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

N I Dzyubenko,E A Dzyubenko

doi:10.18699/vj19.543

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.

Highlights

In most traditional botanical terms inflorescence is a flowering shoot
The development of the Arabidopsis inflorescence can be mostly explained by the function and mutual regulation of three genes: TERMINAL FLOWER 1 (TFL1), LEAFY (LFY ), and APETALA 1 (AP1) (Shannon, Meeks-Wagner, 1993; Blazquez et al, 2006)
Results of expression patterns analyses of TFL1, FUL1, AP1 and SG1 in M. truncatula indicated that they play spe cific role in identity determination of primary inflorescence meristem, secondary inflorescence meristems, floral meristems and common primordia, respectively (Cheng et al, 2018)

Summary

Introduction

In most traditional botanical terms inflorescence is a flowering shoot. Different theories of inflorescence classifications exist, especially in legume. In the present paper for characterization of the mutant inflorescences in alfalfa the terms of the axe of the first order, the axes of the second and higher orders will be used for convenience. Typical inflorescence of alfalfa is an open bracteous compound raceme. Flowering in the wild type inflorescence of alfalfa starts acropetally. In general flowering in angiosperms starts from transition of shoot apical meristem (SAM) to flower apical meristem (FAM). Mutants of inflo rescence development in alfalfa demonstrate the wide range of variability of positions of FAM development

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Conclusion