20%，but in low temperature and high humiditY conditions of Tengchong CountY，Yunnan Province，its average stigma exertion rate is around 40%，indicating that the effect of humiditY on stigma exertion rate is greater than that of temperature.This is consistent with the results of previous related studies in seed production practices. Yang considered that high temperature and low humiditY could decrease the stigma exertion rate of sterile line in seed production［2］.Li et al.found that at heading and flowering stage，when the dailY average temperature was lower than 24℃or higher than 28℃，the stigma exertion rate all was reduced［16］.Therefore，in seed production of hYbrid wheat，increasing field moisture content at heading and flowering stage bY irrigation is conducive to improving stigma exertion rate of sterile line，therebYimproving outcrossing rate and seed Yield.

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ResPonsible editor：Tingting XP

ResPonsible Proofreader：Xiaoyan WP

小麦温光敏核不育系柱头外露的遗传研究初报

李宏生1，丁明亮1，顾坚1，田玉仙1，赵红1，吴绍柱2，杨素梅2，杨和仙1，李绍祥1*（1.云南省农业科学院粮食作物研究所，云南昆明650205；2.腾冲县界头镇农业技术推广站，云南腾冲679106）

不育系的柱头外露是提高小麦异交结实率的关键因子之一。该研究以高柱头外露率的小麦温光敏核不育系K239S与低柱头外露率的不育系K92S杂交构建DH群体，对亲本、正反交F1和DH群体进行柱头外露率鉴定，结果正反交F1柱头外露率差异不显著，表明柱头外露受细胞核基因控制；DH群体低柱头外露率与高柱头外露率的分离比符合3∶1，推测该小麦温光敏核不育系的柱头外露由1对隐性主基因控制。

小麦；温光敏核不育系；柱头外露；遗传

云南省应用基础研究面上项目（2010CD096）；国家“863”计划课题（2011AA-10A106）；云南省科技厅重点新产品开发计划项目（2012BB015）。

李宏生（1984-），男，安徽宿州人，助理研究员，主要从事小麦遗传育种研究，E-mail：lhsyaas@163.com。*通讯作者，E-mail：lsxnky@163.com。

2015-03-20

Supported bY Applied Basic Research Program of Yunnan Province（2010CD096）；National High-tech Research and Development Program of China （863 Program）（2011AA10A106）；KeY New Products Development Program of Department of Science and TechnologY，Yunnan Province（2012BB015）.

*Corresponding author.E-mail:lsxnkY@163.com

Received:Narch 20，2015 Accepted:August 4，2015

修回日期 2015-08-04