Chen M, Loewus M W, Loewus F A
Department of Agricultural Chemistry, Washington State University, Pullman, Washington 99164.
Plant Physiol. 1977 Apr;59(4):658-63. doi: 10.1104/pp.59.4.658.
2-O,C-Methylene-myo-inositol (MMO), a myo-inositol (MI) antagonist, inhibits germination and tube elongation of pollen from Lilium longiflorum cv. Ace or 44. The presence of 5 mm MMO in Dickinson's pentaerythritol medium (Plant Physiol. 43:1-8) partially blocks germination. The tubes produced are short and fail to elongate. In the presence of MI, MMO's toxic effect is blocked. As little as 0.56 mm MI will maintain normal germination in the presence of 43 mm MMO, and pollen tubes continue to elongate for 2 to 3 hr. Eventually, the toxic action of MMO prevents further growth. MMO does not inhibit UDP-d-glucose dehydrogenase from lily pollen.Uptake of MI-2-(3)H and incorporation of tritium into galacturonic acid and pentose units of tube wall pectin are blocked by MMO. The site of this inhibition is undertermined. Uptake of d-glucose-1-(14)C and incorporation of (14)C into 70% ethyl alcohol-insoluble polysaccharides of germinated pollen are not blocked by MMO, but distribution of label into polysaccharide product is altered. In MMO-treated pollen, very little (14)C is found in uronic acid or pentose units. At 30 mm MMO, about two-thirds of the carbon flow from d-glucose to these pectic components is interrupted. MMO also alters d-glucose metabolism in the 70% ethyl alcohol-soluble fraction, but the compound involved must still be identified.These results offer fresh evidence of an intermediary role for MI during UDP-d-glucuronate biosynthesis in germinated pollen.
2 - O，C - 亚甲基 - 肌醇（MMO）是一种肌醇（MI）拮抗剂，可抑制麝香百合品种Ace或44花粉的萌发和花粉管伸长。在迪金森季戊四醇培养基（《植物生理学》43:1 - 8）中添加5 mM MMO会部分抑制花粉萌发。所产生的花粉管短小且无法伸长。在有MI存在的情况下，MMO的毒性作用会被阻断。在43 mM MMO存在时，低至0.56 mM的MI就能维持正常萌发，并且花粉管会继续伸长2至3小时。最终，MMO的毒性作用会阻止进一步生长。MMO不会抑制百合花粉中的UDP - d - 葡萄糖脱氢酶。MMO会阻断MI - 2 -（3）H的摄取以及氚掺入花粉管壁果胶的半乳糖醛酸和戊糖单元中。这种抑制作用的位点尚未确定。MMO不会阻断d - 葡萄糖 - 1 -（14）C的摄取以及（14）C掺入萌发花粉的70%乙醇不溶性多糖中，但标记物在多糖产物中的分布会发生改变。在经MMO处理的花粉中，在糖醛酸或戊糖单元中发现的（14）C极少。在30 mM MMO时，从d - 葡萄糖到这些果胶成分的碳流约有三分之二被中断。MMO还会改变70%乙醇可溶部分中的d - 葡萄糖代谢，但其中涉及的化合物仍有待确定。这些结果为MI在萌发花粉UDP - d - 葡萄糖醛酸生物合成过程中的中间作用提供了新的证据。
