Мutants of inflorescence development in alfalfa (Medicago sativa L.)

Abstract

Alfalfa (Medicago sativa L., Medicago varia Mart., Medicago falcata L.) is a perennial leguminous plant well-known as the queen of forages cultivated all over the world. The general biology and morphology of the plant has been described in detail. The typical inflorescence of the plant is raceme. Due to the multistep inbreeding process in this cross-pollinated species, different mutant forms have been found in inbred progenies. They include long racemes, panicle-like racemes (with fertile and sterile flowers), complicated branched racemes, and fasciated inflorescences. The fasciation trait was discovered first in long racemes and then it was introduced into every mutant inflorescence type by hand pollination. By means of pair hybridization, transitional forms of some mutants were isolated and the new mutant forms combined two or three mutant genes. New gene names are proposed for new duplex and triplex mutant types: lpfas, pi1lpfas, brilpfas. Medicago truncatula is a conventional model species for legume genome research. M. truncatula and alfalfa share highly conserved nucleotide sequences and exhibit nearly perfect synteny between the two genomes. The knowledge about inflorescence development in model M. truncatula plants adds to understanding the genetic nature of mutant inflorescence development in alfalfa; therefore, we compiled the information on the genetic regulation of inflorescence development in M. truncatula. The M. truncatula mutant mtpim has a complicated inflorescence structure resembling panicle-like inflorescence in alfalfa. Presently, it is known that the inflorescence architecture in M. truncatula is controlled by spatiotemporal expression of MtTFL1, MtFULc, MtAP1, and SGL1 through reciprocal repression. Some mutants isolated in M. truncatula resemble alfalfa mutants in phenotype. The mutant generated by retrotransposon insertion mutagenesis and named sgl1-1 has a cauliflower-like phenotype looking just like the cauliflower mutant in alfalfa. New data concerning genes regulating inflorescence development in model legumes approach us to understanding the phenomenon of inflorescence mutations in alfalfa. The information of inflorescence mutants in nonmodel crops may augment our knowledge of plant development and help crop improvement.

Keywords

• medicago sativa l.
• alfalfa
• mutants
• inflorescences
• plant development