Apoptosis Characteristics Of Giant Cells Caused By Meloidogyne Incognita In Solanum Lycopersicum

Nowadays,root-knot nematode can cause serious disease in most of plants in the argriculture production.Using traditional methods to control the root-knot nematodes can't make obvious effect.Giant cells of root-knot play a key role in plant,it can offer nutrients for the growth and development of root-knot nematodes.Some research found that inclusions of giant cells appeared obvious vacuolation in the later infection stage of M.incognita,but the specific mechanism of vacuolation is not yet clear.In this paper,we make Solanum lycopersicum as the host plant to study giant cells,which lay a foundation of revealing the apoptosis characteristic of giant cell caused by root-knot nematodes.Main innovative results are as follows:1.The location of the female root-knot nematode in the root-knot of the host plant was revealed.The root-knot of Ipomoea aquatica and S.lycopersicum were stained by sodium hypochlorite-acid fuchsin staining,the angle between female root-knot nematode and the root stele was measured.Results showed that,the angle between fema le root-knot nematode stele and the root stele was mainly in the range of 40°⁶0°in the root-knot of I.aquatica and S.lycopersicum.2.Embedding angle of paraffin section technology was optimized in plant root knot.According to the enlargement morphological characteristic of I.aquatica and S.lycopersicumroot knot,the measurement of infected angle by female root-knot nematode,the enlargement characteristic tend to one side of root knot were used for paraffin sections,which turn 45°in the opposite direction to its enlargement in wax,it can make the angle between the root stele and the length of rectangle embedding mould about 45°.And the best slice numbers of S.lycopersicum root knot was attained.The Results showed that,the total slices numbers of each root-knot were about 220,giant cells and root-knot nematode can only be found in the slices of paraffin section from No.91 to 150,while giant cells and root-knot nematode can not be observed in the slices of paraffin section from No.1 to 90and No.151 to 220.We make a conclusion that only 10 slices of pre and post the middle position of slice numbers of each root-knot paraffin sections?the middle position of slice numbers=total slice numbers/2?hold both the large part of root-knot nematode body and the maximum number of giant cells.3.The apoptosis process of giant cells in S.lycopersicum was revealed.The area of giant cells and its inclusions gradually increased at 7 DPI?days post inoculation,DPI?,14DPI and 21 DPI,respectively.They increased and became maximum at 21 DPI;the average area of giant cells were10523.3±1562.9?m2and the average area of inclusions were9929.3±1300.6?m2.The area of giant cells inclusions began to increase on 21days of M.incognita infestation,giant cells began to emerge vacuolation.And then the area of giant cells and its inclusions gradually decreased,giant cell emerge the obvious vacuolization on35^th DPI,the area of giant cells and its inclusions decreased to minimum,the area of giant cell were 7613.9±790.1?m2and the area of inclusions was 4933.6±719.3?m2.Apoptosis about giant cells was detected by TUN EL in S.lycopersicum root knot.With the increase of days of M.incognita infestation,the green fluorescence signals in the treatment group increased,and the apoptotic rate of nucleus was 89%up to the highest on 35 DPI.These results demonstrated that giant cells undergo three stages:the process of development-maturation-apoptosis,after the second-stage juveniles of root-knot nematode successfully infect root of host plants.4.The expression characteristics of LeMYB330 gene and MiPDCD6 proteins of M.incognita related to giant cell apoptosis of root-knot were elucidated.The expression of MiPDC D6 and LeMYB330 were detected by real-time fluorescence quantitative technique.It reveals that MiPDCD6 get the highest expression on 21 DPI of M.incognita infestation,and LeMYB330 get the highest expression on 35 DPI of M.incognita infestation.MiPDC D6 proteins of M.incognita were localized in S.lycopersicum root knot by using of immunofluorescentce localization technology.Results showed that,there were strongest green fluorescence signals in the giant cells of 21 DPI.These results demonstrated that MiPDC D6 proteins of M.incognita got the highest expression and the strongest green fluorescence signals when giant cells began to apoptosis process?on 21 DPI?.