Browsing by Author "Qingzhong, Xue"

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    Demarcating day-light-length from temperature effects in PGMS rice using back tracking method.
    (2014) Njiruh, Nthakanio P.; Qingzhong, Xue
    Two near isogenic rice lines ZAU11S106 (Photoperiod sensitive genic male sterile) and ZAU11F121(a ZAU11S106 whose PGMS gene has undergone reverse mutation to become a non-PGMS) were used. These two lines were studied to define the effects of temperature and day light length on PGMS gene expression using forward gene expression tracking method. In this method, ZAU11S106 and ZAU11F121 were divided into 8blocks into which they were grown up to mordial stage. This was a growth stage before the pollen matured to become fertile or sterile, a point called critical sterility point (CSP). At this growth stage, the first block was exposed to short day light length (SDLL) treatment. After four (4) days first and second row were put under SDLL treatment. A row was included under the treatment after every four days till the first row headed after which the treatment was withdrawn and all rice allowed to grow up to maturity under long day light length (LDLL) and high temperature growth conditions. The PGMS grown under long day and high temperature growth conditions had higher spikelet sterility than those grown under influence of long daylight length and lower temperature growth conditions. Thus, high temperatures complement photoperiod in inducing sterility in PGMS rice.
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    Programmed cell death-like behavior in photoperiod-sensitive genic male sterile (PGMS) rice
    (Academic Journals, 2011-04) Njiruh, Nthakanio P.; Qingzhong, Xue
    In photoperiod-sensitive genic male sterile rice (Oryza sativa L.) pollen abort in long day and high temperature, and revert to fertility in short day length and low temperature growth conditions. This type of control of rice plant fertility can facilitate production of hybrid rice using two lines (photoperiodsensitive genic male sterile (PGMS) and restorer) system. Our objective in this study was to determine anatomical changes in PGMS rice pollen cells induced by long day length and high temperature growth conditions that are responsible for the cell abortion. All materials in this study were sown at Zhejiang University research field at Hangzhou, China 30°15’ N. Seeds of ZAU11S106, a PGMS rice line, were sown so as to obtain two bulks, 1) Extreme sterile pollen bulk and 2) fertile pollen bulk. Rice plants for extreme sterile pollen bulk were sown on March 18th and those for fertile pollen bulk on July 15th, so that they flowered under 13 h or more and under less than 13 h respectively of day light. Transmission electronic microscopes were used to study histological sections of anthers while light microscopes were used to examine whole pollen cells. The tapetal layers and the cytoplasm of the sectioned ZAU11S106 rice anthers from extreme sterile pollen bulk were deformed but those from fertile pollen bulk were normal when compared to the control rice lines ZAU11F121 and Xusui163. Pollen cells from anthers of extreme sterile pollen bulk had eroded exine and intine, missing or damaged nucleus, and disintegrating cytoplasm that lead to cell abortion. Our conclusion is that, cell abortion observed in extreme sterile pollen bulk of photoperiod genic male sterile rice, display “programmed cell death–like behavior”.
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    Tracking the expression of photosensitive genic male sterility genes in rice
    (Academic Journals, 2013-11) Njiruh, Nthakanio P.; Qingzhong, Xue
    Photoperiod sensitive genic male sterile rice lines contain genes that induce complete sterility in high temperature and long day light length period, and revert to fertility in optimum low temperature and short day light length period. These lines are good candidates for hybrid rice seed production. The main challenge limiting their use in production of hybrid rice seeds is that of determining the exact time of their growth period when sterility gene(s) is expressed. The objective of this study was to determine the time in the rice growth period when the sterility gene(s) are expressed. Rice line ZAU11S106, a photoperiod sensitive genic male sterile line was used to test the hypothesis: it is possible to estimate time within ±2 days when photosensitive genic male sterility (PGMS) gene is expressed. Sowing was done in 9 rows in Hangzhou, China in the month of May and matured in August when day light length was over 14 h and day temperatures were over 30°C. At 57 days, old plants in row 1 were given short day length treatment and after every four days, the next row was included in the treatment. This was done until plants in row 1 flowered when the treatment was stopped. Plants given short day length treatment at 73 and 77 days old realized 6 and 0% seed set, respectively. At 73 and 77 days old, plants were at dyad and tetrad stages of pollen development, respectively. The conclusion was that, the sterility gene was expressed between the dyad and tetrad stage of pollen development.