Perennial teosinte germplasm introgression into maize conditions a considerable increase of vigour, because they are the two taxa of Zea genetically farther apart. This fact has begun to be used with practical purposes. In spite of that, immediate introgression effects do not seem to be advantageous, because kernels produced by crosses between maize and perennial teosinte germplasm have low viability in most cases. The aim of our work was to research the association between low kernel viability and endosperm storage protein patterns. Three maize inbred lines, OU, SBP and SAP, were pollinated with a donating material from perennial teosinte germplasm, which was a selected F3 progeny (F3S) from hybrids between perennial teosinte and Gaspe. This F3S was selected for its high fertility and predominance of maizoid characteristics. Endosperm proteins were fractionated according to Landry-Moureaux (1970) in lines, donating material and kernels produced by the cross between them (see Table 1).
The lines used have a tripsacoid protein pattern (see MNL 56:106), characterized by its relatively low ratio of saline-soluble and high ratio of glutelin-1 proteins. These lines with tripsacoid protein pattern (associated with other tripsacoid characters such as glume induration) were chosen with the purpose of helping (or favouring) perennial teosinte germplasm combinations. The donating material (F3S) has a normal protein pattern that does not differ significantly from the one of maize.
A deep protein pattern modification may be observed in hybrid kernels, making them significantly different from maize maternal lines. This modification is approximately similar in the 3 analyzed crossings; the protein patterns that result are characterized by: 1) an increase in saline soluble proteins (approx. twice) 2) a diminution in zein and 3) an increase in glutelin-3. The phenomenon presented here is similar to that reported previously (MNL 55:60) in crosses between Gaspe and perennial teosinte.
Without any doubt, the most remarkable fact is the high increase of saline soluble proteins, which have been associated to kernel inviability (see MNL 55:60). Hybrid protein patterns are a lot like those from maize defective kernels. They are also very similar to those protein patterns affected on a higher or lesser scale by several mutants. The results obtained point to a strong association between endosperm protein pattern and low kernel viability. Consequently, it can be stated that the immediate effect of perennial teosinte introgression into maize becomes deleterious, because when endosperm proteins are unbalanced they alter kernel viability. The immediate effect observed differs deeply from introgression mediate effect. In accordance with introgression progress, kernel viability is quickly recovered. Simultaneously, the individuals obtained acquire a tripsacoid protein pattern (correctly balanced) and characterized by its low ratio of saline-soluble and high ratio of glutelin-1 proteins.
Table 1. Endosperm protein pattern of OU, SBP, F3S and its hybrids. SS--saline soluble proteins; Z--zein; G1--glutelin; G2-- glutelin-2; G3--glutelin-3.
Angel Alberto Nivio and Jorge Luis Magoja
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