Study On The Fertility Alteration Law Of Thermo-Photo Sensitive Genic Male Sterile Line K64S In Wheat

The thermo-photosensitive male sterile line is the basis of two-line hybrid wheat,identifying and clarifying their fertility alteration sensitive stages and regulations can provide the scientific basis for hybrid seed production and sterile line reproduct ion,and the cytological composition for abortion studying and regulating their sterile genes.The cytological regulation basis of fertility alteration for the abortion of K64 S is still unclear,hindering its large-scale application and related gene mapping research.Therefore,this study used K64 S as the plant material and performed an artificial growth chamber with different temperature levels,light lengths,and light intensities as treatment.In addition,the changes detecting in the fertility rate as a trait,of pollen grains under different treatments.The influences of different temperatures,critical temperature,light length,sensitive period,and light intensity interactions on fertility alteration were studied.At the same time,the cytological basis of K64 S sterility was investigated by comparing the different development stages of pollen mother cells to mature pollen grains of fertile and sterile K64 S and cultivar Yangmai 33 employed conventional squashing and paraffin.The results as follow:(1)K64S fertility alteration sensitivestage: The temperature fertility alterationsensitive stage and the light fertility alterationsensitive stage of K64 S are both pollen mother cell formation to mononuclear pollen grain formation stages.(2)The critical temperature and light conditions for K64 S fertility alteration:When the light length is 14 h,the critical temperature threshold for K64 S fertility alteration is 14 ℃～14.5 ℃,and when the temperature is lower than 14 ℃,it indicates sterility;the temperature is high than 14.5 ℃,it indicates fertility.When the temperature is 21 ℃,the critical threshold for fertility alteration of light length is 9 h～ 9.5 h.When the light length is lower than 9 h.(3)The experiment of temperature,light length,and light intensity interaction showed that temperature and light length,temperature and light intensity,light length and light intensity,as well as temperature,light length,and light intensity interact ion had significant effects on K64 S fertility alteration.Temperature was the most critical environmental factor affecting K64 S pollen fertility alteration,followed by light length,and light intensity.Under low temperature(12 ℃)treatment,the pollen fertility rate of K64 S was less than 10 %,indicating sterility.However,long-day and high light intensity would increase the pollen fertility rate and cause incomplete abortion;Under high temperature(21 ℃)treatment,K64 S pollen fertility rate is>10 %,indicating fertility.Short-day will reduce its pollen fertility rate,while short-day coupling with low light intensity will also lead to sterility.(4)The development process of K64 S pollen grains: pollen mother cells to mononuclear pollen grains.There was no significant difference between K64 S in sterility and fertility and Yangmai 33.Without binuclear and trinuclear pollen grains were found in K64 S in sterility,while obvious binuclear and trinuclear pollen grains were found in K64 S in fertility and Yangmai 33,indicating that K64 S pollen abortion occurred in the late mononuclear stage,and its development stagnated and did not develop into binuclear pollen.(5)K64S paraffin sectioning results: the sterile K64 S tapetum has obvious degradation in the pollen mother cell stage,which is significantly earlier than the fertile K64 S and Yangmai 33,and by the time of tetrad,it has completely degraded.The early degradation of tapetum may lead to the abortion of K64 S.