A Comparative Study Between Sorghum And Maize On The Physiological And Molecular Mechanism Of Water Stress Resistance

Drought　is　one　major　abiotic　factor　that　adversely　affects　the　crop　production　and　distribution　and　account　for　the　reduction　in　the　yields　of　crops.　At　present,　to　improve　the　crop's　quality　of　water　stress　resistant　ability　through　breeding　anti-water　stress　plants　or　cultivars　is　one　of　the　main　methods　to　solve　this　problem.　As　the　water　stress　resistant　ability　is　controlled　by　multigenes,　using　modern　molecular　and　gene　technology　to　breed　water　stress　resistant　plant　or　genotype　has　not　got　the　good　result.　So　it　is　very　important　and　necessary　to　give　more　attention　to　clear　up　the　water　stress　resistant　mechanism　deeply.　Sorghum　is　a　model　plant　for　researching　the　mechanism　of　water　stress　resistance.　In　this　study,　various　sorghum　cultivars　were　used　as　experimental　materials　to　study　the　mechanism　of　water　stress　resistance　and　compared　with　maize,　which　water　stress　resistant　ability　is　lower　than　sorghum　while　its　geneology　knowledge　is　more　clear.　In　our　study,　we　first　compared　the　osmotic　mechanism　and　antioxidant　ability　between　sorghum　and　maize,　and　then　on　the　base　of　revealing　the　function　of　aquaporin　PIP1　in　maize　leaf　growth　and　water　stress　resistant　ability,　we　studied　the　role　of　the　same　type　aquaporin　in　sorghum,　and　compared　its　change　between　sorghum　and　maize　in　the　level　of　molecular　mechanism.　The　main　results　are　as　follows:　1.Through　the　soil　drought　and　recovered　water　experiment,　we　confirmed　that　the　osmotic　tolerance　and　antioxidant　mechanism　are　all　exit　in　sorghum　and　maize,　while　their　main　osmotic　materials　and　antioxidant　enzymes　are　different.　In　sorghum,　the　soluble　sugar　and　protein　are　the　main　osmotic　substance　and　CAT　is　the　main　antioxidant　enzyme.　In　maize,　it　used　the　K+　and　proline　as　the　main　osmotic　materials　and　SOD　and　POD　as　the　main　antioxidant　enzymes.　We　also　found　the　difference　in　the　osmotic　tolerance　and　antioxidant　ability　between　different　genotype　in　sorghum　or　in　maize,　and　the　same　mechanism　change　between　sorghum　and　maize.　So　the　anti-drought　mechanism　in　the　crop　is　a　complex　net.　Sorghum　has　higher　water　potential　than　maize,　and　has　more　effective　　osmotic　tolerance　and　antioxidant　ability.　It　showed　more　tolerance　to　drought　than　maize.　2.We　first　report　the　role　of　aquaporin　in　sorghum,　and　compared　its　difference　with　maize.　The　sorghum　water　stress　resistant　mechanism　was　revealed　in　some　extent　in　AQP.　At　first,　using　RT-PCR,　Western　blotting　and　in　situ　Western　or　so　molecular　technology,　we　studied　the　aquaporin　PIP1　in　maize　leaf　growth　and　its　water　stress　resistance.　In　mRNA　and　protein　level,　We　found　the　PIP1　play　roles　in　maize　leaf　growth　and　maize　water　stress　resistance,　and　showed　different　change　in　different　maize　genotype.　Base　on　the　maize　experiment,　we　studied　the　function　in　sorghum　and　got　the　same　conclusion.　Then　we　compared　the　difference　of　PIP1　between　sorghum　and　maize　and　found　PIP1　gave　much　more　function　in　maize　than　in　sorghum　at　the　protein　level.　The　function　of　aquaporin　　is　one　of　the　　water　stress　resistant　mechanism　in　plant.