Study On The Development Of Aloe Reproduction And The Effects Of Its SOD, POD Activities And Ultra-structure Under Non-biology Stress

The natural development of pollen is very vital to impregnation and fructification of plant. Explanation one of the reasons leading to Aloe male-sterility through studying its pollen development is very important to improve Aloe sexual reproduction. Observation on Aloe barbadensis Mill ultra-structure and detection on its SOD, POD activities after NaCl, low temperature and drought treatment separately proved that Aloe barbadensis Mill is tolerant to non-biology stress on some degree.The main reason for pollen abortion in Aloe arboresens Mill. was studied through the observation of meiosis and the microspore development of its pollen. mother cells(PMCs). There are 14 chromosomes in the PMC of Aloe arboresens Mill., containing four pairs of long chromosomes and three pairs of short ones, and this karyotype belongs to dichotocarpism. The abnormalities in the PMCs were fallen into four categories:(l) Univalents, they were caused by failure in pairing, asynapsis and precocious cancellation of terminal chiasma. Oriented univalent pair was distributed at two poles normally in anaphase, while non-oriented univalent pair only at one pole. Another factor leading to univalents was that chromosomes were paired but without substantial exchange. (2) Multivalents. They might be produced by translocation heterozygote.(3) Chromosome bridges. There were three kinds of bridges in anaphase I and anaphase II: single and double chromosome bridge as well as "diagonal bridge".(4) A few cells were found with lagged chromosomes, micronuclei and unbalanced segregation of the chromosomes. In the later stages of meiosis, well-spread chromosomal configurations were rare because of the extremely sticky nature of the chromosome. The number and ratio of abnormalities were analysed and the relationship between abnormalities and pollen sterility were discussed. It is concluded that the sticky nature of the chromosome is the main reason for abnormal meiosis of Aloe arboresens Mr//. PMC and pollen sterility. More than 90% of matured pollen grains were sterile.In this paper, Aloe barbadensis Mill anther culture on MS, C₁7, N₆, W₁4 and B₅ media for 45 days separately were studied. Though some useful datas had been obtained, the callus regeneration still was not producible, which is probably related to the browning of the tissues. And other more studies should be conducted to make much progress for Aloe barbadensis Mill anther culture, such as increasing efficiency of inoculation, leveling hormones of calluses by adjusting plant hormone ratio in medium, preparing special medium for Aloe barbadensis Mill and selecting susceptible genotypes for regeneration.The effects of superoxide dismutase(SOD), peroxidase(POD) activities and ultra-structure, such as, plasma membrane, chloroplasts, mitochondria and nucleoli, of Aloe barbadensis Mill mesophyll cell under NaCl(1.8%, equal to 0.3mol/L), low temperature(10℃) and drought(25%, PEG-6000) treatment were studied in this paper and the results are as follows:1) With the time changed (3d, 5d, 7d, 14d)under NaCl and drought stress, the activities of both SOD and POD varied in the way of decrease-increase-decrease-increase detected by UV-754. Which were induced by reactive oxygen species (ROS), the results indictated the enzymatic mechanism of eliminating ROS in Aloe barbadensis Mill were similar, thus the abilities of NaCl and drought resistance of Aloe barbadensis Mill were of relativity. After low temperature treatment, the activities of SOD and POD varied in the way of decrease-increase-increase-increase. Aloe barbadensis Mill belongs to tropic crop and it is sensitve to low temperaturem, and more ROS will be generated in it after low temperature treatment, the Aloe barbadensis Mill would use more SOD and POD to clean out the ROS to survive, therefore the enzyme activities became higher and higher.2) With the 7 days culture by Hoagland liquid after each treatment (NaCl, low temparature and drought), the activities of SOD and POD changed in different way separately and much of them were higher or lower than the...